By studying the brains of obese mice, Dr. Friedman found that leptin rewires feeding circuits in the hypothalamus.  From an evolutionary perspective, susceptibility to obesity can be an advantage or a disadvantage, depending on the resources available in an environment. Genes that predispose individuals to become obese might have evolved to help in surviving times of famine. Dr. Friedman uses population genetics, family history, and detailed medical records to study a population on the Pacific Island of Kosrae suffering an explosive increase in obesity. This research may identify new genes involved in regulating obesity and aid in developing treatments that benefit people on Kosrae and worldwide. From the Series:HHMI’s Understanding Biomedical Research Series