John Welsh (biologist)

John Henry Welsh (August 25, 1901 – November 26, 2002) was an American physiologist who pioneered early work on serotonin as a neurotransmitter in invertebrates. He also studied circadian rhythms, neurosecretion, and neuropharmacology.

Welsh was born August 25, 1901, in Boothbay, Maine. He graduated from Berea College in Kentucky in 1922, followed by a M.A. (1922) and Ph.D. (1928) at Harvard University. Welsh was on the staff of Harvard from 1927 until his retirement in 1970. He was Chairman of the Biology Department from 1947-1950, and served important roles at the Bermuda Biological Station for Research during his career. He taught summer courses in invertebrate physiology at the Marine Biological Laboratory in Woods Hole for nearly 40 years. He was also important in the locating of the Bigelow Laboratory for Ocean Sciences in Boothbay, Maine.