9 Science Facts To Make Your Day

3. Blind People Smile Despite Never Having Seen It

As far as we know, smiling is a cross-cultural phenomenon. Babies do it before they can do pretty much anything else, and, despite never having seen it before, people who have been blind from birth will also crack a smile when they are happy.

The research, which analysed more than 4,800 photographs of both blind and sighted people, suggests that expressions of happiness and sadness are innate, not learned.

We're still not quite sure why it should be the case, but smiling just seems to be one of those basic instincts that everybody in the human race shares.