Conference Proceedings

The Annual Meeting of the Human Behavior and Evolution Society

June 2 - 6, 1999 

Salt Lake City, Utah

Abstracts

Thursday morning plenary address

Borgerhoff Minder Mt Demographic transition: Closing in on an evolutionary explanation?

The radical late 19th century shift in human reproduction, known as the demographic transition, constitutes a major challenge to evolutionary approaches to human behaviour. Why would people ever choose to limit their reproduction voluntarily when, at the peak of the Industrial Revolution, resources were so plentiful? Several hypotheses have been advanced by evolutionary social scientists: Can the transition be attributed to the standard life history tradeoff between quality and quantity of offspring? Is low fertility attributable to cultural evolutionary processes? Or is it simply a maladaptive outcome of novel environmental and social conditions? After reviewing the status of each of these hypotheses, I present empirical work that focuses explicitly on the evolved psychological mechanisms that might underlie the demographic behaviour. Finally I introduce a set of models that link fertility decline to a particular set of economic dynamics between inherited capital, fertility, and wealth accumulation.

I Dept of Anthropology, University of California at Davis. CA 95616, USA. mborgerhoffmulder®ucdavis.edu

1.1 Differential parental investment: Theory and data

Anderson KG2, Kaplan H3, Lancaster JB° Paternity confidence and fitness outcomes: Abortion, divorce, and paternal Investment

Evolutionary theory predicts that males should be less likely to invest in putative genetic offspring who are unlikely to be their actual offspring. Among humans the theory has important practical implications, but has not been directly tested. In this paper we test three predictions concerning the relationship between paternity confidence and fitness outcomes. First, men will provide less direct investment to low paternity confidence offspring. Second, men will be more likely to divorce women who bear them low paternity confidence offspring; since children receive less paternal investment after divorce, divorce is an indirect means of discriminating against low paternity confidence offspring. Third, if the first two predictions are correct, women will respond to anticipated decreased paternal investment in low paternity confidence offspring by being more likely to abort pregnancies for which their partners have low paternity confidence. We tested these predictions using a sample of men living in Albuquerque, New Mexico. Men provided information on their time involvement with 390 children whose mothers they had divorced, the divorce outcomes of 1,901 relationships that produced live births, and the birth outcomes of 2,865 pregnancies that were attributed to the men. The results strongly support all three predictions, confirming that paternity confidence plays an important role in male parental and reproductive strategies.

Z Population Studies Center. University of Michigan, 426 Thompson Saul, Am Arbor. Michigan 48106-1248 (after June 1 1999). kgantiersQunm.edu 3 Dept of Anthropology. University of New Mex

Lvoch K1 Evaluating parental investment hypotheses with structural equation modeling techniques: A test A model invariance for genetic and stepparent families

Using structural equation modeling techniques to analyze data from the National Education Longitudinal Survey, a model representing select factors hypothesized to underlie variation in parental resource distribution was generated and tested on the questionnaire responses from patents of a nationally representative sample of high school seniors. Tests of model fit revealed that a model specifying both direct and indirect (through a child's academic achievement) influences of familial SES on educational investment provided the best fit to the data. Invariance tests were conducted to compare the model estimates derived from families containing two genetic parents with those obtained from stepparent families. Results indicated that measurement of the latent constructs was similar across family type, but a structural nonequivalence was found. Familial SES had a significantly stronger direct influence on educational investment in genetic parent families. Additional analyses, limitations, and a discussion of results will be presented.

Keller MO, Nesse RM3, Hoferth Se Parental investment and anticipated reproductive payoff

Natural selection should have crafted parental investment (PI) to maximize the total fitness of the parent, but it does not necessarily follow that PI will vary in proportion to likely future reproductive success of each individual child. Whether PI is associated with anticipated reproductive payoff should depend on the type and effect of the PI. The Panel Study of Income Dynamics Child Supplement data tracked 3500 respondents about their parental care habits. Time diary data was also collected. No differences in parental investment by sex as a function of status were found. Differences were found in PI as a function of parents' appraisal of "likely future success" of child. These findings are compared to other studies and to derivations arising from evolutionary theory.

Hiraiwa-Hasegawa M3, Hasegawa T6 The excess of female death rates in pre-war Japan

The changes in sex differences in death rates in these 100 years in Japan were investigated. From the beginning of

the 20th century to around 1936, the female death rates always exceeded the male death rates from the age of 2 until around 42. Most of the female deaths during reproductive ages were related to childbirth. However, the higher death rates during infancy through adolescence among women must have different reasons, and most probably, were due to malnutrition and disease from neglect, and from child labor. The situation started to change after the Second World War: the female death rate exceeded the male death rate from the age of 12 until 20 in 1947, and only from 13 to 16 in 1952. The male death always exceeded the female death in all ages since 1955, but the excess of male deaths gradually increased through time. These findings will be discussed in relation to changes in differential parental investment patterns in pre-war and post-war Japan.

Beroldi 67 Darwin's dads: An evolutionary analysis of father absence

This evaluation covers the evolutionary literature on father absence and the mainstream literature upon which it is based. The main contribution of evolutionary work is the possibility that the bases for the complex of psychology and behavior that is associated with being raised in a fatherless household are adaptations and not psychopathology as the mainstream perspective holds. This analysis will look at predictions from each of these perspectives. A "Father Necessity" hypothesis will be offered as the environmental cue that triggers these alternate life history strategies, thereby answering the question that the originators of this field, Draper & Harpending, asked in their 1982 & 1988 works but did not answer. Father presence is theorized as the human evolutionary norm with degrees of father presence explaining the psychology and behavior of contemporary populations. I will take an exploratory look at what kinds of hypotheses about father absence evolutionary biology and the human evolutionary disciplines might have made de novo. Some issues (e.g., developmental vs. concurrent contingency, brain dedication, joint fitness's effect on father involvement, how behavior genetics' models seem to account for more of the effects) will be touched upon. Finally. I will suggest some directions for future research such as using other indices of maturation than menarche, and the evolution of the coordination of the development of psychological & behavioral characters.

7 Dept of Psychology, California State University, Long Beach. Long Beach, CA 90840.0901 gberoldi®csulb.edu (562)938-7520

Natural selection should have equipped humans with cognitive mechanisms which are sensitive to the cues for risks that had reflected the adaptive significance of the risks. In a series of experiments, we examined how decision makers select and use kinship, group composition, group size, and verbal cues in making their risky choices. These decision cues were manipulated in choice problems presented in a statistically identical payoff structure. We assume that primary decision cues have and are used according to their pre-determined Darwinian priorities. Instead of trying to maximize expected utility of choice outcomes, as suggested by various models of rational choice, decision makers are expected to maximize the opportunity of reaching a task-specific goal, determined primarily by evolutionarily meaningful cues (e.g., kinship, group composition). However, in evolutionarily novel contexts where no primary cues are available, decision makers have to resort to subtle meanings of secondary cues (e.g., verbal cues) for adjusting their aspiration levels. For instance, the subjects' risk preference to a sure outcome or a gamble in an ambiguous, anonymous group context was more likely to be affected by the framing (phrasing) of choice options. The empirical results will be discussed in a mean-variability-minimum requirement (MVM) framework. Within the framework, risky choice is viewed as a function of three variables: mean expected value of choice outcomes, variability in choice outcomes, and the minimum requirement (aspiration level) determined by various decision cues. '

Galinsky AM, Wang XTI Hemispheric mechanisms in risky choices

Hemispheric asymmetry and modality were examined as a function of risky choice behavior in human decision making. Participants were asked to evaluate two alternative plans in terms of their estimated outcomes and then to make their choice between the two plans.

A modified dichotic listening technique was used to present the plans while an unrelated message was presented simultaneously to the opposed ear. The competition for pathways between the messages allowed selected messages to be registered hemispherically. Participants' minimum requirement W) for making their decision was measured. Risk preference patterns for left ear-right hemisphere (LE-RH) participants were consistent with the

Psychology Depatunatt, Univaaity of South Dakota, Vamillion, SD. 57069, USA. xtwang@usd.edu 2 Dept of psychology, University of South Dakota, Vwmillion, SD 57069 USA. agalituky0aol.com

prediction that they would be more sensitive to the emotional cues in choice problems. Specifically, framing effects were found for LE-RH participants; however, no significant framing effects were found for right ear-left hemisphere (RE-LH) participants. Consistent with previous findings, risk preference patterns showed a group size, social-context specific pattern. Finally, MR results supported a mean-variance model of human risky decision behavior (Wang, 1996c). MR was higher for participants under negative framing, lower when switching to positive framing, and higher under kinship conditions. This study suggests that risk-sensitive and social-context dependent mechanisms may be lateralized with the right hemisphere being specialized for the processing of emotional cues.

Duchaine BL'4 Grue, necessary connection, and domainspecificity: From poverty of the stimulus to richness of structure

For any finite set of data there are an infinite number of hypotheses that are consistent with the data. Thus, projection of proper hypotheses is critical to the effective operation of any inductive process. Known as the grue problem in epistemology and the poverty of the stimulus problem in psycholinguistics, the recognition of this problem has been critical in the development of theories of word acquisition and grammar acquisition. Outside of these two areas however, the grue problem has had little impact on cognitive theories. This neglect is unfortunate, because consideration of the grue problem provides insight into developmental questions and guidance in developing research questions. In order to illustrate the value of considering the grue problem, I will discuss its potential value for theories of classical conditioning and gaze direction determination.

