The Female Advantage in Object Location Memory According to the Foraging Hypothesis: A Critical Analysis

According to the evolutionary hypothesis of Silverman and Eals (1992, Sex differences in spatial abilities: Evolutionary theory and data. In J. H. Barkow, L. Cosmides, & J. Tooby (Eds.), The adapted mind: Evolutionary psychology and the generation of culture (pp. 533–549). Oxford: Oxford University Press), women evolutionary hypothesis, women surpass men in object location memory as a result of a sexual division in foraging activities among early humans. After surveying the main anthropological information on ancestral sex-related foraging, we review the evidence on how robust women’s advantage in object location memory is. This leads us to suggest that the functional understanding of this type of memory would benefit from comparing men and women in carefully designed and ecologically meaningful cognitive contexts involving, for instance, incidental versus intentional settings that call for either the absolute or relative encoding of the locations of common versus uncommon objects.     

Love, careers, and heights in France, 2001

Short men are less likely to be married or live in a permanent relationship than their taller counterparts. This pattern is not due to their social status. While blue-collar workers are shorter on average than managers, the effects of height on finding a mate are similar in the two social groups. Being tall is also economically advantageous for men. With identical educational attainment levels, tall men have better careers than short men as they are given greater supervisory responsibilities. In making a commitment, some women might take height into account as an anticipated indicator of future resources of the household. Choice of partner is also influenced by social norms--i.e., partners should be physically well-matched--which is more difficult for shorter men.     

An early classic sculpture from El Tajin,Veracruz, Mexico

Us and Them in Modern Societies: Ethnicity and Nationalism in Trinidad, Mauritius and Beyond. 1992. Thomas Hylland Eriksen. Oxford: Oxford University Press, and Oslo: Scandinavian University Press, xii + 208 pp.     

Stature variation in the British American Colonies: French and Indian War records, 1755-1763

Personnel records kept by military units of American colonials during the French and Indian War (1755-1763) are analyzed for relationships between environmental factors and stature. A robust American economy and direct access to high-quality food were apparently critical to tallness of this white American male sample. American-born men were taller at all ages than those who had migrated from Europe. January temperatures, rural versus urban birth, and ethnicity also showed stature relationships within the American-born group; thermal effects were by far the strongest of the non-nutritional factors.     

Does natural selection favour taller stature among the tallest people on earth?

The Dutch are the tallest people on earth. Over the last 200 years, they have grown 20 cm in height: a rapid rate of increase that points to environmental causes. This secular trend in height is echoed across all Western populations, but came to an end, or at least levelled off, much earlier than in The Netherlands. One possibility, then, is that natural selection acted congruently with these environmentally induced changes to further promote tall stature among the people of the lowlands. Using data from the LifeLines study, which follows a large sample of the population of the north of The Netherlands (n = 94 516), we examined how height was related to measures of reproductive success (as a proxy for fitness). Across three decades (1935–1967), height was consistently related to reproductive output (number of children born and number of surviving children), favouring taller men and average height women. This was despite a later age at first birth for taller individuals. Furthermore, even in this low-mortality population, taller women experienced higher child survival, which contributed positively to their increased reproductive success. Thus, natural selection in addition to good environmental conditions may help explain why the Dutch are so tall.     

Height and reproductive success

In Western societies, height is positively correlated with reproductive success (RS) for men but negatively correlated with RS for women. These relationships have been attributed to sexual selection: women prefer tall men, and men prefer short women. It is this success in the marriage market which leads to higher RS for tall men and short women. We have already shown that the relationship between height and RS for women is quite different in a non-Western context. In a subsistence farming community in rural Gambia, height is positively correlated with reproductive success for women, largely owing to the higher survival of the children of tall women. Here, the relationship between height and reproductive success is analyzed for men in the same community. For these Gambian men, there is no significant relationship between height and the number of children they produce, although tall men do contract more marriages than shorter men. We conclude that environmental context needs to be taken into account when analyzing human reproductive behavior.     

