As SciAm's Ferris Jabr explains in the video up top, the short answer is: nociceptors. Many animals have these sensory neurons. Some animals have weird ones. Take naked mole rats, for example — NMRs have mutated sodium channels that limit physiologically "normal" nociceptor firing, thereby blunting sensations of pain
Stranded overnight at the Dallas Fort-Worth airport, photographer Joe Ayala and his buddy videotaped themselves running wild in the terminal that became their home for the night. How is this possible in the TSA era? Watch this amazing video and find out.