GENETIC MARKERS TRACE MY ANCESTRAL LINEAGE


My goal in this section is to learn the when and where of my genetic line. That said, my efforts involve pinpointing the geographic origin of ancestors based on Caitlin Dempsey's belief that when a marker is formed it can be linked to a geographic location and to group populations who bear the same marker by point of origin. Accordingly, there is an ancestral mutation on the average of one every 100 years, which does not necessarily result in the acquiring of a new genetic marker to trace geographically.

Figure 5
My Maternal Tree

Haplogroup O Map

My maternal haplogroup B ancestry, known by its defining genetic marker B4, which orginated ~50,000 years ago in Asia. I show this marker as the base of my ancestral tree in Figure 5.Interestingly, haplogroup B is now most common among populations native to Southeast Asia, as well as speakers of the Austronesian languages. Haplogroup B2, my maternal haplogroup marker, is one of five haplogroups found among the indigenous peoples of the Americas and spread into all of the Americas ~15,000 years ago.

Figure 6
My Paternal Tree

Haplogroup O Map

My haplogroup O ancestry, known by its defining genetic marker O-M175, which orginated ~35,000 years ago. I show this marker as the base of my ancestral tree in Figure 6. O-M175 is mostly found among populations in East and Southeast Asia and mostly associated with the Chinese people and the main Han Chinese lineage of which I am a part. Moreover, Haplogroup O is also marked, along with its corresponding DNA markers, by the family of Sino-Austronesian languages.

As the largest and most dominant component of the East Asian Y chromosome gene pool, O-M175 accounts for 75% of the total paternal lineages of Chinese. Yet, it is almost nonexistent in Western Siberia, Western Asia, Europe, and Africa and is completely absent from the Americas.

About 29,400 years ago my O-M175 ancestral lineage experienced a genetic variation. It resulted in an offspring acquiring a genetic trait his ancestor didn't have, in essence, a new genetic marker. The new offspring of the O-M175 ancestor had formed a new genetic O-M122. As such, the new ancestor with the O-M122 marker is known by the acronym Most Recent Common Ancestor (MRCA). This means he is the most recent man from which all the men in my O-M122 haplogroup branch are directly descended.

The O-M122 marker is the main sublineage of O-M175 and is the predominant sub-group in China. The O-M122 marker is also found at high levels amongst Han Chinese, Tibeto-Burman populations (including many of those in Yunnan, Tibet, Myanmar, Northeast India, and Nepal), Manchu, Mongolians, Koreans, Vietnamese, Malays, Filipinos, Thailand, Polynesians, Naiman tribe of Kazakhs,[5] and Kazakhs in the Altai Republic.

I know when this O-M122 MRCA lived, but only generally where. He lived about 24,700 years ago, during the Paleolithic Period and likely lived as a nomad staying near rivers and lakes.

As the ethnic ancestor of the Han Chinese, he reached the upper and middle Yellow River basin. Continuous migrations of the O-M122 ancestral line makes the specific geographical location of my O-M122 ancestor ambivalent. Possibly he existed along the 600 mile stretch of the Yangtze River believed to be the cradle of ancient civilizations. The Yangtze River plays an important role in China's culture and long history of civilization and it forms the boundary between present day northern and southern China. To that point, my O-M122 ancestor may have lived in the river section known as the Middle Reach and in the general vicinity of the present day Hubei Province of China where the famous Three Gorges are located.

With the passage of time,my haplogroup O lineage would again evolve. About 23,200 years ago in China's Yangtze River Delta my O-M122 ancestor gave rise to an ancestor bearing the DNA Marker O-P201 around present day Chongqing. The O-P201 marker is a major branch of haploroup O in Asia.

It might have been the harshness of ice age weather or global cooling that drove both animals and man south and prompted my O-P201 ancestor's continued southern migration. In any case, it resulted in the emergence of an O-P164 ancestor ~19,200 years ago. Interestingly, with the advent of the Neolithic Period 18,000 years ago the matriarchal clan society existed in China. It was a social system in which the mother was head of the family and descent was traced through the mother's side of the family.

A pattern of genetic variation among my subsequent ancestors would be largely shaped by continued human migration into Southeast Asia. Their journey may have even been overland into the continent of Sundaland, which would not wholly sink under the sea until ~12,000 years ago.

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