USA — As a professor of geography, Michael Medler knows to ask “Why here?”
Combine that with his academic interest in fire, and Medler has developed an intriguing idea – what he calls a “speculation” – about why early ancestors of humans developed where they did.
The Olduvai Gorge in east Africa’s Great Rift Valley has been called the “cradle of mankind” because of important prehistoric discoveries there. The valley is where Homo erectus, a predecessor of contemporary humans, emerged about 1.8 million years ago and spread outward, helped in part by its ability to use fire.
But how did Homo erectus learn to handle fire, and where did the fire come from?
“Fire’s a really missing element,” said Medler, an associate professor of environmental studies at Huxley College of the Environment.
Some researchers have suggested lightning, natural gas vents or spontaneous peat fires may have been sources. Medler has a different idea.
Geologists have recently confirmed lava flows that spread through the gorge for some 200,000 years, back when Homo erectus appeared on the world stage.
They weren’t violent lava eruptions that threatened everyone and everything in their path with immediate destruction, Medler said. Rather, the flows oozed and surged, setting plants ablaze and providing a steady source of heat for pre-humans to learn about fire.
After all, it’s tough to start a fire by rubbing two sticks together. It’s much easier to stick a branch into lava and watch it ignite, or to carry some burning wood home to start a campfire.
Learning to control fire did much more than provide warmth and keep predators at bay. Controlled fire led to cooked food, and that changed the makeup of proto-humans.
Without the need to grind raw food, teeth and jaws became smaller, and there was no longer need for a ridge atop the skull to anchor massive chewing muscles.
Cooked food is easier to digest, so intestines became shorter. And cooked food provides more calories, so brains became bigger.
Such evolutionary ideas have come from other researchers, but Medler, in a recent article, presented the idea that lava ignited the fires that cooked the food that made such changes possible.
He doesn’t insist that lava fires explain every nuance of pre-human development. He does say they shouldn’t be dismissed as a possible and important piece of the evolutionary puzzle.
“I believe fire has been left out of the mix,” he said.
Medler, 48, grew up in the Northwest, the son of a University of Oregon political science professor. He earned a bachelor’s degree in philosophy, but was already leaning toward environmental studies.
During summers and other times away from school, he built trails and fought forest fires. In 1988, he was one of more than 25,000 people called in to battle fires that scorched more than 1.2 million acre in and near Yellowstone National Park.
“That got me to thinking about fire,” Medler said.
He finished a master’s degree in environmental studies at the University of Oregon and then a doctorate in geography at the University of Arizona, with a focus on forests and fire.
Medler has become an active, public voice in the call for smarter fire management to cope with climate change, urban sprawl into forested areas, and the rise of “megafires” that have become much more routine than the label might suggest.
Nearly four years ago, Medler told a congressional committee that fire seasons are growing longer, megafires are more frequent, and efforts to thin forests are lagging. While stronger land-use zoning, building codes and vegetation controls near dwellings would help, Medler made it clear that forest fires have evolved.
“Perhaps megafires should be viewed as similar to hurricanes, floods, earthquakes and volcanic eruptions,” he testified, “natural disturbances that humans must adapt to since we cannot prevent or stop them.”
Michael Medler’s interesting and often witty paper, “Speculations About the Effects of Fire and Lava Flows on Human Evolution” appeared in a recent issue of “Fire Ecology,” an online journal.