The DNA of the Ancient Egyptians - Archaeological Science Ep 4

Ancient Egypt is home to some of the world's greatest archaeological wonders. From the Rosetta Stone to the Pyramids to the Karnak Temple at Thebes, Egypt will never cease to amaze us. But, beyond the temples, tombs, and pyramids, there's another line of evidence that's completely rewriting the population history of Ancient Egypt. Ancient DNA. I'm Madam Archaeologist, your go-to informant on everything archaeology, and in this episode, I'll dive into the DNA of the Ancient Egyptians and tell you who they're genetically closest to. And it may not be what you expect. A fascinating paper came out in 2017 which outlined the results of DNA tests done on Ancient Egyptian mummies, and it drew an interesting conclusion, that the Ancient Egyptians were genetically closest to ancient populations in the Near East. Researchers had successfully extracted and analyzed DNA from mummies from a site in Middle Egypt known as Abusir el-Melek, spanning the New Kingdom to the Late Roman Period, so from roughly 1380 BC to 425 AD. Egypt's history before Alexander the Great's conquest is divided into a series of dynasties, which themselves are grouped into larger periods depending on Egypt's political stability. After Alexander's conquest in 332 BC, Egypt was ruled by the Greek-Mastonian Ptolemies, of which Cleopatra was a part of, and after Cleopatra's death in 30 BC, Egypt was ruled by the Romans until it fell to the Arabs in the mid-7th century AD. This study included DNA from pre-Ptolemaic times, specifically New Kingdom, Third Intermediate Period, and Late Period mummies, as well as DNA from Ptolemaic and Roman times, so the researchers were able to get a good idea of population dynamics in Abusir el-Melek over the long term. The archaeological site at Abusir el-Melek was an important place in Ancient Egypt due to its connection with the cult of Osiris, the Egyptian god of the dead. It was also inhabited for a very long time, from at least 3,250 BC all the way to 700 AD, or the early Islamic period. In the 2017 study, mitochondrial haplogroups were obtained for 90 mummies excavated from the site, while the nuclear genomes were successfully sequenced for three of the mummies. Two of those three mummies date to roughly between 770-560 BC, which coincides with the Third Intermediate to Late Periods, and one dates to Greco-Roman times. Before moving on, I'll quickly go over what the difference between nuclear and mitochondrial DNA is. Nuclear DNA refers to the DNA that is packed into tiny structures called chromosomes, which are found in the nucleus of cells. Humans have 46 chromosomes inherited in pairs. You get one pair, and so 50% of your DNA from your mother, and the other pair and 50% of your DNA from your father. It can be very hard to study nuclear DNA in archaeology because ancient samples are often very degraded, and the amount of DNA that is preserved depends on several factors, the climate and environmental conditions in which a body is deposited being just a couple of them. The 2017 study was revolutionary because it was thought by many that there wasn't any DNA left in mummies that could be studied, and being able to pair both the nuclear and mitochondrial DNA evidence has helped the researchers get a good idea of population dynamics over time at Abu Sir El Malek. Mitochondrial DNA, also known as mtDNA, is located in an entirely different organelle in our cells called the mitochondria. Everybody inherits their mitochondrial DNA solely from their mother, and so it's used in DNA studies to trace direct maternal ancestry. I won't give you too many technical details, but you should know that as mtDNA gets passed down, it accumulates mutations, and geneticists use these mutations to assign you to a haplogroup, for example L2A1 or K1A. These mutations took place at specific points in time and places, so your haplogroup can tell you about your ancient ancestry. In the 2017 study, the DNA evidence showed, I quote from a summary article by Nature, that the mummies' closest kin were ancient farmers from a region that includes present-day Israel and Jordan, and that ancient Egyptians shared little DNA with modern sub-Saharan Africans. Instead, their closest relatives were people living during the Neolithic and Bronze Ages in an area known as the Levant. Strikingly, the mummies were more closely related to ancient Europeans and Anatolians than to modern Egyptians. The researchers found that modern Egyptians have about 8% more sub-Saharan African DNA than the ancient Egyptians. The researchers think that the trans-Saharan slave trade may have played a big role in this, but we need more DNA studies to confirm this theory. These results also suggest that there was genetic continuity in the