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San Bushmen who are direct descendants of the first Modern Humans Photograph: National Geographic Society
By analyzing DNA from people in all regions of the world, American geneticist Dr. Spencer Wells has concluded that all humans alive today are descended from a San bushman who lived in Africa around 60,000 years ago. Modern humans, he contends, didn't start their spread across the globe until after that time. Most archaeologists would say the exodus began 100,000 years ago - a 40,000-year discrepancy.
Proponents of the Out of Africa theory believe that over the last 2 million years, there have been many different human species, all but one of which became extinct - Modern Humans.
Wells says that around 20,000 years ago there are no people in America; 40,000 years ago in Europe, the Neanderthals were in in charge. At 50,000 years ago, Australia is part of an uninhabited continent. Before that (apart from the Neanderthals) you only find people living in Africa. He says to head back to 100,000 years ago, there seem to be more people - but still limited to Africa - and finally settle on 60,000 years ago as the low point. Then there were as few as 2,000 humans in existence. The worst time in the history of our species; one we nearly didn't survive.
Around 60,000 years ago the Earth was in the middle of an ice age, the effect of which was pretty chilling in the far north but in Africa it caused different problems. The ice sheets sucked up much of the world's moisture, causing widespread droughts particularly in Africa where the tropical latitude and intense sunshine, coupled with the lower moisture levels had a major environmental effect.
Wells says that several recent discoveries have revealed ape-like creatures that could walk upright around 5m years ago. Perhaps the best documented is Ardipithecus, discovered in the 90s. Around the time of Ardipithecus it seems that some apes decided to walk around on two legs. This probably happened again as a result of climate change.
Dr Wells says that
homo erectus, the master toolmaker of the era, had a much bigger brain
than his ancestors and developed many of the elements of modern human
behaviour, probably including the use of fire and some form of
rudimentary language. He even seems to have wandered out of Africa
around 1.8m years ago - Java Man and Peking Man were both part of the
Homo erectus family. He didn't stray far from the tropics, though
(particularly when the world cooled down during the periodic ice ages),
and was already on his way to extinction around 100,000 years ago.
After this change
in abilities that led to the erectus African exodus, a long period of
stasis seems to have set in. The hominids in the ensuing 1.7m years grew
larger brains; several species appeared and then became extinct, and
some even wandered out of Africa - giving rise to the Neanderthals in
Europe about a quarter of a million years ago. During this time there
were no big innovations. The tools used a million years ago in Africa do
not differ much from those used by the Neanderthals 900 millennia
Then about 60,000 years ago, besides climate change, the San people in the Rift Valley of East Africa also had brain power that gave birth to the modern human race.
National Geographic/IBM Genographic Project: Tracking the Hennigan Y-Chromosome
DNA analysis shows that the ancestors of most Irish people came from the Iberian Peninsula, who moved north after the last Ice Age, which had depopulated Ireland.
Dr Daniel Bradley, genetics lecturer at Trinity College Dublin, has said that a study published in 2004, into Celtic origins revealed close affinities with the people of Galicia, in North-Western Spain.
Historians have for long believed that the Celts, originally from the Alpine regions of central Europe invaded the Atlantic islands in a massive migration 2,500 years ago.
However, DNA analysis debunks this theory and conforms with the lack of archaeological evidence in Ireland, that the "Keltoi" who had invaded ancient Greece, had migrated in large numbers, to Ireland.
What did happen, was that the prominent Irish clan leadership adopted European Celtic culture from trade and other contacts. A variation of the Celtic language had been in use by their ancestors in the Iberian Peninsula.
Dr Bradley said it was possible migrants moved from the Iberian peninsula to Ireland as far back as 6,000 years ago up until 3,000 years ago.
The study found that people in areas traditionally known as Celtic, such as Ireland, Wales, Scotland, Brittany and Cornwall, had strong links with each other and people in Ireland have more in common with Scots than any other nation.
The study, conducted by Dr. Bradley and Brian McEvoy, a Ph.D student conducted the genetic study with the support of the Irish government to determine "whether there was a large incursion by Celtic people 2,500 years ago," as is widely believed.
The scientists compared the DNA samplesof 200 volunteers from around Ireland with a genetic database of 8,500 individuals from around Europe. (The Celts came from Central Europe stretching as far as Hungary).
They found that the Irish samples matched those around Britain and the Pyrenees in Spain. There were some matches in Scandinavia and parts of North Africa.
The scientists concluded that the Irish genetic makeup stems from the onset of an ice-age around 15,000 years ago that forced prehistoric man back into Spain, Italy and Greece, which were still fairly temperate. When the ice started melting again around 12,000 years ago, people followed the retreating ice northwards as areas became hospitable again.
The TCD study produced a map of Europe with contours linking places that are genetically similar. One contour goes around the edge of the Atlantic touching Wales, Scotland, Ireland, and includes Galicia in Spain as well as the Basque region.
"Theprimary genetic legacy of Ireland seems to have come from people from Spain and Portugal after the last ice age,"said McEvoy. "They seem to have come up along the coast through Western Europe and arrived in Ireland, Scotland and Wales. It's not due to something that happened 2,500 years ago with Celts. We have a much older genetic legacy."
Paternal ancestry is traced via the transfer of the Y-chromosome from father to son, which has happened over 2,000 generations, back to one male human who lived in East Africa, about 60,000 years ago.
