The Evolutionary Origin of Extracellular Chemical Messengers

To the Editor: We congratulate Roth and his colleagues for their excellent work (March 4 issue). 1 However, we would like to point out that some years ago, we proposed an almost identical theory for the original nature and evolution of hormones, although in contrast to Roth and his group, we have concentrated on steroidal messengers. Hormonal steroids were first isolated from mammalian adrenals and gonads. By the early 1970s, the idea of their exclusively mammalian or vertebrate role had been successfully challenged. 2 The omnipresence of vertebrate-type hormonal steroids is now generally accepted, and we have documented the general occurrence or . . . No extract is available for articles shorter than 400 words.