Offspring sex and maternal aging

A study suggests that offspring sex can affect maternal aging rates in mammals. Males are larger than females in many animal species, and in such species male offspring tend to place greater demands on parental resources than female offspring, with potential long-term effects on parental aging. However, evidence for such effects is limited. Mathieu Douhard and colleagues assessed the differential costs of male versus female offspring in a wild bighorn sheep population in Alberta, Canada that has been monitored since the early 1970s. Bighorn sheep exhibit pronounced male-biased sexual size dimorphism from birth but lack the complicating sociocultural factors present in human populations. The authors examined the effects of reproduction during the first 7 years of life on reproductive success, defined as the number of offspring surviving to 1 year, from age 8 onward. For a given number of offspring, females that weaned more male than female offspring in early life exhibited a faster decline in reproductive success with age than other females. Much of this decline could be attributed to a more rapid decline in offspring winter survival with age among females that weaned more male than female offspring early in life. The results suggest a need to consider offspring sex ratios in studies of aging, according to the authors.

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Article #19-14654: “Sons accelerate maternal aging in a wild mammal,” by Mathieu Douhard, Marco Festa-Bianchet, and Fanie Pelletier.

MEDIA CONTACT: Mathieu Douhard, Université de Sherbrooke, CANADA; e-mail: <

[email protected]

>; Fanie Pelletier, Université de Sherbrooke, CANADA; tel: 819 821-8000 x 61092, e-mail: <

[email protected]

>