title: Cognitive performance across the life course of Bolivian forager-farmers with limited schooling.
abstract: Cognitive performance is characterized by at least two distinct life course trajectories. Many cognitive abilities (e.g., "effortful processing" abilities, including fluid reasoning and processing speed) improve throughout early adolescence and start declining in early adulthood, whereas other abilities (e.g., "crystallized" abilities like vocabulary breadth) improve throughout adult life, remaining robust even at late ages. Although schooling may impact performance and cognitive "reserve," it has been argued that these age patterns of cognitive performance are human universals. Here we examine age patterns of cognitive performance among Tsimane forager-horticulturalists of Bolivia and test whether schooling is related to differences in cognitive performance over the life course to assess models of active versus passive cognitive reserve. We used a battery of eight tasks to assess a range of latent cognitive traits reflecting attention, processing speed, verbal declarative memory, and semantic fluency (n = 919 individuals, 49.9% female). Tsimane cognitive abilities show similar age-related differences as observed in industrialized populations: higher throughout adolescence and only slightly lower in later adulthood for semantic fluency but substantially lower performance beginning in early adulthood for all other abilities. Schooling is associated with greater cognitive abilities at all ages controlling for sex but has no attenuating effect on cognitive performance in late adulthood, consistent with models of passive cognitive reserve. We interpret the minimal attenuation of semantic fluency late in life in light of evolutionary theories of postreproductive life span, which emphasize indirect fitness contributions of older adults through the transfer of information, labor, and food to descendant kin. (PsycINFO Database Record
authors: Department of Anthropology, University of California, Santa Barbara.
authors: Michael
authors: M
authors: Gurven
authors: Department of Anthropology, University of California, Santa Barbara.
authors: Eric
authors: E
authors: Fuerstenberg
authors: Department of Anthropology, University of California, Santa Barbara.
authors: Benjamin
authors: B
authors: Trumble
authors: Institute for Advanced Study in Toulouse.
authors: Jonathan
authors: J
authors: Stieglitz
authors: Department of Anthropology, University of New Mexico.
authors: Bret
authors: B
authors: Beheim
authors: Department of Anthropology, University of Utah.
authors: Helen
authors: H
authors: Davis
authors: Department of Anthropology, University of New Mexico.
authors: Hillard
authors: H
authors: Kaplan
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001838:Bolivia; D002648:Child; D003071:Cognition; D000066492:Cognitive Aging / Q000523:psychology*; D003430:Cross-Sectional Studies; D004522:Educational Status; D000067565:Farmers / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D011581:Psychological Tests; D055815:Young Adult