Darwin Was Right (1924)

Just as he is about to experiment with an elixir of youth, Prof. Henry Baldwin is kidnapped by Courtney Lawson with his secretary, Egbert Swift, and his butler, Alexander, and placed in an asylum. A runaway dogcart deposits three babies in the house, and three escaped chimpanzees take their place. As a result, Alice and Priscilla Baldwin are led to believe that the professor has taken an overdose and has proved that Darwin was correct in theorizing that man is descended from the monkey. There are merry chases when the researchers escape and are pursued by asylum attendants. The villains and the chimpanzees are finally routed.