A Grown-up Guide to Oceans

How did we get from single celled organisms to the incredibly diverse ocean ecosystem we have today?

After two billion years of painfully slow evolutionary change what happened to scramble the system and allow the earth to get messy with life? The answer again lies in the ocean. Ben finds out how changing conditions in the ocean allowed animals to evolve from their single celled origins to the huge diversity we see today, and meets some of the first weird and wonderful animals to roam the ocean bottom in Evolutionary Explosions.