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, de 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.

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 yearsold. Because hunters achieve adult size and strength much earlier in life, these results areconsistent with the embodied capital hypothesis and its emphasis on the gradual masteryof cognitively complex hunting strategies […]
Our analysis supports the general conclusion that skill peaks between 30 and 35 years ofage, well after the age of reproductive maturity. Peak skill is typically not much higher thanskill during early adulthood, however. Declines with age are typically slow—an average56 year old has the same proportion of maximum skill as an average 18 year old. There isconsiderable 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 rateof 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

 

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

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.

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