counteract the high albedo of the ice-covered earth and precipitate what is believed to be a violent deglaciation or meltdown, of all the ice under the influence of an enormously elevated carbon-dioxide load in the atmosphere. narrator: the timing of these radically different climates occurs intriguingly close to the beginning of what is known as the cambrian explosion, when complex life on earth began. this closeness in timing has led to questions about the possibility that the snowball earth and its greenhouse aftermath may have been somehow linked to the sudden appearance of many new kinds of animals in the fossil record. hoffman: there were stresses associated with the glaciation. there were obviously stresses associated with the greenhouse aftermath. so you could imagine that that would be an environment in which there would be strong selective pressure and, therefore that might be an incentive for evolutionary change. but the arrival of multicellular animals is not just a change. this is a biological innovation. this is a change to a world in which you had organisms which achieved a level o

counteract the high albedo of the ice-covered earth and precipitate what is believed to be a violent deglaciation, or meltdown, of all the ice under the influence of an enormously elevated carbon-dioxide load in the atmosphere. narrator: the timing of these radically different climates occurs intriguingly close to the beginning of what is known as the cambrian explosion, when complex life on earth began. this closeness in timing has led to questions about the possibility that the snowball earth and its greenhouse aftermath may have been somehow linked to the sudden appearance of many new kinds of animals in the fossil record. hoffman: there were stresses associated with the glaciation. there were obviously stresses associated with the greenhouse aftermath. so you could imagine that that would be an environment in which there would be strong, selective pressure, and, therefore, that might be an incentive for evolutionary change. but the arrival of multicellular animals is not just a change. this is a biological innovation. this is a change to a world in which you had organisms which achieved a lev