If the chosen male of a female African cichlid fish gets into a fight with another male, a more ancient part of the brain fires up, sending strong signals of anxiety to the rest of the brain. In the fish, this newfound concern is generally enough to make the female find a new mate, and a more subtle form of this may well go on in human brains as well. Researcher Julie Desjardins explains: “It is the same as if a woman were dating a boxer and saw her potential mate get the crap beat out of him really badly. She may not consciously say to herself, ‘Oh, I’m not attracted to this guy anymore because he’s a loser,’ but her feelings might change anyhow.”