Swarming locusts are famous for devouring everything in their path. Looking for the trigger that makes billions of locusts form one of these devastating hordes, scientists discovered that serotonin turns the usually solitary grasshoppers into highly social -- and highly mobile -- insects.
When there's plenty of forage, locusts are solitary, happily going about their business eating and pooping. As resources dwindle during dry periods, the locusts get more and more crowded and come into physical contact with each other. However, instead of this crowding triggering fighting and increased competition, it instead causes them to be more social. They actively seek each other out, according to this article from ScienceDaily.
The research team found that they could easily make solitary locusts gregarious simply by tickling their hind legs, which simulates the jostling they'd get in the wild. This tickling caused a jump in serotonin in the locusts' brains, which happen to be located in their thoraxes.
According to the story:
Dr Swidbert Ott, from Cambridge University, one of the co-authors of the article, said: "Serotonin profoundly influences how we humans behave and interact, so to find that the same chemical in the brain is what causes a normally shy antisocial insect to gang up in huge groups is amazing."
Professor Malcolm Burrows, also from Cambridge University: "We hope that this greater understanding of the mechanisms causing such a big change in behaviour will help in the control of this pest, and more broadly help in understanding the widespread changes in behavioural traits of animals."
Animals like people? Okay, and why am I covering this in a blog about oxytocin?
The oxytocin and serotonin systems are closely related, and both neurochemicals seem to influence social behavior. Low-serotonin monkey mothers aren't as nice to their babies, and lower levels of mothering behavior in mice create fewer oxytocin receptors in the brains of their pups -- even when they grow up.
It's likely that both of these hold true for humans; and evidently these researchers think their locust research could apply to mammals. Connecting the dots:
Could we be an under-nurtured, low-serotonin, low-oxytocin society? Could this by why we can no longer come together as a unified society, but instead get more stressed out and angry, the closer we get?
University of Cambridge (2009, January 29). How A Brain Chemical Changes Locusts From Harmless Grasshoppers To Swarming Pests.
See also: Oxytocin Deficit Disorder