What contribution might our understanding of evolution make to economic policy? Recent years have seen an increasing reliance on the use of economic market forces to guide and coordinate human behavior. This is based in part on theory that suggests that, for the most part, the more efficient and freely operating the marketplace, the better. But there is and important way in which just what this system does well-that is, give us ever more precisely what we want-can be the source of future problems.

In a limited evolutionary environment, the relationship between a motivated action and its associated motivational element need not be close; the lack of alternative

4 Dept of Psychology, UCSB, Santa Barbara. CA 93106 USA. duchaineOpaych.uabedu s 26 Handy Street, New Brunswick, NJ 08901-2821 USA. ImgelOpegasats.tutgas.edu

opportunities allows sorry distance between the motivation and the motivator. For instance, this distance is observable in the human sex drive, which motivates reproduction only indirectly. Creating a product that matches the motivational aspects directly may create a more 'desirable' product, but since other relationships are not maintained (including those associated with the real evolutionary benefits), the behavior resulting may not have the benefits that the motivational dynamic evolved to serve. In this way, this economically-driven motivator replacement can be expected to 'destructure' human behavior.

Silverman It, Choi J, MacKewn A, Moro J, Olshansky E, Fisher M The hunter-gatherer theory of spatial sex differences: A naturalistic study

This study was based on Silverman and Eals' huntergatherer theory of spatial sex differences. The main hypothesis was derived from an attempt to conceptually link three-dimensional (3D) mental rotations ability, the spatial attribute showing the largest and most reliable male advantage, to direction-finding in a natural setting. Participants were led individually on a circuitous route through a wooded area during which they were stopped at prescribed places and required to set an arrow pointing toward where the route had begun. As a further measure,the participant was eventually asked to lead the researchers AWL' AM the he,Vjnairrg OWN bY the moll dul^ct IOIIM In a later session, participants completed a test battery consisting of 3D mental rotations, two non-rotational spatial tests, and a test of general intelligence. Participants also supplied salivary samples for analyses of sex hormone levels, which were correlated with all other measures. Preliminary data analyses, excluding hormonal measures, supported the hypothesis that males excelled on directionfinding in the woods. Also, as expected, direction-finding was related to 3D mental rotations ability, but not to nonrotational spatial abilities or to general intelligence.

1.3 Symposium: Examining the validity of the waistto-hip ratio hypothesis of human female attractiveness

Symposium abstract Waist-to-hip ratio (WHIR) is a reliable signal of a woman's reproductive age, fertility, and health. Men from various cultures judge women with

lower WHRs as more attractive than women with high WHRs. Recently the relationship between WHR and female attractiveness has been questioned by Tassinary and Hansen (1998). Furthermore, Yu and Shepard (1998) claim that preference for low WHIZ is a western media artifact. In this symposium Bronstad will present data showing that the female line drawings developed by Tassinary and Hansen confounded body weight and hip size. Bronstad shows that when perceived body weight of the figures is controlled men and women prefer figures with low (- .7) WHIZ. Streeter reports preference for 0.7 WHR in female photographs that were altered to represent a wide range of WHRs and varying chest and hip sizes. Sugiyama presents data collected from men of the Shiwiar tribe that suggests attractiveness judgments are influenced by both WHR and body weight. Singh will present data showing consensus for representation of male and female WHRs in ancient sculptures from four different cultures. The different contributions to this symposium demonstrate the validity of the WHR hypothesis of human female physical attractiveness within a historical and cross-cultural context.

Bronstad PM4, Singh I?5 Why did Tassinary and Hansen (1998) fail to replicate the relationship between WHR and female attractiveness?

Man ystu&eshavefounalhatmen judge women with low waist-tohip ratio (WER) as attractive, healthy, and desirable for romantic relationships. Tassinary and Hansen (1998) recently challenged the WHR hypothesis of female physical attractiveness. They claimed that all research on WHR and attractiveness relied on the same set of confounded line drawings. They also claim that none of the research investigated whether abnormally low WHRs were judged as more or less attractive than WHRs in the normal range. They developed a new set of line drawings in which they claimed to manipulate several bodily dimensions orthogonally (waist, hip, and body weight). With these new line drawings they found that a) line drawings with masculine WHRs were ranked as more attractive than feminine WHRs and b) low WHIZs are judged as more fertile. Thus, men prefer women who are more masculine and less fertile. However, they created low WHRs by expanding the size of the hip. This manipulation confounded WHIZ, hip size, and perceived body weight. Using their line drawings we find that within each weight category (under-, normal-, and overweight) line drawings with low WHR are judged to be up to 20 pounds heavier and up to 14 years older than figures with high WHR. The

I Dement of Psychology, University of Texas a Austin, Austin, TX 78712. bmsttOmail.uoexas.edu s ibid. singhOpsy.utexas.edu

confound between WHR and perceived body weight ac- of explanations rooted in cultural determinism. I present counts for Tassinary & Hansen's findings. We will show (i) a task analysis of some of the problems a WHR asthat once the confound is statistically corrected the rela- sessment mechanism must solve, (ii) predictions based

Streeter SAt, McBurney DH Z Waist-hip ratio and attractiveness: New evidence and a critique of "a critical test"

Singh (e.g.,1993) has suggested that a low waist-hip ratio

(WHR) in women is an honest signal of fertility. A series

of studies by Singh and others has consistently found that

men and women rate a WHR of about 0.7 most attrac

tive. Tassinary & Hansen (1998), however, using a new

set of line drawings in which they claimed (incorrectly)

to have varied WHR independently of weight, found no

relationship between attractiveness and WHR We tested

attractiveness of photographs of one woman that we ma

nipulated to give a range of WHRspanningthe lst 99th

percentiles of anthropometric data (0.5, 0.6, 0.7, 0.9,1.2).

In addition we varied both hip and chest size. College

students judged the photos for attractiveness on a seven

point scale and also estimated the weight of each figure

in pounds. For almost all combinations of hip and chest

size the preferred WHR was 0.7. Medium chest size was

preferred to large or small. Men found most photos more

attractive than did women, and showed a greater relative

preference for a 0.7 WHR. The effect of WHR was more

pronounced when data were analyzed as the residuals of

attractiveness regressed on weight. We will discuss rea

sons for Tassinary and Hansen's failure to find an effect

of WHR. For example, Tassinary and Hansen's data ac

tually show considerable evidence of preference for 0.7

WHR when plotted separately for each hip size, instead

of for each waist size.

Sugiyama L3 1s beauty in the domain specific, context sensitive, mufti-modular adaptations of the beholder? Shiwiar use of female WHR and body weight in assessments of attractiveness.

As adaptationist hypotheses about the human psyche have gained wider attention, a number of conceptual issues have been overlooked. For instance, in recent tests of the hypothesis that men have adaptations which use female waist-to-hip ratio (WFBt) in assessments of female sexual attractiveness, neither the context-sensitive nor the multi-modular nature of information processing adaptations has been adequately considered. This has led to a misinterpretation of empiricalresults, and the reassertion

Department of Psychology, University of Pitg6. Pittstxug6. PA 15260. sybil®timanet.na Z ibid. mey@imap.pia.edu

Institute for Cognitive and Decision Sciences, Uttivasity of Oregon, Eugene, OR 97403. sugiyarna0darkwing.tioregaLedu

Singh D4, Frohlich t:'s, Haywood M6 Waist-to-hip ratio representation in ardent sculptures from four cultures

The relationship between female attractiveness and low waist-tohip ratio (WIHt) has been demonstrated in men from US, England, Germany, India, Indonesia, Hong Kong, and Africa (Guine-Bissau). Recently Yu and Shepard (1998) argued that the preference for low WHR in all these cultures is caused by exposure to western media. These investigators argue that even minimal exposure to western media can alter centuries-old indigenous beauty ideals. One way to test the validity of this argument is to examine the consensus in body shape preferences in diverse societies prior to the emergence of the western media. We measured WHR in 286 sculptures from India, Egypt, Greece (Greco-Roman) and Africa. In all these cultures the mean female WHR was significantly lower than the mean male WHR despite cultural within-sex variability. We conclude that preference for female WHR can vary between cultures but the preferred WHR is always lower than the preferred male WHR The western media may alter local beauty ideals by illuminating and exaggerating the perceived difference between male and female WHR

Wetsman A7, Marlowe Fs How Universal are Preferences for Female Waist-to-Hip Ratios? Evidence from the Hadza of Tanzania.

Female waist-to-hip ratio (WIHt) Gas been proposed by evolutionary biologists to be an important component of human male mate choice since this trait is thought to provide a reliable cue to a woman's reproductive value. Based largely upon work conducted in industrialized soclerics, the claim has been made that preferences for low

F~99

WHR are culturally invariant. Recent research with subjects who practice swidden agriculture, however, revealed that this trait was not preferred. A logical extension of such an inquiry is to test WHR preferences in a foraging population. This was done with the Hadza of Tanzania who were shown figures of females that varied by weight and waist-to-hip ratio. Again, low WHR was not preferred. Hadza men do not consider waist-to-hip ratio when expressing preferences for mates. Instead, they are most interested in the weight of potential partners. Coupled with the earlier work with the horticultural group, this work brings into question whether preferences for low WHR are culturally invariant.

