New model to find out what makes individuals nice or nasty

Researchers have developed an innovative mathematical model to study why some individuals evolve to be genetically programmed to be nice, while others stay nasty.
Sasha Dall from University of Exeter in the UK and international colleagues designed a new mathematical framework for examining social behaviour in a range of different species that will help advance our understanding of the evolution of sociality.
The theory of kin selection has for some time allowed biologists to explain why some animals and other organisms adopt altruistic behaviour, at their own expense, for the benefit of their relatives- worker bees laying down their lives to promote the welfare of their mother, the Queen, for example, researchers said.

But up until now scientists have not been able to explain the role of genetic polymorphism, or why some individuals appear to be genetically programmed to help others whilst living side-by-side with others who tend to exploit their generosity, they said.
Using colony-living microbes as inspiration to explore why some individuals are by nature generous and others less so, researchers produced an innovative model of social evolution that allows them to understand how far this is likely to be influenced by conditioning or the surrounding environment.
They found that the behaviour of individuals can often evolve to be determined by a set of inherited genetic tendencies that accurately predict social relationships, including their likely relatedness to other members of their community, and their surroundings rather than in direct response to what they sense or experience.

"What we have been able to show is how you can get a situation where you end up with distinct levels of genetically determined niceness coexisting within populations," said Dall.
"Social evolution theory has not previously addressed genetic polymorphism. We have developed a model that allows us to explore this within a general framework alongside other behavioural influences," said Olof Leimar from Stockholm University in Sweden.
The findings were published in the journal PLOS Computational Biology.