Monday, December 27, 2021

The energetics of uniquely human subsistence strategies: Efficiency leads to leisure, allowing our ancestors to spend more time in contexts that facilitated social learning and cultural development

The energetics of uniquely human subsistence strategies. Thomas Kraft et al. Science Dec 24 2021, Vol 374, Issue 6575. https://www.science.org/doi/abs/10.1126/science.abf0130

Efficiency leads to leisure

Humans are animals—merely another lineage of great apes. However, we have diverged in significant ways from our ape cousins and we are perennially interested in how this happened. Kraft et al. looked at energy intake and expenditure in modern hunter-gatherer societies and great apes. They found that we do not spend less energy while foraging or farming, but we do acquire more energy and at a faster rate than our ape cousins. This difference may have allowed our ancestors to spend more time in contexts that facilitated social learning and cultural development. —SNV


Structured Abstract

INTRODUCTION: Relative to other great apes, humans have large brains, long life spans, higher fertility and larger neonates, and protracted periods of childhood dependency and development. Although these traits constitute the unique human life history that underlies the ecological success of our species, they also require human adults to meet extraordinarily high energetic demands. Determining how human subsistence strategies have met such extreme energy needs, given time and energy expenditure constraints, is thus key to understanding the origins of derived human traits.

RATIONALE: Two major transitions in hominin subsistence strategies are thought to have elevated energy capture: (i) the development of hunting and gathering ~2.5 million years ago, which coincided with brain enlargement and extended postnatal growth, and (ii) the rise of agriculture ~12,000 years ago, which was accompanied by substantial increases in fertility and population densities. These transitions are associated with the exploitation of novel food sources, but it is not clear how the energy and time budgets of early human foragers and farmers shifted to accommodate expensive traits. Some evolutionary reconstructions contend that economical locomotion, cooperation, the use of sophisticated tools, and eventually agriculture increased energy efficiency (i.e., energy gained versus energy spent), beyond that of other great apes. Alternatively, unique human subsistence strategies may reduce time and improve yield, increasing return rates (i.e., energy gained versus time spent).

To test these ideas, we compared subsistence costs (energy and time) and energy acquisition among wild orangutans, gorillas, and chimpanzees with high-resolution data on total energy expenditure, food acquisition, and time allocation, collected among Tanzanian hunter-gatherers (Hadza) and Bolivian forager-horticulturalists (Tsimane). Both populations actively forage (hunt, gather), whereas the Tsimane also practice slash-and-burn horticulture, which permits exploration of further changes in the energetics of subsistence associated with farming. We also assembled a global subsistence energetics database of contemporary hunter-gatherers and horticulturalists.


RESULTS: Relative to other great apes, human hunter-gatherers and horticulturalists spend more energy daily on subsistence, and they achieve similar energy efficiencies despite having more economical locomotion and using sophisticated technologies. In contrast, humans attain much greater return rates, spending less time on subsistence while acquiring more energy per hour. Further, horticulture is associated with higher return rates than hunting and gathering, despite minimal differences in the amount of time devoted to subsistence. Findings from our detailed study of the Hadza and Tsimane were consistent with those from the larger cross-cultural database of subsistence-level societies. Together, these results support prior evidence that the adoption of farming could have been motivated by greater gains per time spent working, and refute the notion that farming lifestyles are necessarily associated with increased labor time.

CONCLUSION: These findings revise our understanding of human energetics and evolution, indicating that humans afford expanded energy budgets primarily by increasing rates of energy acquisition, and not through energy-saving adaptations (such as economical bipedalism or sophisticated tool use) that decrease overall costs. Relative to other great apes, human subsistence strategies are characterized by high-intensity, high-cost extractive activities and expanded day ranges that provide more calories in less time. These results suggest that energy gained from improvements in efficiency throughout human evolution were primarily channeled toward further increasing foraging intensity rather than reducing the energetic costs of subsistence. Greater energetic gains per unit time are the reward for humans’ intense and behaviorally sophisticated subsistence strategies. Humans’ high-cost but high-return strategy is ecologically risky, and we argue that it was only possible in the context of increased cooperation, intergenerational food sharing, and a division of labor. We contend that the time saved by human subsistence strategies provided more leisure time for social interaction and social learning in central-place locations, which is critical for cumulative cultural evolution.

Abstract: The suite of derived human traits, including enlarged brains, elevated fertility rates, and long developmental periods and life spans, imposes extraordinarily high energetic costs relative to other great apes. How do human subsistence strategies accommodate our expanded energy budgets? We found that relative to other great apes, human hunter-gatherers and subsistence farmers spend more energy but less time on subsistence, acquire substantially more energy per hour, and achieve similar energy efficiencies. These findings revise our understanding of human energetic evolution by indicating that humans afford expanded energy budgets primarily by increasing rates of energy acquisition, not through energy-saving adaptations such as economical bipedalism or sophisticated tool use that decrease subsistence costs and improve the energetic efficiency of subsistence. We argue that the time saved by human subsistence strategies provides more leisure time for social interaction and social learning in central-place locations and would have been critical for cumulative cultural evolution.


