Humanity

The Stats menu option is accessible from the pause menu after collecting 42 Goldies (the big golden guys). The first stats to unlock are related to Trials. After collecting 58 Goldies, you unlock the Dog stats. Finally, after collecting 88 Goldies, you unlock the People stats. I unlocked this at beginning of level 5, after collecting all Goldies from level 1,2,3, and most of 4.
I don't remember if the achievement unlocks right after you unlock the Goldy reward, or after you open the Stats menu with all the Stats unlocked.