What caused the Cambrian explosion?

For most of the Earth s history, life consisted of the simplest organisms; but then something happened that would give rise to staggering diversity, and, ultimately, life as complex as that which we see today. Scientists are still struggling to figure out just what that was. Subscribe NOW to The Economist: http://econ.st/1Fsu2Vj Get more The Economist Follow us: https://twitter.com/TheEconomist Like us: https://www.facebook.com/TheEconomist View photos: https://instagram.com/theeconomist/ The Economist videos give authoritative insight and opinion on international news, politics, business, finance, science, technology and the connections between them.