Deadly Sibling Rivalry

Living species have varying reproductive strategies. Plants and insects produce as many offspring as possible because most of them will not survive. Mammals produce fewer offspring, but devote lots of time and energy to keep them alive. Then there are some species, like certain fishes and birds, that nurture their young while not getting too attached to them. They depend on sibling rivalry to cull the herd, so to speak, and keep only the fittest as their surviving progeny. MinuteEarth introduces us to some families that actually encourage offspring to kill each other. It seems a cruel strategy, but nature is only interested in what works. The video is only 2:25; the rest is an ad.