His Markov Formula grants him unparalleled intellect, but it insidiously steals more than it gives, making him increasingly dull-witted and bestial in form. Despairing, the doctor fled to a tropical island he dubbed Markovia, where he tests new versions of his formula on the local fauna in hopes of recovering his waning genius. As a result of these tests, animals across Markovia now possess sapience and have been deluded into believing Markov is their god.
-Van Richten's Guide to Ravenloft, pg. 170