Moreover, the same is true of nine out of every 10 animal species, meaning that nearly all of Earth's creatures living today sprang into being recently from some seminal, Big Bang-like event.

Mark Stoeckle at Rockefeller University and David Thaler at the University of Basel reached this striking conclusion after analyzing the DNA "bar codes" of five million animals from 100,000 different species. The bar codes are snippets of DNA that reside outside the nuclei of living cells – so-called mitochondrial DNA, which mothers pass down from generation to generation.

With each reproduction, errors creep into the bar code, as they do when you repeatedly photocopy a document. By measuring the accumulated errors – the blurriness or "diversity" among the bar codes – scientists are able to infer the passage of time.