Baby-Making Proves Costly for Baboon Moms

Even for primates, the day a mother gives birth to her child should be a happy day - except new research reveals that baboon moms' health is at stake while carrying their offspring and even after they're born.

Baboon females are mostly injured on days when they are likely to conceive, the study reports.

Reproduction can be dangerous and energetically costly, exposing individuals to physical harm, infectious disease and reduced immunity. To investigate how long-lived, slow-reproducing species such as primates adjust to this, scientists observed the animals in Kenya over the span of 29 years, making it the longest-running study on wild primates.

After observing groups of yellow baboons, researchers noted 707 injuries to 160 female baboons between 1982 and 2011.

This data is useful in predicting the risk of injury to specific females by taking their ovarian cycle, dominance rank and age into account, as well as whether their social group is separating into two or more distinct groups. Ovulating females are, for instance, twice as likely to be wounded as those who are in the less fertile days of their cycle. Such injuries occur in the context of reproductive competition through interactions with both adult males and females.

Furthermore, lactating baboons were 21 percent less likely to heal within a certain time period compared to their non-lactating counterparts.

In terms of low-ranking females and their susceptibility to injury, scientists note that these subordinate primates are at higher risk of an attack and subject to more aggression than their peers who are higher up in the ranks.

And older females might incur more injuries because they take greater risks to make the best of their declining reproductive years, or because their health and resilience is generally failing.

"As yet it's unclear if these costs of reproduction influence female survival, but in many species injuries and slow healing have important functional consequences, including reduced mobility and greater risk of infection or predation," Elizabeth Archie of the University of Notre Dame, lead researcher, said in a statement. "Our results contribute to a growing understanding of the costs of reproduction in long-lived species."

The findings are published in the journal Behavioral Ecology and Sociobiology.