Roaches may not make fascinating dinner guests (unless you’re an entomologist perhaps,) but researchers say that they do possess character traits — and that some are more outgoing than others.
Scientists studied how different members of this “gregarious species” — periplaneta americana, or the American cockroach — behaved when seeking shelter from out in an open space. Noting consistent difference among individuals in how quickly they skittered to shelter, how much they explored their environment, and how long they stayed hidden overall, researchers found broad differences.
“We have categorized the observed personalities. We call them ‘shy or cautious’ and ‘bold or explorers’,” researcher Isaac Planas Sitjà of the Université libre de Bruxelles told the Guardian. His team published their findings in the journal Proceedings of the Royal Society B.
“Shy individuals are those that spend more time sheltered and explore less the arena or the surroundings. Instead, bold individuals are those that spend most part of the time exploring the surroundings and spend less time sheltered.”
The presence of a variety of personalities within a species is thought to be an evolutionary advantage in the case of a widespread crisis or threat. Different personalities mean a variety of responses to catastrophe and an increased likelihood that at least one of those responses will lead to survival.
“Shy or cautious” individuals may be better at avoiding predators, or the swift thud of a human foot, but “bold or adventurous” roaches may be better at seeking out new food sources.
— Mia (@mia_ki_mia) February 5, 2015
Even Bold Roaches Don't Stray
The research team placed radio transmitters on the backs of 304 roaches and released them in groups of sixteen into an open “arena,” kept dark during the experiment, to study their movements as they sought out plastic shelters that had been set up for them.
A group dynamic or “collective personality” also came into play, however, and despite individual differences in behavior — observed when a cockroach was isolated — the group would always end up together under the same shelter eventually.
“There is a collective dynamic — a social influence — that dilutes the individual personality differences,” said Planas-Sitjà. “So in the group, you end up with a similar behavior in everyone.”
Planas-Sitjà said cockroaches were of particular interest in studying personality because — unlike other “gregarious insects” such as ants, for example — they don’t have hierarchies or social structures within their social groups.
“They are all independent, even though they are gregarious,” he says.
“Shy” or “bold” — something to consider the next time a roach flits under the fridge or takes a moment to stare you down first.