How did woolly mammoths survive Ice Age?
Woolly mammoth hemoglobin contains unique regions (blue) that interact with other regions (red) to deliver oxygen at a steady rate regardless of temperature. Photo: Royal British Columbia Museum
Remember "Manny"? The beloved woolly mammoth in the Hollywood blockbuster animated series "Ice Age"? For years scientists have wondered how such massive creatures managed to endure such punishing cold weather up until 10,000 BC or so. A recent study by a Canadian-led team of international researchers discovered for the very first time that, mammoths had, in fact more than woolly coats to protect themselves from the frigid conditions of the Arctic's gruelling sub-zero temperatures. To put it simply, the extinct towering creatures had a form of "anti-freeze" blood to keep their bodies supplied with oxygen and stay worm!
Published in the latest edition of the journal Nature Genetics, this breakthrough experiment was headed by noted biologist Dr. Kevin Campbell of the University of Manitoba. The meticulous process of this significant experimentation literally "resurrected" a woolly mammoth's blood protein, also known as haemoglobin, by extracting DNA from the remains of three woolly mammoths that lived in Siberia between 25,000 and 43,000 years ago. It must be mentioned here that it is this haemoglobin that ferries oxygen around the body. Dr. Campbell's team worked closely with DNA expert Prof. Alan Cooper of University of Adelaide, Australia, to isolate the mammoth gene responsible for haemoglobin. The mammoth DNA sequences were converted into RNA (a molecule also similar to DNA and central to the production of proteins) via a process called site-directed mutagenesis, and then inserted into Escherichia Coli (E. coli) bacteria that acted as a host which in turn proficiently manufactured the mammoth's oxygen-transporting protein haemoglobin. According to Dr. Campbell, "It's no different from going back 40,000 years and taking a blood sample from a living mammoth". This was followed by the intense examinations of the mammoth haemoglobin which scientists compared with that of Asian and African elephants (created in the same process using genes from the living animals injected into E. coli). The result was the discovery that elephant haemoglobin functioned much like human one, which is, delivering oxygen more efficiently at warmer temperatures. But in the case of mammoth haemoglobin, it was found that, it released oxygen at a steady rate regardless of the temperature. This means, the mammoth haemoglobin is capable of delivering oxygen to blood cells even in the freezing conditions whereas in the case of humans or elephants, the haemoglobin is temperature sensitive. Meaning it gets sticky as the temperature gets cold and fails to deliver oxygen causing cell death and commencing conditions such as frost bites. Dr. Campbell further suggests that, in addition to the tiny ears and thick wool, these species of mammoths may have developed ways to let their limbs and extremities cool significantly to save energy and conserve their body's core temperature, a physiological behaviours noticed within the cold-adapted modern wild animals like reindeer and muskoxen.
The woolly mammoths migrated from their tropical origin to the Arctic more than two million years ago. And the recent findings concerning the defence mechanisms of this ancient creature to combat intense cold is being considered a great step towards the knowledge of evolutionary biology which especially involves experimentation of ancient DNA. In a statement released by the University of Manitoba last week, Dr. Campbell stated, "This is the first time we've been able to study biological processes of an extinct animal in precisely the same way we would for living species". Scientists are hoping that this brand new approach would open up new ways to understand how, even at the molecular level, the extinct species adapted to the paleo-envrionments that are no longer present here on Earth.
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