Better explicating the strengths and shortcomings of these models will help refine projections and improve transparency in the years ahead.
Image credit: Witsawat.S.
Contributed by James W. Vaupel, October 17, 2016 (sent for review July 26, 2016; reviewed by Michael Murphy and Deborah Roach)
Significance
Public interest in social and economic equality is burgeoning. We examine a related phenomenon, lifespan equality, using data from charismatic primate populations and diverse human populations. Our study reveals three key findings. First, lifespan equality rises in lockstep with life expectancy, across primate species separated by millions of years of evolution and over hundreds of years of human social progress. Second, industrial humans differ more from nonindustrial humans in these measures than nonindustrial humans do from other primates. Third, in spite of the astonishing progress humans have made in lengthening the lifespan, a male disadvantage in lifespan measures has remained substantial—a result that will resonate with enduring public interest in male–female differences in many facets of life.
Abstract
The human lifespan has traversed a long evolutionary and historical path, from short-lived primate ancestors to contemporary Japan, Sweden, and other longevity frontrunners. Analyzing this trajectory is crucial for understanding biological and sociocultural processes that determine the span of life. Here we reveal a fundamental regularity. Two straight lines describe the joint rise of life expectancy and lifespan equality: one for primates and the second one over the full range of human experience from average lifespans as low as 2 y during mortality crises to more than 87 y for Japanese women today. Across the primate order and across human populations, the lives of females tend to be longer and less variable than the lives of males, suggesting deep evolutionary roots to the male disadvantage. Our findings cast fresh light on primate evolution and human history, opening directions for research on inequality, sociality, and aging.
Footnotes
- ↵1To whom correspondence may be addressed. Email: jvaupel{at}health.sdu.dk or alberts{at}duke.edu.
Author contributions: S.C.A. and J.W.V. designed research; F.C., R.R., A.B., S.C.A., and J.W.V. performed research; F.C., J.A.B., and A.B. contributed new reagents/analytic tools; F.C., R.R., O.R.J., J.A.B., A.L., L.N., A.S., J.S., C.T., and V.Z. analyzed data; J.A., D.K.B., A.M.B., L.M.F., A.E.P., T.S.S., K.B.S., and S.C.A. provided long-term data; and F.C., D.A.C., A.B., S.C.A., and J.W.V. wrote the paper.
Reviewers: M.M., London School of Economics; and D.R., University of Virginia.
The authors declare no conflict of interest.
Data deposition: The data used in this paper are available from the following websites: nonhuman primate data, http://datadryad.org/resource/doi:10.5061/dryad.v28t5; human life tables, www.mortality.org/; nonhuman life tables, www.demogr.mpg.de/en/laboratories/evolutionary_biodemography_1171/projects/datlife_the_demography_of_aging_across_the_tree_of_life_database_744.htm.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1612191113/-/DCSupplemental.
Freely available online through the PNAS open access option.
Emergence of longevous populations
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