Gorillas’ strategy for survival

COMMUNAL living has its advantages; pooling resources benefits everybody.

Extra eyes and ears provide security from predators, knowledge of food sources can be shared and more mating partners are available. However, there are also downsides. With brothers and sisters living cheek by jowl, ‘consanguinity’ may occur; incest isn’t recommended.

Health defects will appear when particular recessive genes are expressed. A problem gene may be carried, but unexpressed, for generations, over-ruled in each individual by a dominant one from the other parent. These genes ‘run’ in families so, with incestuous relationships, there is an increased risk that copies of a rogue one will be inherited from both sides. The danger is greatest among closely-knit social groups where daughters stay at home well into adulthood.