1. Longévité et espérance de vie dans les sociétés pré-industrielles.
2. Records de longévité contemporains.
3. L’hypothèse de la grand-mère.
Longévité et espérance de vie dans les sociétés pré-industrielles
Jeremy Koster et al., 2019
Walker et al.(2002) and Gurven et al. (2006) report data from the southern Neotropics that subsistence hunters achieve high proficiency only after reaching advanced ages, roughly 35 to 45 years old. Because hunters achieve adult size and strength much earlier in life, these results are consistent with the embodied capital hypothesis and its emphasis on the gradual mastery of cognitively complex hunting strategies […]
Our analysis supports the general conclusion that skill peaks between 30 and 35 years of age, well after the age of reproductive maturity. Peak skill is typically not much higher than skill during early adulthood, however. Declines with age are typically slow—an average 56 year old has the same proportion of maximum skill as an average 18 year old. There is considerable variation both among sites and individual hunters within study sites. Variation among individuals is described more by heterogeneity in the rate of decline than the rate of gain.
Le second graphique représente l’évolution des décès des adultes par âge. L’âge modal au décès est celui où sont constatés le plus de décès. Il est de l’ordre de 70 ans dans la plupart des sociétés de chasseurs-cueilleurs.
Population and developpement revue, 2007
Older age becomes common late in human evolution
Rachel Caspari & Sang-Hee Lee
Whereas there is significant increased longevity between all groups, indicating a trend of increased adult survivorship over the course of human evolution, there is a dramatic increase in longevity in the modern humans of the Early Upper Paleolithic. We believe that this great increase contributed to population expansions and cultural innovations associated with modernity.
Certaines études un peu anciennes ont pu sous-estimer les âges au décès des adultes, pour des époques historiques, mais sans doute aussi préhistoriques :
INED, Population et sociétés n°380, 2002
Evolutionnary anthropology, 2000
The genetic structure of a tribal population, the Yanomama Indians.
James V. Neel, Kenneth M. Weiss
American journal of physical anthropology, 1975
Records de longévité contemporains
Evidence That Jeanne Calment Died in 1934—Not 1997
Rejuvenation research, 2019
I present a body of data that, I argue, cumulatively casts serious doubt on the validity of Jeanne Calment’s accepted world record of human life span. First, I assess the plausibility of the record based on the life spans of other centenarians in the International Database of Longevity (IDL) and critique some arguments put forward previously in support of that plausibility, including the longevity of Calment’s ancestors. Second, I review the literature dedicated to Calment and discuss multiple contradictions in her interviews, biographies, photos, and documents. I argue that the evidence from these sources motivates renewed consideration of the previously rejected hypothesis that Jeanne’s daughter Yvonne acquired her mother’s identity after her death to avoid financial problems and that Jeanne Calment’s death was reported as Yvonne’s death in 1934. Finally I discuss the importance of reconsidering the principles of validation, due to the possibility of similar problems regarding other exceptionally long-lived people and the mistaken inferences that researchers may draw from flawed datasets. The phenomenon of Jeanne Calment may prove to be an instructive example of the uncertainty of seemingly well-established facts.
The plateau of human mortality: demography of longevity pioneers
Barbi et al
The increasing number of exceptionally long-lived people (Table 1) and the fact that their mortality beyond 105 is seen to be declining across cohorts—lowering the mortality plateau or postponing the age when it appears—strongly suggest that longevity is continuing to increase over time and that a limit, if any, has not been reached. Our results contribute to a recently rekindled debate (15–17) about the existence of a fixed maximum life span for humans, underwriting doubt that any limit is as yet in view.
Comment on “The plateau of human mortality: Demography of longevity pioneers”
Beltran-Sanchez et al.
Barbi et al. (Reports, 29 June 2018, p. 1459) reported that human mortality rate reached a “plateau” after the age of 105, suggesting there may be no limit to human longevity. We show, using their data, that potential lifespans cannot increase much beyond the current 122 years unless future biomedical advances alter the intrinsic rate of human aging.
Response to Comment on “The plateau of human mortality: Demography of longevity pioneers”
Barbi et al.
Beltrán-Sánchez et al. based their comment on misleading calculations of the maximum survival age. With realistic numbers of people attaining age 105 and the estimated plateau, the Jeanne Calment record is indeed plausible.
Errors as a primary cause of late-life mortality deceleration and plateaus
Saul Justin Newman
Here, it is shown that late-life mortality deceleration (LLMD) and late-life plateaus are caused by common demographic errors. […] ageing does not slow or stop during old age in humans, and that there is a finite limit to human longevity.
