Igloolik menarche

On the average, menarche occurred at an earlier age in Hall Beach premenopausal mothers (13.4 ± 0.2 yr) than in Igloolik pre- menopausal mothers (14.3 ± 0.2 yr) (t = 2.394, p<.05). In addition, this same group of Hall Beach mothers had their first baby at an earlier age (16.9 ± 0.3 yr) than did their counterparts in Igloolik (17. 9 ± 0.3 yr) (t = 2.554, p<.025). Age at menopause and duration of reproductive period. The mean age at menopause was 52.3 ± 1.0 yr for the 11 naturally postreproductive women in Igloolik for whom data were available and 49.3 ± 1.7 yr for the four naturally postreproductive women in Hall Beach. As the difference between these means was not statistically significant, the two groups were combined. The mean age at menopause was 51.5 ± 0.9 yr for all naturally postreproductive mothers. The period from menarche to natural menopause ranged from 28 to 43 years with a mean of 36.3 ± 1.9 yr for the eight Igloolik mothers for whom these data were available.

Fertility and other Demographic Aspects of the Canadian Eskimo Communities of Igloolik and Hall Beach

Phyllis J. McAlpine and Nancy E. Simpson

Human Biology , Vol. 48, No. 1 (February 1976), pp. 113-138

Published by: Wayne State University Press

Article Stable URL: http://www.jstor.org/stable/41464386

L and Sexual Maturity inferred

Estimation of potential maximum longevity in mammals.-- For nearly 50 years, thanks to the research initiated by Sacher (1959, 1975; Staffeldt and Sacher 1974), a close relationship has been known in extant mammals, including primates, between maximum potential longevity (L) and the biometric characters of brain weight (E) and body weight (P) (Cutler 1975, Hofman 1993; for a review see: Hofman 1993, Hawkes 2006). This relationship is based on the biological quasi-continuum between related species, which are connected by their phylogenies, and the many similarities they generate. Used as an estimator of L for fossil hominins, this relationship has produced values of 52, 78, 93 and 94 years for Homo habilis, Homo erectus, Neanderthals and Homo sapiens sapiens (Hss), respectively, as well as age at sexual maturity taken as one fifth of L, i.e., 12-13, 13-14, 18-19 and 18-19 years respectively (Sacher 1975, Cutler 1975). These estimates were incorporated into palaeodemography 35 years ago, as parameters influencing the shape of the death distribution of fossil hominins (Bocquet and Masset 1977, 1982; Bocquet-Appel 1982). Updated estimates of L, from biometric (estimated) data in more recent literature 1 , using the Hofman regression (1993) 2 , have produced 111.7 and 111.2 years for Neanderthals and Hss respectively, i.e. identical figures between the two metapopulations and similar to those of Sacher (1975) and Cutler (1975). These estimates also suggest that other important determinants of life history, such as age at menarche or duration of gestation, were similar between Neanderthals and Hss, which allows them to be set within a common demographic frame.

Cutler RG. 1975. Evolution of human longevity and the genetic complexity governing aging rate. Proc Natl Acad Sci USA. 72(11):4664-8.

Hawkes K. 2006. Life history theory and human evolution: A Chronicle of ideas and findings. In The Evolution of human life history, K Hawkes and RR Paine (eds). School of American Research press, James Currey: Oxford, UK: 45-93.

Hofman MA. 1993. Encephalization and the evolution of longevity in mammals. Journal of Evolutionary Biology 6: 209-227.

Sacher GA. 1959. Relation of lifespan to brain weight and body weight in mammals. In The lifespan of animals Wolstenholme G.E.W, O'Connor M CIBA Foundation Colloquia on Ageing vol. 5 pp. 115–133. Eds. Boston, MA:Little, Brown.

Sacher GA. 1975. Maturation and Longevity in relation to cranial capacity in hominid evolution. In: Tuttle R Primate Functional Morphology and Evolution. Primate Functional Morphology and Evolution. The Hague. p 417–441.

Sacher GA and Staffeldt EF. 1974. Relation of gestation time to brain weight for plancental mammals: implications for the theory of vertebrate growth. Am. Nat. 108, 593–615.