Although members of the same species share more than 99 percent of their genetic makeup, individuals often have small differences, such as in their appearance, susceptibility to disease, and life expectancy. Another difference, one that has gone overlooked from the evolutionary perspective, is personality variation. Even identical twins can have personality types at opposite ends of the spectrum.
This observation has led researchers to ask how evolution may have selected for personality variation within a species. A team from the UK has recently suggested a novel yet simple answer: that variation begets variation. They explain how there is no single ideal personality (as there is an ideal hand or eye, which we all share), but nature instead promotes different personalities.
In their recent study, John McNamara, Philip Stephens, and Alasdair Houston from the University of Bristol, and Sasha Dall of the University of Exeter, Cornwall Campus, explain how natural selection can prevent individuals in a species from evolving toward a single optimum personality, using a game theory scenario.