Hypothèse de la grand-mère
Postreproductive killer whale grandmothers improve the survival of their grandoffspring
Stuart Natrass et al.
Why humans and some species of whales go through menopause remains an evolutionary puzzle. In humans, postreproductive females gain genetic benefits by helping family members—particularly increasing their number of surviving grandoffspring. The extent to which these grandmother benefits are important in the evolution of menopause in whales remains unclear. Here, we test the grandmother effect in resident killer whales, where females can live for decades after their last reproductive event. We show that grandmothers increase the survival of their grandoffspring, and these effects are greatest when grandmothers are no longer reproducing. These findings can help explain why killer whales have evolved the longest postreproductive life span of all nonhuman animals.
Crucial Contributions: A Biocultural Study of Grandmothering During the Perinatal Period
Brooke A. Scelza & Katie Hinde
Human Nature, 2019
Maternal grandmothers play a key role in allomaternal care, directly caring for and provisioning their grandchildren as well as helping their daughters with household chores and productive labor. Previous studies have investigated these contributions across a broad time period, from infancy through toddlerhood. Here, we extend and refine the grandmothering literature to investigate the perinatal period as a critical window for grandmaternal contributions. We propose that mother-daughter co-residence during this period affords targeted grandmaternal effort during a period of heightened vulnerability and appreciable impact. We conducted two focus groups and 37 semi-structured interviews with Himba women. Interviews focused on experiences from their first and, if applicable, their most recent birth and included information on social support, domains of teaching and learning, and infant feeding practices. Our qualitative findings reveal three domains in which grandmothers contribute: learning to mother, breastfeeding support, and postnatal health and well-being. We show that informational, emotional, and instrumental support provided to new mothers and their neonates during the perinatal period can aid in the establishment of the mother-infant bond, buffer maternal energy balance, and improve nutritional outcomes for infants. These findings demonstrate that the role of grandmother can be crucial, even when alloparenting is common and breastfeeding is frequent and highly visible. Situated within the broader anthropological and clinical literature, these findings substantiate the claim that humans have evolved in an adaptive sociocultural perinatal complex in which grandmothers provide significant contributions to the health and well-being of their reproductive-age daughters and grandchildren.
Chapman et al.
Current biology, 2019
The presence of maternal grandmothers aged 50–75 increased grandchild survival
after weaning, confirming the fitness advantage of post-reproductive lifespan. However, co-residence with paternal grandmothers aged 75+ was detrimental
to grandchild survival, with those grandmothers close to death and presumably in poorer health particularly associated with lower grandchild survival. The age limitations of gaining inclusive fitness from grandmothering suggests that grandmothering can select for post-reproductive longevity only up to a certain point.
Kristen Hawkes & Barbara L. Finlay
Physiology & behavior, 2018
Among mammals, including humans, adult brain size and the relative size of brain components depend precisely on the duration of a highly regular process of neural development. Much wider variation is seen in rates of body growth and the state of neural maturation at life history events like birth and weaning. Large brains result from slow maturation, which in humans is accompanied by weaning early with respect to both neural maturation and longevity. The grandmother hypothesis proposes this distinctive combination of life history features evolved as ancestral populations began to depend on foods that just weaned juveniles couldn’t handle. Here we trace possible reciprocal connections between brain development and life history, highlighting the resulting extended neural plasticity in a wider cognitive ecology of allomaternal care that distinguishes human ontogeny with consequences for other peculiarities of our lineage.
Ellis et al.
Ecology and evolution, 2017
despite considerable interest, the taxonomic prevalence of post-reproductive stagesremains unclear and debated. In this study we use life tables constructed from pub-lished data on wild populations of mammals, and statistical measures of post-repro-ductive lifespans, to distinguish true post-reproductive stages from artefacts ofsenescence and demography in 52 species. We find post-reproductive stages are rarein mammals and are limited to humans and a few species of toothed whales.
Mirkka Lahdenperä et al.
we found that grandcalves from young mothers (<20 years) had 8 times lower mortality risk if the grandmother resided with her grandcalf compared to grandmothers residing elsewhere. Resident grandmothers also decreased their daughters’ inter-birth intervals by one year. In contrast to the hypothesis predictions, the grandmother’s own reproductive status did not modify such grandmother benefits. That elephant grandmothers increased their inclusive fitness by enhancing their daughter’s reproductive rate and success irrespective of their own reproductive status suggests that fitness-enhancing grandmaternal effects are widespread and challenge the view that grandmother effects alone select for menopause coupled with long post-reproductive lifespan.