The perceived benefits of height: strength, dominance, social concern, and knowledge among Bolivian native Amazonians

Research in industrial countries suggests that, with no other knowledge about a person, positive traits are attributed to taller people and correspondingly, that taller people have slightly better socioeconomic status (SES). However, research in some non-industrialized contexts has shown no correlation or even negative correlations between height and socioeconomic outcomes. It remains unclear whether positive traits remain attributed to taller people in such contexts. To address this question, here we report the results of a study in a foraging-farming society of native Amazonians in Bolivia (Tsimane')--a group in which we have previously shown little association between height and socioeconomic outcomes. We showed 24 photographs of pairs of Tsimane' women, men, boys, and girls to 40 women and 40 men >16 years of age. We presented four behavioral scenarios to each participant and asked them to point to the person in the photograph with greater strength, dominance, social concern, or knowledge. The pairs in the photographs were of the same sex and age, but one person was shorter. Tsimane' women and men attributed greater strength, dominance, and knowledge to taller girls and boys, but they did not attribute most positive traits to taller adults, except for strength, and more social concern only when women assessed other women in the photographs. These results raise a puzzle: why would Tsimane' attribute positive traits to tall children, but not tall adults? We propose three potential explanations: adults' expectations about the more market integrated society in which their children will grow up, height as a signal of good child health, and children's greater variation in the traits assessed corresponding to maturational stages.     

Tool‐using chimpanzees

Review of Folk Physics for Apes. The Chimpanzee’s Theory of How the World Works by Daniel J. Povinelli, in collaboration with James E. Reaux, Laura A. Theall, and Steve Giambrone. Oxford, Oxford University Press, 2000, xiii + 391 pp, 98 fig., 35 tab., $85.00.     

Partitioning a morphology among its controlling factors

In the first known attempt to use a sympatric, non-mimetic convergence (‘a naturally controlled experiment in evolutionary morphology’) to quantitatively partition a morphology among its controlling factors, shells of the polygyrid land snails Neohelix major (Binney) and Mesodon normalis (Pilsbry) were analysed in a factorially designed rearing experiment. The complete absence of character displacement or character release confirmed previous field studies. Growth rate, a determinant of adult shell size, was controlled 50% by direct environmental induction (with temperature twice as effective as humidity), 10% by proximate natural selection (with a shorter growing season selecting for faster growth), 10% by genotype-environment interaction (with moisture generally inducing a greater growth surge in a drier climate), and 30% by within-cohort variation (apparently heritable). Spire height confirmed predictions that flatter shells make better estivators (shelterers from drought) and that taller shells make better climbers and tall/flat niches are readily filled: high within-cohort variation (70% of total) provides the raw material for niche-filling (but is reduced in severe climates by stabilizing selection); environmental induction (10%) is strictly by humidity, which makes shells taller for foraging more widely under more favourable conditions; proximate natural selection (10%) produces taller shells in moister climates (with intensity of effect dependent on evolutionary time); and genotype-environment interaction (10%) makes the drought-induction of flat shells stronger in more drought-prone areas. Coiling tightness, allied to whorl-expansion rate, shows distinct evidence of adaptive neutrality: 60% of total variance is explained by phylogenetic constraints despite an estimated 120 million years of genetic isolation and despite the demonstrated ability of related clades to converge; the 10% due to genotype-environment interaction is generally random and nonadaptive in its response; and the remaining 30% appears random, non-induced, and non-selected. This study's protocol of experimentally partitioning a ‘closed universe’ of morphology among a full set of controlling factors is recommended as an alternative to the usual practice of analysing the effects of one or a subset of factors on an ‘open universe’ of morphology. One advantage of this new protocol is that it obviates the ‘nature-nurture debate’ by quantifying the relative contributions of each, which in this snail-shell case differ drastically among the various components of a single morpholocgyy.     

