Brock said:
Whenever I'm bored I can always make myself guffaw with glee at
fainting goats, but what kind of evolutionary f**k up can possibly account for such an obviously useless feature in an animal? Does it stop them running off cliffs when startled by a thunder clap or something?
I'd imagine the gene is a mutation, and probably recessive in the wild, but breeding by man has produced a strain of animals in which it's dominant. Once animals are domesticated by man, straight evolution stops playing such a large role in survival. It may be that the same gene is also linked to some positive trait which outweighs the negative (for example, the link between malaria resistance and suckle cell anaemia in humans - developing sickle cell is bad, but malaria resistance is good, and in a malarial area, convers a reproductive advantage)
On the other hand, possums 'play dead' by fainting, in order to put off a predator not keen on scavenged meat. Maybe it's a similar responce?