Symposium abstract Biopoetics is a rapidly growing area of interest among members of the Human Behavior and Evolution Society. It includes a number of researchers seeking to apply an evolutionary framework to the understanding of human creativity and symbolic processes. More specifically, the biopoetics perspective may be seen as adding the following ingredients to the overall mission of HBES: (a) it promotes research into the creative interplay of domain-specific modules as they are actualized in specific behavioral environments, (b) it focuses on the relatively unexplored intersections of evolutionary processes and material culture, and (c) it promises to grow rapidly in depth and breadth by reexamining from an evolutionary perspective primary data found in fields such as art history, literary theory, and communication studies. This symposium highlights current research and surveys the developing conceptual framework responsible for this distinctive approach to the study of evolution and human behavior.

Acquiring knowledge first-hand can be dangerous and costly; we may therefore expect selection to have favored a system or systems by means of which information could be acquired at second hand. Language is perhaps the most obvious means of accomplishing this task Verbal communication takes several forms, however: conversation, precautions, threat, argument, and so on. In other words, verbal communication appears to be specialized: it is possible that each of the several forms it

takes performs a different task. One of these specialized forms is narrative. If humans are designed to learn from experience-that is, if the mind contains structures designed to process and retain useful information gleaned through first-hand experience-then a system that simulated first-hand experience might reasonably be expected to produce the same result. This is precisely what narrative does: dedicated to constructing integrated representations of the human physical, social, and mental environment, the narrative faculty serves as a virtual reality. In this paper, then, I argue that selection favored the integration of the language faculty with numerous cognitive structures used to process and retain first-hand experience (theory of mind, causal reasoning, temporal perception, locational memory)-otherwise known as narrative-as a means of exploiting the benefits of firsthand experience while removing many of the costs.

Dissanayake E3 The poetics of bsbytalk I: "Macro"poetics

Even at birth, human infants can perceive sequences, detect contingencies, and develop expectancies. Combined with inborn receptivity to human faces and voices, these temporal abilities predispose infants to engage in complex dyadic social interactions ("babytalk") in which the partners influence each other's behavior. By responding with demonstrably close attunement to the temporal presentation of facial, vocal, and gestural signals, they adjust to their partner's perceived emotional state. For this paper, and the next, a transcript of spontaneous speech to an 8-week infant was analyzed for both "macropoetic" and "micropoetic" features. Macropoetics refers to large-scale formal structure (e.g., framing, closure, line length, theme and variation, parallelism), or to dynamic variation (e.g., pauses, pacing, pitch, and tonal considerations). When utilized in the temporal arts (i.e., music, dance, mime, and poetic language), such features are considered to be sources of "aesthetic" affect. The capacity in preverbal infants w respond to these signals and their temporal manipulation by another person in a context of emotional affiliation and conjoinment suggests a function of the temporal arts besides that of sexual display. That is, one can also view these arts as culturally-created extensions and elaborations of innate affective signals which engender and sustain affiliative emotion and accord between individuals, as their precursors do between mothers and infants.

Mull DS° The poetics of babytalk II: "Micro"-poetics

3 1605 E. Olive Street, Ii104, Seattle WA 98122 4 Deportment of Eog>uh, Uaivasity of Altxrta, Edmonton. Caortda T6G 2E5

confound between WHR and perceived body weight accounts for Tassinary & Hansen's findings. We will show that once the confound is statistically corrected the relationship changes and WHRs of 0.7 are most preferred.

Streeter SAt, McBumey DHZ Waist-hip ratio and attractiveness: New evidence and a critique of "a critical test"

Singh (e.g.,1993) has suggested that a low waist-hip ratio

(WHR) in women is an honest signal of fertility. A series

of studies by Singh and others has consistently found that

men and women rate a WHR of about 0.7 most attrac

tive. Tassinary & Hansen (1998), however, using a new

set of line drawings in which they claimed (incorrectly)

to have varied WHR independently of weight, found no

relationship between attractiveness and WHR. We tested

attractiveness of photographs of one woman that we ma

nipulated to give a range of WHR spanning the lst 99th

percentiles of anthropometric data (0.5, 0.6, 0.7, 0.9,1.2).

In addition we varied both hip and chest size. College

students judged the photos for attractiveness on a seven

point scale and also estimated the weight of each figure

in pounds. For almost all combinations of hip and chest

size the preferred WHR was 0.7. Medium chest size was

preferred to large or small. Men found most photos more

attractive than did women, and showed a greater relative

preference for a 0.7 WHR. The effect of WHR was more

pronounced when data were analyzed as the residuals of

attractiveness regressed on weight. We will discuss rea

sons for Tassinary and Hansen's failure to find an effect

of WHR. For example, Tassinary and Hansen's data ac

tually show considerable evidence of preference for 0.7

WHR when plotted separately for each hip size, instead

of for each waist size.

Sugfyama L3 1s beauty In the domain specific, context sensitive, multi-modular adaptations of the beholder? Shiwiar use of female WHR and body weight in assessments of attractiveness.

As adaptationist hypotheses about the human psyche have gained wider attention, a number of conceptual issues have been overlooked. For instance, in recent tests of the hypothesis that men have adaptations which use female waist-to-hip ratio (WHR) in assessments of female sexual attractiveness, neither the context-sensitive nor the multi-modular nature of information processing adaptations has been adequately considered. This has led to a misinterpretation of empirical results, and the reassertion

I Department of Psychology, University of Pittsburgh, Pittsburgh, PA 15260. sybiletimesua.ne< 2 ibid. mcbmney®imap.pitt.edu

Institute for Cognitive and Decision Science:. University of Oregon, Eugene. OR 97403. sugiyama0da<icwing.uoeegon.edu

of explanations rooted in cultural determinism. I present (i) a task analysis of some of the problems a WHIR assessment mechanism must solve, (ii) predictions based on this analysis about the expected design of adaptations that could solve these problems, and (iii) data on Shiwiar WHR, body fat, and assessments of female attractiveness showing that (iv) Shiwiar males use both WHIR and body weight in assessments of female attractiveness in predicted ways. Slight changes in experimental method predictably obscure or uncover the expression of WHR preference in ways that account for recent cross-cultural "falsification" of the WHR hypothesis.

Swgh D~, Frohlich 0, Haywood M6 Waist-to-hip ratio representation in ancient sculptures from four cultures

The relationship between female attractiveness and low waist-tohip ratio (WIHt) has been demonstrated in men from US, England, Germany, India, Indonesia, Hong Kong, and Africa (Guise-Bissau). Recently Yu and Shepard (1998) argued that the preference for low WHR in all these cultures is caused by exposure to western media. These investigators argue that even minimal exposure to western media can alter centuries-old indigenous beauty ideals. One way to test the validity of this argument is to examine the consensus in body shape preferences in diverse societies prior to the emergence of the western media. We measured WHIR in 286 sculptures from India, Egypt, Greece (Greco-Roman) and Africa. In all these cultures the mean female WHR was significantly lower than the mean male WHR despite cultural within-sex variability. We conclude that preference for female WHIR can vary between cultures but the preferred WHR is always lower than the preferred male WHR. The western media may alter local beauty ideals by illuminating and exaggerating the perceived difference between male and female WHR.

Wetsman A7, Marlowe F a How Universal are Prefer. ences for Female Waist-to-Hip Ratios? Evidence from the Hadza of Tanzania.

Female waist-to-hip ratio (WEt) has been proposed by evolutionary biologists to be an important component of human male mate choice since this trait is thought to provide a reliable cue to a woman's reproductive value. Based largely upon work conducted in industrialized societies, the claim has been made that preferences for low

WHR are culturally invariant. Recent research with subjects who practice swidden agriculture, however, revealed that this trait was not preferred. A logical extension of such an inquiry is to test WHR preferences in a foraging population. This was done with the Hadza of Tanzania who were shown figures of females that varied by weight and waist-to-hip ratio. Again, low WHR was not preferred. Hadza men do not consider waist-to-hip ratio when expressing preferences for mates. Instead, they are most interested in the weight of potential partners. Coupled with the earlier work with the horticultural group, this work brings into question whether preferences for low WHR are culturally invariant.

Symposium abstract Biopoetics is a rapidly growing area of interest among members of the Human Behavior and Evolution Society. It includes a number of researchers seeking to apply an evolutionary framework to the understanding of human creativity and symbolic processes. More specifically, the biopoetics perspective may be seen as adding the following ingredients to the overall mission of HBES: (a) it promotes research into the creative interplay of domain-specific modules as they are actualized in specific behavioral environments, (b) it focuses on the relatively unexplored intersections of evolutionary processes and material culture, and (c) it promises to grow rapidly in depth and breadth by reexamining from an evolutionary perspective primary data found in fields such as art history, literary theory, and communication studies. This symposium highlights current research and surveys the developing conceptual framework responsible for this distinctive approach to the study of evolution and human behavior.