Family values

Evolutionary Genetics (2nd edn) by J. Maynard Smith, Oxford University Press, 1998. £50.00 hbk, £19.95 pbk (368 pages) ISBN 0 19 850232 X/0 19 850231 1Selection in Natural Populations by J.B. Mitton, Oxford University Press, 1998. £50.00 hbk (252 pages) ISBN 0 19 506352 XProgress and Prospects in Evolutionary Biology edited by J.R. Powell, Oxford University Press, 1997. £49.50 hbk (576 pages) ISBN 0 19 507691 5Evolution on Islands edited by P.R. Grant, Oxford University Press, 1997. £24.99 pbk (348 pages) ISBN 0 19 850 1714     

God’s punishment and public goods

Cooperation towards public goods relies on credible threats of punishment to deter cheats. However, punishing is costly, so it remains unclear who incurred the costs of enforcement in our evolutionary past. Theoretical work suggests that human cooperation may be promoted if people believe in supernatural punishment for moral transgressions. This theory is supported by new work in cognitive psychology and by anecdotal ethnographic evidence, but formal quantitative tests remain to be done. Using data from 186 societies around the globe, I test whether the likelihood of supernatural punishment—indexed by the importance of moralizing “high gods”—is associated with cooperation. Dominic Johnson is a fellow in the Princeton University Society of Fellows. He holds a D.Phil. in biology from Oxford University and a Ph.D. in political science from Geneva University. His research revolves around the evolutionary biology of human behavior and how this impacts on conflict, cooperation, politics, and religion. His recent book, Overconfidence and War: The Havoc and Glory of Positive Illusions, was published in 2004 by Harvard University Press.     

Female Ascetics in Hinduism; The Graceful Guru: Hindu Female Gurus in India and the United States; Offering Flowers, Feeding Skulls: Popular Goddess Worship in West Bengal

Female Ascetics in Hinduism. Lynn Teskey Denton. Albany: State University of New York Press, 2004. 218 pp.
The Graceful Guru: Hindu Female Gurus in India and the United States. Karen Pechilis, ed. Oxford: Oxford University Press, 2004. 260 pp.
Offering Flowers, Feeding Skulls: Popular Goddess Worship in West Bengal. June McDaniel. Oxford and New York: Oxford University Press, 2004. 356 pp.     

Homology, female orgasm and the forgotten argument of Donald Symons

The ‘byproduct account’ of female orgasm, a subject of renewed debate since Lloyd (The case of the female orgasm, Harvard University Press, Cambridge, 2005), is universally attributed to Symons (The evolution of human sexuality, Oxford University Press, Oxford, 1979). While this is correct to the extent that he linked it to the adaptive value of male orgasm, I argue that the attribution of the theory as we understand it to Symons is based on a serious and hitherto unrecognised misinterpretation. Symons had a different explanation of why women can orgasm, and beneath this explanation lies an obscure line of argument, including a particularly obscure use of the word ‘homologous’.     

Say hello to our little friends

A review of Invertebrate Zoology, edited by Donald T. Anderson. New York, Oxford University Press, 1999, 467 pp, $55.00 paperback.     

Individual Male Calling Pattern and Male Mating Success in the European Treefrog (Hyla arborea): Is there Evidence for Directional or Stabilizing Selection on Male Calling Behaviour?

