Extras

Other eye-catching studies that didn't make the final cut this fortnight:

How losing a close friend to cancer affects our own long-term decision making.

We use a person's distinctive facial movements to help us recognise them.

Does heading the ball affect the cognitive function of female football players?

Chimps create their own weapons for hunting; females and youngsters more than adult males.

Please send us links to eye-catching studies you've seen.