Acquiring knowledge first-hand can be dangerous and costly; we may therefore expect selection to have favored a system or systems by means of which information could be acquired at second hand. Language is perhaps the most obvious means of accomplishing this task. Verbal communication takes several forms, however: conversation, precautions, threat, argument, and so on. In other words, verbal communication appears to be specialized: it is possible that each of the several forms it

t Dept of Communication, University of Utah. godwntffinconnect.com 2 English Dept., Unrvetsity of Oregon, Eogerte, OR 97403

takes performs a different task. tnre or mess o~,.o...._,. forms is narrative. If humans are designed to learn from experience-that is, if the mind contains structures designed to process and retain useful information gleaned through first-hand experience-then a system that simulated first-hand experience might reasonably be expected to produce the same result. This is precisely what narrative does: dedicated to constructing integrated representations of the human physical, social, and mental environment, the narrative faculty serves as a virtual reality. In this paper, then, I argue that selection favored the integration of the language faculty with numerous cognitive structures used to process and retain first-hand experience (theory of mind, causal reasoning, temporal perception, locational memory--otherwise known as narrative-as a means of exploiting the benefits of firsthand experience while removing many of the costs.

Dissanayake E3 The poetics of babytslk I: "Macro"poetics

Even at birth, human infants can perceive sequences, detect contingencies, and develop expectancies. Combined with inborn receptivity to human faces and voices, these temporal abilities predispose infants to engage in complex dyadic social interactions ("babytalk") in which the partners influence each other's behavior. By responding with demonstrably close attunement to the temporal presentation of facial, vocal, and gestural signals, they adjust to their partner's perceived emotional state. For this paper, and the next, a transcript of spontaneous speech to an 8-week infant was analyzed for both "macropoetic" and "micropoetic" feattrrrs. Macropoetics refers to large-scale formal structure (e.g., framing, closure, line length, theme and variation, parallelism), or to dynamic variation (e.g., pauses, pacing, pitch, and tonal considerations). When utilized in the temporal arts (i.e., music, dance, mime, and poetic language), such features are considered to be sources of "aesthetic" affect. The capacity in preverbal infants to respond to these signals and their temporal manipulation by another person in a context of emotional affiliation and conjoinment suggests a function of the temporal arts besides that of sexual display. That is, one can also view these arts as culturally-created extensions and elaborations of innate affective signals which engender and sustain affiliative emotion and accord between individuals, as their precursors do between mothers and infants.

Mull DS° The poetics of babytalk II: "Micro"-poetics

3 1605 E. Olive Stnxt, X104, Seadle WA 98122 4 Depermoan of En&* University of Alberta. Edmonton. Canada T6G 2E5

In this paper, and the previous one, we extend studies by others of mother-infant interactions (`babytalk") in which mothers use temporally-organized behaviors (special infant-directed vocalizations, facial expressions and gestures) to engage their preverbal infants' attention and attempt to regulate their emotional state. We have identified in the sound stream of maternal utterances both global (macropoetic) and small-scale (micropoetic) structural and dynamic devices that create and direct emotional response. For their part, preverbal infants appear to be innately ready to prefer and respond to these features. Specifically, in the present paper, the mother's speech exhibits a systematic use of "micropoetic" metrical stresses and other rhythmic features, as well as phonetic variations and contrasts, that facilitate the mutual regulation of affective and perceptual interaction-that is, they engage, direct, and reengage the infant's attention, and respond to his changing behaviors. Because of their spontaneity, rapidity, and flexibility, these appear to be produced by the mother without deliberation, yet they reveal a rich structuring of the mother-infant relationship.

Tooby il, Cosmides L2 Art, imagination, and the adapted mind: Towards a theory of aesthetics

Puzzlingly, humans engage in many activities that appear to have no evolutionary utility, such as contemplating sunsets or immersion in fictional worlds, images, and experiences. However, in addition to the adaptive problems involved in performing fitness-enhancing activities, there are the less well-studied problems involved in building the neural adaptations and knowledge stores that proximately cause fitness-producing behavior. We suggest that many seemingly non-utilitarian aspects of human life are grounded in a set of developmental adaptations that are indispensable for the successful construction of neurocomputational adaptations to exacting standards, and for the ongoing construction of vast, richly detailed knowledge systems (e.g., evolved information contained in encapsulated formats may be unpacked and related to elements in the local environment through fictional experiences). The domain of interactions that can organize an adaptation is far broader than the domain in which it must perform functionally. Activities that organize an adaptation can be liberated from the constraints of encountering the actual task (e.g., tag and predator escape), if there is an abstract isomorphism between elements in the organizing experience and elements in the adaptive task, and if there are adaptations that detect activities embodying this isomorphism, extract the organizing information present

I Center for Evolutionary Psychology, Dept. of Antdeopology, University of California, Santa Barbara. CA 93106 Z ibid

in them, and decouple the irrelevant aspects from being stored as relevant

Rodeke MK3, Waters GS°, Cianelli S, Fours RSs Shdlarlties and differences in drawings by children and crossfostered chimpanzees

The drawing patterns of three adult cross-fostered chimpanzees and human children between the ages of 2 to -5 years old were investigated with respect to marks on pictures, marks on hand written words, marks in blank spaces and marks crossing boundaries. Subjects were given a 8.5 by 11 piece of paper, divided into 9 equal size rectangles bordered by black lines. Each rectangle contained either hand written words, a picture, or was left blank. The arrangement of hand written words, pictures and blank spaces were counterbalanced with regard to placement on the page. Ten drawing pages were given to the children and the chimpanzees in a random order. Non-toxic crayons or non-toxic colored pencils were used. Similarities were found between the children and chimpanzees with respect to boundaries, and a strong tendency for coloring in pictures. Differences included the chimpanzee's concentration of marks over both pictures and hand written words, while children tended to concentrate their marks over pictures. Individual differences between the chimpanzees are discussed.

Thursday afternoon plenary address

Rice WR6 Adaptation and coevolution of the sexes: Genderspecific fitness, Interlocus contest evolution (ICE), and sexually antagonistic genes

Two phenomena are described that may strongly influence adaptation and coevolution of the sexes. The first is intersexual ICE (Interlocus Contest Evolution). ICE is a Red Queen process that is manifest at the level of interacting genes within the gene pool of the same species, rather than the traditional Red Queen that concerns interacting species within a community. Intersexual ICE encompasses antagonistic coevolution between alleles at different loci that code for phenotypes that mediate contests between the sexes in the context of reproduction. Data from the literature and from recent experiments in my laboratory motivate the hypothesis that intersexual ICE plays a central role in the evolution of reproductive isolation during the speciation process. The second phenomena influencing adaptation and coevolution of the sexes

3 Cbimpeoxee and Human Communication Inaitute. CWU. EUasburB. WA 989267573 4 ibid s ibid 6 Univ of Califaoia at Santa Barbara Dept of Ecology. Evolution. & Marine Biology. Sam Bacbn.

CA 93106-9610. rix9lifeaci.uab.edu

is sexually antagonistic genes, i.e., genes that are segregating for alleles that are advantageous to one sex during ontogeny but disadvantageous W the other sex. Because the sexes are constrained to abate a common gene pool, and since most genes are not gender-limited, the common occurrence of sexually antagonistic alleles would substantially interfere with the adaptive evolution of each sex. A theoretical rationale for widespread polymorphism of sexually antagonist genes is developed. New experiments are described that a) cloned entire haploid genomes, b) express these full sets of genes in both males and females , and then c) measured sex-specific life-time fitness. These experiments indicate that that sexually antagonistic genes are common in the genome and contribute substantially to the standing variance in fitness.

2 Early Thursday afternoon paper sessions

Davis JNt, Hertwig R2, Sulloway FJ3 Parental investment and the inequality of equality

How should parents divide investment among their children? Previous research on such decisions in birds has shown that, from the parental standpoint, the ideal distribution is highly contingent on the amount or resources available. The more parents have, the more equitably they ought to distribute them among their offspring, achieving essentially equal distribution when parents have enough to successfully raise their entire brood to adulthood. If we assume that human parents typically regulate family size so that they have appropriate levels of resources to raise all of their children, then we might expect a more or less similarly equitable distribution of investment to occur in human families. The equity heuristic, a boundedly rational decision rule that takes into account the typical conditions of human decision making, namely, limited time, knowledge, and computational power, specifies that parents should attempt to subdivide resources equally among their children. We will present a counterintuitive implication of the equity heuristic: Whereas an equity motive produces a fair distribution at any given point in time, it yields a cumulative distribution of investment that is unequal. We test this analytical observation against evidence reported in studies exploring parental investment, and we

Center for Adaptive Behavior and Cognition, Max Planck Institute for Human Development, Lentzeallee 94, 14195 Benin. davis0mpib-benin.mpg.de 2 ibid 3 Cema for Advanced Study in the Behavioral Sciences. Stanford University, Palo Alto, CA

show how it can provide an explanation of why the literature reports a diversity of birth-order effects.

Michalski RL4, Shackelforrt TKs Does birth order cowry with mating strategy?

