Cockroaches may not be anyone's idea of a cute or cuddly creature, but they do have personalities, or at least individual character traits, researchers in Belgium have discovered.
The finding could go a long way in explaining their evolutionary success as survivors able to adapt to inhospitable environments, the scientists at the Université Libre de Bruxelles say.
Scientists observed the cockroaches, which they characterize as "gregarious insects," to see how they would seek shelter when released into an open area under a bright light.
If all cockroaches were the same "personality-wise," then they should all exhibit identical behavior.
However, the researchers found, there were clear differences in behavior exhibited by individual cockroaches.
"We have categorized the observed personalities," says researcher Isaac Planas-Sitjà. "We call them 'shy or cautious' and 'bold or explorers'."
Shy ones sought shelter and kept hidden much as possible while more adventurous individuals continued to explore their surroundings, he says.
"From studying the way they find shelter, we show that individuals have consistent behavior which can differ between individuals in a group -- cockroaches have personalities," the researchers summarized in a report in the Proceeding of the Royal Society B.
The ability to make an individual choice of whether to remain in the light or hide in a shelter distinguishes cockroaches from other insects like ants and termites, which act together in a strict social hierarchy, they said.
Cockroaches, in contrast, have no leaders, which means they have no followers either, just individuals able to make their own decisions.
That doesn't mean they can't eventually come to a consensus decision as a group, Planas-Sitjà says.
"There is a collective dynamic -- a social influence -- that dilutes the individual personality differences," he explains. "So in the group, you end up with a similar behavior in everyone."
Still, a range of personalities within a group would likely increase the survival chances of cockroaches because the resulting range of varying behaviors would increase the chances of at least some surviving any disaster, the researchers suggested.
Adventurous ones would have a better chances of finding food following a catastrophe, while shy ones would have better chances of avoiding predators, they said, the behaviors taken together increasing the overall chances of a group's survival.
The study results could be applied to other species with similar behavioral patterns, Planas-Sitjà says.
"We have a group of equal individuals that reach a choice, can have consensus decision-making as we can see in sheep, bats, some monkey species, fish, birds, for example, or also humans in this case," he says.