Whether in the Olympics or the NCAA basketball tournament, it's more than just our taste for drama that leads humans to root for the unlikely winner with a compelling back story.
It's in our DNA.
"It's in our genes to root for our own team, but if you don't have your own team playing, you root for the underdog," said University of Tennessee professor Sergey Gavrilets, an ecology and evolutionary biologist.
In fact, we are genetically inclined to help weaker victims fight back against dominating bullies, according to research by Gavrilets published in the Proceedings of the National Academy of Sciences.
Using a mathematical model and specific rules about when someone might be more aggressive against a bully, Gavrilets has chronicled how the human race may have evolved from a species dominated by the strong to a society that values equality.
Other animals that live in communities, such as chimps, are ruled by alpha males, with the weak left to fend for themselves. Humans, meanwhile, have evolved to become interdependent, though our instincts to look out for others isn't just about empathy. It's all motivated by our own well-being, Gavrilets said.
The inherent human drive is to be the best, strongest and most prosperous among our peers, but we also benefit when everyone else is equal. Leveling the playing field means no one else has an advantage to rise above us, Gavrilets said.
"It's something our ancestors did and they achieved an egalitarian state and moral values that emerged later and society became very collaborative, and the species now dominates Earth because of this collaborative behavior," he said.
His research examines a theory that's long existed -- that our species also was once ruled by a hierarchy that put the strongest at the top but eventually became more cooperative. While culture allowed for humans to maintain a society where the weak are protected -- through such things as law enforcement -- there had to be an instinctive, genetic change that happened before the evolution of language and communication, Gavrilets said.
By examining these tendencies, he was able to develop a model that shows it's possible for those instincts to be passed through generations until it becomes a dominant trait. It's information that could be used in the future as we better understand human nature and how we are programmed to interact with each other.
"Take bullying behavior in boys and girls -- it is not because they're bad, it's because it's in their genes. It's an echo of our past of struggle to achieve a high level of social dominance in a group," Gavrilets said. "At the same time, as the model suggests, we also have a counter-dominant (trait) in our genes. It also suggests tendencies to help people."