This study addresses differences between firstborns and laterborns relating to adult long-term and short-term mating strategies. Because research suggests that firstborns display a stronger sense of responsibility than do laterborns, we hypothesize that this translates into greater pursuit of alongterm mating strategy by firstborns. Laterborns, in contrast, are hypothesized to pursue a short-term mating strategy involving casual sex. Furthermore, laterborns involved in a long-term relationship are hypothesized to be more likely than firstborns to become sexually involved with people other than their longterm partner. Self-report data on birth order and on sexual strategy (pursuit of short-term versus long-term romantic relationships) was collected from several hundred male and female college students. Results clarify the relationships between birth order and sexual strategy, and suggest the value of an evolutionary psychological perspective. Discussion addresses limitations of this research and important directions for future work.

Building on Sulloway's niche-theory of birth order, Salmon and Daly (1998) have investigated the special character of middleborn children. Compared with first and lastborns, middle-horns report less sentiment towards their parents but stronger sentiment towards siblings and peers. Firstborns, whose greater value lies in their parents' earliest possible reproductive return, can expect the lion's share of parental investment. Lastborns benefit for two reasons: Parents should invest all remaining resources in a lastborn child, and lastborns never need endure dilution of investment. Middle-horns, it is argued, have no advantages. We extend these arguments to differences in attachment style. The greater investment enjoyed by first and lastborns should translate into a higher likelihood of secure attachment style relative to middle-horns. Based on Salmon and Daly (1998), middle-horns should be more likely to display a secure attachment style to friends as opposed to romantic partners. A sample of 347 undergraduate students completed a questionnaire on birth order and attachment. Early results indicate that middle-horns are less likely to be securely attached to both romantic partners and friends, confirming our first hypothesis. Middleborns were more securely attached to friends compared to

4 Florida Atlantic University, Division of Science, 2912 College Avenue, Davie, FL 33314. Fie:odian®aol.oom s ibid tstuacloel0fau.edu 6 Dept of Psychology. University of BC, Vancouver, BC, V6T 1W4, Canada 7 ibid.

romantic partners, but so were first and lastborns, failing to sustain our second hypothesis. Our discussion suggests attachment style develops as a complex function of family sentiment.

Salmon CAI Who's keeping in touch? Sex, birth order and contact with kin.

Previous research by the author has indicated that birth order is a strong predictor of familial sentiments, with middleborns being less family-oriented than first or lastboras. In this study, the effects of sex and birth order on the actual frequency of contact of Canadian undergraduates with maternal and paternal kin were examined. Undergraduate subjects saw maternal kin more frequently than paternal kin (ten times per year as opposed to seven). In the GSS sample, maternal kin were also visited more frequently than paternal (eleven times a year as opposed to eight). While the birth order of subjects did not appear to have a significant influence on contact, the birth order of the undergraduate subjects' parents did, with the offspring of middleborn mothers having relatively little contact with maternal grandparents and the offspring of middleborn fathers having relatively little contact with paternal grandparents. However, the same pattern of birth order effects was not found in a General Social Survey sample. The implications of this are discussed with regard to sex differences in the use of kin ties, birth order and parental solicitude, and life stage specific familial contact.

2.2 Pregnancy, prenatal effects, and fertility

Manning JT2, Baron-Cohen S3, Wheelwright S4, Sanders Gs, Slumming V6 The 2nd to 4th digit ratio in autistic children and elite musicians

It has been hypothesised that prenatal exposure to high levels of testosterone may be important in the aetiology of autism and musical ability. The 2nd to 4th digit ratio (2D:4D) is sexually dimorphic (2D:4D men < 213:413 women) and negatively correlated with testosterone and sperm numbers in men. 213:41) ratio is determined in utero and therefore may be a correlate of prenatal testosterone concentrations. We present 213:413 ratios from (a) autistic children and their families and (b) elite musicians. The 213:413 of our samples is compared with population norms and with measures of the intensity of the expression of the traits (i.e. autism and musicality). The evolutionary implications of prenatal testosterone exposure are

I Dept of Psychology, McMaster University, Hamilton, ON Canada L&S 4K1 2 University of Liverpool 3 University of Cambridge

discussed including the possibility of viewing musicality as an honest advertisement of male fertility.

Flynn JP', Ellison P7a, Fneizinger 1N9, Domar ADt°

Stress redaction does not change ovarian function in Infertile women

Previous studies have suggested that female reproduction can .be suppressed due to psychosocial stress sad that stress reduction may lead to better pregnancy outcomes. In a clinical study, Domar et al. (1998) found that infertile women who participated in a ten week Mind Body (M/B) stress reduction group conceived at higher rates than a control group of infertile women. The current study investigated the possible mechanisms through which stress and its reduction may influence the probability of conception. Ten infertile women were recruited to participate in a M/B group. Subjects collected morning saliva samples and kept daily logs of coital frequency for one menstrual cycle before and one cycle after the M/B tnaunent. Subjects also completed the Beck Depression Inventory before and after the M/B treatment. Saliva samples were radioimmunoassayed for progesterone, estradiol and cortisol. There were no changes in any of the hormonal indices as a result of the MAD treatment. However, scores on the Beck Depression Inventory were significantly lower after the MB treatment, indicating that subjects' affective states improved as a result of the group. Coital frequency rates also significantly increased. These results suggest that the increased conception rates associated with psychosocial stress reduction are not due to changes in ovarian function, but may be influences by changes in coital frequency.

Norberg KI1 Paternal involvement daring pregnancy predicts the human sex ratio at birth

Over the last three decades, there has been a decline in the human sex ratio at birth in a number of industrialized countries. Some authors have attributed this decline to large-scale climate change or environmental exposures. However, a rise of the sex ratio among black infants in the US over the same period suggests a demographic or behavioral mechanism instead. I use US natality statistics from 1969 to 1996, the National Longitudinal Survey of Youth, and other data sets to show an associaton between the sex ratio at birth and the involvement of the father before or during pregnancy. For example, in the NLSY, mothers who were living with a male partner at

7 Dept of Anthropology, Harvard University. Peabody Mnsenm, Cambridge. MA 02138 USA. jAynu®fas.harvsrdedu s Ibld pelfi:onQfa:.6wacd.edu 9 Mind/Body Medical Institute, Beth Israel Deaconess Medical Center, Harvard Medial School. Boston. MA. USA t° ibid. It National Bureau of Economic Research, 1050 Mawdtusdts Ave, Cambridge. MA 02139 norberg0nbacxg

the time of the child's conception had 52.496 boys; mothers who were not living with a male partner at conception had 51.496 girls. The effect holds true even when the comparison is made among children born to the same mother, and may explain most of the changes in sex ratios among black and white births in the US since 1970. The association is consistent with the hypothesis that the sex ratio of offspring may be adapted to the availability of parental resources.

Lummaa Vt, Haukioja E2, Lemmetyinen R3, Pikkola M°

Human twinning as a reproductive strategy in pre

industrial Finland-double fitness or double trouble?

Highest twinning rates for Caucasian populations have been recorded in the Finnish archipelago, while twin doliveries in' adjacent inland areas have historically been rarer. Here we present evidence for divergent selection pressure on twinning between these two areas during preindustrial era (1752-1850) and show how differences in brood size in traditionally relatively isolated populations may be maintained by natural selection. We used an extensive demographic data set collected from Finnish church books to compare the lifetime reproductive success of mothers with a probable genetic tendency for twinning with control mothers delivering only singleton offspring. Twin and singleton mothers in the archipelago did not contribute differently to the subsequent population, while in the inland twin mothers' reproductive output was significantly lower than that of control mothers. With regard to causal factors, differences in the profitability of twinning between the areas are in line with the general assumption of life history theory, according to which predictable resource levels favour evolution of reproductive strategies with large brood sizes. In the archipelago the food situation has traditionally been relatively high and constant, whereas in poor inland areas crop failures and subsequent famines have been common throughout the centuries. Relationship between environmental conditions and cost of producing different sexes, and the effect of enlarged brood size on this, will be discussed.

2.3 Symposium: Darwinian ecology: Evolutionary perspectives on environmental problems. Part 1

lbld s Dept of Biology, University of Utah, Salt Laloe City, UT.

petut®bitdogymab.edtt

Symposium abstract Overpopulation, environmental degradation, and the loss of biodiversity are arguably the most important problems facing our species in the next century. Since our environmental problems are often the result of human behavior, the solutions lie in social policy rather than technology. Several newly emerging social sciences, such as ecological economics, have begun to integrate ecological principles into their framework; however, they still ignore evolutionary biology. Environmental philosophy and policy is often based on misconceptions and myths about human behavior. Evolutionary biology provides important insights into environmental problems, such as Hardin's 'tragedy of the commons' Speakers in this session will show how recent advances in evolutionary ecology and psychology provide badly needed insights into overpopulation and other environmental problems. This is the first session on the newly emerging field of Darwinian ecology, which applies evolutionary principles to address environmental problems.

Low BS6 Ecological sustainsbility and demographic transitions

The behavioral ecology of conservation gives us pause in considering how to design ecologically sustainable practices: in the evolutionary history of our and other species, "more" has always been reproductively more profitable-more resources, more or better-invested (more consumptive) offspring. Popular environmental movements call for something evolutionarily novel: a combination of both low fertility and low consumption, something that has previously been associated with relatively low reproductive success in any species. Family planning programs typically focus on lowered fertility, and not on fertility timing or on consumption levels. As a result, demographic vansitions tend to be local and reversible, and vary greatly in their speed and ecological impact. I discuss the impacts of several current patterns: age-specific fertility, human discount rates, and conflicts of reproductive interests.

