A Comparative Analysis of Age Differences in Social Networks

PROJECT SUMMARY
Strong social relationships are essential for health and well-being, especially in later life. However, as people
age, their social networks shrink, raising concerns about social isolation and its negative effects on older adults’
health. Socioemotional selectivity theory (SST) suggests this narrowing of social networks is not necessarily
detrimental, but instead reflects a shift in older adults’ priorities. According to SST, as people get older, they
become more aware that their time left to live is limited, and this leads them to selectively focus on emotionally
meaningful relationships. SST asserts that these social changes should be unique to humans, as they exclusively
possess the ability to contemplate their mortality and future time horizons.
However, recent research challenges this human-centric view. Nonhuman primates also exhibit age-related
reductions in social networks, despite lacking the cognitive ability to reflect on mortality. Evidence of social
selectivity in nonhuman primates suggests that age-related network narrowing may be a more universal adaptive
response to cognitive decline. Prior research shows that as cognitive abilities decline with age, individuals shift
from exploration (seeking new opportunities) to exploitation strategies (making use of known resources). This
shift could explain why older individuals across species prioritize established relationships over exploring new
ones, as this is a strategy that could optimize resource efficiency in later life.
This project will examine age-related differences in the social networks of capuchin monkeys, comparing
these patterns to those observed in humans. We expect to replicate prior reports of age differences in social
network size in both species (Aim 1). Additionally, we will test whether cognitive abilities (Aim 2) or explore-
exploit tendencies (Aim 3) account for age-related differences in social behavior. Finally, the project will examine
how age differences in social behavior are linked to biomarkers sensitive to physiological aging and
neuropathology, to provide insight into the health implications of these patterns (Aim 4).
In addition to advancing our understanding of social aging, this project will equip Dr. Barber with essential
training in comparative research. Dr. Barber is an established NIH-funded investigator whose research focuses
on social and cognitive aging in humans. Her interest in this project stems from her previous research testing
tenants of SST in humans. While Dr. Barber has no prior experience working with nonhuman primates, this K18
award will provide her with the skills needed to conduct cross-species aging research and foster interdisciplinary
collaborations. Her training will be enhanced through formal coursework in primatology and directed readings in
comparative aging, overseen by her mentor, Dr. Karen Bales. Upon completing the proposed K18 activities, Dr.
Barber will be well-positioned to lead comparative aging research and to explore factors that contribute to species
differences in healthspan and lifespan.

Grant Number: 1K18AG095817-01
NIH Institute/Center: NIH
Principal Investigator: Sarah Barber