Alpheus Hyatt II was born in Washington, D.C. to Alpheus Hyatt and Harriet Randolph (King) Hyatt. He briefly attended the Maryland Military Academy and Yale University, and after graduating from Harvard University in 1862, he enlisted as a private in the Massachusetts Volunteer Infantry for the Civil War, emerging with the rank of captain.
He and his wife, Audella Beebe, were the parents of famed sculptor Anna Hyatt Huntington; their other children were Harriet Randolph Hyatt Mayor, who was a less well known sculptor (and mother of the art historian A. Hyatt Mayor), and Alpheus Hyatt III.
Neo-Lamarckism
Hyatt's views on the evolution of species was expressed in his 1866 paper on On the Parallelism between the Different Stages of Life in the Individual and Those in the Entire Group of the Molluscous Order Tetrabranchiata. In this he claimed that extinction of a species was analogous to death of individual organisms. He proposed that there was an acceleration and a deceleration in the number of species over time which preceded extinction. The movement toward this Neo-Lamarckian understanding was supported by Edward Drinker Cope and Alpheus S. Packard. They were joined by Wiilliam H. Dall, Thomas Meehan, Joel A. Allen, Clarence King, Joseph Le Conte, and Henry Fairfield Osborn.[5]
