DNA/Ancestry
General Mayflower Ancestry
Cushman Family Line
DNA...
The building blocks of who we are as human beings.
I have often wondered how these building blocks of "us" can tell us about our ancestry.
As I am researching the history of another of my ancestors, my 11th Great Grandfather, Robert Cushman, I came across a very interesting article on how our DNA as a species and its mutations through history has resulted in pretty much everyone who has English-European ancestry.
The fossil record places human origins in Africa some 150,000 years ago, but science continues to search for details about the incredible journey that took Homo sapiens from Africa to the far reaches of the Earth.
How did each of us end up where we are?
Why do we have such a wide variety of colors and features?
Through the eons of time, the full story of human ancestry remains written in our genes. When DNA is passed from one generation to the next, most of it is recombined by the processes that give each of us our individuality. But some parts of the DNA chain remain largely intact through the generations, altered only occasionally by random mutations, which become what are called genetic markers. The order in which these markers occur allows geneticists to trace our common evolutionary time line back many generations.
Different populations carry distinct mutation, or genetic markers. Identifying and following the markers back through generations reveals a relationship shared by all humans, best conceptualized in the form of a genetic tree. Today, thousands of diverse branches, corresponding to unique human groups, can be followed backward to their common African root more than 100 millennia ago.
The following missive is a fairly easy read and a good introduction to how these genetic markers can trace our ancestry back to the very beginnings of time and the birth of the human race.
I recently purchased a "23 & ME" DNA Testing Kit and plan on submitting my DNA sample soon.
The focus of the following article is some of the specific DNA genetic markers, that through time, resulted in me and my siblings and their children from our ancestry from our 11th great grandfather.
Mostly everyone with European ancestry will also have most of the same markers.....
Our Ancient Ancestry
Modern humans left a genetic trail when they first ventured out of Africa about 60,000 years ago. All people living today carry genetic markers that show when our ancient human ancestors moved from place to place. These genetic markers also make it possible to map the basic routes of their migration, as our ancient ancestors spread throughout the world.
Each of us is made up of an almost infinite shuffling of the genetic cards through many generations. But there is one constant for males: certain markers on the Y-chromosome of every male are passed virtually unchanged from father to son, and then to their sons, throughout the generations. Once in a while, a harmless but easily detected mutation in the Y-DNA can occur. When that happens this change in the DNA sequence will be passed on to sons, and their sons through the generations.2
Scientists have studied these subtle changes in the Y-DNA. They use them to estimate the approximate time these mutations took place, and also establish where the founder of the new lineage was living. This information makes it possible to understand the migration out of Africa, and the subsequent spread of peoples throughout the world.
The Genetic Trail to Europe & My Mayflower Ancestors
By exploring our deep genetic ancestry, and using a broad brush, we can map the migration of our ancestors from their origins in Africa to their eventual arrival in England, and the ancestral home of Robert Cushman and the Pilgrims who came over on the Mayflower and helped to found the nation that I now call home.
The journey for all of us began, 50,000-60,000 years ago (some 2,000 generations ago 3), at the beginning of what is known as the Paleolithic era.
A simple, harmless change in a single man's Y-DNA sequence appeared between 31,000 and 79,000 years ago, somewhere in Africa.
He was the first man to have an ancient Y chromosome marker called M168. He is the common ancestor of everyone living today outside of Africa.
M168/M89/M9/M45/M173/M343Genetic Markers
According to Spencer Wells of the National Genographic Project: "The migrations of the original M168's descendants took them out of Africa where they became the first to survive, to the present day, away from humanity's birth place."
Other people eventually developed slight changes in their Y-chromosome sequence. These harmless, subtle mutations began to define additional branches of the human tree and also define different migration routes.
For our purposes, we will only track the changes that are most relevant for our own deep ancestry.
A distinctive new marker called M89 arose on the original lineage (M168) about 45,000 years ago in an ancestor of ours -- one man -- probably living in Northern Africa or the Middle East. This genetic marker defined a large inland migration of hunters who followed expanding grasslands and plentiful game to the Middle East. M89 is found today in men living from Ethiopia to Tierra del Fuego.
