Evolution by Mixing and Matching
Skeletons of the early horse-relative Eohippus (left) and modern Equus (right). From Animals of the Past by Lucas.
During the early 20th century many biologists were considering a variety of mechanisms other than natural selection as the primary cause of evolutionary change. The trouble was that many of those researchers were often vague when it came to the details of how such alternative processes might work. Such was the case with paleontologist Frederic Augustus Lucas, who apparently preferred to think of evolution as variations stimulated by the environment building upon themselves over time.
I found this to be rather baffling. The process Lucas presented sounded similar to natural selection but clearly was not the same, and he