To unlock this achievement, you need to evolve the following:
Simian Neuro-genesis
Ape Colonies
Ape Migration
Scouts*
Inter-genus Dissemination 1
Inter-genus Dissemination 2
Sebaceous Excretion AND/OR Blood Gift
Cutaneous Transfer
Submissive Conception
Excrement*
*required for the achievement
You may have to wait a little while, but if done correctly, you should get the pop-up and achievement.