What makes a Wooly Mammoth different from a circus elephant?
A. They cannot stand on one leg.
B. New discoveries in DNA are beginning to answer this question.
Both answers are correct. Human training is needed for the first.
Since 2008, genetic material has been analyzed from tissues of several mummified mammoths and well-preserved bones. The extracted DNA has varied in quality and a lot of effort has gone into piecing together fragments to come up with complete genomes. The ancient remains date over a range between 4,000 and 60,000 years ago.
How have mammoths changed since sharing ancestors with living elephants? We know that African and Asian elephants evolved in different directions seven million years ago. A million years later, mammoths split off from the evolving line of the Asian elephants. This confirms that mammoths are most closely related to Asian elephants.
These ancestral mammoths came out of Africa three million years ago to populate the temperate, wooded habitats of Europe. From this population, about 1.7 million years ago, those that adapted to cooler conditions and the eating of more grass became distinct as Steppe Mammoths and spread across the northern hemisphere.
Wooly Mammoths, specialized for cold conditions, evolved in Siberia 700,000 years ago and later evolved into two genetically distinct sub-populations. Both groups entered North America about 200,000 years ago and inhabited a large region of the joined continents.
Mammoths became a keystone species of the steppe-tundra during the late glacial periods, having an enormous effect on other animals and plants on the landscape. An eastern genetic branch of Wooly Mammoths dominated, causing a Siberian branch to go extinct 45,000 years ago. The last 40,000 years saw a reduction in genetic diversity to the time of the last living mammoths of Wrangel Island, Siberia, 3,700 years ago.
What does the DNA tell us about Wooly Mammoths?
The DNA we have for direct comparative studies is from Wooly Mammoths living in the last 60,000 years. We are now able to identify specific genes that make the Wooly Mammoth different from modern elephants. These adaptive changes have evolved for better survival in a colder northern climate. The obvious physical traits, reflecting genetic changes, are long hairy coats, thick layers of fat, and small ears that prevent heat loss.
From our current knowledge of the function of specific genes we see changes in mammoth genes specific to the circadian rhythms, adaption to all day light in the summer and darkness in the winter; changes in genes known to control fat cells; genes that encode a skin protein and regulate hair growth; and genes involved in sensing heat and transmitting information to the brain.
We have learned that of over four billion mammoth DNA base pairs, or markers, about 1.4 million are different than those of elephants. These genetic changes have altered over 1,600 protein-coding genes – genes that produce proteins that have a known function. So far there is no evidence for a gene that would better adapt circus elephants to stand on one leg.
Have we learned enough to genetically engineer a living mammoth?
There are two ways in which we can, at least partially, create a mammoth. One is by cloning. This involves taking the nuclei of mammoth somatic cells (body cells, such as those of internal organs, skin, bones and blood) and implanting them into the nuclei of egg cells of a donor Asian elephant.
Embryos would be created that would be implanted in an elephant’s uterus, where they would gestate for 22 months. Although the first step is feasible, the act of it successfully coming to term is a long shot. The success rate with established frozen cloning procedures is only about 30 per cent. If the fetus did come to full term, the baby might look like a mammoth but not necessarily have all the characteristics of a mammoth – especially its behaviour.
The second way to recreate an animal that looks like a mammoth is to insert its specific genes into the cells of living elephants. These cells are first programmed to behave like embryonic cells – that is, cells that can be turned into various cell types. This process will allow scientists to understand how specific mammoth proteins work in different tissues before the final gene implantation that will produce mammoth characteristics.
What scientists often overlook is the nature of the chemical interactions between a mother and a fetus. Genetic material can be exchanged across the placenta between the mother and baby. We know this happens with humans, but do not know what effect this has. The environmental chemistry of the womb, the amniotic fluid and what is called the womb milk that a fetus receives before the mother’s milk, as well as the mother’s milk and her interactive hormonal activities, are unknown variables.
The increasing pace of new discoveries and DNA analysis is rapidly expanding our knowledge of the history of mammoths and their relatives and the possibilities of recreating a new hybrid animal that, at least, will have the outward appearance of a mammoth.