Question: Why do some people faint at the sight of blood?

Andrew Swale answered on 20 Jun 2013:

I had to google this – and got an interesting answer!

Apparently this is known as ‘vasovagal syncope’ and is present in all of us, although we don’t all exhibit it

It has been preserved through evolution – for example, if a caveman came and chopped your arm off and you saw the blood and fainted, he may think you were dead and therefore leave, and you would therefore survive