Scientists’ view of animal relationships has changed since the mid-1900s. What development led to this change in scientists’ understanding of the relationships between animals
Work by the American zoologist Libbie Hyman in the mid-1900s
provided the basis for scientists’ understanding of the relationships
among invertebrate species. Hyman based her phylogeny, or evolutionary
history, on major events in development.
The ability to
compare ribosomal DNA and Hox genes has helped to both confirm
and rearrange some relationships among invertebrate animal groups.