Endocrines: problems of phylogeny and evolution

摘要

The phyletic differences between groups of vertebrates indicate that the endocrine system has been subject to evolutionary change. A basically simi-lar complement of hormones has been identified throughout the Verte-brata, but several chemical variations of a hormone may exist, and these often have a characteristic phyletic distribution so that putative pathways for their chemical evolution have been proposed. As pointed out by P. B. Med-awar, however, the more fundamentally important aspect of endocrine evo-lution appears to have been the assumption of different functions by the hormones or, as put more precisely by J. B. S. Haldane, "changes in tissue responses to them."