Why do we faint?

Swooning maidens and clever horses feature in today's Curious Cases, sent in by listeners to [email protected].

The Squeamish Swoon Science sleuths Hannah Fry and Adam Rutherford investigate the following question sent in by Philip Le Riche:

'Why do some people faint at the sight of blood, or a hypodermic needle, or even if they bash their funny bone? Does it serve any useful evolutionary purpose, or is just some kind of cerebral error condition?'

Adam is strapped onto a hospital tilt table in an attempt to make him blackout and Hannah receives an aromatic surprise.

Featuring consultant cardiologists Dr Nicholas Gall and Dr Adam Fitzpatrick and cardiac physiologist Shelley Dougherty.

The Counting Horse Our second case was sent in by retired primary school teacher Lesley Marr, who asks:

"Can horses count? I think they can. Any ideas about which animals can count and which can't?”

The team considers the case of Clever Hans, and hears from Dr Claudia Uller who has been conducting modern studies on equine counting.

Mathematician Prof Marcus Du Sautoy explains the basic concept of counting to Adam, and Hannah looks across the animal kingdom to find the cleverest mathematical creature.

If you have any questions you'd like the duo to investigate, please email [email protected]

Producer: Michelle Martin

Image: A Canadian guard faints, Credit: Carolo Allegri/AFP/Getty Images