scholarly journals Inclusive fitness and differential productivity across the life course determine intergenerational transfers in a small-scale human society

2015 ◽  
Vol 282 (1803) ◽  
pp. 20142808 ◽  
Author(s):  
Paul L. Hooper ◽  
Michael Gurven ◽  
Jeffrey Winking ◽  
Hillard S. Kaplan
Keyword(s):  
Life History ◽  
Inclusive Fitness ◽  
Human Life ◽  
Intergenerational Transfers ◽  
Essential Element ◽  
Life History Evolution ◽  
Small Scale ◽  
Human Society ◽  
Extended Lifespan ◽  
The Life Course

Transfers of resources between generations are an essential element in current models of human life-history evolution accounting for prolonged development, extended lifespan and menopause. Integrating these models with Hamilton's theory of inclusive fitness, we predict that the interaction of biological kinship with the age-schedule of resource production should be a key driver of intergenerational transfers. In the empirical case of Tsimane’ forager–horticulturalists in Bolivian Amazonia, we provide a detailed characterization of net transfers of food according to age, sex, kinship and the net need of donors and recipients. We show that parents, grandparents and siblings provide significant net downward transfers of food across generations. We demonstrate that the extent of provisioning responds facultatively to variation in the productivity and demographic composition of families, as predicted by the theory. We hypothesize that the motivation to provide these critical transfers is a fundamental force that binds together human nuclear and extended families. The ubiquity of three-generational families in human societies may thus be a direct reflection of fundamental evolutionary constraints on an organism's life-history and social organization.

scholarly journals Accurate age estimation in small-scale societies

2017 ◽  
Vol 114 (31) ◽  
pp. 8205-8210 ◽  
Author(s):  
Yoan Diekmann ◽  
Daniel Smith ◽  
Pascale Gerbault ◽  
Mark Dyble ◽  
Abigail E. Page ◽  
...  
Keyword(s):  
Life History ◽  
Bayesian Approach ◽  
Age Estimation ◽  
Human Life ◽  
The Philippines ◽  
Monte Carlo Algorithm ◽  
Small Scale ◽  
Hunter Gatherers ◽  
Cultural Life ◽  
Ranking Order

Precise estimation of age is essential in evolutionary anthropology, especially to infer population age structures and understand the evolution of human life history diversity. However, in small-scale societies, such as hunter-gatherer populations, time is often not referred to in calendar years, and accurate age estimation remains a challenge. We address this issue by proposing a Bayesian approach that accounts for age uncertainty inherent to fieldwork data. We developed a Gibbs sampling Markov chain Monte Carlo algorithm that produces posterior distributions of ages for each individual, based on a ranking order of individuals from youngest to oldest and age ranges for each individual. We first validate our method on 65 Agta foragers from the Philippines with known ages, and show that our method generates age estimations that are superior to previously published regression-based approaches. We then use data on 587 Agta collected during recent fieldwork to demonstrate how multiple partial age ranks coming from multiple camps of hunter-gatherers can be integrated. Finally, we exemplify how the distributions generated by our method can be used to estimate important demographic parameters in small-scale societies: here, age-specific fertility patterns. Our flexible Bayesian approach will be especially useful to improve cross-cultural life history datasets for small-scale societies for which reliable age records are difficult to acquire.

The evolution of childhood as a by-product?

2006 ◽  
Vol 29 (3) ◽  
pp. 288-289
Author(s):  
Peter Kappeler
Keyword(s):  
Life History ◽  
Life Histories ◽  
Nonhuman Primates ◽  
Homo Sapiens ◽  
Human Life ◽  
Life History Evolution ◽  
History Evolution ◽  
Linguistic Skills

The proposition that selective advantages of linguistic skills have contributed to shifts in ontogenetic landmarks of human life histories in early Homo sapiens is weakened by neglecting alternative mechanisms of life history evolution. Moreover, arguments about biological continuity through sweeping comparisons with nonhuman primates do not support various assumptions of this scenario.

Endocrinology

2019 ◽  
pp. 612-672
Author(s):  
Richard G. Bribiescas
Keyword(s):  
Life History ◽  
Social Dynamics ◽  
Human Life ◽  
Life History Evolution ◽  
Sexually Dimorphic ◽  
Human Variation ◽  
Men And Women ◽  
Metabolic Hormones ◽  
Gene Environment ◽  
Key Aspects

This chapter on endocrinology aims to shed light on the biology of hormones within the context of human life history evolution. An evolutionary perspective contributes to not only our understanding of human evolution, but also to the contemporary and emerging health challenges across the spectrum of ecologies and environments. Evolutionary endocrinology extends our understanding of human biology and health through the engagement of gene–environment interactions, social dynamics, human variation, and how hormones regulate life history traits such as growth, immune function, metabolism, and ageing. This chapter describes key aspects of endocrinology that are specific to men and women, while also being mindful of the importance of human variation. For example, men and women exhibit reproductive states that deploy specific functions. In women, these are menstruation, gestation, and lactation. These processes are governed largely by the hypothalamic–pituitary–ovarian axis and how it responds to environmental challenges such as nutritional demands, activity, and social stresses. Men also exhibit reproductive states, although they are mostly in the form of investment in sexually dimorphic tissue and behavioural variation. These states are governed by hormones which allocate resources between tissues that are indicative of different forms of reproductive effort. These include sexually dimorphic muscle tissue and adiposity. Spermatogenesis is obviously key but has differential effects on fertility compared to gametogenesis in women. Additional aspects of human evolutionary endocrinology include stress homoeostasis and metabolism, which involve the hypothalamic–pituitary–adrenal axis as well as the thyroid and other metabolic hormones.