Mysterud h The effect of information and social incentives in obtaining economic support for an environmental find-raising campaign: An evolutionary approach

In two reviews, Bobbi S. Low and Joel T. Heinen (1992, 1993) focus on a behavioral ecological approach in studying resource use, environmental problems and sustainable development. Several ways to affect people in a desired direction were discussed, among others the use of information (about the consequences of the behavior and how

b University of Michigan Sebool of Natowl RUM= 7 Depatament of Biology, University of Oslo, PO. Box 1050 Blindan, N-0316 Oslo. Norway. mysterad®math.oio.no

to solve the problem) and social incentives. The latter is based on reciprocity (both "direct", sensu Trivers 1971 and "indirect", sensu Alexander 1987) and the fact that humans are a social species. "Indirect reciprocity" means that person A cooperates with person Bin a given situation such that person B receives a direct benefit at the expense of A. In reality, this act conveys in effect a longterm benefit to A in future interactions with persons C, D, etc. when they observe A's cooperation with B. Indirect reciprocity concerns therefore the reputation a person gets through his/her social interactions which affect those in the future with other people. This paper reports results from a study that tests the effect of various combinations of information and a social incentive based on indirect reciprocity in motivating a sample of 200 students to support economically a certain fund-raising campaign by an environmental organization in Norway. Our working hypothesis was that information about an environmental problem presented with a social incentive would be more efficient than presenting the information alone.

Palmer CT' An evolutionary peeve on overfishing in northwest Newfoundland

Evolutionary concepts are used to explain several aspects of commercial overfishing on the west coast of Newfoundland. First, individual level selection can explain the failure of fishers to conserve resources for the long term good of the group. Second, kin selection can account for the hiring of close kin as crewmembers even when it is economically inefficient to do so. Third, reciprocal altruism is the key to understanding the competition among fishplants trying to process the declining resource. Additional ways evolutionary concepts can be used to improve existing models of human ecology are also discussed.

Penn DZ Why do empowered women have fewer offspring?

Although global population is growing exponentially. it has stabilized in some rich, developed countries (demographic transition). This is puzzling because we expect people to have more, not fewer children when they obtain more resources. However, these recent fecundity declines are more closely associated with increases in women's power (education, social status, and control over reproduction) than economic wealth per se. How can we explain this response? In humans and other polygynous species, there is an evolutionary conflict of interest over the optimal family size between males and females: women have more to lose than men when they bear too

I Dept of Anthropology, University of Colorado at Colorado Springs. Colorado Springs. CO 80933 USA cpslma0conoentric.ner 2 Dept. Biology, University of Utab, Salt LAloe City, UT 84112

many children, therefore, they may have lower optima and mechanisms to resist male pronatalistic coercion. Sexually emancipated societies are an evolutionarily novel environment that may result in women sometimes overcompensating and having no offspring. This sex-specific family size hypothesis needs to be tested since it has important implications for the debate over the importance of economic growth versus sexual equality for reducing the earth's population growth.

In my book, The Biological Origins of Art (Praeger, 1998), I argue that natural threat stimuli are used in art to evoke emotion. I outlined the netuobiological processes that make this possible and offered speculation as to why art should evoke fear: Now the publication of The Handicap Principle by Amotz and Avishag Zahavi (Oxford, 1997) offers a theory of signal selection which provides explanatory power to my speculation. This paper will discuss just a couple of threat examples but the Za6avi's theories provide ample support for other notions of art in an evolutionary context.

Allen WE3 Cold cuisine in the cansdian subarctic: Shamanic revenge motifs is traditional oral narratives

Oral narratives have been-employed by traditional indigenous peoples the world over for millennia. Motifs about good and bad shamans, "medicine" battles and sorcery, and subsequent acts of revenge can be found in the narratives of almost all indigenous hunters and gatherers. Such narratives likely have their origin in our evolutionary past - i.e., they are rooted in our evolved psychology. We spent 99.996 of our evolutionary history in band and tribal-level societies that were characterized by chronic internecine violence. One of the functions of traditional oral narratives has been to symbolically convey the moral proscriptions and prescriptions that legitimize individual and group identity. The following paper presents two oral narrative collected among the Dene Athabascans in the Northwest Territories, Canada in the winter of 1994, along with a brief discussion of the significance of the shamanic revenge themes that recur in such narratives.

3 Dept of Commuaicatioo, University of Utah. gadwulfQiuconnectcom · PRO. Box 27, Guysville, ox 45735 s Drat of Mduopotogy. Minnesota State Univa:ity. Mankato, Mankato, MN 56002-8400 6 Depaoment of English, University of Missouri--St. Louis, St. Louis, MO

Novelists and playwrights have almost unanimously proclaimed that fictions and dramas depict "human nature:" Sociobiologically oriented critics have thus far made use of this principle by attempting to analyze literary representations as depictions of a universal human nature. I shall describe and illustrate a way to use human universals that gives us greater access to the particularity of literary meaning. I propose that we take human universals as elementary components that can be combined in various but predictably limited ways. Literary meaning resides not only in the universal itself, but in the specific way any given universal interacts with other universals. To illustrate the method I propose, I shall focus on a single human universal, the tendency for females to "marry up" socially. As Symons explains, this tendency is the consequence of females being a limited sexual resource. I shall reference dozens of instances in which this universal serves as a central principle in the organization of plots, and I shall argue that the different ways authors present this universal gives us access to their particular and distinct forms of literary meaning. These differences of meaning reflect distinct cultural circumstances, the personality characteristics of individual authors, and the use of specifically literary formal structures, but all these differences can be formulated as variations and combinations within a finite set of universal elements.

Recent discoveries of mummified remains of tattooed humans have led to a resurgence of interest in permanent forms of body decoration. Tattooing is ancient (the mummies are prehistoric), widespread (found on mummies in such places as Chile, Greenland, China, and the Alps), has potentially high costs (pain and possible infection and death), and is often placed on highly visible parts of the body. Hypotheses accounting for such permanent decoration fall roughly into four categories: It ( I ) reflects beliefs (e.g., the decoration provides magical protection), (2) provides pain relief (i.e., primitive form of acupuncture), (3) communicates prowess and sexual attractiveness (e.g., deer tattoos on good deer hunters or the good genes of men strong enough to withstand pain and risk infection), (4) identifies particular categories of individuals (slaves as one example). I will build upon the last two explanations to argue that an important function of permanent decoration in traditional societies is the communication of common ancestry, and thus kinship.

t Depart of MVuopology, University of Missouri, Columbia MO 83211

3 Late Thursday afternoon paper sesS10nS

Cosmides L2, Tooby J, Montaldi A, Thrall N Character counts: Cheater detection is relaxed for honest individuals

Research suggests that the evolved architecture of the human mind contains an expert system designed for reasoning about social exchange, with a subrountine specialized for cheater detection. We will report the results of experiments investigating whether information about an individual's character can activate or deactivate the cheater detection subroutine. Information indicating that an individual is honest appears to selectively deactivate the mechanism. That is, subjects are less likely to seek out information that would tell them whether the honest individual has cheated, but their tendency to monitor others for cheating remains high. Information indicating that an individual often cheats does not appear to increase subjects tendency to monitor that individual, at least when compared to the (already high) level of monitoring they exhibit when they have no charactemlogical information.

Barrett HO Guilty minds: How perceived intent, incentive, and ability to chest influence social contract reasoning

Across cultures, people distinguish between intentional and unintentional failure to comply with social contracts. In terms of evolutionary psychology, this implies that there must be an intersection between the domains of "theory of mind" and "social exchange" reasoning. In fact, people must bring inferences from many domains to bear in determining whether someone has "cheated" on a social contract, as evidenced by questions such as: "Did the suspect intend to do it?" "What was his motive?" and "Was he physically able to do it?" In this study I examined the influence of these three factors on social contract reasoning using the Wason selection task, a test of cheater detection in social contract reasoning. I presented six versions of a social contract Wason task to 239 subjects, varying whether the protagonist in the accompanying story 1) intended to break the social contract rule, 2) had an incentive to break the rule, and/or 3) was physically able to break the rule. Each subject saw a combination of 1, 2 or 3 of these factors. The results showed that removing intent, incentive, and ability each decreased performance,

2 Cents for Evolutionary Psychology. Dept. of Anthropology, UCSB, Santa Barbara. CA 93106, tooby*secf.ucsb.edu 3 Center for Evolutiornry Psychology, Dept of Anthropology, UCSB, Saran Barbara. CA 93106 USA. 65006cbQucsbuxa.ucsb.edu

additively, by about 2096 from a ceiling of 65. In other words, people track others' intentions, motives, and abilities, each of which influences social contract reasoning. I discuss the implications of this study for the architecture of social contract reasoning, in particular, how inferences from multiple domains are combined in social decisionmaking.

Moore Ct, Brown WM; 1s prospective altruist-detection an evolved solution to the adaptive problem of subtle cheating in cooperative ventures?

