Across taxa adverse early-life environments such as drought and psychosocial stress are associated with reduced growth and smaller body size in adulthood. However in wild primates we know very little about whether and to what extent individuals grow plastically in response to adverse early-life environments. Here we use parallel-laser photogrammetry to assess inter-individual predictors of body size in a population of wild female baboons studied since birth. Using over 2000 measurements of 127 females we present the first cross-sectional growth curve of wild female baboons from juvenescence through adulthood. We then tested whether females exposed to three main sources of early-life adversity - drought maternal loss or a cumulative measure of adversity – were smaller for their age compared to females who experienced less adversity. Prolonged early-life drought predicted smaller limb length but not smaller torso length; our other two measures of early-life adversity did not predict differences in body size. We also calculated the first estimates of heritability and maternal effects for body size in a wild primate population. Our results suggest that baboon limbs but not torsos grow plastically in response to energetic early-life stress.
