[MUSIC] Whatever happened Neanderthals are extinct now, but extinction may not be what it used to be if you leave behind a genome. We can already read the information in the DNA of extinct species like Neanderthals. We can synthesize that DNA and we can put it into cells for the growing in the laboratory. Then we can look at what the gene does and how the gene functions differently from the human version of the gene. That was how we found out that Neanderthals were red heads. George Church, professor of genetics at Harvard medical school, suggested that you could create an entire Neanderthal genome in a laboratory and put that DNA into a modern human cell and reproduce or resurrect a Neanderthal person. Well obviously, there's a lot of bioethical issues here not least the need for a woman decide that she's gonna be the first mother of a Neanderthal child. The point is that, that we not only have the technology to look into people, to find things about our ancestry, we will likely sometime in the future, the technology to to create with the knowledge we have. Attached to the lecture a couple of interviews with church and the links get you to the TED DeExtinction event held in March 2013. Now, eventual DeExtinction as they put it or extinct species like these is a real possibility. And the TED event was about beginning public discussion of how DeExtension projects can best proceed responsibly. Okay, then let's have a look now to the recent evolution of our species. The other means are very interesting and difficult undertaking. Within the last hundred thousand years, a small founding populations of humans in Africa have expanded to colonize nearly every part of the world. During this time we developed complex languages and cultures, we have medicine, we modify our environment to make it habitable, some people think that culture protects us from evolution. We change our environment rather than change ourselves. Some people think that culture is actually an accelerator and drives evolution, particularly as for much of this time we lived in isolated populations. Not surprisingly, there's disagreement as to the extent which local environments in Africa, Europe, Asia, and elsewhere have altered our genetics and biology. It is however incontrovertible that humans differ in many ways, from skin palettes to immune systems. While some traits probably became widespread by chance, others may have given their owners some sort of evolutionary advantage and were therefor favored by natural or sexual selection. Skin color is a clear example of our changing according to the environment. Skin color correlates with latitude because melanin is a natural sunblock. It's an example of natural selection. We've also been subject to sexual selection. The Maasai, a tribe in east Africa, Maasai women prefer taller men and Maasai men are amongst the tallest in the world. That's sexual selection. A study that appeared in the prestigious journal PNAS in April 2013 reported that penis size matters to women within limits. The findings suggest that women's preferences could have fueled the evolution of the human male penis which is longer, thicker than that of any other male primate. Well, a puzzle about a lot of these theories is that one would expect, given the strength of sexual selection, that all men would have large penises and that all women would fit some standard idea of beauty. In fact, you must have noticed we are immensely variable compared to other species, humans seem particularly prone to mutations of the face, mutations that change our appearance. Some of these mutations seem trivial even though they're conspicuous. In his book The Third Chimpanzee, Jared Diamond suggests that there may have been selection for mutations that allow us to be more tribal to distinguish us from them whoever them might be. Diamond points out that our cultural differences in language and religion heavily influence mating decisions encouraging us to discriminate against others. Once cultural differences had achieved initial separation, he suggests genetic differences accumulated that made it easier for us to notice variation and to distinguish our own kind from others. But in essence, Diamond is suggesting that there's been selection for discrimination fodder for genes that produce conspicuous characteristics that allow us to discriminate against other people. Okay, well let's have a look then at what the genomes have told us so far about the evolution of differences between people. Mathematically minded geneticists have models and methods that can detect rapid evolutionary changes in genomes. And when they look at the similarities and differences between people, they find loci science in the genome that to the change in different human populations over the last 10,000 years. As I mentioned before, every major innovation led to new selective pressures, which in turn led to the selection of genes. The most spectacular innovation has been agriculture but is associated high-density populations, new diseases, changes in diet. Dietary changes required genetic changes. That started a long time ago with eating a lot of meat and taming fowl is continued with more recent innovations like drinking milk. When we first tried milk the lactose it contains made us ill. So we developed a cultural trick we turned milk into cheese but to really exploit milk, we needed mutations. All human babies produce the enzyme lactase to digest milk lactose. Now, mutations in regulatory sequences that allow some of us to produce the lactase enzyme right through our life, not just when we are babies. And now just to be Mampires, mutants that live off the milk of another species. The oldest mutation for this appeared 8,000 years ago in Europe. This 8,000 year old mutant is found throughout Europe and India. They are suspected of being behind the massive expansion of the Indo-Europeans which eventually determined the spoken language of half mankind. This would all have started with a mutation in just one person. That proves, if anything does that a single person changed the world. What Indo-European languages including Spanish, English, Hindi, Russian, Sanskrit. Sanskrit's probably close to the mother tongue of the person with the mutation. Another popular set of mutations allows many of us to consume alcohol. It may surprise you to know that this ability may have been crucial when we took to living in crowded cities. Drinking alcoholic drinks was healthier than drinking plain water as it avoids water-borne pathogens like cholera. Genes that reduce the risk of alcoholism therefore, prevailed. Okay, so I've given a couple of examples where the roles of the rapidly evolving genes is mostly clearly understood. I've also given you examples involving disease resistance, metabolism, and the shape of some of our body parts. The function of most of the rapidly evolving DNA regions are still unknown, which suggests we are more different from each other than we know. In 2013, a team led by Pardis Sabeti at the Broad Institute examined the genomes from 179 people from around the world and they identified 412 DNA regions that were selected for in different population. Well, the challenge of course, is to find out how each mutation in each of these 412 regions changed us and how? So Sabeti's group focused on one gene E-D-A-R, EDAR, known to play a role in the development of hair, teeth, and sweat glands. A version called EDAR370A, those in China are 30,000 years ago, and is found mostly in East Asians and some Native Americans. Now, previous studies have already linked this allele with increased scalp hair thickness and shovel shaped incisors in humans. To further explore the consequences of variety 370A, Yana Kamberov of Harvard Medical School of 370A into mice. Resulting genetically modified mice had thicker hair fibers, more sweat glands in their foot pads, and less fatty mammary glands, which in other words means smaller vests. When they looked they confirmed that Chinese people with EDAR370A have thicker hair fibers and more sweat glands on their hands. EDAR370A clearly has multiple functions. In genetics we call a gene with multiple functions pleiotropy. Well due to the pleiotropy of 370A, it's not clear which of the things it does is beneficial and so would have been selected from. Sweat glands, help humans keep cool in the humid Chinese climate or perhaps Asian men simply found small breasts attractive. Well, evolution is sort of given is really simple. So perhaps all of these things are true. EDAR comparing genomes for selection is now in full swing. Typically in these screens, hundreds of regions show evidence of recent selection so we're very lucky mice are so similar to us. It's estimated that 80% of genes in the mouse genome have exactly one counterpart in us, less than 1% have no counterpart. Through mouse models we may be able to work out what our rapidly evolving DNA sequences do proving our understanding of how humans were shaped by evolution and perhaps even have it continued to this day. [SOUND]