Haplogroup and Haplotypes
A haplogroup is a collection of closely related haplotypes - groups of closely linked genes.
Each of us carries DNA that is a combination of genes passed from both our mother and father, giving us traits that range from eye colour and height to athleticism and disease susceptibility. One exception is the Y chromosome, which is passed directly from father to son, unchanged, from generation to generation.
Unchanged, that is unless a mutation "a random, naturally occurring, usually harmless change" occurs. The mutation, known as a marker, acts as a beacon; it can be mapped through generations because it will be passed down from the man in whom it occurred to his sons, their sons, and every male in his family for thousands of years.
In some instances there may be more than one mutational event that defines a particular branch on the tree. This means that any of these markers can be used to determine your particular haplogroup, since every individual who has one of these markers also has the others.
When geneticists identify such a marker, they try to figure out when it first occurred, and in which geographic region of the world. Each marker is essentially the beginning of a new lineage on the family tree of the human race. Tracking the lineages provides a picture of how small tribes of modern humans in Africa tens of thousands of years ago diversified and spread to populate the world.
In a DNA analysis that was done for the National Geographic Genographic Project, my Y-chromosome results identify me as a member of haplogroup R1b.
The genetic markers that define our common ancestral history reach back roughly 60,000 years to the first common marker of all non-African men, M168, and follow my lineage to present day, ending with M343, the defining marker of haplogroup R1b.
Today, roughly 70 percent of the men in southern England belong to haplogroup R1b. In parts of Spain and Ireland, that number exceeds 90 percent.
Not surprisingly, today the number of descendants of the man who gave rise to marker M173 remains very high in Western Europe. It is particularly concentrated in northern France, Ireland and Britain. and the Britain where it was carried by ancestors who had weathered the Ice Age in Spain.
The markers of most Irish define them as being in the Atlantic Modal Haplotype,which confirm the strong links with Northern Spain.
High King of Ireland - Niall of the Nine Hostages
One in 12 Irish men could be descended from Niall Noígíallach-Niall of the Nine Hostages, the High King who ruled at Tara, west of the site that became Dublin, from 379 to 405 AD, according to research conducted at Trinity College Dublin. He was the founder of theUí Néill(which literally translated means "descendants of Niall") dynasty that ruled Ireland until the 11th century.
Researchers at the Smurfit Institute of Genetics at Trinity, headed by Dr. Bradley, have estimated that there could be as many as 3m men worldwide descended from Niall. The highest concentration of his progeny is in North-West Ireland, where one in five males have inherited his Y chromosome.
The Trinity study examined the Y chromosome and Laoise Moore, a PhD student working on the Wellcome Trust-funded project, took DNA samples by mouth swab from 796 male volunteers and recorded the birthplace of their paternal grandfather.
Dr, Daniel Bradley, who supervised the PhD, analysed the genetic fingerprints of the samples and found the same Y chromosome in 8% of the general population, with a cluster in the North-West of Ireland where 21% carried it.
They calculated that the most recent common ancestor was likely to have lived about 1,700 years ago. Coupled with the geographical distribution centred on the North-West, this pointed to the
Uí Néilll dynasty.
Brian McEvoy, one of the team at Trinity said that North-West Ireland has previously been the subject of anthropological writings "and has shown a strikingly high % of men from Haplogroup R1b (98%) versus 90% in South-East Ireland. According to McEvoy, this area was the main powerbase of the Uí Néill.
The following are the Markers when a 12 marker test is applied:
Irish Type III Cluster and Hennigan Paternal Line
In April 2006, American scientist Dr. Ken Nordtvedt, identified a cluster where the ancestral geographical area appears to be predominately Irish, but the haplotype was quite different from other Irish ones. It has been given the name "Irish Type III."
The following are the Markers when a 12 marker test is applied to the Hennigan Y chromosome:
US databases of people with this haplotype, show that some 75% claim their ancestral line came from Ireland, many stating the counties of Clare, Tipperary or Limerick.
These counties are the seat of many of the Dalcassian (Dál gCais ) clans, the principal one having been the O'Brien clan.
The most famous member of the O-'Brien clan was Brian mac Cennétig, called Brian Bóruma born in 926 or 941, known as Brian Boru in English) who was High King of Ireland from 1002 to 1014. Although the exact details of his birth are unknown, he was born in the early tenth century near Killaloe (Kincora) (in modern County Clare). His father was Cennétig mac Lorcain, King of Thomond and his mother was Binn ingen Murchada, daughter of the King of West Connacht. He was killed in a battle at Clontarf, Dublin, in 1014, between Irish, with Vikings on both sides. Like St. Patrick and the snakes,Irish historians had for long mythologised Brian Boru, as the man who drove the "Danes" from Ireland.
In the main text on the Hennigan genealogy, I had speculated that we may have moved south to West Cork with the McCarthys, who were driven out of Tipperary by the O'Briens, even though we were closer cousins to the latter.
The Y-Search US database produces 425 direct matches with Spanish, Portuguese, Mexican, Puerto Rican and Chilean names among them. There is one direct match for a McCarthy whose latest known ancestor came from Dunmanway, County Cork, in the 19th century. There are two McCarthy ancestors who came from Bandon, County Cork and another from Kilbarry, Dunmanway, whose DNA is not Irish Type III. Members of a clan may not have always held the same surname because of a biological patrilineal connection.
