Evolution of Sociality

We have established that beavers are very social animals within their tight knit family groups. This creates all of their different communication behaviors that we have looked at so far. Why would these animals choose to live in groups and not just by themselves?

This can be answered by looking at the evolution and advantages of sociality. Sociality evolves if an individual in a group has a higher fitness than it would on its own. Benefits to living in a group include reduced food search times, enhanced resource defense, lower physiological costs of thermoregulation and movement, and shared tasks. These are all great but living in groups also adds some costs. These costs include increased aggression, predator attraction, and disease transmission.

Cooperation between animals is a driving factor for group living. Cooperation is a mutually beneficial interaction where an individual increases the fitness of another individual. When a behavior that results in an increased fitness for one individual and a cost to the other, this is called altruism. Why would an individual just help another out if it was a cost to them? Animals have a desire for their genes to be carried on into future generations. So often times organisms will favor the reproductive success of a relative over their own. This is called kin selection. This evolutionarily supports altruism because their genes will still persist in their relatives. This also supports why altruism is usually stronger with a higher degree of relatedness compared to just doing tasks for random strangers (Nordell & Valone, 2016).

All this can be used to explain why beavers live specifically in family groups and not just with strangers. There are overall benefits to living in these groups and if not for the individual, then for their kin. let's take a look at some of the costs and benefits of the different communication methods to see examples of how sociality and altruism may benefit them!