Had read some midrash or zohar that some apes were human beings who were banished and became apes. Don't remember the source. Does anyone know this?
Masheches Sanhedrin 109 mentions this idea. The Mishna said that the dor haflaga has no share in the world to come. The gemara asks what they did, and says they built a tower. Rav Yermiya bar Elazar says there were three groups:
Some wanted to live in the heavens, so Hashem scattered this group.
Others wanted to serve avoda zarah, so Hashem mixed their languages up.
The last group wanted to fight Hashem, so Hashem turned them into monkeys, ruchot (spirits), and sheidim.