Life in the slow lane revisited: Ontogenetic separation between chimpanzees and humans

Robert Walker, Kim Hill, Oskar Burger, A. Magdalena Hurtado

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


This study investigates the evolution of human growth by analyzing differences in body mass growth trajectories among three populations: the Ache of eastern Paraguay, the US (NHANES, 1999-2000), and captive chimpanzees. The relative growth statistic "A" from the mammalian growth law is allowed to vary with age and proves useful for comparing growth across different ages, populations, and species. We demonstrate ontogenetic separation between chimpanzees and humans, and show that interspecific differences are robust to variable environmental conditions. The human pattern of slow growth during the lengthened period from weaning to the beginning of the adolescent growth spurt is found among the Ache (low energy availability and high disease load) and also in the US (high energy availability and low disease load). The human growth pattern contrasts with that of the chimpanzee, where absolute growth rates and relative "A" values are faster and less prolonged. We suggest that selection has acted to decrease human growth rates to allow more time for increased cognitive development with lower body-maintenance costs.

Original languageEnglish (US)
Pages (from-to)577-583
Number of pages7
JournalAmerican journal of physical anthropology
Issue number4
StatePublished - Apr 1 2006
Externally publishedYes


  • Ache foragers
  • Chimpanzees
  • Growth rates
  • Human life history

ASJC Scopus subject areas

  • Anatomy
  • Anthropology


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