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Eurasia 98 Friday, 5 June, 1998, 18:19 GMT 19:19 UK
What is anthropological genetics?
Genetic information is repeated through the generations
Genetic information is repeated through the generations
The field of anthropology is concerned with the scientific study of humans and their close relatives, the non-human primates.

As portrayed in the popular press, this entails long hours of careful observation of remote human or ape populations, recording behavioral minutiae in an effort to detect a coherent pattern.

Recently, however, molecular biologists - more at home in the laboratory than the field - have begun to venture into the realm of the great, observational anthropologists such as Margaret Mead, Jane Goodall and Dianne Fossey. Genetic methods are now being applied to studies of the differences between humans and apes, the size and geographic origin of early hominid populations, and the earliest migrations of anatomically modern humans.

Volunteer donors will be needed
Volunteer donors will be needed
The field of anthropological genetics uses patterns of genetic similarity among human populations to infer demographic history: mating structure, the history of migration and admixture with surrounding groups, and population size fluctuations. While it ultimately comes down to who had sex with whom, the details are fascinating.

The raw material for this work is DNA, the chemical "blueprint" found inside every living cell in the human body.

The linear DNA molecule - a long, coded string of instructions arranged in the famous double helix pattern - describes the proteins and other constituents of every single cell in our bodies.

The most obvious pattern we see upon looking at the same region of DNA in several individuals is how alike we all are - there is hardly any variation from person to person. Only one in a thousand nucleotide "sites" differ between two individuals chosen at random, which means the other 999 are exactly the same in yourself as in the person sitting next to you.

Moreover, even when we compare the 0.1% of nucleotide sites which do vary, the vast majority of variation in human DNA can all be found within a regional population - the English west Midlands, for instance. If by some twist of fate the people of Birmingham and environs were the only humans alive tomorrow morning, 80-90% of the genetic variation present in H. sapiens would still be found in these lucky individuals.

Circumcision party
Cultural clues can also help trace common origins
Surprisingly, only 5-10% of the genetic variation present in the human species (that is, 5-10% of the 0.1% of the genome which does vary from person to person) distinguishes one "racial" group from another. This number is exceedingly small, and shows that the superficial features, which we often think of as defining human ethnic groups, are literally only skin deep.

While there has been a sizeable amount of research on human origins, with most evidence pointing toward an African genesis around 100,000 years ago - the so-called "African Eve" - there is more and more interest in the patterns of relationship among existing human populations.

What can be teased out of the small percentage of the genome distinguishing modern human groups? A few recent results:

  • Native Americans are clearly of Asian origin, and entered the Americas less than 40,000 years ago.

  • Modern Europeans entered Europe from the Middle East, although the dates are uncertain. The two conflicting schools argue over an early entrance - (Mesolithic, about 30,000 years ago) or late (Neolithic, about 8,000 years ago).

  • Polynesians are descended from southeast Asians, and moved across the Pacific from west to east, eventually reaching remote islands such as Easter and Hawaii. Thor Heyerdahl may have been an intrepid sailor, but ancient South Americans apparently weren't.

  • Europeans are not the descendants of Neanderthals - in spite of what you may think of the person in the office next door. Homo sapiens last shared a common ancestor with our robust cousins around 600,000 years ago, well prior to the origin of both modern humans (see above) and Neanderthals.

  • Preliminary work on our first Central Asian collecting expedition to Uzbekistan and Kyrgyzstan in the summer of 1996 has shown the migration of Middle Eastern genetic markers along the Silk Road to China, reconstructed the routes followed by early Indo-Europeans in their wanderings across the steppes, and has suggested that the Mongols seem to have done rather more pillaging than raping during their conquest of Asia.

Information about the genetic makeup of populations offers powerful new evidence for the consideration of anthropologists and historians. It is able to confirm studies based on cultural, linguistic and archaeological evidence and in some cases contradict existing theories. It is the scientific objectivity of genetic studies that gives it the power to say "at around this time, these people were here", freeing anthropologists to discuss the human developments - biological, societal, even political - that led populations to move and spread throughout the world.

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