In anurans, call properties are commonly classified based on within‐male variability as being either static or dynamic. Numerous playback experiments in the laboratory have indicated that female preferences based on dynamic call properties are usually strongly directional, while female preferences based on static call properties are often stabilizing or weakly directional. However, there are only few studies demonstrating that female preferences for high values of dynamic call properties indeed exert directional selection on male calling behaviour in natural populations. Moreover, field studies investigating whether female preferences for values of static call properties around the mean of the population lead to currently operating stabilizing selection on male calling patterns in natural populations are completely lacking. Here I investigate for two consecutive breeding seasons male calling patterns and male mating success in a population of individually marked European treefrogs (Hyla arborea), a hylid frog with prolonged breeding season and a lek mating system. Individual male calling pattern as analysed in terms of seven temporal and spectral call properties did not differ between males that survived from one breeding season to the next and those not surviving. None of the seven call properties investigated differed significantly between mated and unmated males, indicating that there is no strong directional selection on male calling behaviour in the study population. However, in one study season males that produced calls with a number of pulses around the mean of the population were significantly more likely to obtain matings than males that produced calls with a number of pulses at the low or high end of the distribution. Thus, this study provides preliminary evidence for the operation of stabilizing selection on a static call property (i.e. the number of pulses per call) in a natural population of an anuran amphibian.     

Young,formidable men show greater sensitivity to facial cues of dominance

There is considerable evidence that human male faces contain honest, detectable cues to their physical dominance, which are related to their objective facial masculinity. As such, some have argued that the extent to which observers' rate masculinised male faces as appearing more physically dominant is a useful measure of their ability to detect cues of dominance and threat in other men. We found across 3 studies (total n = 272) that younger, taller, and stronger men showed greater sensitivity to facial cues of dominance. Additionally, participants were more likely to associate younger than older masculinised faces with physical dominance. Self-perceived social dominance did not moderate perceptions. These results contrast with previous work which found that shorter, less socially dominant men had greater ability to detect facial cues of dominance. We propose the hypothesis that younger, more formidable males show greater sensitivity to facial cues of dominance as they are more likely to engage in violent intrasexual competition.     

The frequency of chromosome aberrations in tall men with special reference to 47, XYY and 47, XXY.

All men born during the years 1944-1947 to mothers who were inhabitants of Copenhagen when they gave birth, were identified. The adult heights of all but 2,552 of these 31,438 men were obtained; a group of 4,591 men at least 184 cm tall were selected for examination. Samples for chromosome studies were obtained from 4,139 (90.2%) of these tall men. A total of 41 (1%) abnormalities were identified (33 sex chromosome abnormalities, including 12 XYYs (0.3%) and 16 XXYs (0.4%), 6 autosomal abnormalities, and two of uncertain origin). The XYY and XXY groups were taller than the selected sample of tall XY men.     

Review article: Colour and the American system of justice

A. Leon Higginbotham, In the Matter of Color: Race and the American Legal Process ‐the Colonial Period; New York, Oxford University Press, 1978. 536 pp. £8.50.     

Comparative hydraulic and anatomic properties in palm trees (Washingtonia robusta) of varying heights: implications for hydraulic limitation to increased height growth

As trees grow taller, the energetic cost of moving water to the leaves becomes higher and could begin to limit carbon gain and subsequent growth. The hydraulic limitation hypothesis states that as trees grow taller, the path length and therefore frictional resistance of water flow increases, leading to stomatal closure, reduced photosynthesis and decreased height growth in tall trees. Although this hypothesis is supported by the physical laws governing water movement in trees, its validation has been complicated by the complex structure of most tree species. Therefore, this study tested the hydraulic limitation hypothesis in Washingtonia robusta (H. Wendl.), a palm that, while growing to tall heights, is still structurally simple enough to act as a model organism for testing. There were no discernable relationships between tree height and stomatal conductance, stomatal densities, guard cell lengths, leaf dry mass per unit area (LMA) or sap flux, suggesting that these key aspects of hydraulic limitation are not reduced in taller palms. Taller palms did, however, have higher maximum daily photosynthetic assimilation rates, lower minimum leaf water potentials that occurred earlier in the day and fewer, smaller leaves than did shorter palms. Leaf epidermal cells were also smaller in taller palms compared with shorter ones. These findings are consistent with hydraulic compensation in that tall palms may be overcoming the increased path length resistance through smaller, more efficient leaves and lower leaf water potentials than shorter palms.