NATIONAL GEOGRAPHIC SUMMARY ON JOURNEY OUT OF AFRICA TO EUROPE:
Your Y-chromosome results identify you as a member of haplogroup R1b.
The genetic markers that define your ancestral history reach back roughly 60,000 years to the first common marker of all non-African men, M168, and follow your lineage to present day, ending with M343, the defining marker of haplogroup R1b.
If you look at the map highlighting your ancestors' route, you will see that members of haplogroup R1b carry the following Y-chromosome markers:
M168 > M89 > M9 > M45 > M207 > M173 > M343
Today, roughly 70 percent of the men in southern England belong to haplogroup R1b. In parts of Spain and Ireland, that number exceeds 90 percent.
Your Ancestral Journey: What We Know Now
M168: Your Earliest Ancestor
Time of Emergence: Roughly 50,000 years ago
Place of Origin: Africa
Climate: Temporary retreat of Ice Age; Africa moves from drought to warmer temperatures and moister conditions
Estimated Number of Homo sapiens: Approximately 10,000
Tools and Skills: Stone tools; earliest evidence of art and advanced conceptual skills
Skeletal and archaeological evidence suggest that anatomically modern humans evolved in Africa around 200,000 years ago, and began moving out of Africa to colonize the rest of the world around 60,000 years ago.
The man who gave rise to the first genetic marker in your lineage probably lived in northeast Africa in the region of the Rift Valley, perhaps in present-day Ethiopia, Kenya, or Tanzania, some 31,000 to 79,000 years ago. Scientists put the most likely date for when he lived at around 50,000 years ago. His descendants became the only lineage to survive outside of Africa, making him the common ancestor of every non-African man living today.
But why would man have first ventured out of the familiar African hunting grounds and into unexplored lands? It is likely that a fluctuation in climate may have provided the impetus for your ancestors' exodus out of Africa.
The African ice age was characterized by drought rather than by cold. It was around 50,000 years ago that the ice sheets of northern Europe began to melt, introducing a period of warmer temperatures and moister climate in Africa. Parts of the inhospitable Sahara briefly became habitable. As the drought-ridden desert changed to a savanna, the animals hunted by your ancestors expanded their range and began moving through the newly emerging green corridor of grasslands. Your nomadic ancestors followed the good weather and the animals they hunted, although the exact route they followed remains to be determined.
In addition to a favorable change in climate, around this same time there was a great leap forward in modern humans' intellectual capacity. Many scientists believe that the emergence of language gave us a huge advantage over other early human species. Improved tools and weapons, the ability to plan ahead and cooperate with one another, and an increased capacity to exploit resources in ways we hadn't been able to earlier, all allowed modern humans to rapidly migrate to new territories, exploit new resources, and replace other hominids.
M89: Moving Through the Middle East
Time of Emergence: 45,000 years ago
Place: Northern Africa or the Middle East
Climate: Middle East: Semiarid grass plains
Estimated Number of Homo sapiens: Tens of thousands
Tools and Skills: Stone, ivory, wood tools
The next male ancestor in your ancestral lineage is the man who gave rise to M89, a marker found in 90 to 95 percent of all non-Africans. This man was born around 45,000 years ago in northern Africa or the Middle East.
The first people to leave Africa likely followed a coastal route that eventually ended in Australia. Your ancestors followed the expanding grasslands and plentiful game to the Middle East and beyond, and were part of the second great wave of migration out of Africa.
Beginning about 40,000 years ago, the climate shifted once again and became colder and more arid. Drought hit Africa and the grasslands reverted to desert, and for the next 20,000 years, the Saharan Gateway was effectively closed. With the desert impassable, your ancestors had two options: remain in the Middle East, or move on. Retreat back to the home continent was not an option.
While many of the descendants of M89 remained in the Middle East, others continued to follow the great herds of buffalo, antelope, woolly mammoths, and other game through what is now modern-day Iran to the vast steppes of Central Asia.
These semiarid grass-covered plains formed an ancient "superhighway" stretching from eastern France to Korea. Your ancestors, having migrated north out of Africa into the Middle East, then traveled both east and west along this Central Asian superhighway. A smaller group continued moving north from the Middle East to Anatolia and the Balkans, trading familiar grasslands for forests and high country.
M9: The Eurasian Clan Spreads Wide and Far
Time of Emergence: 40,000 years ago
Place: Iran or southern Central Asia
Estimated Number of Homo sapiens: Tens of thousands
Tools and Skills: Upper Paleolithic
Your next ancestor, a man born around 40,000 years ago in Iran or southern Central Asia, gave rise to a genetic marker known as M9, which marked a new lineage diverging from the M89 Middle Eastern Clan. His descendants, of which you are one, spent the next 30,000 years populating much of the planet.
This large lineage, known as the Eurasian Clan, dispersed gradually over thousands of years. Seasoned hunters followed the herds ever eastward, along the vast super highway of Eurasian steppe. Eventually their path was blocked by the massive mountain ranges of south Central Asia�the Hindu Kush, the Tian Shan, and the Himalayas.
The three mountain ranges meet in a region known as the "Pamir Knot," located in present-day Tajikistan. Here the tribes of hunters split into two groups. Some moved north into Central Asia, others moved south into what is now Pakistan and the Indian subcontinent.
