In the new experiment, roosters made fewer alarm calls, meant to warn peers of predators, when placed in front a mirror versus when standing near another rooster. Stefano Spaziani / picture alliance ...

Infinite mirrors are a fun party trick, but the physics behind this phenomenon explains why it may not be true. When you purchase through links on our site, we may earn an affiliate commission. Here’s ...

Daniel Povinelli was in high school when he first read about a clever experiment, published in 1970, that showed chimpanzees—but not monkeys--can recognize themselves in mirrors. "I bought into the ...