by: Greg Williams
Published in MSN.com
Your testicles are outside your body for a reason, and the reason is this: It’s good for your sperm. Your swimmers develop best at temperatures two to three degrees cooler than the rest of your anatomy, hence the evolution of the unseemly bag of skin and muscle that you lug around all day with your Treo and iPod. Reptiles don’t have to do this, nor do birds, their reproductive organs being discreetly tucked away, like Murphy beds, inside their bodies. But you’re a mammal, and to be a male mammal is to have testicles—and to be a human male mammal in the 21st century is to fret about their ability to function.