I have turned on the steam game recorder on all my games so i can share clips with friends with something funny happens. Turns out the recorder puts a marker in the timeline whenever you get an achievement, and reading the website it mentions that games can place their own pins on the recorder timeline.
I think it would be cool if the game added pins to the steam recorder whenever we evolve our creatures, or otherwise hit a milestone that is not quite worthy of an achievement but is interesting nonetheless.