Alternatives to the Grandmother Hypothesis
we found that the survival of the maternal grandmother and grandfather, but not the paternal grandmother and grandfather, was associated with decreased grandoffspring mortality. […] When tested against the predictions of five hypotheses (confidence of paternity; grandmothering, kin proximity, grandparental senescence, and local resource competition), our meta-analysis results are most in line with the local resource competition hypothesis. In patrilineal and predominantly patrilocal societies, the grandparents who are most likely to live with the grandchildren have a less beneficial association than those who do not. We consider the extent to which these results may be influenced by the methodological limitations of the source studies, including the use of retrospective designs and inadequate controls for confounding variables such as wealth.
Michael Gurven & Hillard Kaplan
Sara Grainger & Jan Beise
Max Planck institute (working paper, jamais publié ?), 2004
Marlowe proposes that extended life span was selected for early in human evolutionary history but that the primary selection pressure was the improved status and mating opportunities that age affords men.
[…] it may pay to cease reproduction atthe point when the risk of maternal mortality (death caused by pregnancy or birth)reaches a certain threshold. This hypothesis has become known as the ‘mothering’ or‘stopping-early’ hypothesis and has received wide support.
[…] Father’s are not expected, froman evolutionary point of view, to be the most dependable helpers given their lack ofcertainty regarding relatedness to offspring. Hawkes et al therefore propose that humanfemales evolved longevity past the age of reproductive-senescence in order to help theirdaughters raise grandoffspring, an idea that has become known as ‘the grandmotherhypothesis’.
[…] if post-generative women also decrease their grandoffsprings’ mortality by 10%, and increasetheir daughters’ fertility by 10%, then women who experience menopause have greaterreproductive fitness than those who do not.
[…]Hawkes (2002) does argue that it would be physiologically possible forreproductive life span to be expanded if there were sufficient selection pressure.
[…]grandmothers seem to have only a very limited effect on thefertility of their daughters, but a significant influence on the survival of grandoffspring.
[…] While there may never have beenany pressure to increase numbers of offspring born, there is surely constant pressure toreduce offspring mortality and thus achieve the optimal number of offspring withminimal loss. The results of the present study suggest that this pressure may have beengreat enough to result in the evolution of post-generative longevity.
[…] In conclusion, if one accepts that it is post-generative life span, rather thanmenopause, that is the anomaly in human life history requiring explanation, the resultsof the current models provide support for the grandmother hypothesis, but little supportfor the stopping-early hypothesis.
The grandmother effect
Why do women live long past the age of child-bearing? Contrary to common wisdom, this phenomenon is not new, and is not due to support for the elderly. Rather, grannies have a lot to offer their grandchildren.
The patriarch hypothesis. An alternative explanation of menopause
Human nature, 2000
Menopause is puzzling because life-history theory predicts there should be no selection for outliving one’s reproductive capacity. Adaptive explanations of menopause offered thus far turn on women’s long-term investment in offspring and grandoffspring, all variations on the grandmother hypothesis. Here, I offer a very different explanation. The patriarch hypothesis proposes that once males became capable of maintaining high status and reproductive access beyond their peak physical condition, selection favored the extension of maximum life span in males. Because the relevant genes were not on the Y chromosome, life span increased in females as well. However, the female reproductive span was constrained by the depletion of viable oocytes, which resulted in menopause.
Grandmothering, menopause, and the evolution of human life histories
Hawkes et al.
Long postmenopausal lifespans distinguish humans from all other primates. This pattern may have evolved with mother–child food sharing, a practice that allowed aging females to enhance their daughters’ fertility, thereby increasing selection against senescence. Combined with Charnov’s dimensionless assembly rules for mammalian life histories, this hypothesis also accounts for our late maturity, small size at weaning, and high fertility. It has implications for past human habitat choice and social organization and for ideas about the importance of extended learning and paternal provisioning in human evolution.
Voyage en terres gérontocides : l’élimination des vieillards comme remède à la vieillesse ?
Cahier des études anciennes, 2018
L’importance aux yeux des Grecs des notions d’âge et de classes d’âge conduit nos auteurs à poser un âge défini pour les exécutions, exprimé en multiples de 10 qui plus est, aussi surprenant soit-il pour des peuples jugés non civilisés et ignorants des computations calendaires15. De telles précisions traduisent des présupposés bien étranges pour les populations citées et renvoient plus sûrement aux déterminations de seuils fonctionnels ou physiologiques de la vieillesse en pays grec, à 60 ou 70 ans
« L’inconséquence de ce qui nous arrive après l’âge de la reproduction n’avait guère d’importance quand on mourait peu d’années après la puberté ».
Laurent Alexandre, La mort de la mort, p44.