Over the 20th century, the social sciences developed without taking much notice of humans' nature as products of evolution. In the 1970s this attitude was challenged by behavioral biologists (1, 2) who asserted that general principles concerning the behavior of life forms must also be relevant to understanding human behavior. They argued that because human cognition and emotions had evolved by natural selection, these behavior-generating mechanisms should generally shape behavior so that it maximizes biological fitness. Not all social scientists agreed. Cultural anthropologists, in particular, were mostly aghast at the rigidly scientific and overtly biological nature of this perspective, viewing it as blatantly flawed (3). They claimed that differences between and within human societies were mainly due to variant cultural belief systems. On page 292 of this issue, Barsbai et al. (4) show that adaptation to local ecological conditions is an important determinant of variation in human behavior in traditional societies.
The sample analyzed by Barsbai et al. consists of 339 hunter-gatherer societies that are most appropriate for comparison because their members' lives and livelihoods are intimately constrained by the natural world. The authors show that variation in hunter-gatherer patterns for 15 behavioral variables statistically converges on the same characteristics that are most common in birds and mammals in the same local regions of the world. These traits include diet composition, mobility patterns, paternal investment, divorce rates, social group size, and social stratification. In other words, in places where hunter-gatherers are more polygynous, there also tend to be more polygynous bird and mammal species. These patterns appear to be driven by ecological and habitat similarity, not by locational proximity per se. Not only are hunter-gatherers behaviorally similar in similar ecologies, but even mammals and birds in those ecologies tend to exhibit the same behavioral regularities as do the human populations. Hence, the study appears to validate the basic premise of the evolutionary perspective called “human behavioral ecology” (5, 6).
However, it is a mistake to conclude from this that culture is unimportant. Beginning in the 1980s, researchers in human behavioral sciences developed a sophisticated, scientific, evolutionary theory accounting for the role of culture in human behavior (7, 8). These scientists provided both theoretical and empirical evidence that social learning was a prime determinant of human behavioral variation. The affective and cognitive mechanisms that underpin social learning are adaptations and are in large part responsible for our species' spectacular ecological success, but they also create historical patterns absent in other species and lead to outcomes not predicted by theories developed for noncultural creatures.
Penan hunter-gatherers from Borneo extracting sago palm starch, their dietary staple. The Penan were one of 339 societies around the world showing convergence in behavioral patterns with bird and mammal species living in the same habitats (Barsbai et al., this issue).
PHOTO: YVAN COHEN/LIGHTROCKET/GETTY IMAGES
Barsbai et al. show convincingly that ecological factors explain much variation in human behavior, but so too does cultural history. For example, Mathew and Perreault (9) studied the causes of variation among 172 native American groups in western North America. Like Barsbai et al., they found that ecological factors explained a substantial amount of variation, particularly in behaviors related to subsistence and technology. But the variation in subsistence-related behaviors was equally well explained by the linguistic distance between groups, which proved to be an even better explanation than ecological factors for the variation in political organization, religious practice, and kinship organization. Moreover, the effect of cultural history seems to persist for hundreds or even thousands of years.
Cultural evolution can also lead to outcomes not predicted by the evolutionary mechanisms applied to other species. Barsbai et al. show that variation in human residential group size has the same relationship to ecology as in other species. However, human foragers are much more cooperative than other primates (10), and sometimes they cooperate in groups numbering hundreds of individuals in communal foraging, construction of shared capital facilities, and warfare (11). No other vertebrate cooperates on these scales. Exactly why this is the case is controversial, but it seems likely that culturally transmitted social norms play an important role.
Culture and genes are linked in a tight coevolutionary embrace, and this leads to complex patterns of genetic and cultural co adaptation. For example, Henrich has recently argued (12) that the extent to which people are embedded in networks of kin obligation is a function of both ecological factors (cooperative intensive agriculture) and cultural history (church edicts against kin marriage and collective property institutions), and that variations in the intensity of kin-network embeddedness ultimately transformed human psychology into that observed today in “WEIRD” (Western, educated, industrialized, rich, democratic) societies, where individualism is paramount, rather than the psychology of traditional societies, where collectivism and kin-group favoritism predominate. Experiments show that the cognitive, emotional, and psychological effects of these different cultural histories are profound, and imply that findings from Western modern societies may often be irrelevant to predicting behavior in non-Western and traditional societies. Likewise, the spread of monogamy in modern societies, despite increasing wealth stratification, appears to be a puzzle that requires both adaptive modeling (13) and a recognition that monogamous social norms substantially increased cooperation with societies, and this norm can spread by group competition and cultural imitation (12). Coevolution between genes and culture in different ecologies may lead to uniquely human patterns not anticipated by animal studies. These examples illustrate just how complex human behavioral studies will become when the social sciences fully integrate an adaptive evolutionary view with a view of human behavioral variation in terms of cultural social norms. So far, a complete theory that predicts when culture will override fitness maximizing ecological adaptation and vice versa is not available. That will be the challenge for the next generation of social scientists, as an “either/or” view is replaced with an integrated evolutionary theory of human behavior.
"behavior" - Google News
January 15, 2021 at 01:54AM
https://ift.tt/3bKoHgn
Behavioral convergence in humans and animals - Science Magazine
"behavior" - Google News
https://ift.tt/2We9Kdi
Bagikan Berita Ini
0 Response to "Behavioral convergence in humans and animals - Science Magazine"
Post a Comment