Evolution de la longévité et de l’espérance de vie

 Longévité et espérance de vie sont deux notions différentes. L’espérance de vie fait référence à l’âge moyen auquel meurt un individu. Elle est généralement de 30 à 40 ans au maximum chez les chasseurs-cueilleurs, et plus généralement dans l’ensemble des sociétés précédant la révolution industrielle, et de l’ordre de 80 ans dans les sociétés industrielles. La longévité est l’âge auquel peut prétendre parvenir un individu s’il échappe aux différentes causes de mortalité accidentelles. Elle est de l’ordre de 70 à 80 ans chez les chasseurs-cueilleurs. La différence entre les deux valeurs s’explique par l’importante mortalité infantile que connaissent les sociétés pré-industrielles, et par une mortalité plus modeste, mais toujours supérieure à celle des sociétés industrielles, tout au long de l’âge adulte.

1. Longévité et espérance de vie dans les sociétés pré-industrielles.
2. Records de longévité contemporains.
3. L’hypothèse de la grand-mère.
4. Divers


Longévité et espérance de vie dans les sociétés pré-industrielles

The life history of human foraging : cross-cultural and individual variation
Jeremy Koster et al., 2019
https://www.biorxiv.org/content/biorxiv/early/2019/03/12/574483.full.pdf
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.
Chasseurs-cueilleurs compétences Koster 2019
L’espérance de vie à 70 ans est encore d’une dizaine d’années chez la plupart des chasseurs-cueilleurs. Elle est encore de quelques années à 80 ans, ce qui signifie que cet âge peut même être dépassé.
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.
Longevity among Hunter-Gatherers: A Cross-Cultural Examination
Gurven et Kaplan, 2007 Age modal au décès

Older age becomes common late in human evolution
Rachel Caspari & Sang-Hee Lee
PNAS, 2004
https://www.pnas.org/content/101/30/10895

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 :

A quel âge mouraient nos ancêtres ?
Claude Masset
INED, Population et sociétés n°380, 2002
https://www.ined.fr/fichier/s_rubrique/18771/pop_et_soc_francais_380.fr.pdf
répartition des décès passés
Ici, chez les Aché, environ 20% des individus atteignent l’âge de 70 ans, environ 10% pour les Hiwi.
A Theory of Human Life History Evolution: Diet, Intelligence, and Longevity
Hillard Kaplan et al.
Evolutionnary anthropology, 2000
https://www.unm.edu/~hkaplan/KaplanHillLancasterHurtado_2000_LHEvolution.pdf
Kaplan et al., 2000
Cette étude chez les Yanomami rapporte environ 5% de survie à 70 ans et encore 1% à 80 ans.

The genetic structure of a tribal population, the Yanomama Indians.
James V. Neel, Kenneth M. Weiss
American journal of physical anthropology, 1975
https://onlinelibrary.wiley.com/doi/abs/10.1002/ajpa.1330420105

Esperance-de-vie-et-survie-yanomami

Records de longévité contemporains

Evidence That Jeanne Calment Died in 1934—Not 1997
Nicolay Zak
Rejuvenation research, 2019
https://www.liebertpub.com/doi/full/10.1089/rej.2018.2167

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
Science, 2018
https://science.sciencemag.org/content/360/6396/1459

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 (1517) 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.
Science, 2018
https://science.sciencemag.org/content/361/6409/eaav1200.full

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.
Science, 2018
https://science.sciencemag.org/content/362/6412/eaav3229.full

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
PLOS, 2018
https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2006776

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

La ménopause est un phénomène rare chez les mammifères. Elle concerne les femmes humaines et quelques femelles d’autres espèces. L’immense majorité des femelles mammifères restent fécondes jusqu’à leur mort. Il a été fait l’hypothèse, il y a une vingtaine d’années, que les femmes ménopausées pouvaient être d’une aide précieuse pour les groupes humains, en améliorant la fécondité des femmes en âge de procréer, en améliorant les chances de survie des enfants, en améliorant la transmission des savoirs… Cela a été théorisé sous le nom d’hypothèse de la grand-mère. Des publications récentes semblent confirmer cette hypothèse, au moins dans certaines limites.

Postreproductive killer whale grandmothers improve the survival of their grandoffspring
Stuart Natrass et al.
PNAS, 2019
https://www.pnas.org/content/early/2019/12/03/1903844116

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
https://www.researchgate.net/publication/337743720_Crucial_Contributions_A_Biocultural_Study_of_Grandmothering_During_the_Perinatal_Period

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.

Limits to Fitness Benefits of Prolonged Postreproductive Lifespan in Women
Chapman et al.
Current biology, 2019
https://www.sciencedirect.com/science/article/abs/pii/S0960982219300089
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.
Mammalian brain development and our grandmothering life history
Kristen Hawkes & Barbara L. Finlay
Physiology & behavior, 2018
https://www.sciencedirect.com/science/article/abs/pii/S0031938418300192
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.
Postreproductive lifespans are rare in mammals
Ellis et al.
Ecology and evolution, 2017
https://www.researchgate.net/publication/322830590_Postreproductive_lifespans_are_rare_in_mammals
despite considerable interest, the taxonomic prevalence of post-reproductive stages
remains 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 of
senescence and demography in 52 species. We find post-reproductive stages are rare
in mammals and are limited to humans and a few species of toothed whales.
Nearby grandmother enhances calf survival and reproduction in Asian elephants
Mirkka Lahdenperä et al.
Nature, 2016
https://www.nature.com/articles/srep27213
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
Beverly I. Strassmann & Wendy M. Garrard
Human nature, 2011
https://link.springer.com/article/10.1007/s12110-011-9114-8

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.

Beyond the Grandmother Hypothesis: Evolutionary Models of Human Longevity
Michael Gurven & Hillard Kaplan
https://pdfs.semanticscholar.org/a4d9/c122b53b3e17849dfd001a7d90364d18caa5.pdf
Gurven Kaplan grand mère contributions
Menopause and post-generative longevity: Testing the ‘stopping-early’ and ‘grandmother’ hypotheses
Sara Grainger & Jan Beise
Max Planck institute (working paper, jamais publié ?), 2004
https://www.demogr.mpg.de/papers/working/wp-2004-003.pdf
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
Kristen Hawkes
Nature, 2004
https://www.nature.com/articles/428128a

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
Frank Marlowe
Human nature, 2000
https://link.springer.com/article/10.1007/s12110-000-1001-7

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.
PNAS, 1998
https://www.pnas.org/content/95/3/1336

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.

 


Divers

Voyage en terres gérontocides : l’élimination des vieillards comme remède à la vieillesse ?
Nadine Bernard
Cahier des études anciennes, 2018
https://journals.openedition.org/etudesanciennes/1102

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

Il semble assez courant chez les transhumanistes de penser que la vie au paléolithique n’apportait aucun avantage évolutif après la naissance du dernier enfant. Au contraire, il leur semble avantageux pour les enfants que les parents décèdent rapidement, pour leur laisser des ressources. C’est très mal connaître l’organisation des sociétés primitives, le temps d’éducation nécessaire aux enfants, et l’importance de la survie des parents, voire des grands parents.
« 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.
Diamandis sur longévité.png
Kurzweil sur longévité