A research team has found that maternal stress leads to changes in the development of primate offspring. Wild macaque mothers that had experienced food shortages gave birth to offspring that grew rapidly but fell behind in other areas, such as motor skill development. The details are in a paper that was just published in the journal Proceedings of the Royal Society B: Biological Sciences.
Previous studies have already shown that maternal stress can affect the development of a fetus. Most animal research has focused on short-lived animals, however, especially those that can be raised in a laboratory. Studies with mice and rats are common but there was a lack of research for wild, long-lived species such as macaques.
Assamese macaques (Macaca assamensis) are Old World monkeys that are found throughout southern Asia. A team of researchers studied macaque populations from a field station in Thailand. The team tracked macaque mothers and their offspring for about two years, noting factors such as food availability. The team also recorded the mothers’ stress hormone levels and data on their offsprings’ motor skill milestones.
The research team found that the offspring of mothers who had experienced food shortages during pregnancy grew faster than normal. This rapid growth came at a cost, however, and these same offspring were late to develop proper motor skills. They were also more vulnerable to conjunctivitis but there wasn’t enough data for the researchers to draw any conclusions. The team does note that maternal stress appeared to affect the immune system development of offspring.
There may be an evolutionary advantage to having offspring develop faster when food availability is low. If offspring grow quickly, they can reach sexual maturity rapidly and reproduce. This makes it more likely that they’ll pass on their genes in a harsh environment. The researchers found several downsides, however, including slower motoric development.
The findings support current evidence that maternal stress affects the development of offspring, even after birth. Macaque mothers exposed to food shortages gave birth to offspring that grew rapidly compared to their peers. More research is needed to determine if rapid growth actually leads to better reproductive success as adults. The team also plans to investigate the effect of maternal stress on cognitive development.
Andreas Berghänel et al. Prenatal stress effects in a wild, long-lived primate: predictive adaptive responses in an unpredictable environment. Proceedings of the Royal Society B: Biological Sciences (2016).