bpk/Aegyptisches Museum und Papyrussammlung, SMB/Sandra Steiss
Ancient mummies are yielding a new treasure — DNA. The genetic material unwrapped from 90 of these preserved bodies in Egypt, a part of North Africa, show their family roots extend seemingly to the Middle East. They appear to have far less in common with ancient peoples throughout most of the rest of Africa.
What this means, researchers now say, is that the ancient Egyptians had relatives in what is now the Middle East, and possibly Europe.
An Egyptian mummy provided the first sample of ancient human DNA in 1985. But scientists had doubts about how trustworthy the DNA was. The reasons? The chemicals used to mummify bodies can degrade DNA. So can Egypt’s steamy climate. And, there were some worries that any tested samples might have been tainted with DNA from the people who worked on them when they were first unearthed.
Enter Verena Schuenemann and her team. Schuenemann had been studying the genetics of ancient microbes at the University of Tübingen in Germany. She had become an expert at finding really old DNA. And to do this, she used the latest technology to sequence the DNA — map its building blocks to read its genes.
These researchers extracted and analyzed two types of DNA. The mitochondrial (My-toh-KON-dree-ul) type is genetic material that passes directly from a mother to her child. The other type, from cell nuclei, is passed down from both parents.
The researchers focused on sampling teeth and bones. These harder body parts had more preserved DNA than did soft tissues, such as muscle. The scientists screened for the highest quality samples and then checked for any sign of contamination with modern DNA.
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Their hard work paid off. The team got usable mitochondrial DNA from 90 mummies. Three also yielded readable samples of the nuclear DNA.
The mummies date from 1388 B.C. to A.D. 426. All came from a popular burial site in central Egypt. Called Abusir el-Meleq, this site was a hub for a religious cult that was devoted to Osiris (Oh-SY-ris). That’s the ancient Egyptian god of the dead. A Jewish-German archaeologist had excavated the site in 1905. At the time, he reported evidence of a Greek influence on the burial site. But he offered few details about individual graves. And most of his research never survived World War II.
The new analysis reveals genetic ties to Greece and the Middle East. This is not a huge surprise since Egypt was a center of travel and trade at that time. But today’s Egyptians are more closely related to sub-Saharan Africans to the south. Those genetic links were notably missing in the mummy DNA. Their absence suggests that foreigners from sub-Saharan Africa moved into the region later, the researchers say.
Schuenemann’s group described its findings May 30 in Nature Communications.
The new analysis leaves many open questions. The mummies found at Abusir el-Meleq come from a range of social classes. Even so, the researchers point out that people from just one site can’t be counted on to reflect all of ancient Egypt’s people. Still, the study shows that mummies can offer a glimpse into that nation’s genetic roots.
cell The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall.
chemical A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.
climate The weather conditions that typically exist in one area, in general, or over a long period.
degrade To break down into smaller, simpler materials — as when wood rots or as a flag that’s left outdoors in the weather will fray, fade and fall apart. (in chemistry) To break down a compound into smaller components.
DNA (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.
gene (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
genetic Having to do with chromosomes, DNA and the genes contained within DNA.
microbe Short for microorganism. A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.
mitochondrial DNA DNA passed on to offspring, almost always by their female parent. Housed in mitochondria, this DNA is double-stranded but circular. It’s also very small, only possessing a small share of the genes found in the main package of DNA, the material found in a cell’s nucleus.
mummify (n. mummy) The process by which a corpse is preserved chemically or through drying. In many cases, communities have intentionally preserved certain members of their society. But bodies of some humans and animals have naturally mummified as the tissues dried out before microbes could degrade them (break them down, as by rotting).
muscle A type of tissue used to produce movement by contracting its cells, known as muscle fibers. Muscle is rich in protein, which is why predatory species seek prey containing lots of this tissue.
social (adj.) Relating to gatherings of people; a term for animals (or people) that prefer to exist in groups. (noun) A gathering of people, for instance those who belong to a club or other organization, for the purpose of enjoying each other’s company.
technology The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.
tissue Made of cells, any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.
V.J. Schuenemann et al. Ancient Egyptian mummy genomes suggest an increase of Sub-Saharan African ancestry in post-Roman periods. Nature Communications. Vol. 8, May 30, 2017. (online). doi:10.1038/ncomms15694.