The cockroach - one of the nature's great survivors, hated by building residents throughout the entire world, just got more interesting. According to a new study published in the journal Proceedings of the Royal Society B, cockroaches have individual and even group personalities; in other words, cockroaches do have a character.
“Cockroaches are a simple animal, but they can reach a complex decision,” said lead author Isaac Planas-Sitjà, a behavioral ecologist at the Free University of Brussels in Belgium, according to Reuters. “So with little information, with little interactions, only knowing if I have a partner here or not, only with this information, they can make complex decisions.”
Truth be told, cockroaches get a lot of needless bad rep - only 30 species out of 4,600 are associated with human habitats, and out of these, just four species are well known as pests. But those who are pests, are really hard to deal with; cockroaches are generally regarded as some of the most sturdiest species in the world, and for good reason. Some species are capable of remaining active for a month without food and are able to survive on limited resources, such as the glue from the back of postage stamps. Some can go without air for 45 minutes. In one experiment, cockroaches were able to recover from being submerged underwater for half an hour. The cockroach's ability to withstand radiation is also well known, though they are not exceptionally radiation-resistant compared to other insects, such as the fruit fly.
Scientists chose cockroaches for this personality test because they don't live in a clearly layered society, with leaders and workers. Planas-Sitjà and colleagues placed radio frequency identification chips to 304 roaches to track their movements when placed in a new environment, dividing them into 19 groups of 16 individuals. Three days a week, researchers would place each group in a brightly lit plastic area conceived as a shelter, and recorded how they behave. They noted that some cockroaches liked to stay in the shelters more, while others were more shy and didn't enjoy spending time there. Some cockroaches were more bold and spent more time exploring the surroundings, while others took cover immediately.
“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,” said Planas-Sitjà.
The way individuals acted also affected group dynamics: if one roach was quick to settle under a shelter then it might encourage others to do the same, reducing the total amount of time needed to achieve the end result. This came as quite a surprise.
"The fact, and we didn't expect it, is that they always reach this consensus," Planas explained. "So we expected that some groups have more trouble than others to resist consensus or to choose a shelter, but at the end, no, they always finished aggregated. So it is something really inside the individuals or in the cockroaches. So that was really, that was amazing."
It's not the first time surprisingly complex behavior was reported in cockroaches. In 2014, a different team, also from Belgium, found that cockroaches make democratic group decisions. They presented 50 cockroaches with the choice of staying in two or three shelters, and they split equally (25 and 25) into two shelters; however, when they gave them a large enough shelter, they all shared the same shelter.
All in all, Belgium researchers seem adamant to show that cockroaches are much more complex than we previously thought, and they're succeeding. The little insects deserve some recognition - after all, they do have character.