These different migration routes through the Pamir Knot region gave rise to separate lineages.
Most people native to the Northern Hemisphere trace their roots to the Eurasian Clan. Nearly all North Americans and East Asians are descended from the man described above, as are most Europeans and many Indians.
M45: The Journey Through Central Asia
Time of Emergence: 35,000
Place of Origin: Central Asia
Climate: Glaciers expanding over much of Europe
Estimated Number of Homo sapiens: Approximately 100,000
Tools and Skills: Upper Paleolithic
The next marker of your genetic heritage, M45, arose around 35,000 years ago, in a man born in Central Asia. He was part of the M9 Eurasian Clan that had moved to the north of the mountainous Hindu Kush and onto the game-rich steppes of present-day Kazakhstan, Uzbekistan, and southern Siberia.
Although big game was plentiful, the environment on the Eurasian steppes became increasing hostile as the glaciers of the Ice Age began to expand once again. The reduction in rainfall may have induced desertlike conditions on the southern steppes, forcing your ancestors to follow the herds of game north.
To exist in such harsh conditions, they learned to build portable animal-skin shelters and to create weaponry and hunting techniques that would prove successful against the much larger animals they encountered in the colder climates. They compensated for the lack of stone they traditionally used to make weapons by developing smaller points and blades�microliths�that could be mounted to bone or wood handles and used effectively. Their tool kit also included bone needles for sewing animal-skin clothing that would both keep them warm and allow them the range of movement needed to hunt the reindeer and mammoth that kept them fed.
Your ancestors' resourcefulness and ability to adapt was critical to survival during the last ice age in Siberia, a region where no other hominid species is known to have lived.
The M45 Central Asian Clan gave rise to many more; the man who was its source is the common ancestor of most Europeans and nearly all Native American men.
M207: Leaving Central Asia
Time of Emergence: 30,000
Place of Origin: Central Asia
Climate: Glaciers expanding over much of Europe and western Eurasia
Estimated Number of Homo sapiens: Approximately 100,000
Tools and Skills: Upper Paleolithic
After spending considerable time in Central Asia, refining skills to survive in harsh new conditions and exploit new resources, a group from the Central Asian Clan began to head west towards the European subcontinent.
An individual in this clan carried the new M207 mutation on his Y chromosome. His descendants ultimately split into two distinct groups, with one continuing onto the European subcontinent, and the other group turning south and eventually making it as far as India.
Your lineage falls within the first haplogroup, R1, and gave rise to the first modern humans to move into Europe and eventually colonize the continent.
M173: Colonizing Europe�The First Modern Europeans
Time of Emergence: Around 30,000 years ago
Place: Central Asia
Climate: Ice Age
Estimated Number of Homo sapiens: Approximately 100,000
Tools and Skills: Upper Paleolithic
As your ancestors continued to move west, a man born around 30,000 years ago in Central Asia gave rise to a lineage defined by the genetic marker M173. His descendants were part of the first large wave of humans to reach Europe.
During this period, the Eurasian steppelands extended from present-day Germany, and possibly France, to Korea and China. The climate fostered a land rich in resources and opened a window into Europe.
Your ancestors' arrival in Europe heralded the end of the era of the Neandertals, a hominid species that inhabited Europe and parts of western Asia from about 29,000 to 230,000 years ago. Better communication skills, weapons, and resourcefulness probably enabled your ancestors to outcompete Neandertals for scarce resources.
This wave of migration into Western Europe marked the appearance and spread of what archaeologists call the Aurignacian culture. The culture is distinguished by significant innovations in methods of manufacturing tools, more standardization of tools, and a broader set of tool types, such as end-scrapers for preparing animal skins and tools for woodworking.
In addition to stone, the first modern humans to reach Europe used bone, ivory, antler, and shells as part of their tool kit. Bracelets and pendants made of shells, teeth, ivory, and carved bone appear at many sites. Jewelry, often an indication of status, suggests a more complex social organization was beginning to develop.
The large number of archaeological sites found in Europe from around 30,000 years ago indicates that there was an increase in population size.
Around 20,000 years ago, the climate window shut again, and expanding ice sheets forced your ancestors to move south to Spain, Italy, and the Balkans. As the ice retreated and temperatures became warmer, beginning about 12,000 years ago, many descendants of M173 moved north again to repopulate places that had become inhospitable during the Ice Age.
Not surprisingly, today the number of descendants of the man who gave rise to marker M173 remains very high in Western Europe. It is particularly concentrated in northern France and the British Isles where it was carried by ancestors who had weathered the Ice Age in Spain.
M343: Direct Descendants of Cro-Magnon
Time of Emergence: Around 30,000 years ago
Place of Origin: Western Europe
Climate: Ice sheets continuing to creep down Northern Europe
Estimated Number of Homo sapiens:
Tools and Skills: Upper Paleolithic
Around 30,000 years ago, a descendant of the clan making its way into Europe gave rise to marker M343, the defining marker of your haplogroup. You are a direct descendent of the people who dominated the human expansion into Europe, the Cro-Magnon.
The Cro-Magnon are responsible for the famous cave paintings found in southern France. These spectacular paintings provide archaeological evidence that there was a sudden blossoming of artistic skills as your ancestors moved into Europe. Prior to this, artistic endeavors were mostly comprised of jewelry made of shell, bone, and ivory; primitive musical instruments; and stone carvings.