Reciprocal altruism in humans may be made possible in part by the existence of information-processing mechanisms for the detection of overt cheating. However, cheating may not always be readily detectable due to the division of labour. Subtle cheating poses a serious problem for the evolution of altruism. This paper argues that subtle cheating may have exerted selective pressures on early hominids to be sensitive to information regarding the genuineness of an altruistic act. In two experiments, subjects were required to complete Wason selection tasks designed to allow for the detection of altruism. Performance on the altruist-detection tasks was compared to performance on control Wason selection tasks (Experiment 1) and to performance on control and cheater detection tasks (Experiment 2). Participants were significantly better at solving cheaterdetection and altruist-detection versions compared to control versions of the problems and there was no significant difference between altruist and cheater detection. Results are discussed in relation to recent conceptual models for the evolution of altruism. Specifically, it is argued that non-kin altruism may be an evolutionarily stable strategy if altruists can detect one another and form mutually beneficial social support networks.

Hiraishi K3, Hasegawa 74 Detecting free-riders in cooperative groups: A study on Wason selection task

It is widely accepted that "utility" affects reasoning and elicits a thematic-content-effect on the Wason Selection Task (WST). Taking a Darwinian approach this paper proposes that detection of free-riders in cooperative groups has utility for humans and elicits a thematic-contenteffect. In a cooperative group where members selectively share resources with in-group members, freeriding can take two forms; the consumption of resources by outgroup members, or the failure of in-group members to share resources. The detection of free-riders is essential for the maintenance of cooperative relationships, so

Depnmxat of Psychology, Life Sdtxm Dalhousie University, 1355 Oxford St., Halifax, Nova Scotia, B3H Q1 Canada, wmbrown@is2.daLca 2 ibid wmbrown9is2.dal.ca 3 Dept of Life Scieexs, Graduate School of Alts and Sciences, University of Tokyo, 3-g-1 Knmaba, Meguto-ku, Tokyo. Japan. kai@datwin.c.u-tokyo.ac jp

it was predicted that people would be efficient at detecting freeriding on the WST. Taking the perspective of the resource provider, undergraduates (Study 1) and 6th grade pupils (Study 2) completed the WST. Our prediction was supported in both experiments, as respondents in both age groups showed a thematic-content-effect and checked for the existence of outgroup members taking undeserved resources. Taking the perspective of the resource recipient, both undergraduates (Study 3) and 5th and 6th pupils (Study 4) also showed a thematic-contenteffect. However, there were important differences between the getups. While the undergraduates checked only for the existence of out-group members taking undeserved resources, our prediction received the strongest support from the pupils who also checked for the existence of ingroup members being denied access to resources.

Anderson NKs, Park hlb, Johnston VS', Giddon DBs AnthropomeMc measures contributing to judgments of female facial attractiveness by four ethnic groups

As part of an overall study for determining the physical bases of perception of faces, four groups of judges (Chinese, Japanese, Korean, and Other) (N = 54) were required to rate attractiveness and to classify the ethnicity of 60 gray scale, full face images of female Asians. Attractiveness ratings were based on a 5-point scale (1=very attractive, 5=very unattractive); judges were asked to classify faces as Most and Least Likely Chinese, Japanese, or Korean (Most Likely=1, Least Likely=3). A total of 49 linear, angular, and proportional measures were examined statistically to determine the specific anthropometric characteristics used in making these judgments. In agreement

with prior studies (Johnston 8c Franklin, 1993), a specific set of measures (e.g. short lower face height, thin nose, etc.) were found to be significantly correlated (p < .05) with the attractiveness ratings for all judge groups. Additional anthropometric measures were found to be specific for ratings of attractiveness by some of the judge groups (e.g. Chinese judges preferred low-set eyebrows). Unlike ratings of attractiveness, the judges' criteria for assessing the ethnicity of the faces were consistent within the ethnic judge groups, but varied widely across judge groups. There was some overlap however between the anthropometric measures used to determine the ethnicity of a face and those associated with attractiveness. These findings

s Health Progtama Intematioaat, Weth'aley, MA. andatonOripWik.net 6 Columbia University. New York, NY 7 New Mexico State University. LAS Cruces, NM. s Harvard University, Boston. MA.

are discussed within the framework of natural and sexual selection.

Hume DKt, Montgomerie RZ Facial attractiveness and symmetry in humans

We investigated the role of facial symmetry in assessments of attractiveness. Because fluctuating asymmetry (FA) is predicted to be negatively related to aspects of fitness, symmetry should be found attractive in potential mates. Grammer & Thornhill (1994) found a positive relationship between measured facial symmetry and facial attractiveness. However, Swaddle & Cuthill (1995) manipulated facial symmetry and found symmetry to negatively effect attractiveness. We tested the relationship between symmetry and attractiveness using two different methods of image presentation. First, viewers rated the attractiveness of 32 subjects, where each subject was seen only once, and each image seen represented some level of symmetry manipulation (similar to Swaddle & Cuthill). Then viewers ranked four symmetry manipulated images of the same subject in order of attractiveness. Both methods clearly showed that symmetrical faces were found to be most attractive. We suggest that variation in facial expressions among Swaddle and Cuthill's images might explain the differences between their results and ours. Facial expressions in our sample were held constant, thus removing this potential confound.

Hunt CB3, NoMuhl DK°, Figueredo AP Females' first impressions of males: Are they accurate and how are they used to judge attractiveness?

Sexual selection research has shown that females and males prefer specific qualities in their mates. Because females assume most of the initial reproductive burden, however, their choice of mate carries more consequence than that of males. We hypothesized that females are adapted to utilize information contained in visual and vocal cues to form accurate firstimpressions of males' mating strategies and personality. We predicted that females use these impressions to judge males' attractiveness based on their own mating strategy and personality. Forty-two males completed personality and mating strategy questionnaires and were videotaped for 3 minutes as they provided un-prompted information about how they would start a conversation with a female they found attractive. One hundred forty-three females completed the same questionnaires. Additionally, females viewed

t BioMgy Depareaarnt, Queen's University, Kingston, Ontario K7L 3N6, Cum& hume®biologyqueenau.ca 2 ibid Mont=a®e9biologyqueensn.ca 3 Ethology and Evolutionary PsyCbotogy, Depsirtmatt of Psycbology. University of Arizona. Tucson. AZ gs721-0068 USA. hantc*aarizona.edn 4 tbid dln@u.arizoua.edo 5 fbid ajf®u.arizowedn

videotapes of five randomly-chosen males. Females rated each male's personality and mating strategy and indicated their attractiveness. Females generally perceived males as being more emotional, less active, and less monogamous than males perceived themselves. Generally, females were less attracted to males they perceived as highly emotional, sociable, or promiscuous. Highly sociable females, however, went attracted to highly sociable males. Promiscuous females were attracted to most males, except those they rated as highly monogamous. These results suggest that females' first-impressions of males are reasonably accurate and used as a basis for attraction. Most females appear to value emotional stability in mates, perhaps as an indication of consistent providing. Positive assortative mating appears to operate on dating strategies and certain personality traits.

Bnecke PA6, Long WP Reconciliation between and within countries: A "rational choice" or "reasoned instinceg

This study explores two explanations for reconciliation between and within countries. The first explanation, based on the rational choice paradigm, argues that reconciliation emerges from costbenefit calculations by leaders of countries or leaders of major groups within countries. Depending upon the circumstances, leaders send signals to their counterparts and their own constituencies indicating their preferences and commitment to a major restructuring and improvement in relations. The second explanation, based heavily on research on social behavior in evolutionary psychology, posits that reconciliation reflects a prior, more fundamental process. Reconciliation results from an internal re-evaluation of oneself and one's counterpart combined with an awareness that actions to re-establish social harmony and structure are advantageous. The desire for reconciliation arises from a deep, emotive understanding. In those instances where there has been a long history of interaction, and each actor relies on the other for his well being, the willingness to reconcile becomes more salient.

This study reports our project to determine which explanation best fits the data. Initial findings suggest that rational choice is a superior explanation for reconciliation between countries. The paper will also report research underway to test whether that finding breaks down when we move to the withincountry situation in which cooperation with the counterpart becomes more important.

6 Sam Noon School of International Affairs, Gewgia Institute of Technology, Atlanta, GA 30332-0610 USA. peterbrecloeQinta.gatech.edu 7 ibid. william.loogQiata.gatxh.edu

3.3 Symposium: Darwinian ecology: Evolutionary perspectives on environmental problems. Part 2

Ruttan LAP, BorgerhofMulder M Are East African pastoralists truly conservationists?

Controversy exists among anthropologists, conservation biologists and development workers as to whether the concept of the "ecologically noble savage" is a myth. Central to this debate are the problems of how to identify conservationist behavior and the issue of whether sound management practices of common property arc likely to evolve. While social scientists have documented instances where restraint over the use of resources occurs, those who adopt an evolutionary perspective are challenged to identify the selective mechanisms whereby such altruistic conservation acts might be maintained in a population. Here a game theoretic approach is used to analyze the case of pastoralist grazing reserves. We demonstrate that under some conditions, conservation can be the result of narrow self-interest and there is no collective action problem. However, the range of these conditions is much broader for wealthy individuals and thus, the wealthy may also find it advantageous to coerce others into conserving. In conclusion, we propose an extension of the definition of conservation that is of greater generality for use in nonforaging populations, and incorporates the essential political element of how conflicts over resource use are resolved.

