The Proceedings of the National Academy of Sciences

To survive, all organisms must regulate their appetite. Hormones and small proteins called neuropeptides perform this process, stimulating feelings of hunger and fullness. When researchers noted the similarities between GAWamide, a neuropeptide that regulates feeding in the Cladonema jellyfish, and myoinhibitory peptide, a neuropeptide that regulates feeding in fruit flies, they decided to test whether they could exchange the two. Their success in doing so highlights the deep evolutionary origins of feeding regulation.