The cave paintings of the Cro-Magnon depict animals like bison, deer, rhinoceroses, and horses, and natural events important to Paleolithic life such as spring molting, hunting, and pregnancy. The paintings are far more intricate, detailed, and colorful than anything seen prior to this period.
Your ancestors knew how to make woven clothing using the natural fibers of plants, and had relatively advanced tools of stone, bone, and ivory. Their jewelry, carvings, and intricate, colorful cave paintings bear witness to the Cro-Magnons' advanced culture during the last glacial age.
National Geographic's The Genographic Project
National Geographic's The Genographic Project, which was launched in April 2005, seeks to chart new knowledge about the migratory history of the human species and answer age-old questions surrounding the genetic diversity of humanity. The project is a nonprofit, five-year, global DNA-sampling research partnership of National Geographic and IBM, led by distinguished population geneticist Dr. Spencer Wells. With support for field research from the US Waitt Family Foundation, Wells and a group of the world' leading scientists are engaged in collecting and analyzing more than 100,000 DNA samples from people all over the world.
Core components of the project are:
Public Participation and Awareness Campaign
The goal of the Genographic Project is to help people better understand their own ancient history, learn about migratory paths our ancestors took to populate the planet, and how, in spite of our diverse appearances, we all are part of the same family tree and share common origins.
"We see this as the 'moon shot' of anthropology, using genetics to fill in the gaps in our knowledge of human history," said project leader Dr. Spencer Wells. "Our DNA carries a story that is shared by everyone. Over the next five years we'll be deciphering that story, which is now in danger of being lost as people migrate and mix to a much greater extent than they have in the past."
The resulting public database will house one of the largest collections of human population genetic information ever assembled and will serve as an unprecedented resource for geneticists, historians and anthropologists.
Customized IBM field software captures the "context" data of DNA samples on a given expedition. It's designed so that dozens of languages and regions are acknowledged while cross populating other fields with related data, making collecting for a group of people in the same region much faster and more accurate.
The team is helping to deal with the challenges of intermittent connectivity in remote locations of the world as well as security to protect the identity of the sample donors and the integrity of the data. Once the sample information is collected and inputted it is automatically assigned a unique, random Genographic Project I.D. to ensure participant anonymity.
"The task of gathering genetic and associated data into a combined format that is usable by scientists and researchers remains daunting in its complexity," said Ajay Royyuru, Senior Manager, IBM Computational Biology Center. "Bringing scientific expeditions into the modern era is an example of IBM's core value of driving innovation that matters to the world."
The Quest to find a common ancestor
The primary means that Wells uses in his quest to find a common ancestor (Adam) is theY-chromosome, which the programme likens to a family name, passed down from father to son. By getting samples of the Y-chromosome, Wells just follows DNA trails into the past. It's what he calls "genetic time travel".
Wells has found trails that lead back to famous historical icons like Mongolian conqueror Genghis Khan and United States president Thomas Jefferson.
Wells believes that the key in this project is being able to identify what he calls "super ancestors" - men who have left their genetic imprint on huge numbers of people.
With Thomas Jefferson the findings are even more surprising. Jefferson's Y-chromosome can be traced back not to Europe, but to the Middle East. This discovery shows that what we look like may not really tell us where we come from at all -something many may find hard to accept. Even if the DNA trail says so.
Another interesting concept explored is that three of the world's most dominant religions - - Christianity, Islam and Judaism - - all believe one man fathered us all. And Wells seems intent on finding some sort of balance between faith and Science. He reported to even go as far as looking for a descendent of King Solomon, who in the book of Luke in the Bible, is cited as a direct descendent of Adam.
Wells says that the Multiregionalism Theory which states that we evolved depending on the region our ancestors settled in, we now know to be untrue. Our ancestors came from Africa and the Y Chromosome of human DNA has been used to uncover secrets. Earlier, for tracing family trees, it was necessary to dig up bones from the ground. The problem with this is that there are different fossils and so it doesn't give us an idea as to who our direct ancestors are. When we study DNA sequences any changes form a line of descent.
Dr. Spencer Wells discusses with the MSNBC TV crew about their family trees and their genes to trace their history deeper:
The advantage of the Y Chromosome is that it is handed down only by the male parent unmingled with a woman's DNA. So it can stay the same from generation to generation.It can only change with a mutation which is an accidental but natural change in the genetic code. This can happen to strengthen the immune system from newly emerged diseases.
Wells says that the project uses this molecule, DNA, which is contained in every cell in our body. (Our red blood cells kick out the nuclei when they become mature, so they don't actually contain any DNA, but pretty much every other cell in our body does.) This is the blueprint to make a version of you. You have to pass on half your DNA to your child in a shuffled way, a process called recombination. DNA is very long. It's made up of four nucleotide bases - A, C, G, and T - and it's the order of those that provide the information. Because it's so very long - it's three billion of those in length - you occasionally make a mistake when you're copying it and passing it along.Those are called mutations, and everybody carries some mutations that distinguish them from their parents, roughly 30 of them per genome per generation. When those are passed on through the generations, they become markers of descent.They occur very rarely, so the odds are that most sites are not going to have any. When they do happen they occur uniquely at a single site. You hardly ever mutate the same site twice. So when two people share these markers in common, it's a sign that they share ancestry at some point. Dr. Wells says:"What we do is start in the present with DNA from people who are alive today and trace back through these lineages that are defined by the markers that have been passed on through many, many generations, back to the point where they share a common ancestor. When we do that with people who are members of the same family, we very quickly reach a point where they share a common ancestor. But, it turns out, we can also do that with people all over the world. By asking a really stupid question (it's pretty much hypothesis-free): 'Are we related, and if so, how are we related?' we trace back to a single ancestor on the Y chromosome, which, it turns out, is the most recent ancestor we all share. This man, this Y chromosome, existed 60,000 years ago. And it turns out he existed in Africa. That means our species was still limited to Africa in its distribution 60,000 years ago.It's only in the last 60,000 years, or 2,000 generations, roughly, that we have left Africa to go out and take over the world."