Wtlson M3, Daly M'° Sex differences in disregard of personal health risks and environmental degradation

We hypothesize that women and men differ, as a result of sexual selection, in their willingness to tolerate health hazards and other risks in pursuit of material and social benefits. In an experimental study utilizing a hypothetical dilemma, a financial incentive had slightly more appeal for men than for women, whereas a health hazard was a strong disincentive for women but not for men. We also hypothesized that men would be more likely to downplay environmental degradation in the pursuit of profit on the logic that men may discount the future more than women as a result of prioritizing present profits. In another hypothetical dilemma about a choice of crop to farm, men were significantly more likely than women to choose the soildegrading but higher profit crop. A number of other expectations can be derived if we assume there is an evolved

' Dept of Biology, University of Utah, Salt Lace City. UT. Penn@biology.utah.edu 2 Deparoment of Enviromnental Science and Policy, University of California at Davis, Davis CA 95616 USA, Imruttan®ucdsvis.edu j Dept. of Paycdology. McMaater Uaivasity, Hamilton, Ontario, Canada LSS 4K1. wilaon®mcmaaterca 4 itid dalyQMcMaster.CA

Atzwanger Ks, Schafer Kd Visual complexity and per-

Because choice of habitat exerts a powerful influence on survival and reproductive success, the mechanisms involved have been under strong selection for millenia (Orians 8c Heerwagen 1992), so that those structures which have in the course of human evolution conferred high habitat quality also trigger positive responses today. Several models of scenic quality are based on an assumed relationship between visual complexity and increasing aesthetic quality, influenced by the finding that increasing ecological stability is related to environmental quality. In urban environments Herzog (1992) was able to demonstrate with rating studies that order and complexity appeared to be consistent predictors for preference. Most studies confirm a positive correlation between visual complexity and interest (e.g. Nasar 1987). The relationships between preference and complexity are less consistent. A problem of these studies is that complexity was only derived from human judgments that turned out to be influenced by content categories. We therefore directly measured the physical characteristics of the scenes (urban squares in Austria and Germany) using computer image processing (fractal dimension), and having them rated for perceived complexity, interest and preference. Our data indicate a strong positive correlation between objective complexity measurements, subjective evaluation and preference at least in urban environments. This may result from a lack of enough complexity, far from producing a downturn in preference. We conclude that this result is of high interest for urban design planners.

Kay CEO Aboriginal overkill and the myth of the "ecologically noble savage'-A continuous-time analysis of wildlife observations made by Lewis and Clark

Lewis and Clark's journals are often cited as an example of how the West teemed with wildlife before that area was despoiled by advancing European civilization. To test this hypothesis, I performed a continuous-time analysis of wildlife observations made by Lewis and Clark on their expedition across the continent in 1804-1806. This included bison, elk, mule deer, white-tailed deer, black-tailed deer, moose, pronghorn antelope, bighorn

s University of Vienna, Institute for Human Biology a: Ludwig-BoltrmannIostitnte for Urban Etdology, Ahfiao:a 14, A- 1090 Patna, An:aia 6 ibid 7 Department of Political Science, Utah State University, Logan. Utah 84322

sheep, grizzly bears, black bears, and gray wolves. I also recorded all occasions on which Lewis and Clark met native peoples. Those data show that Native Americans controlled the distribution and numbers of wildlife throughout the West. As predicted by the Aboriginal Overkill hypothesis, the only places Lewis and Clark reported an abundance of game were in aboriginal buffer zones between tribes at war, but even there, wildlife populations were not food-limited. Bison, grizzlies, bighorn sheep, and wolves were seldom seen except in aboriginal buffer zones. Moreover, Lewis and Clark were only able to complete their journey because of the food, horses, and above all else, knowledge that they received from native people. There was no wilderness. Finally, as noted by Lewis and Clark, the West was even more densely populated prior to the smallpox pandemic that decimated native people in 1780.

3.4 Symposium: The psychology and physiology of human sperm competition

Symposium abstract Sperm competition occurs when the sperm of two or more males simultaneously occupy the reproductive tract of a female. Some empirical work has been conducted on human sperm competition. The majority of this work focuses on the physiological outcomes of sperm competition, such as sperm number per ejaculate. This symposium highlights recent work on the psychology and physiology that underlie human sperm competition. LeBlanc et al. propose that sperm competition generated several adaptive problems for males and that males have evolved mechanisms designed to solve each of these problems. Weekes et al. tested the hypothesis that female coital orgasm is an adaptation for retaining the sperm of males with high genetic quality. Using physical attractiveness as a proxy for "good genes;' the researchers find that a woman's coital orgasm positively covaries with her partner's physical attractiveness. Pound et al. had men provide ejaculates by masturbation while watching pornographic videos. The content of the videos had several unique effects on ejaculate parameters. Additionally, time spent sexually aroused positively covaried with the number of sperm ejaculated. Shackelford et al. assessed sperm competition risk as the time a man has spent apart from his partner since the couple's last copulation. Men at greater risk of sperm competition report, for example, (a) that their partner is more attractive and

t Florida Atlantic University, Division of Science, 2912 College Avenue, Davie, Florida 33314. tshackel0fau.edu

(b) greater interest in having sex with their partner. The four presentations report some of the first work that addresses the psychology and physiology that may underlie human sperm competition.

LeBlanc GJl, Shackelford TK3, WeekeS VA° Preventing, correcting, and anticipating sperm competition in humans

Sperm competition occurs when the sperm of two or more males simultaneous occupy the reproductive tract of a female. Sperm competition has been documented or inferred in a variety of animal species, including humans. Female infidelity is the primary context for sperm competition. Males face tremendous costs associated with a female partner's infidelity. A principal cost is investing limited resources in genetically unrelated offspring. Female infidelity and sperm competition generated several sets of adaptive problems that males faced over evolutionary history. These include preventing sperm competition, correcting the problems posed by sperm competition, and anticipating sperm competition. It is proposed that males have evolved physiological and psychological mechanisms specifically designed to solve each of these problems.

WeekeS VAs, Shackelford TK6, LeBlanc GJ7, Bleske AL8, Euler HA9, Hoier St° Human female coital orgasm is predicted by her partner's physical attractiveness

Human female orgasm may be an adaptation, having evolved to solve problems that threatened survival or reproduction. Work guided by Sperm Competition Theory suggests that female coital orgasm functions to suck up sperm and that the timing of female orgasm relative to male ejaculation affects the number of sperm retained in the reproductive tract. It also has been hypothesized that female coital orgasm functions to preferentially retain the sperm of males higher in genetic quality. 388 women involved in committed, heterosexual relationships and residing in the United States or Germany completed a survey about their sexual behavior. The present research tested the hypothesis that women's coital orgasm covaries with ratings of their partners' physical attractiveness, a heritable indicator of male genetic quality. Results support the hypothesis, even when controlling for women's relationship satisfaction, the woman's age, her partner's

Florida Atlantic University, Division of Science, 2912 College Avenue, Davie, Florida 33314. gleb2044Qfamedu 3 ibid tahackel@fau.edu 4 ibid vwee9812®fau.edu 3 Florida Atlantic University, Division of Science, 2912 College Avenue, Davie, Florida 33314. vwee9812®fau.edu 6 ibid tshaclwl®fau.edu

ibid g1eb2W4*fau.edu s University of Texas a Austin, Departmeru of Psychology, Austin, Texas 78712. bleskeQroail.uteus.edu. 9 F803 Psychologie, University of Kassel. 34109 Kassel. Ganmany. eulaOhmuni-kassade 10 ibid

age, and relationship duration. Discussion integrates current findings with previous work, and highlights the active role of female sexuality, in general, and female coital orgasm, in particular.

Pound Nt, Javed MH, Ruberto C, Shaikh MA, Del Valle

AP Factors affecting human ejaculate composition

An early prediction of sperm competition theory was that males should inseminate more sperm when the risk of double mating, and hence sperm competition, is high. R. R. Baker & M. A. Bellis (1989) reported that the number of sperm in human ejaculates varies in accordance with this theory and in recent years evidence has accumulated to suggest that males of many other species are also capable of adaptive regulation of ejaculate composition. However, little attention has been paid to the psychological and physiological mechanisms that may underlie adaptive regulation of sperm delivery in human males. In the present study, volunteers produced semen samples by masturbation while watching pornographic videos. The content of the pornographic videos had important effects on certain ejaculate parameters once other sources of variability had been taken into account. Sperm motility was greater for samples collected in the morning while across subjects sperm concentration and motility, but not ejaculate volume, were positively correlated with the time taken to produce the sample. If time taken to produce the sample is closely related to the time spent in a state of sexual arousal then the latter variable is a strong predictor of the total number of sperm ejaculated. These results will be discussed in the context of a general theory of facultative adjustment of ejaculate composition and copulatory behaviour.

Shackelford TK2, LeBlanc GJ3, Weekes VA4, Bleske ALs, Euler HA Hoier S7 Absence makes the heart grow fonder, but only for men: The psychological arch