William H. Calvin,
A Brain for All Seasons: Human Evolution and Abrupt Climate Change.
The Atlantic Monthly cover story, "The Great Climate Flip-flop," first alerted the general public to how the Gulf Stream has failed many times. From a warm-and-wet climate like today’s, the earth suddenly flips into a mode that is cool, dry, windy, and dusty. And it has done this every few thousand years, affecting the climate not only of America and Europe but the entire world.
The article also puzzled many friends of its author, who knew University of Washington professor William H. Calvin as the author of ten insider books about brains and evolution — not about oceanography and the need for major computer simulations of climate change dynamics.
“But what they didn’t know was that I had been following the ice-core story for a dozen years,” Calvin explains. “Climate change is the flip side of the coin from slow evolutionary adaptations for efficiency. Suddenly, just within five years, all of your hard-earned efficiencies are mostly worthless. A flip is so abrupt that adaptations cannot track it. However our ancestors were making a living, they had to scramble for a new niche. And then there’s another climate flip madhouse several thousand years later.”
That’s why Calvin got to know the people who drilled ice cores in Greenland and the oceanographers who studied the Gulf Stream. “It is only when the climate instabilities began 2.5 million years ago that our ancestors’ brains began to enlarge and they learned how to make stone tools. I had long been interested in what those three things — ice ages, toolmaking, and bigger brains — had to do with one another.”
Calvin’s new book, A Brain for All Seasons: Human Evolution and Abrupt Climate Change, is designed as a travelogue, as if it were a seminar by e-mail with a traveling professor. It's about what sudden climate flips did to human evolution, both the downsizing challenges and the abrupt expansionistic opportunities. It starts at the country home of Charles Darwin, just outside London, telling the story of human evolution and climate change as he visits Africa, discussing the unusual opportunities that our ancestors got after the widespread forest fires that the sudden worldwide droughts produced.
ends with a flight over Greenland, looking down on sites where the Gulf Stream
sinks and discussing how this conveyor belt for warmth can fail — and the
prospects for postponing the next failure and the famines and wars it would
spark. It explains why gradual global warming is a likely setup for another
abrupt, catastrophic cooling.
Here is the text of the inside cover, from University of Chicago Press:
One of the most shocking realizations of all time has slowly been dawning on us: the earth's climate does great flip-flops every few thousand years, and with breathtaking speed. In just a few years, the climate suddenly cools worldwide. With only half the rainfall, severe dust storms whirl across vast areas. Lightning strikes ignite giant forest fires. For most mammals, including our ancestors, populations crash.
Our ancestors lived through hundreds of such abrupt episodes since the more gradual Ice Ages began two and a half million years ago--but abrupt cooling produced a population bottleneck each time, one that eliminated most of their relatives. We are the improbable descendants of those who survived--and later thrived.
William H. Calvin's marvelous A Brain for All Seasons argues that such cycles of cool, crash, and burn powered the pump for the enormous increase in brain size and complexity in human beings. Driven by the imperative to adapt within a generation to "whiplash" climate changes where only grass did well for a while, our ancestors learned to cooperate and innovate in hunting large grazing animals.
Calvin's book is structured as a travelogue that takes us around the globe and back in time. Beginning at Darwin's home in England, Calvin sits under an oak tree and muses on what controls the speed of evolutionary "progress." The Kalahari desert and the Sterkfontein caves in South Africa serve as the backdrop for a discussion of our ancestors' changing diets. A drought-shrunken lake in Kenya shows how grassy mudflats become great magnets for grazing animals. And in Copenhagen, we learn what ice cores have told us about abrupt jumps in past climates.
Perhaps the most dramatic discovery of all, though, awaits us as we fly with Calvin over the Gulf Stream and Greenland: global warming caused by human-made pollution could paradoxically trigger another sudden episode of global cooling. Because of the accumulation of greenhouse gases in the atmosphere, the oceanic "conveyor belt" that sends warmer waters into the North Atlantic could abruptly shut down. If that happens again, much of the earth could be plunged into a deep chill within a few years. Europe would become as cold and dry as Siberia. Agriculture could not adapt quickly enough to avoid worldwide famines and wars over the dwindling food supplies--a crash from which it would take us many centuries to recover.
With this warning, Calvin connects us directly to evolution and the surprises it holds. Highly illustrated, conversational, and learned, A Brain for All Seasons is a fascinating view of where we came from, and where we're going.