Choosing from too many options can lead to suboptimal results (choice overload); monkeys do not experience choice overload

No evidence of the choice overload effect in a computerized paradigm with rhesus macaques (Macaca mulatta) and capuchin monkeys (Sapajus apella). Maisy D. Englund, Michael J. Beran. Behavioural Processes, Volume 194, January 2022, 104545. https://doi.org/10.1016/j.beproc.2021.104545

Highlights

• Choosing from too many options can lead to suboptimal results (choice overload).

• This study is the first to test nonhuman animals on the choice overload effect.

• Results indicate that monkeys do not experience choice overload with this paradigm.

• The methodology used here provides insights for future avenues of research.

Abstract: Given the choice, people are often drawn toward more options over fewer options in decision-making scenarios. However, mounting evidence indicates that sometimes, choosing from large arrays can result in suboptimal outcomes. The tendency to be overwhelmed, regretful, or less satisfied with a choice when there are many options to choose from is called choice overload. This effect has been well-studied in adult humans, but comparative research, such as with nonhuman primates, is lacking, despite the fact that such choice behavior may be related to general aspects of cognition that underlie behaviors such as foraging in the wild. In addition, research with monkeys can shed light on whether choice overload is a human-unique phenomenon that may be driven by sociocultural factors, or whether this effect may be shared more broadly among mammals. This experiment tested whether monkeys were susceptible to choice overload effects by using a computerized paradigm in which monkey subjects could choose from three, six, or nine task options. No evidence of choice overload was found for monkeys, although this may have been due to methodological limitations that are described.

Keywords: Choice overloadComparative cognitionNonhuman primatesOverchoiceParadox of choice


Unpleasant odors are registered in the brain particularly fast and at an early stage of olfactory information processing

Localizing the human brain response to olfactory stimulation: A meta-analytic approach. A.Torske, K. Koch, S. Eickhoff, J. Freiherr. Neuroscience & Biobehavioral Reviews, December 27 2021. https://doi.org/10.1016/j.neubiorev.2021.12.035

Highlights

•  This paper provides the scientific community with an all-encompassing, up-to-date perspective on the human olfactory cortex through the quantification of all relevant and available data by implementing a robust meta-analytic approach.

•  The human olfactory cortex exhibits distinct activation patterns for different odor categories.

•  The neural underpinnings of the human sense of smell allows for a deeper understanding of human behavior through the extraction of valuable odorous information from the environment.

Abstract: The human sense of smell and the ability to detect and distinguish odors allows for the extraction of valuable information from the environment, thereby driving human behavior. Not only can the sense of smell help to monitor the safety of inhaled air, but it can also help to evaluate the edibility of food. Therefore, in an effort to further our understanding of the human sense of smell, the aim of this meta-analysis was to provide the scientific community with activation probability maps of the functional anatomy of the olfactory system, in addition to separate activation maps for specific odor categories (pleasant, food, and aversive odors). The activation likelihood estimation (ALE) method was utilized to quantify all relevant and available data to perform a formal statistical analysis on the inter-study concordance of various odor categories. A total of 81 studies (108 contrasts, 1053 foci) fulfilled our inclusion criteria. Significant ALE peaks were observed in all odor categories in brain areas typically associated with the functional neuroanatomy of olfaction including the piriform cortex, amygdala, insula, and orbitofrontal cortex, amongst others. Additional contrast analyses indicate clear differences in neural activation patterns between odor categories.

Keywords: Olfactory cortexSmellNeuroimagingActivation likelihood estimationMeta-analysis


National Latino and Asian American Study: Extramarital sex associated with marital satisfaction, religious attendance; odds of men reporting engaging in extramarital sex was 3.52 times greater than odds of women

Diversity in the prevalence and correlates of extramarital sex in a probability sample of Latino adults. Sanchez, L., Whisman, M. A., Hughes, J. A., & Gordon, K. C. (2021). Diversity in the prevalence and correlates of extramarital sex in a probability sample of Latino adults. Journal of Family Psychology, Dec 2021. https://doi.org/10.1037/fam0000942

Abstract: Individuals from different Spanish-speaking countries are often combined into a single Latino group. However, this group is diverse, with immigrants and naturalized citizens coming from multiple countries. The present study was conducted to (a) examine potential differences in the annual prevalence of extramarital sex as a function of cultural group (Mexican, Cuban, Puerto Rican, or other Latino) and nativity (born inside or outside the United States) and (b) identify explanations for any observed differences in the prevalence of extramarital sex, drawing on known correlates of extramarital sex and other psychosocial constructs that may be associated with cultural group or nativity that could account for such associations. Results from the National Latino and Asian American Study, a probability sample of Latinos in the United States, indicated that the annual prevalence of extramarital sex was significantly higher among (a) Puerto Ricans relative to Mexicans and (b) foreign-born individuals relative to those born in the United States. Probability of extramarital sex was significantly associated with marital satisfaction and frequency of religious attendance, but these variables did not account for the subgroup differences in the prevalence of extramarital sex. Marital adjustment, acculturation (English proficiency and use), enculturation (ethnic identity), and family cohesion were not significantly associated with probability of extramarital sex. Results underscore the need for continued research on understanding subgroup differences in the prevalence of extramarital sex within the diverse Latino community and identifying characteristics that account for such differences.