So perhaps intelligent aliens might be subject to alien parasites.
Flinn and his colleagues favor another theory, though.
They argue that humanity underwent a runaway cycle of brain evolution because of hominins' social nature.
The ecological dominance-social competition hypothesis works like this: Human ancestors reached a point in which their interactions with one another were the most important factor in whether they'd survive and pass on their genes.
Many anthropologists and evolutionary biologists have tried to pinpoint the special circumstances that make these huge brains worth the expense.
Charles Darwin suggested that perhaps males developed cleverness to attract females, much as a male peacock developed showy tail feathers to prove to potential mates that he could strut his stuff. could evolve a more efficient, yet just as clever, organ.
Unfortunately, scientists aren't so sure that an actual intelligent alien would be so benign.
[Fight, Fight, Fight: The History of Human Aggression] "If you can walk away from a fight and reproduce another day, you do that," he said.Showing off one's cleverness may be a way of showing off how resistant one is to infection.After all, if you're smart enough to invent language and art, you must be pretty good at battling brain parasites.The evolution of aggression A key part of this theory is competition.Chimps form coalitions that battle against other chimps. So if an alien species were to evolve intelligence, would aggression be an inevitable part of the package? The evolution of aggression is a question unto itself.Finding food and shelter was still important, Flinn said, but it wasn't the main factor determining evolutionary success.