Human childbirth can be a long, painful, drawn-out process, needing assistance and sometimes taking days. So why do close living relatives like chimps have an easier labour, giving birth in hours ...

Following is a transcript of the video. Imagine giving birth to a 24 pound baby. That’s 3 times the size of the average human newborn. Ouch! But for kiwi birds, giant chicks are the norm.

And human moms aren't alone here ... than normal thanks to their brain's salience network. Scientists think giving birth activates this network to help a mother detect threats and protect her ...