Causes of psychopathology

2015 ◽  
pp. 94-112 ◽  
Author(s):  
Martin Brüne
Keyword(s):  
Life History ◽  
Human Life ◽  
Well Being ◽  
Life History Strategies ◽  
Small Scale ◽  
Immunological Diseases ◽  
Proximate Causes ◽  
Suboptimal Design ◽  
Epigenetic Modulation ◽  
The Impact

The causes of psychiatric and psychosomatic conditions can be categorized into two groups: proximate and ultimate (evolutionary) causes. Proximate causes comprise genetic factors, epigenetic modulation, childhood trauma and other life events, and senescence. Ultimate or evolutionary causes concern mismatch between adaptation and current environment, suboptimal design, and design compromises. Examples of evolutionary causes of dysfunction include cognitive and emotional adaptations to small-scale societies (mismatch), anxiety (suboptimal design), premature birth (design compromise), and other features associated with human life history. Furthermore, many ‘diseases of civilization’ fall under the category of mismatch, as well as immunological diseases that may arise from a lack of exposure to pathogens early in life. Prevention of psychopathology, though desirable, may not always be possible due to the fact that evolution does not select for emotional well-being. However, reducing the impact of early adversity and helping people develop alternative life-history strategies may be an attainable goal.

scholarly journals O brother, where art thou? Investment in siblings for inclusive fitness benefits, not father absence, predicts earlier age at menarche

2017 ◽  
Vol 13 (10) ◽  
pp. 20170464 ◽  
Author(s):  
Daniel Smith
Keyword(s):  
Inclusive Fitness ◽  
Human Life ◽  
Life History Evolution ◽  
Father Absence ◽  
Alternative Interpretation ◽  
Reproductive Age ◽  
Independent Effect ◽  
Age At Menarche ◽  
Parents And Children ◽  
Fitness Benefits

Numerous studies have indicated that father absence is associated with earlier age at menarche, with many evolutionary theories assuming that father absence is a causal factor that accelerates reproductive development. However, an alternative interpretation suggests that offspring may reproduce earlier in the presence of half- or step-siblings as the indirect fitness benefits to investing in them are lower, relative to delaying reproduction and investing in full siblings. From this perspective, father absence may perform no causal role in facilitating the onset of menarche. Using data from the Avon Longitudinal Study of Parents and Children, I find that individuals with only half- or step-siblings reach reproductive age earlier than those with only full siblings, with no independent effect of father absence. These results suggest that inclusive fitness benefits to investing in siblings, rather than father absence, may predict variation in age at menarche. These results provide a greater understanding of the adaptive mechanisms involved in reproductive decision-making, as well as potential implications for human life-history evolution and cooperative breeding more broadly.

scholarly journals Kinship dynamics: patterns and consequences of changes in local relatedness

2021 ◽  
Vol 288 (1957) ◽  
pp. 20211129
Author(s):  
Darren P. Croft ◽  
Michael N. Weiss ◽  
Mia L. K. Nielsen ◽  
Charli Grimes ◽  
Michael A. Cant ◽  
...  
Keyword(s):  
Life History ◽  
Social Evolution ◽  
Inclusive Fitness ◽  
Natural Populations ◽  
Life History Evolution ◽  
The Mean ◽  
The Individual ◽  
Changes Over Time ◽  
Insight Into ◽  
Over Time

Mounting evidence suggests that patterns of local relatedness can change over time in predictable ways, a process termed kinship dynamics. Kinship dynamics may occur at the level of the population or social group, where the mean relatedness across all members of the population or group changes over time, or at the level of the individual, where an individual's relatedness to its local group changes with age. Kinship dynamics are likely to have fundamental consequences for the evolution of social behaviour and life history because they alter the inclusive fitness payoffs to actions taken at different points in time. For instance, growing evidence suggests that individual kinship dynamics have shaped the evolution of menopause and age-specific patterns of helping and harming. To date, however, the consequences of kinship dynamics for social evolution have not been widely explored. Here we review the patterns of kinship dynamics that can occur in natural populations and highlight how taking a kinship dynamics approach has yielded new insights into behaviour and life-history evolution. We discuss areas where analysing kinship dynamics could provide new insight into social evolution, and we outline some of the challenges in predicting and quantifying kinship dynamics in natural populations.

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