Imagine falling asleep in your familiar world. And when you wake up, suddenly your whole world has changed. Would you be crying? Cranky? Clinging to the only thing you still know?

Researchers Hetty van de Rijt and Frans Plooij discovered something remarkable in baby chimpanzees in Tanzania in 1971. After showing visible progress, the baby chimpanzees went through periods of regression. They needed the old familiar things and showed decline in independence. After coming home and continuing their research in families, they discovered that it’s no different for human babies.

They found that these changes were down to a sudden leap in brain development. And there are 10 unique leaps in the first 20 months. Using the due date we can even predict when these 10 leaps will begin.