I am continually gob-smacked by the obsessive public interest in Atlantis. Why, oh why, does a mere mention of this fabled continent quicken the heartbeat of so many? Google, as I just did, “continent of Atlantis,” and you will turn up a whopping 1,020,000 hits. And a depressing number are devoted to bizarre lunatic-fringe theories concerning the location of the sunken continent (my current favorite puts Atlantis somewhere off the coast of the Indonesia).
By contrast, try mentioning Beringia to your friends and kids. How many of them have heard of it? It’s a real, honest-to-goodness sunken land–a huge chunk of northern real estate that once connected Alaska to Siberia and that now lies at the bottom of the Bering Sea. It drowned, as many of you undoubtedly know, when huge ice sheets melted at the end of the last Ice Age and topped up sea levels by some 330 feet.
In my humble opinion, Beringia has it all over Atlantis in terms of sheer wonder. Although much of Beringia lay north of the Arctic Circle, it escaped glaciation at the height of the last Ice Age, a time when Canada was a big lump of ice. Indeed, Beringia was a cold Arctic grassland where all manner of strange and wonderful animals roamed, from giant short-faced bears that stood 12 feet tall when upright, to scimitar cats that possessed steak-knife like teeth for hamstringing prey. (The Yukon Beringia Interpretive Centre has an online gallery showing several cool images of these critters.)
I’ve been thinking about Beringia today because of a marvelous study that Kevin Campbell, a University of Manitoba biologist, and his colleagues just published online in Nature Genetics, and that my colleague Andrew Curry reported in an excellent article in ScienceNow. Essentially Campbell and his team wondered how a mammoth, whose ancestors evolved in the warmth of Africa, managed to adapt to the bitter cold of Ice Age Europe, Beringia and the Americas. Good question, eh?
To answer it, Campbell and his team extracted mammoth DNA from a bone preserved in the Siberian permafrost, then isolated the mammoth gene that regulated hemoglobin. The team then inserted this gene into Escherichia coli bacteria that they cultivated in a laboratory Petri dish. The E. coli produced enough mammoth hemoglobin to analyze and to compare with the hemoglobin from African and Asian elephants, close relatives of the now extinct mammoths.
Here’s what the team found. Elephant hemoglobin works best at warm temperatures, transporting oxygen more efficiently as muscles heat up. But mammoth hemoglobin works very differently. It transports oxygen at a steady rate, no matter what the temperature. This means that mammoths were able to deliver oxygen to their extremities, even when temperatures plunged– avoiding frozen feet. When you combine this physiological adaptation with physical features such as a thick shaggy coat and little ears, you begin to see why mammoths became the lords of Beringia in their great herds.
I find this study both elegant and insightful. We see plenty of DNA studies these days showing us the ancestry of various species. That’s great. But this study goes one important step further, showing us how mammoths developed the ability to master a cold climate. Ralf-Dietrich Kahlke, a mammoth expert at the Senckenberg Research Institute in Weimar, Germany, told ScienceNow that “This is sort of the first result in paleophysiology.”
I suspect we are about to see many more such studies.
(I apologize to readers who have wondered why I have not been posting regularly recently. I’ve been swamped with assignments, and so could not scrap together the time to write a good post. I’ve decided that it’s better to post quality rather than quantity. So please bear with me. I’ll post as often as I can.)
Photo of Mammoth Model at ZOO Dvůr Králové, Czech Republic, taken by Mistvan.
Map of Beringia. Source: US National Oceanic & Atmospheric Administration (NOAA)
Photo of naturally mummified mammoth taken in what appears to be Russia sometime between 1990-2000. Source: US National Oceanic & Atmospheric Administration (NOAA)