town of Abusir el-Melek over the time period in question. For the three mummies whose nuclear genome was studied, the researchers used something called principal component analysis, where they compared the DNA of these three Egyptians to other genetic groups. On this graph, the Abusir el-Melek individuals clustered together, alongside groups in West Asia. Of course, since this study only pertains to one specific place in Egypt, we can't use it to generalize about the genetics of all the ancient Egyptians. But this study is very interesting because it's the first of its kind to reliably give us details on the genetics of the ancient Egyptians using genome-wide analysis, and what we see here is that the ancient Egyptians are more similar to West Asians than to sub-Saharan Africans. You can pause here if you'd like to see which groups the ancient Egyptians were compared to, and how genetically similar or different they all are to the mummies. The researchers were even able to determine what one of the mummies probably looked like based on his genetics. The mummy was radiocarbon dated to 769-560 Cal BC, so before Alexander the Great's conquest. One gene they looked at was SLC24A5, where a mutation led to skin pigmentation. Genes are sections of DNA, some determine what a person will look like, and in this gene, a mutation known as a single nucleotide polymorphism, or SNP, took place, where a nitrogenous base was substituted for another. Our DNA is a double helix composed of four nitrogenous bases that pair up, these are adenine, thymine, guanine, and cytosine, abbreviated A, T, G, and C. A always pairs with T, and G always with C. In gene SLC24A5, a SNP known as RS1426654, refers to the substitution of guanine for adenine. These are called alleles. Adenine is the derived allele, and guanine is the ancestral allele. In other words, if you carry the derived allele, you carry the allele associated with lighter skin color, as does the mummy at Abu Sir el-Balek. Meanwhile, he carried the ancestral allele for eye color in the gene HERK2, meaning that his eyes were most likely brown. For the mitochondrial DNA analysis, 44 out of the 90 mummies were from the pre-Ptolemaic period, 27 from the Ptolemaic period, and 19 from the Roman period. The researchers found that mummies from all three categories were genetically similar in that they are closer to modern populations in the Levant and West Asia generally than modern Egyptians are. Now, a close affinity to the Middle Easterners makes sense. Geographically, Egypt isn't just a part of the African continent, it's attached to West Asia, and the ancient Egyptians had close interactions with populations in that area. These are well documented archaeologically and historically. Let's also not forget that by sea, Egypt is connected to the greater Mediterranean world. Most importantly, however, this research adds support to the theory of a back migration from West Asia into Egypt. But when did that back migration take place? It's possible that Neolithic farmers from the fertile present settled in Egypt early on, eventually giving rise to the Egyptian civilization. We also know that people from the Levant settled in Egypt during the 2nd millennium BC, these people are referred to as the Hyksos, and they ruled Northern Egypt during the Second Intermediate Period. But, we have no idea to what extent they contributed their DNA to the ancient Egyptian gene pool. Also, we have something important to consider here. That derived allele in gene SLC24A5, associated with lighter skin pigmentation, arose only once in our history, and the archaeogenetic evidence strongly points to an origin in the Middle East or West Asia around 22 to 28,000 years ago. This was a time when people were still hunter-gatherers. Agriculture came with the Neolithic revolution around 10,000 BC. The fact that that allele was found in an Egyptian mummy suggests there had to have been migration from the Middle East back into Egypt after the time that that allele arose. Whether that allele was brought by hunter-gatherers moving back south, or Anatolian farmers after the advent of agriculture, because we know that that allele was fixed in the Anatolian population during the Neolithic period, or if it was brought for the first time by the Hyksos in the 2nd millennium BC, I don't know. But, what we do know is that that allele arose once, and the place of origin is very likely the Middle East. The Back Migration Hypothesis and its timing can be tested with DNA from much older mummies and skeletons, and I'm really excited to find out what we're going to find out next. That's it for the episode, don't forget to give this video a like, and subscribe for more cool content via your go-to informant on everything archaeology, Madam Archaeologist.