When it comes to mating, fruit flies can make rational choices

Humans make rational choices - though perhaps not all the time. But does the ability for rational decision-making extend to other members of the animal kingdom? If so, how far are they from the human lineage? The answer, according to researchers from the University of Washington, is pretty far. In a paper published Jan. Communications , they report that fruit flies - perhaps the most widely studied insect in history - show signs of rational decision-making when choosing a mate. Through a complex series of behavioral experiments, the team shows that male fruit flies, when presented with a pair of females as potential mating partners, display a key component of rational choice: transitivity. "Transitivity is a hallmark of rational decision-making,” said senior author Daniel Promislow , a UW professor of pathology and biology. "Essentially, it is the process of establishing a rank order of preference, and then making behavioral decisions based on that hierarchy.