There are two things to watch if you want to understand your DNA. Most important are two types of mutations that are printed on the Y-chromosome. If you can follow the changes that are printed on the Y-chromosome that your ancestors have bequeathed, you will learn a lot about your ancestors.
1. The first mutations to watch are the known SNPs (Single Nucleotide Polymorphism) or Haplogroup. For example SNP L22.
2. Other mutations that are monitored are named STRs (Short Tandem Repeats) or Haplotypes. These haplotypes are expressed by markers. This gives following figure as: 12 15 13 12 29 22 10 11 12 16 11 15
If haplogroups give us change for a large group of individuals, haplotypes give us much more information about our ancestors specify. You can read a lot of things with a reading of markers that are characteristic to your DNA. This reading has a name "modal haplotype".
Now it is time to explore your Haplogroup and your Modal Haplotype.The story of The DNA of our ancestors begin with a super volcano. The Toba supereruption occurred between 69,000 and 77,000 years ago at Lake Toba (Sumatra, Indonesia), and it is recognized as one of Earth's largest known eruptions. The related catastrophe theory holds that this supervolcanic event plunged the planet into a 6 to 10 year volcanic winter, which resulted in the world's human population being reduced to 10,000 or even a mere 1,000 breeding pairs, creating a bottleneck in human evolution. Some researchers argue that the Toba eruption produced not only a catastrophic volcanic winter but also an additional 1,000-year cooling episode.
Migration after Toba
It is currently not known where human populations were living at the time of the eruption. The most plausible scenario is that all the survivors were populations living in Africa, whose descendants would go on to populate the world.
Recent analyses of mitochondrial DNA have set the estimate for the major migration from Africa from 60,000 to 70,000 years ago, around 10—20,000 years earlier than previously thought, and in line with dating of the Toba eruption to around 66,000 to 76,000 years ago. During the subsequent tens of thousands of years, the descendants of these migrants populated Australia, East Asia, Europe and finally the Americas.
Map of early human migrations(The latest data are too recent to have been placed on this graph. I have placed to give you an overview of human migration.)
It has been suggested that nearby hominid populations, such as Homo erectus soloensis on Java, and Homo floresiensis on Flores, survived because they were upwind of Toba.
In the midst of this last great cold spell, very roughly about 25,000 years ago, a little baby boy was born with a mutation in his Y-chromosome. No one knew anything about it, least of all the little boy; it didn’t affect his life at all. But geneticists have come to recognize the mutation which took place at the time of this little boy’s conception—marker M170—as the beginning of a new and distinct gene group, called a “Haplogroup,” and lettered as the letter “I”.
Y-DNA Haplogroup I represents nearly one-fifth of the population of Europe. It can be found in the majority of present-day European populations; the greatest density to be found in Bosnia and Herzegovina, Croatia, Norway, Sweden, Serbia, Sardinia, Denmark and Germany. The haplogroup is almost non-existent outside of Europe or Asia Minor, suggesting that it arose in Europe.
After the birth of the haplogroup I
The earth has experienced warm period. But this improvement in the climate would not endure. Early occupation of Europe was arrested then reversed, as another prolonged period of severe cold gripped the continent—the last Ice Age. It continued for thousands of years; it’s most severe stage is called the Last Glacial Maximum, or LGM, which encompassed the furthest extent of the ice sheets upon the land.
This image shows Palaeolithic Europe 18 000 years ago in the grip of the last ice age. Glacial ice 2km thick covers much of Northern Europe and the Alps. Sea levels are approx. 125m lower than today and the coastline differs slightly from the present day. For example, Britain and Ireland would have been connected to continental Europe
(not shown on map).
The air would have been on average 10-12 degrees cooler and much more arid. In between the ice and the tree line, drought-tolerant grasses and loess dunes would have dominated the landscape.
