Archive for category: Motherlode

L3

“Mitochondrial Eve,” the common ancestor of all living humans, was born in Africa some 150,000 years ago. All existing MtDNA diversity began with Eve and it remains greatest, and subsequently oldest, in Africa.

Y chromosome polymorphisms on the male line of descent also point to an African origin for all humans, but our male common ancestor, “Adam,” lived only about 60,000 years ago.

MtDNA and the Y chromosome are independent parts of our genetic makeup and each tells a different tale of successive genetic mutations over the eons. That is why their approximate coalescence points are different. Yet while the dates vary, both paths point emphatically to a surprisingly recent African origin for all humans.

The oldest known fossil remains of anatomically modern humans were found in Ethiopia’s Omo River Valley. The skeletons, known as Omo I and Omo II, have been dated to about 195,000 years ago.

Although haplogroup L3 does not appear outside of Africa it is an important part of the human migrations from that continent to the rest of the world.

A single person of the L3 lineage gave rise to the M and N haplogroups some 80,000 years ago.

All Eurasian mtDNA lineages are subsequently descended from these two groups.

The African Ice Age was characterized by drought rather than by cold. But about 50,000 years ago a period of warmer temperatures and moist climate made even parts of the arid Sahara habitable. The climatic shift likely spurred hunter-gatherer migrations into a steppe-like Sahara—and beyond.

This “Saharan Gateway” led humans out of Africa to the Middle East. The route they took is uncertain. They may have traveled north down the Nile to the Mediterranean coast and the Sinai. Alternatively, they may have crossed what was then a land bridge connecting the Bab al Mandab to Arabia, after which they either skirted the then-lush, verdant eastern coast of the Red Sea or headed east along the Gulf of Aden towards the Arabian Sea.

When the climate again turned arid, expanding Saharan sands slammed the Saharan Gateway shut. The desert was at its driest between 20,000 and 40,000 years ago, and during this period Middle East migrants became isolated from Africa.

From their new Middle East location, however, they would go on to populate much of the world.

M*

M is a macro-haplogroup whose various sub groups are found in Eastern Eurasia, East Asia (M7, M8), America (C, D), and the Indian subcontinent—though not in Europe.

The M lineage arose from the African haplogroup defined by L3. With haplogroup N, this lineage traces the first human migrations out of Africa.

Haplogroup M ancestors were part of a great coastal migration that took place some 50,000 years ago. Hunter-gatherers skilled at seaside living wandered along the coasts of the southern Arabian Peninsula, India, Sri Lanka, and Southeast Asia.

This ancient southern coastline was drowned by rising sea levels at the end of the last ice age. The rising waters also swallowed most archaeological traces of these early coastal-dwelling peoples.

Yet in places their physical footprint endures. Some of the fast-moving migrants reached and populated distant Australia soon after leaving Africa. Australian archaeological evidence, such as rock art, confirms their presence as early as 40,000 or perhaps even 60,000 years ago.

During the glacial Pleistocene era (about 50,000 years ago) sea levels in some places were 330 feet (100 meters) lower than they are today. The landmass known as Sunda (comprised of modern Sumatra and Borneo) was separated by just 62 miles (100 kilometers) of open water from Sahul, a second landmass comprised of Australia, New Guinea and Tasmania.

Though Australia was never connected to the continent by a land bridge, such short stretches of relatively calm water were apparently navigable by these early seafarers.

Haplogroup M is a broad group comprised of many as-yet undefined branches. Learning more about such lineages will add further clarity to the big picture of human genetic diversity, and is a primary goal of the Genographic Project.

M168

The very widely dispersed M168 marker can be traced to a single individual, Eurasian Adam. This African man, who lived some 31,000 to 79,000 years ago, is the common ancestor of every non-African person living today. His descendants migrated out of Africa and became the only lineage to survive away from humanity’s home continent.

Population growth during the Upper Paleolithic era may have spurred the M168 lineage to seek new hunting grounds for the plains animals crucial to their survival. A period of moist and favorable climate had expanded the ranges of such animals at this time, so these nomadic peoples may have simply followed their food source.

