Unraveling the mysteries of ancient DNA

No, it was not unexpected to discover that Roma have a genetic makeup very similar to that of our closest relatives, and that they have the blood of both apes and humans. One of the most amazing genetic discoveries of the past few years happened when the DNA of one of the earliest known humans from the Pleistocene period—some 6,000 years ago—was sequenced. However, these genomes do not directly tell us whether or not these individuals actually lived 5,000 years ago.

Years of scientific investigation were needed to understand the question of who exactly this population of a “migration” from Africa would be. At this time, the genome of these “Ardi” individuals differed greatly from that of our modern people. We know they may have migrated via trails that snakes and other animals may have used to cross the ocean, but we don’t have enough information to know for sure whether they crossed over the Golden Gate Bridge or climbed Mount Tamalpais. And what about the California coast? Were they from Europe, Africa, or Asia? Was their culture any different than the rest of our descendants?

Although these Ardi individuals lived as far back as 6,000 years ago, their genes are not unique. Other early humans from the same geographic region, mostly in southern Siberia, came over to our shores several thousand years later in the Pleistocene period. So we have a living and well-defined population of ancient humans who may have come from the same region, yet who have very different ancestors.

What is a geneticist to do? After all, an ancient ancestor is the highest degree of proof of anything. Nevertheless, science is constantly expanding the boundaries of science and the boundaries of knowledge. One of the ways is by analyzing ancient populations in modern day populations to see how we “might” have lived, based on where we diverged from our ancestors. After all, it seems self-evident that the sites where the first groups descended from Africa are in much closer proximity to modern day northern Siberia, compared to how northern Europe, Northern Asia, or South America compared to the African mainland. It makes sense, then, that a large portion of the genetic material for these individuals likely originated from the so-called Former Soviet Union (which has pretty much disappeared nowadays). This is the same group that was studied by Genomics Canada researchers in new research announced today.

The Breslin Center for Biodiversity at the University of Toronto assembled a diverse group of scientists—scientists from different countries, disciplines, and perspectives. They sequenced the genome of twenty-six individuals from the Troika field unit of Russia’s Federal Medical and Biological Agency and from the Siberian Plateau in China. The Russian specimens were collected from geographically distant archaeological and paleogenetic sources. The samples were from members of a population that split between what is now the Republic of Georgia and Western Russia many thousands of years ago. The team also analyzed a wider variety of DNA from neighboring Austro-Austrian Yupkian populations. The main focus of the study was to identify a common ancestor of the two groups. Their results revealed that:

• The individuals have the same population origin but their genetic ancestry ranged from 8 percent to 40 percent Eurasian and 80 percent Neanderthal.

• Their genomes were 97.2 percent homo sapiens, 5.4 percent Tibetan and 8.1 percent further afield.

• All participants lived at or near the top of the long-range human food chain, which included the Aztecs, Incas, Greeks, and other pre-civilization populations.

As with all humans, this genetic distribution spans much broader geographic regions than many of us think, including the Caucasus Mountains of Russia. If any of us were to place a bet that we would find a common ancestor between these two groups, let alone a “brother” or “sister” to our modern people from an ancient, perhaps homo erectus connection, we would probably be wrong. But we are an evolutionary species, and it is human nature to try and make sense of our unprecedented relationship with our relative neighbors on the planet.

So how much difference are we expected to see between a primitive (Pleistocene) Russian Neanderthal and a “modern” DNA-matched Russian man? Not as much as we might think, even if they did exist as single-celled organisms 6,000 years ago.

The way people have settled down these past few thousand years suggests that homo sapiens, rather than simple caveman DNA—as represented by archaic hominins—was responsible for establishing one of the world’s oldest “family trees.” Modern man evolved into complex

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