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SNP's and Haplogroups |
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-What are haplogroups? |
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The topic of haplogroups is becoming an increasing source
of interest with those that have received their Y-chromosome
haplotypes. This is because your haplotype can give you hints
to your ancient origins. |
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We’ve all seen illustrations that show the evolutionary
branches of primates, and how millions of years ago, chimpanzees,
gorillas, gibbons, and orang-utans diverged off from our primate
family tree. |
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Man (hominids) went off in a different evolutionary direction,
and there have been several different lines that have since
died off, Neanderthals being a notable example. With his origins
in Africa, modern man has spread himself around the globe.
As he did so, he adapted to his surroundings. These adaptations
can be seen in the lightened skin colour due to the lack of
sun away from the equator, stockier build as observed in peoples
in the Arctic regions to maintain body-heat, and better oxygen
absorption capability as seen in inhabitants of mountainous,
oxygen-poor regions. |
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Over time, many mutations in the DNA strand have occurred.
The Y-chromosome, whose main job is just to turn on the male
baby switch, has also picked up mutations of a particular type
as time has passed. This type of mutation is called a SNP (or
Single Nucleotide Polymorphism). This is quite a simply where
one letter of the DNA strand is changed to another letter (e.g.
T changes to a A). |
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These SNP’s are so rare as to be considered unique and
are passed down faithfully from father to son. Because of this,
they have been used to define several broad groups into which
every male in the world can be placed in. These broad groups
are called ‘haplogroups’. |
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As man has migrated around the world over time, these haplogroups
can be used to trace their paths. This is incredibly useful
and is an extra tool used alongside archaeological and linguistic
data. |
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Because some haplotypes (from STR tests) are found to be
common within particular haplogroups, it is very often possible
to make a prediction of what your haplogroup
is from your haplotype.
Where it becomes interesting for genealogists is that they
can gain some insight into their very ’deep’ ancestry
– i.e. thousands of years ago – of their direct
paternal ancestors. |
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For example, when it comes to Europe, the haplogroups observed
can be broadly split into two groups, Palaeolithic and Neolithic.
The first image (Map 1) 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). |
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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 dunes would have dominated the
landscape.
The Neanderthals would have died out around 14,000 years
ago leaving the nomadic hunter-gatherer Cro-Magnon (modern
man) to pursue the animals of the time. Due to the cold and
the need for food, the populations of the day waited the ice
age out in the three locations shown on the map. These were
the Iberian Peninsula, the Balkans and the Ukraine.
These people were skilled in flint-knapping techniques and
various tools such as end-scrapers for animal skins and burins
for working wood and engraving were common. Cave painting
using charcoal had been around for a couple of thousand years
although at this time they were now more subtle than mere
outline drawings. These artistic expressions are significant
as it shows that people are able to obtain some leisure time.
Whether this is ‘art for art’s sake’ or
objects of ritual is not known.
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If we fast forward to 12,000 years ago (Map 2), 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?). |
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The three groups of humans had taken refuge for so long that
their DNA had naturally picked up mutations, and consequently
can be defined into different haplogroups. As they spread from
these refuges, Haplogroups R1b, I and R1a propagated across
Europe.
- Haplogroup R1b is common on the western Atlantic coast as
far as Scotland.
- Haplogroup I is common across central Europe and up into Scandinavia.
- Haplogroup R1a is common in eastern Europe and has also spread
across into central Asia and as far as India and
Pakistan.
These three major haplogroups account for approx 80% of Europe's
present-day population. |
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Around 8,000 years ago (Map 3), the Neolithic peoples of the
Middle East that had developed the new technology of agriculture
began moving into Europe. There were several haplogroups involved,
mainly E3b, F, J2 and G2. |
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These Neolithic haplogroups came in several waves over time
and are found predominantly along the Mediterranean coast. Around
20% of the present-day population are from these Neolithic haplogroups.
What is interesting to note is that the agricultural technology
spread much further than the people who first 'invented' it. |
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A little later, around 4,500 years ago, Haplogroup N3 began
moving across from west of the Ural mountains. Haplogroup N3
follows closely the spread of the Finno-Ugric languages. |
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North American office: P.O. Box 1028, Richmond, TX 77406-1028 USA tel/fax: Toll free 866-7-DNA-DNA |
European office: 40 Preston Road, Weymouth, Dorset,
DT3 6PZ, UK tel:+44 (0) 1305 834936 fax:+44 (0)
1305 835925 |
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