Mammoth DNA Is World’s Oldest



On February 17, researchers at the Centre for Palaeogenetics* in Sweden made an incredible announcement. They declared that they had successfully extracted DNA from the tooth of a 1.2-million-year-old mammoth. The remarkable achievement marks a new record for the world’s oldest DNA.

As part of their study, researchers analyzed the genomes * of three ancient mammoths. The DNA was recovered from teeth found buried in Siberian permafrost.*

Extracting the DNA proved to be a challenge. The teeth had only small traces of DNA, and even those tiny fragments had degraded over time. To reassemble the pieces and make sense of the DNA, the researchers used the genomes of modern-day elephants. Elephants are relatives of mammoths, so their genetic data can be used as a guide to help fit the pieces of mammoth DNA together.

Using an algorithm, the researchers identified and removed all foreign DNA from other species, and were left with pure mammoth genes.

In all, the scientists recovered millions of DNA base pairs* for each of the three mammoths. This allowed them to estimate the age of the samples by comparing them to younger mammoth fossils and calculating the rate of genetic mutation. They also dated nearby fossils and rocks to check their accuracy. To their amazement, the team discovered that the oldest of the three fossils belonged to a previously unknown species of mammoth. They called it the Krestovka mammoth, after the village where the tooth was found.

“All previous studies had indicated that there was only one species of mammoth in Siberia at that point in time, called the steppe mammoth,” said the study’s lead author, Tom van der Valk.

However, the DNA analyses clearly show that there were in fact two distinct species.

The previous record-holder for the oldest DNA belonged to a horse that lived about 780,000 years ago. As scientists continue to refine their methods, even older genomes are sure to be discovered in the future.

Questions:
1. What was the recently discovered "world's oldest DNA?" Where did the researchers find that?
2. Illustrate how challenging the DNA extraction was. Why did they even utilize modern-day elephants' genomes?
3. Briefly discuss the procedures employed involving the DNA base pairs. What was the most dated out of the 3 mammoth fossils?
4. How significant is it to continue learning more about fossils? Does this even apply to extinct animals from way back?
5. With the ever advancing technology, how do you think this can aid us in understanding the animal culture and history?

Vocabulary:
1. Palaeogenetics - the study of the past through the examination of preserved genetic material from the remains of ancient organisms

2. Base pairs - a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds​