Svante Pääbo: DNA clues to our inner neanderthal

Link: Svante Pääbo: DNA clues to our inner neanderthal

neuroticthought:

Svante Pääbo and his team at the Max Planck institute are using the technique of genome mapping to determine the history of modern humans. This TED video covers some of the conclusions that the team has found to date.

To start, I want to briefly cover the technique, which is certainly new to me. By mapping the genome I mean cataloging the bases connecting the two strands of the double helix DNA (notated as ATCG). It’s known that mutations can occur when DNA is used, or RNA is synthesized using this base template. The number of mutations that can occur in the synthesis of RNA from DNA increases as a function of time (across history).

Svante Pääbo covers two differences found between genomes from Africa, the Middle East, Europe, and Asia. First, that the genetic difference between two races show that no single mutation is found between the two groups, but rather many different mutations that determine the observed physical differences. These differences are only seen in physical areas of the body that directly relate to the external environment (such as skin colour, hair texture, and some components of the immune system.) Second, the number of differences between Africans and the other four continents increases as you move away from Africa. In a way this shows how modern humans spread from Africa to the other continents.

Now to ancient ancestors: Svante Pääbo used this same genome technique to map and compare as much of the Neanderthal’s genome as possible (~55% so far). They found Neanderthal traits in genomes of those only outside of Europe, and these traits have been around for ~100,000 years. The Neanderthals therefore lived around Europe and probably met modern humans as they came out of Africa around that time. The team applied the same technique to another discovered ancestor, the Denisovans, and found they have common sequences with Neanderthals that date around 640,000 years ago and with humans 804,000 years ago. These sequences were only found in people from New Guinea and some of the other surrounding islands, meaning the Denisovas probably lived around East Asia and the Pacific Islands.

I think the lesson is that we have always mixed, mixed with these earlier forms of humans wherever we met them, and we have mixed with each other ever since.