seedmagazine.com: by Peter Ward

If almost every species on Earth was killed some 250 million years ago, how did our ancient ancestors survive and evolve into us?

In the deep history of our planet, there have been at least five short intervals in which the majority of living species suddenly went extinct. Biologists are used to thinking about how environmental pressures slowly select the organisms most fit for survival through natural selection, shaping life on Earth like an artist sculpting clay. However, mass extinctions are drastic examples of natural selection at its most ruthless, killing off vast numbers of species at one time in a way that is hardly typical of evolution. [ read more ]