I have been raising a litter of rat pups for the last few weeks, and that led to a discussion with some friends on the cuteness (and lack thereof) of different species of newborns. Horses, deer, guinea pigs, and hares are born precocious, which means they have fur, open eyes, and can move around on their own. Rats, mice, rabbits, and pandas are born altricial, which means they are blind, helpless, and undeveloped. It is a breeding strategy to shorten gestation and protect the young in a den or nest (precocious animals often live out in the open with a herd). The most altricial mammals are marsupials, which, lacking placentas and the hormones involved with them, have to conceive and give birth within a single estrus cycle. A kangaroo joey is born with nothing more than arms to crawl to the pouch and a mouth to suckle. I considered using a kangaroo for this gag, but a panda seemed a more accessible joke, since there are real toys that portray supposed newborn pandas. (They are cute toys, btw. Realism is not always the best strategy.)