Improved tools and rudimentary art appeared during this same epoch, suggesting significant mental and behavioral changes. These shifts may have been spurred by a genetic mutation that gave Eurasian Adam’s descendants a cognitive advantage over other contemporary, but now extinct, human lineages.

M89

Some 90 to 95 percent of all non-Africans are descendants of the second great human migration out of Africa, which is defined by the marker M89.

M89 first appeared 45,000 years ago in Northern Africa or the Middle East. It arose on the original lineage (M168) of Eurasian Adam, and defines a large inland migration of hunters who followed expanding grasslands and plentiful game to the Middle East.

Many people of this lineage remained in the Middle East, but others continued their movement and followed the grasslands through Iran to the vast steppes of Central Asia. Herds of buffalo, antelope, woolly mammoths, and other game probably enticed them to explore new grasslands.

With much of Earth’s water frozen in massive ice sheets, the era’s vast steppes stretched from eastern France to Korea. The grassland hunters of the M89 lineage traveled both east and west along this steppe superhighway and eventually peopled much of the continent.

A group of M89 descendants moved north from the Middle East to Anatolia and the Balkans, trading familiar grasslands for forests and high country. Though their numbers were likely small, genetic traces of their journey are still found today.

M9

Some 40,000 years ago a man in Iran or southern Central Asia was born with a unique genetic marker known as M9, which marked a new lineage diverging from the M89 group. His descendants spent the next 30,000 years populating much of the planet.

Most residents of the Northern Hemisphere trace their roots to this unique individual, and carry his defining marker. Nearly all North Americans and East Asians have the M9 marker, as do most Europeans and many Indians. The haplogroup defined by M9, K, is known as the Eurasian Clan.

This large lineage dispersed gradually. Seasoned hunters followed the herds ever eastward, along a vast belt of Eurasian steppe, until the massive mountain ranges of south central Asia blocked their path.

The Hindu Kush, Tian Shan, and Himalaya, even more formidable during the era’s ice age, divided eastward migrations. These migrations through the Pamir Knot region would subsequently become defined by additional genetic markers.

M45

The marker M45 first appeared about 35,000 to 40,000 years ago in a man who became the common ancestor of most Europeans and nearly all Native Americans. This unique individual was part of the M9 lineage, which was moving to the north of the mountainous Hindu Kush and onto the game-rich steppes of Kazakhstan, Uzbekistan, and southern Siberia.

The M45 lineage survived on these northern steppes even in the frigid Ice Age climate. While big game was plentiful, these resourceful hunters had to adapt their behavior to an increasingly hostile environment. They erected animal skin shelters and sewed weathertight clothing. They also refined the flint heads on their weapons to compensate for the scarcity of obsidian and other materials.

The intelligence that allowed this lineage to adapt and thrive in harsh conditions was critical to human survival in a region where no other hominids are known to have survived.

M242 – Haplogroup Q

Haplogroup Q, defined by marker M242, appeared on the M45 lineage and includes most Native Americans. Its origin lies in Siberia some 15,000 to 20,000 years ago—during the savagely cold climate of that period.

The adaptable descendants of M242 survived by hunting large mammals and inventing cold-weather living techniques still employed by their modern Arctic descendents. They developed new shelters, new types of clothing, and new tools for an increasingly challenging environment.

In the ice-free regions of Siberia these people sat poised to enter a new world. About 15,000 years ago they did just that. With much of Earth’s water locked up in ice sheets, period sea levels were some 350 feet (100 meters) lower than at present. Consequently a land mass called Beringia connected present-day Siberia and Alaska and provided a crossing for the peopling of the Americas.

The genetic data coincide with archaeological evidence for a Beringia crossing that enabled North American settlement only after about 15,000 years ago.

Somehow the progeny of M242 migrated further south through the Americas. Just how they gained passage through the era’s prevalent ice cover is unknown. Some speculate that an ice-free Rocky Mountain corridor allowed safe travel, while others favor a hypothesis of coastal migration.

Whatever their route out of modern Alaska, the descendents of M242 were the first explorers of the New World.

The Entire Migration – not quite

And that’s the whole journey…or what’s known so far.

I wonder, what point in time does my direct line turn back and return to India?

You can explore more off this at the official site.