Only domesticated pigs have curly tails – wild pigs actually have straight tails. There are a number of theories on why this might be the case, the most unexciting being that there is no real reason. The degree of curliness varies in that some domesticated pigs have a slight kink, while others have more of a curl.
Another theory suggests that the curly tail evolved to protect pigs when fighting, as a curlier tail is harder to grasp. However, a more widely held belief is that the curled tail was artificially bred by Chinese farmers as they felt it was more aesthetically pleasing. This seems likely, given that the domestication of pigs occurred in China 8,000 years ago.
