Next Up for Consideration as a Hopelessly Unlikely Solution to the Cambrian Mystery? Global Warming
Add this to the growing pile of improbable causes for complex body plans: volcano heat. In "Volcanic mayhem drove major burst of evolution," over at New Scientist, Catherine Brahic says that had it not been for volcanoes creating a mega-continent, life on Earth would have stopped at its earliest stages.
We now have the best evidence yet that an enormous wave of volcanism, caused by several continents crashing together to form the even greater landmass known as Gondwana, was the reason for a sharp rise in global temperature. This change was the driving force for evolutionary explosions that made life more diverse and laid the foundations for all future animal species. (Emphasis added.)
How, one might ask, does heat turn a cell into a trilobite? She doesn't say. She only finds a coincidence between the Cambrian explosion and "a change in the climate from frigid chill to sweltering heat," according to a "new study" by Ryan McKenzie of the University of Texas at Austin. Before the heat, life just dazed along on a Snowball Earth, getting no further than simple Ediacaran fronds. But add global warming, and the magic happens:
Then came the Cambrian explosion. "You had single cell organisms, single cell, single cell, then weird Ediacaran oddballs, and -- suddenly -- snails and bivalves and sea stars and a whole range of groups that typify the record for the rest of time," says McKenzie's colleague Paul Myrow of Colorado College in Colorado Springs.
McKenzie goes on to ascribe later extinctions and explosions to climate change. For evidence, he appeals to zircon crystals he collected around the world. Within these crystals, he could see volcanoes popping off, raising the temperature as continents rose from the sea. Then he saw the sweltering heat and all the extra CO2 driving simple animals to develop complex body plans.
"This is a fundamentally new and radical idea," says Cin-ty Lee of Rice University in Houston, Texas.
If this hypothesis sounds acceptable for a science magazine, it's a wonder today's climate scientists don't welcome global warming. Think of all the evolutionary novelties that might emerge! Our zoos would be filled with strange, new exotic animals.
"Now we have greater confidence that volcanism and its effect on the greenhouse gas content of the atmosphere drove climate change in deep time," says Kump. "This had direct effects on rates of biotic diversification."
"Biotic diversification" is jargon for the abrupt appearance of two dozen phyla in a geological instant. It's all a function of heat, you see. Heat is a "driving force" that turns a cell into a trilobite.
You can't make this stuff up. Scientific realists might prefer some empirical rigor, some appeal to causes known to produce information-rich systems as exemplified by the Cambrian animals. For that, read Darwin's Doubt, by Stephen Meyer.
Image: Aerial view of the edge of the ice in Nunavut/Wikipedia.