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. 17 in the journal Nature 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.”
Transitivity has been shown in other animals, such as some bird species, while searching for food. But Promislow’s team, led by first author and postdoctoral researcher Devin Arbuthnott, is among the first to see if rationality extends to mate choice.
The researchers showed that individual male fruit flies from one wild-derived strain, called Canton-S, displayed transitivity when presented with potential female mates from 10 different laboratory strains of fruit flies. In these tests, a researcher would place one Canton-S male in an arena with a pair of females, each from a different strain, and note if the male mated with either female.
Read the full article in UW Today.