Some 40,000 years ago, a man in Iran or southern Central Asia was born with a unique genetic marker known as M9. It marked a new lineage diverging from the M89 group. Most residents of the Northern Hemisphere trace their roots to this unique individual, and carry his defining marker. M9 marks a turn east toward the game-rich Eurasian grasslands.
For thousands of years, carrying M9 in their DNA, the population of our ancestors expanded. These seasoned hunters followed the herds ever eastward, along a vast belt of Eurasian steppe, until the massive mountain ranges of the Hindu Kush, the Pamirs, and the Tien Shan in south central Asia blocked their path. These mountains caused subsequent eastward migrations to take different routes. Our ancestors took the northern route and moved on to the broad rolling steppes of Central Asia.
Marker M45 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 to an increasingly hostile environment. They erected animal skin shelters and sewed watertight clothing. They also refined the flint heads on their weapons to compensate for the scarcity of obsidian and other materials.
Marker M173 (Haplogroup R1) emerged among a westward movement of Central Asian steppe hunters defined by M45. The descendants of M173 arrived in Europe around 35,000 years ago and immediately began to make their own dramatic mark on the continent. Famous cave paintings, like those of Lascaux and Chauvet, signal the sudden arrival of humans with artistic skill. There are no artistic precedents or precursors to their appearance.
Soon after this lineage's appearance in Europe, the era of the Neanderthals came to a close. Genetic evidence proves that these hominoids were not human ancestors but an evolutionary dead end. Smarter, more resourceful human descendants of M173 likely out competed Neanderthals for scarce Ice Age resources, hastening their disappearance.
M343 (Haplogroup R1b) first appears 35,000 years ago. People defined by marker M343, are descended from ancestral M173 peoples, as are people with the P25 marker.
Eighteen thousand years ago, half of the land mass of Great Britain was covered by ice. The rest was uninhabitable. The last glacial ice age maximum forced our ancestors south to the Iberian Peninsula, in the extreme southwest of Europe. There, between 30,000 and 15,000 years ago, as Europe moved into the depths of the last ice age, there was a substantial reduction in population size. It was followed by a population expansion from the few survivors of the last ice age.
By 10,000 as the ice retreated, they moved north out of this isolated refuge, colonized what was still the extreme-north-western peninsula of the Eurasian land mass, and left an enduring, concentrated trail of the M173 marker every place they went.
Today, M343 (R1b) is the most frequent Y-chromosome haplogroup in Europe, and is particularly concentrated along the western seaboard of Europe - Portugal to Norway including the British Isles-and extending inland to the German/Poland border. In Southern England, the frequency of R1b is about 70% 5 and in parts of Spain, Portugal and Ireland, it is as high as 90%.
Scientists are now subdividing this large R1b haplogroup into smaller classifications. Over time, we can expect further refinement of the twigs and branches of the R1b tree.
For example, geneticists eventually discovered that P25 is downstream from M343 and, therefore, many people who were formerly classified as R1b, including the author, are now classified as haplogroup R1b1a2.
Below the North Sea today lie the low hills and estuaries of Doggerland, the drowned world between Britain and Denmark where once herds and people moved in annual rituals. At that time Doggerland would have covered an area about the size of England. But every year the sea rose imperceptibly, until about 8,000 years ago, when the North Sea waters poured again through the channel moat separating the British peninsula from the continent. Britain and Ireland were once again islands, as they have been ever since.
The pace of our migration was imperceptible because it took place over such a long period of time. Indeed, the world was pretty small for most of our ancestors. Our English ancestors, for example, did not venture but a few miles from their birthplace. Generation after generation lived in the same place, at least until quite recently, the last 150 years or so. This tends to make people living in the same region genetically similar to each other, over time, and to increase the genetic differences between geographically separated localities.
The longer two isolated groups have been separated, the more genetic differences there will be. This is also reflected in differences in language, in accents, dialects and so forth.
This concept has allowed us to determine the probable Y-DNA signature or profile of the descendants of Robert Cushman of Kent, and to locate his probable ancestral home in Kent, England.
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