Walnut, a red deer born in 1995 on the island of Rum off the coast of Scotland, lived a long life and raised 14 offspring before passing away at the age of 21. In her later years, she spent most of her time away from the herd, often seen grooming another female deer named Vanity. After Walnut’s death, Vanity spent most of her time alone and eventually passed away at the age of 23. This behavior of older female deer distancing themselves from the group is common, as researchers have observed a decrease in social connections as individuals age.
Researchers studying the red deer population on Rum found that older deer tend to associate with fewer others as they age. This social behavior change is not solely due to the loss of friends, as older deer who recently lost companions tended to socialize more. It appears that older deer have smaller home ranges and prefer taller, less nutritious vegetation, possibly due to competition from younger, more energetic deer. Additionally, older deer may reduce social contacts to avoid exposure to gastrointestinal worms, which are prevalent on the island.
Similar social behavior changes have been observed in aging Soay sheep on the island of Hirta. Older sheep tend to reduce the size of the area they roam, possibly due to physical decline and higher parasite burdens. As animals age, their immune systems may become less effective in fighting off infections, leading to an increased risk of disease. This behavioral tendency to limit social interactions in older animals may be a way to avoid illness and injury.
In contrast to deer and sheep, rhesus macaques on Cayo Santiago spend a significant amount of time engaging in cooperative behaviors like grooming. Older female macaques groom and are groomed just as often as younger animals but become more selective in their social networks. They tend to focus on kin and long-term partners to avoid aggression and injury. After a hurricane devastated the island, socially connected macaques were more likely to survive, indicating the importance of social bonds in challenging times.
While the social behavior changes observed in animals may not directly apply to humans, there are lessons to be learned. Studies of aging animals can provide insights into how social connections impact health and well-being in later life. Understanding the changes in social behavior as animals age can inform interventions and support systems for elderly individuals. Building and maintaining positive social connections can contribute to overall well-being, even in the twilight years when evolutionary adaptations may no longer play a significant role.