He says that the present-day inhabitants of Ethiopia, Sudan and southern Africa carry the clearest signals of our earliest ancestry, signals that have been lost in the rest of us. So they give us a glimpse of our 60,000 year-old Adam. Adam would have been fully modern, both in terms of his appearance and his brain function.
Wells says that DNA sequencing undergoes mutation every generation. It is because of this complete gradual mutation between 31,000 and 79,000 years ago that first Eurasian Adam, the ancestor of all non-Africans, came into existence. The latest spread of Y-chromosome lineage is known to have taken place nearly 10,000 years ago.
Spencer, on the basis of the study of mitochondrial DNA (passed on through the maternal family line)and the Y chromosome (passed from father to son), says that the modern-day man is not a descendant of Neanderthals and that the human race can trace its origin to one Adam and Eve.
Adam and Eve did not meet. Our common African foremother lived approximately 150,000 years ago.
Image courtesy University of Texas Austin
Did humans and Neanderthals ever live side-by-side?
Spencer says that they did. He says, we see evidence of Neanderthal remains at 30,000 years ago, and we know that modern humans were in Europe by around 35,000 years ago, so there must have been some overlap. There was certainly temporal overlap, and it's believed that they probably did know about each other and encounter each other's material culture. There is no evidence, though, for any interbreeding in the genes of people alive today. Modern Europeans seem to have come out of Africa with everybody else, and they didn't descend from the Neanderthals and in fact it doesn't seem like there was any mixture between these incoming groups of modern humans of African origin and the Neanderthals that were already there. The Neanderthals were like distant cousins who split off maybe 500,000 years ago from the lineage that later gave rise to us. How would we know if there was any interbreeding?
Dr. Spencer says that we have this coalescence point - this Adam - who lived 60,000 years ago in Africa. We have knowledge therefore of the level of diversity we expect to see in the human species, which is all in the last 60,000 years. If we saw a lineage, particular one limited to southwestern Europe,where we know the Neanderthals were living, that fell well outside of that and coalesced to 500,000 years ago, that would be good evidence that it was Neanderthal in origin. We do not see that. All of the European lineages we look at trace back to Africa within the last 60,000 years.
On expedition in Chad, Spencer Wells explains the Genographic Project to local village leaders. Photograph by David Evans/NGS 2006
Africa's San people
Africa's San people, the hunter-gathers once known as Bushmen, are genetically the oldest humans on earth. Their DNA carries more ancient evolutionary lineages than any other people and provides a direct link to the original common ancestor of all humans known as "Adam". He lived in Africa some 60,000 years ago, which means all humans lived in Africa until at least that time.
Unlike his Biblical namesake, this Adam was not the only man alive in his era. Rather, he is unique because his descendants are the only ones to survive to the present day.
It is important to note that Adam does not literally represent the first human. He is the coalescence of all the genetic diversity found in the world's disparate peoples. Adam had human ancestors as well but we have no remaining genetic evidence of them. The changes to the Y chromosome that is followed back through the generations to identify Adam end in the commonality of that shared ancestor.
A San bushman with Dr. Spencer Wells Photograph: National Geographic Society
The National Geographic says that genes aren't the only evidence linking the San to our earliest human ancestors.Their speech is characterized by clicking sounds used for word construction, which sound much like those used to guide a horse or simulate dripping water. The !Xu tribe employs an amazing 141 of them, while two-thirds of the world's languages use only 20 to 40 distinct sounds. Such linguistic complexity suggests ancient origins for the language. In a similar way, genetic lineages become increasingly diverse with age.
Today, the remnant of about 50,000 San, live in the Kalahari Desert of Namibia and Botswana, and the adjoining area of Angola. The San, were called Bushmen by the Dutch in South Africa and only one third of them continue their traditional nomadic lifestyles.
The following is from an IBM summary on the project:
The story of the Genographic Project must start where we ourselves began. That San Bushman might serve as a guide, for his features may reflect, as some anthropologists suspect, those of "Adam" himself.
We were born on the African savanna. Humanity is rooted there. For many years, science had looked to Asia for the place of our birth. But not Louis and Mary Leakey. They probed the fossil-rich cliffs of Tanzania's Olduvai Gorge for traces of our earliest ancestors. The Leakeys discovered abundant remains of early hominids, straight standing, sure-footed primates that gave rise to Homo sapiens. Supported by National Geographic grants, several generations of the Leakey clan have won renown as - the first family of paleoanthropology - because more than anyone else, their work revealed that Africa was the likely birthplace of humankind.
