The brain chemical serotonin has been linked to mood in people. It plays a role in sexual desire, appetite, sleep, memory and learning, too.
Under certain conditions, locusts triple the amount of serotonin in their systems, changing the insects from loners to pack animals, Burrows and his co-authors report in Friday’s edition of the journal Science.
These packs can be devastating. They affect 20% of the Earth’s land. Last year a swarm nearly four miles long plagued Australia. They also occur in Africa and Asia and have affected the western U.S.