Many tens of thousands of years ago, the tundra landscape of Northern Eurasia and America was significantly different. It was part of a high pressure system, giving a more temperate climate, leading to a greater biodiversity than the present day. The picture would typically be of herds of woolly rhinoceroses, bison and wild horses grazing on shrubs and herbaceous plants. However, the dominant animal here was the massive woolly mammoth. These impressive mammals grew up to 3.4 metres tall and weighed in at perhaps as much as 6 tonnes. The most striking feature of these animals was their huge tusks, some as long as 4.2 metres.
The reason these animals hold the public imagination (more so than other remarkable creatures, such as the giant sloth) is that many specimens have been immaculately preserved in ice. This is also why the mammoth is one of only two extinct organisms to have had its DNA sequenced (the other being Neanderthals). This sequencing has opened many intriguing possibilities.
Firstly, the DNA of the mammoth had to be extracted. This stage was done using 20 balls of hair found frozen in Siberian permafrost. The hair was more advantageous to use than bones for two reasons: less contamination because the keratin (the protein found in hair and nails) protected the DNA, and the DNA was more easily removed.
Next the DNA was sequenced. Essentially DNA is the genetic code for all organisms. It consists of ‘bases’, of which there are four, called A, T, C and G. Previously, mammoth DNA had only been sequenced from the mitochondria in the cell (only 13 of the 20,000 genes are here). However this experiment studied the nuclear DNA, which codes for the actual physical characteristics of the mammoth. The research was carried out by biologists at Penn State University.
The results of the experiment yielded many interesting observations. The first was that the mammoth population split into two different sub-populations around 2 million years ago. One of these populations went extinct 45,000 years ago, whereas the other about 10,000 years ago. The data also showed that mammoths had a low genetic diversity, which meant that they were much more susceptible to a particular disease, which is a possible cause of extinction. Perhaps we owe the cavemen a sincere apology for blaming them?
The question most will now be asking themselves is evident: using this data, is there the possibility of bringing the mammoth back to life? The answer, in short, is yes, but there are obvious stumbling blocks. There are two feasible methods which would allow for the recreation of the species.
One method would involve taking an elephant egg cell, removing the genetic material and replacing it with the nucleus from mammoth tissue. This fertilised egg (or zygote) would then be inserted back into a female elephant, and the calf would be a clone of the mammoth whose DNA was used. This method is virtually identical to that used to create Dolly the sheep in 1996. The method is known to work, since it was employed in 2011 when the first ever extinct animal, the Pyrenean Ibex, was brought ‘back to life’. However, the new-born kid (baby goat) only survived for seven minutes after birth due to lung defects. This is a reminder of the difficulties faced in cloning complex animals. It took 277 attempts to make Dolly.
The second method would involve the artificial insemination of an elephant egg cell with the sperm cell from a frozen mammoth. The offspring would be a hybrid of an elephant and a mammoth (perhaps a mammophant?!) but after successive cross-breeding of the hybrids, an almost pure mammoth would result. A problem with this method is that sperm cells of living mammals are potent for 15 years at most after deep-freezing.
Despite the difficulties, a team of Japanese, Russian and U.S scientists have aimed to create a mammoth within 6 years, using the first method (using the information from the DNA sequencing). Questions have been raised as to how ethical the result would be: mammoth were very sociable animals and may not be happy without a herd. Secondly, the mammoth’s habitat is much colder now (unfortunately for 20th Century Fox, Manny and Sid from the Ice Age films may never have seen snow). Some people have, therefore, argued that it would be a better use of money to protect the endangered elephants of Africa.
To conclude, the idea of recreating the mammoth is fraught with ethical and technical difficulties, but may provide one of the most testing yet satisfying challenges in modern biology. I suppose in the end, all we really know is that if you cross-bred a mammoth with a kangaroo, you would end up with huge holes in the ice (!)