Scientists who study evolution are 'evolutionary biologists'. 'Evolutionist' is defined as:
1. a person who believes in or supports a theory of evolution, especially in biology.
- Dictionary.com
1. a person who believes in a theory of evolution, esp Darwin's theory of the evolution of plant and animal species
- Collins English Dictionary
a student of or adherent to a theory of evolution
- Merriam-Webster Medical Dictionary
The term dates back to early debates about evolution in the 19th century. Minority Report was using the word perfectly correctly, and his meaning was obvious. Let's move on, eh?