Data from: Prenatal stress effects in a wild, long-lived primate: predictive adaptive responses in an unpredictable environment

Prenatal maternal stress affects offspring phenotype in numerous species
including humans, but it is debated whether these effects are
evolutionarily adaptive. Relating stress to adverse conditions, current
explanations invoke either short-term developmental constraints on
offspring phenotype resulting in decelerated growth to avoid starvation,
or long-term predictive adaptive responses (PARs) resulting in accelerated
growth and reproduction in response to reduced life expectancies. Two PAR
subtypes were proposed, acting either on predicted internal somatic states
or predicted external environmental conditions, but because both affect
phenotypes similarly, they are largely indistinguishable. Only external
(not internal) PARs rely on high environmental stability particularly in
long-lived species. We report on a crucial test case in a wild long-lived
mammal, the Assamese macaque (Macaca assamensis), which evolved and lives
in an unpredictable environment where external PARs are probably not
advantageous. We quantified food availability, growth, motor skills,
maternal caretaking style and maternal physiological stress from faecal
glucocorticoid measures. Prenatal maternal stress was negatively
correlated to prenatal food availability and led to accelerated offspring
growth accompanied by decelerated motor skill acquisition and reduced
immune function. These results support the ‘internal PAR’ theory, which
stresses the role of stable adverse internal somatic states rather than
stable external environments.