Mankind could do little more than survive, and was forced to retreat south to a few scattered enclaves in Asia and Europe. Scientists speculate that human enclaves favored the high ground because it provided commanding views of the territory below and maximized sunlight by avoiding the shadows of the valleys. At this time our species numbered in the hundreds of thousands, but the earth could not support an increase in Homo sapiens sapiens. The emphasis was merely on survival. “During this time, it isn’t possible to venture too far north within Europe as the ice sheets cover much of northern Europe and tundra exists for several miles beneath them. The humans in this part of the world are relatively recent visitors and are not so adapted to the colder climes as are the people of Siberia. Thus, they take refuge below the tree line which at 18,000 years ago, the time of the last glacial maximum, extends across southern Europe. The refugia of Iberia(R1b), the Balkans(I) and Ukraine(R1a) allow people to ‘wait out’ the worst of the ice-age.”
This map shows the spread of Haplogroups R1b, I and R1a (12,000 years ago). These three major haplogroups account for approx 80% of Europe's present-day population.
If we fast forward to 12 000 years ago as shown here, the ice has retreated and the land has become much more supportive to life. Many animal species have returned to inhabit the land, although the snake, harvest mouse and mole never made it as far as Ireland before the land bridges re-flooded (ever wondered why there are no snakes in Ireland?).
Today distribution of Haplogroup I-M170.
This image gives us more information about the haplogroup I. The image allows us to see the subclades that are downstream.
There is a good possibility that there was a large extinction in our ancestors 5000 years after the founding of I - haplogroup.
Today, the genetic tree of humanity indicates there were only 8 males living at that time who were contributors do ALL of today's I-haplogroup population
The 8 contributing males living 5000 years after the founding of I-haplogroup were certainly not the total population of living I-haplogroup males of that time. But this suggests how precarious that haplogroup was for a long period of its early existence.
The first mutation that gives rise to subclade I2 appeared 7,750 years ago*.
The original breakup of I into multiple surviving branch lines occured in SE Europe. I2 has members from Turkey, Georgia, Armenia, Greece as well as elsewhere in Europe. Our ancestors separated about that date.
During the Neolithic period, pre-I1 and I1 people were part of the sucessive Ertebølle culture (5300-3950 BCE) and Funnelbeaker culture (4000-2700 BCE). The Corded Ware period (3200-1800 BCE) marks the arrival of the Indo-European R1a people from the Ukrainian steppes.
The megalithic structures (5000-1200 BCE) of Europe were built by I1 people.
I1 is identified by at least 15 unique mutations, which indicates that this lineage has been isolated for a long period of time, or experienced a serious population bottleneck. Although the first mutation splitting I1 away from I2 may have arisen as long as 7,750 years ago*, people belonging to this haplogroup all descend from a single man who lived less than 5,000 years ago. This corresponds to the arrival of the Indo-European, suggesting that a high percentage of the indigenous I1 men could possibly have been killed by the new immigrants.
The first mutation that gives rise to subclade I1 appeared 3,500 years ago*.(1,500 years before Christ)
The most recent common ancestor (MRCA) of I1 lived from 3,500 years ago somewhere in the far northern part of Europe, perhaps Denmark, according to Nordtvedt. His descendants are primarily found among the Germanic populations of northern Europe and the bordering Uralic and Celtic populations, although even in traditionally German demographics I1-M253 is overshadowed by the more prevalent Haplogroup R.
Haplogroup I1-M253 is the most common I subclade. It is found mostly in Scandinavia and Northern Germany, where it can represent over 35% of the population. Associated with the Norse ethnicity, it is found in all places invaded by the ancient Germanic tribes and the Vikings.
Density map of HG I1. The darkest areas approach only around 45% of the population.
It should be noted that the concentration of Haplogroup I1 is very similar to the Viking settlements and the Viking expansion.
Sublade L22 was born 3,000 years ago*(1,000 years before Christ). I1d is a north European clade, but it is not as north in origin as the Scandinavian haplogroup, although that's where a large fraction of the I1d ended up.
I1d-L22 was probably born early in the history of I1 in the very south of Scandinavia or in the very north of Germany --- Baltic coast, Schleswig or Jutland? The origin of this halogroup is assumed to be located in the province of Schleswig* on the German/Danish border.
Here's a chart I received from a member of the group I1d. It's a search that took data on FTDNA and Ken Nordvedt.