As human DNA is passed from parents to offspring, most of it is recombined and mutated, giving rise to all of those characteristics that make each person unique. Some components of our genetic inheritance, however, remain relatively stable over the course of generations. Occasional mutations in these components are easily identified and accumulate in a particular order and at a particular rate so that, compared across a broad spectrum of DNA samples, they act as a kind of time line. These "genetic markers" never disappear but are passed on to each generation. Over eons, different populations accumulate their own distinctive set of markers.
To scientists like Dr. Wells, such distinguishing signs are the equivalent of tribal or clan emblems: each identifies progressively more ancient lineages. They can be painstakingly traced deeper and deeper, down branching pathways to the earliest layers of our ancestry. By comparing DNA samples from different populations, a shape begins emerging, the shape of the human family tree, from twigs back to root, as encoded in our genes.
It is the shape of the human story as well. "The greatest history book ever written," Wells says, "is the one hidden in our DNA." Now a National Geographic explorer-in-residence, Dr. Wells is in the forefront of this exciting new blend of history and science. With his mentors and associates, he has focused primarily on mapping the markers on two relatively stable genetic components. Those on mitochondrial DNA (passed from mother to offspring in long maternal chains of descent) have been charted so far back that they have reached a - coalescence - point, a genetic ancestor now shared by every person alive today - indicating that we are all children of one ancestral female. This "Eve," as she has been dubbed, lived in Africa roughly 150,000 years ago. At that time the total human population was probably quite small, and it was more by chance than destiny that only her line survived.
The other relatively stable genetic component is the Y chromosome, passed only from father to son, and the markers on it, too, have been traced back to a coalescence point, indicating we all share a common male ancestor as well. This "Adam" also lived in Africa, but only 60,000 years ago. He probably looked very much like our San Bushman, who stems from one of humanity's oldest genetic stocks.
"We're all effectively cousins," Wells points out, "separated by no more than 2,000 generations."
These generations are represented by the maze of branching pathways lying between the coalescence points and the great sweep of our present genetic diversity. By comparing DNA evidence collected in the field, Wells, author of
The Journey of Man and presenter of the National Geographic Channel/PBS film of the same name, is tracking the genetic world.
One by one, the outlines of epic migrations are being sketched. For example, the frequency with which the Y chromosome genetic marker, M130, is found in Australian Aborigine males and other populations in southern Asia - and its relative scarcity elsewhere - indicates a prehistoric migration that left Africa and followed the coasts of Arabia, India, and Southeast Asia to Australia more than 50,000 years ago. Similarly, the near universal presence of the ancient genetic marker M9 in the vast majority of Eurasian and Native American men points ultimately to the grasslands of Central Asia, which acted as a kind of secondary hearth for our species. Arriving there roughly 45,000 years ago, early humans spent thousands more years in these game-rich regions before moving to Europe, Asia, or the Americas, each migration signaled by its own particular genetic marker.
So a map is emerging, but it is a map with much terra incognita. To chart more accurately this formative stage of human history, we need to expand the pool of genetic samples available to science. Only then can we better understand the distribution of genetic markers and complete the task of mapping their accumulated changes.
This is not only necessary, it is also urgent. Genetic markers are not stamped with their place of origin. Chronological sequence can only be inferred by carefully comparing the DNA from various populations that have been genetically - and geographically - stable for centuries. Most of the world's population is now in constant flux, and many genetic signals are being scrambled. Ripped from their geographic context, these signals become hard to decipher. The key to reading the annals of migration lies in the genes of the world's few remaining indigenous peoples, those still living in such remote and inaccessible regions that they have preserved some measure of long-standing ethnic identity.
Globalization is uprooting and scattering even these indigenous peoples. Their numbers are rapidly declining as dominant populations engulf and incorporate them. Their languages, customs, and traditions are disappearing at alarming rates. Can we glimpse the stories encoded in their genes before they are obscured? Can we capture a genetic "snapshot" of human history before the key to its interpretation is lost?
That's why the National Geographic Society and IBM are undertaking the Genographic Project, a massive, five-year effort to collect at least 100,000 DNA samples from the world's remaining indigenous peoples.
The project is rooted in partnership. Dr. Wells serves as director. IBM is providing advanced technology and research assistance. The Waitt Family Foundation is helping underwrite the costs of global field research. The National Geographic Society is coordinating these efforts and telling the story through its broad media outreach.
Key participants are ten research laboratories around the globe, each affiliated with a university or similar institution and responsible for sampling indigenous populations in particular geographic areas. One lab is in Europe, where ancient groups like the Basques still exist. Two are in North and South America, where native tribes are found from the Arctic to the Amazon. A fourth lab is in India, a patchwork of peoples so complex that 24 languages are officially recognized and hundreds of dialects still spoken.
Other labs are canvassing areas in East and Southeast Asia, Australia, and the Pacific, regions harboring many genetically distinct populations. Another is working in the old crossroads of civilization, the Middle East and North Africa, where desert nomads still roam. And one is covering countries that were part of the former Soviet Union, where seemingly every valley has its own tribe and language.
Finally, there's a lab working in sub-Saharan Africa, where human genetic diversity remains greatest. Most of the world's population stems from one giant limb of our common tree that has branched out in many directions. In contrast, modern Africans are the continuing extensions of a trunk still vast with genetic possibility. There might be more genetic variation in one African village than in many Asian or North American cities.
