Willing to stand between the neighborhood bully and your pal next door?
California lizards doing just that may have a genetic quirk that scientists have been looking for since the 1960s but hardly ever found.
The search for the genetic phenomenon began as theorists wondered why altruism doesn't just self-sacrifice itself out of existence, explains Andrew G. McAdam of Michigan State University in East Lansing.
One explanation proposed a powerful gene that lets carriers recognize each other and pushes them to do favors for others of their species who happen to carry the gene. For example, men sporting green beards might do good deeds for other green-bearded men, even if they're not brothers or even cousins.