Your Ape can evolve to get one of the 4 major roles; Scientist, Businessman, Artist or Farmer by going on a retreat.
Normal retreat has a 60% chance of him getting a role - cost of 333 $PUFF
DMT retreat has a 80% chance - cost of 666 $PUFF
Ayahuasca retreat has a 100% chance - cost of 1420 $PUFF