Each lab is sending scientists into the field to visit indigenous peoples whose DNA might contain clues to unsolved puzzles in human migratory history. Working with tribal elders and village chieftains, the scientists will collect blood samples to be analyzed for a range of genetic markers, including those on the Y chromosome and in mitochondrial DNA. Each lab might sample upwards of a hundred or so distinct populations. If each also collects at least 2,000 samples a year, then in five years we will reach the goal of 100,000 samples worldwide.
IBM's Computational Biology Center, a global leader in information intensive life sciences research, will supply the labs with state-of-the-art technologies and tools to provide unmatched analytical capability.
While coordinated through National Geographic's Washington headquarters, the Genographic Project is by nature international and decentralized. Dr. Wells as overall director is harnessing a network of local scientists and research labs. All activities will be overseen by an advisory board of representatives from participating indigenous communities and internationally recognized experts in genetics, linguistics, archaeology, paleontology, and cultural anthropology.
This board is setting guidelines, identifying populations for sampling, establishing research and collecting protocols, and ensuring that laws governing genetic sampling are rigidly followed. It will also zealously protect the interests of indigenous peoples. The Genographic Project is not about exploiting their genetic legacy. Rather, it highlights the crucial importance of these groups in today's fast-changing world.
But not everyone is a member of an indigenous group. If the project is to be truly global, it must sample the genetic inheritance of us all - and this provides an opportunity for broad public participation as well.
Public participation is critical to the project's success. By purchasing a Genographic Project Public Participation Kit, you may discover something about your own genetic past as well. You have an ancient story encoded in your genes, too.
Proceeds from the sale of the kits will be channeled back into the project to support additional research and to fund educational and cultural preservation efforts benefiting indigenous communities participating in the research.
The primary feature of the kit is the cheek swab test, an easy, painless way to sample your own DNA. Simply follow the instructions. Your samples will be processed by Family Tree DNA, one of the world's leading genetic genealogy companies, in conjunction with the University of Arizona Research Laboratories. Samples will be analyzed for genetic markers found in mitochondrial DNA and on the Y chromosome. We want to be very clear - the cheek swab test is not conventional genealogy. Your results will not write the names of forgotten ancestors on your personal family tree or tell you where your great-grandparents lived. Rather, they will indicate the maternal and paternal genetic markers those ancestors bequeathed you thousands of years ago, which chart your remote ancestors - migratory wanderings and indicate from which branch you hang on the global family tree. And if you choose to add your results to the research database, your profile will help fill out that greater tree, better articulating its profusion of twigs and branches.
After mailing your cheek swab and allowing several weeks for processing, you may access your results in complete anonymity by entering your Genographic Participant Identification Number onto a secure Web page . The genetic profile you receive is more than a static set of data. It is like an ongoing subscription to your genetic history. Your profile might become more detailed as the Genographic Project amasses more data from around the world. We are all members of the same extended family, and any one DNA profile may help illuminate many others as well.
At National Geographic's headquarters, the Society and IBM are building one of the world's largest databases of genetic information. As the data gathered from the Genographic Project's network of research labs is compiled and integrated with that obtained from the Public Participation Kits, it will be analyzed and interpreted. The result will be the genotyping, for the same set of genetic markers, of potentially hundreds of thousands of individuals.
This is an anthropological genetic database only. Only genetic information that reflects human origins and early movements - a fraction of the human genome - is being extracted for the project. Nevertheless, it will be an unprecedented achievement, the most comprehensive resource for mapping the migration and development of humankind ever assembled.
The public face of this vast resource is the Genographic Project's web site at www.nationalgeographic.com/genographic, powered by IBM. Here the stories encoded in our blood and cells will be told as they are uncovered.
The Web site will feature maps, news stories, a genetics primer, and historical time lines.
Multimedia presentations on topics spanning human origins, migration, archaeology, climate, and linguistics will appear alongside information on indigenous peoples and population genetics - all culminating in a unique Virtual Museum of Human History.
By frequent visits to the Web site, you might find answers to tantalizing questions that the Genographic Project hopes to address. Did Alexander the Great's armies leave a genetic trail as they crossed the Hindu Kush? What role did the Silk Road, with its caravans and bazaars, play in dispersing genetic lineages across Eurasia? Can we pinpoint the geographic cradle of the Bantu people and trace their expansion across Africa? Do genetic patterns actually correlate with the Australian Aborigines "Songlines," traditional narratives that connect landscape features with the footprints left by wandering mythological ancestors?
We will also probe more profound questions: How has human culture - with its traditional gender roles, patterns of marriage, distinctions of caste - affected genetic diversity? Or, since linguistic and genetic diversity mirror each other - both developing in relative isolation - what can our genes tell us about the origin and dispersal of languages?
And, if we share such a recent common ancestry, why do we all look so different? At present, the signals we detect in our genes are not strong enough to tell us these kinds of things. Nevertheless, as essayist Sir Thomas Browne wrote, such questions -are not beyond all conjecture. - We can't predict today what we might learn tomorrow. More genetic markers are waiting to be discovered. We only need a more complete worldwide sampling of human DNA.
If the Genographic Project can capture a snapshot of the history preserved in our DNA before this history is lost, this project will have done humanity a great service. It will have wrested from oblivion a story we all share, a story of human unity in diversity and the great journey we took to get here today.