Abstract
Mothers are crucial for mammals' survival before nutritional independence, but many social mammals reside with their mothers long after. In these species the social adversity caused by maternal loss later in life can dramatically reduce fitness. However, in some human populations these negative consequences can be overcome by care from other group members. We investigated the consequences of maternal loss in mountain gorillas and found no discernible fitness costs to maternal loss through survival, age at first birth, or survival of first offspring through infancy. Social network analysis revealed that relationships with other group members, particularly dominant males and those close in age, strengthened following maternal loss. In contrast to most social mammals, where maternal loss causes considerable social adversity, in mountain gorillas, as in certain human populations, this may be buffered by relationships within cohesive social groups, breaking the link between maternal loss, increased social adversity, and decreased fitness.
Highlights
Maternal loss, along with a number of other indicators of early-life adversity, is one of the strongest predictors of lifespan in humans and other social mammals
To determine the effect of maternal loss on survival, we carried out a Cox-proportional hazards analysis separating individuals based on four maternal orphan classes based on the age at which their mother died: a) infants (2-4 years), b) juveniles (4-6 years), c) sub-adults (6-8 years) and d) non-orphans (>8 years) if mothers died after reaching maturity
Our analyses suggest that the strengthening of relationships with group members post-maternal loss may be greater for younger individuals, which could further reduce the likelihood that they disperse later in life
Summary
Along with a number of other indicators of early-life adversity, is one of the strongest predictors of lifespan in humans and other social mammals. Mothers are vital for the survival of young offspring which are nutritionally dependent on their mother’s milk. Social species with slow life histories , mothers continue to provide benefits to their offspring throughout immaturity and even into adulthood and can dramatically influence their fitness. Maternal loss can reduce the fitness of offspring in a far broader age range through long-term effects on their social environment, negatively influencing their social integration and social status. . Multiple studies have confirmed effects on survivorship for individuals orphaned well past the period of nutritional dependency, with these negative changes to their social environment, often termed social adversity, posited to be the key mechanism by which
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
