A study published in the May 10, 2005, Current Biology has ramifications for neuroscience, developmental genetics, evolutionary biology and, possibly, human teratology (a branch of pathology and embryology concerned with abnormal development and congenital malformations). Among other results, the study, which was carried on frog and chick embryos: • Provides the first molecular support for the idea that serotonin is utilized as a large-scale left-right patterning mechanism, thus offering new insight into the basis of position of the heart and other asymmetric, visceral organs. • Identifies a possible novel serotonin signaling pathway, providing evidence that serotonin can signal inside the cell. If also found in mammals, such signaling, which may be important in brain functioning, would suggest numerous new roles and possible targets for serotonin-related drugs like the selective serotonin reuptake inhibitors (SSRI antidepressants such as Prozac and Zoloft) or the monoamine oxidase inhibitors (MAOIs). • Could lead to a greater understanding of potential health risks from drug families that target the serotonin pathway in human patients. • Sheds light on the evolutionary origin of a crucial neurological control system, suggesting that neuronal synapses using serotonin as a neurotransmitter may have arisen through the adaptation of ancient, fundamental cell-cell signals to a new purpose as nervous systems evolved. The team was led by principal investigator Michael Levin, assistant professor at Harvard Medical School. The study was funded by the National Science Foundation and the American Heart Association.