English People Less Diverse

[Orleander]

How is this possible??
More people from more countries are there, yet the gene pool is smaller??

English Less Diverse Than 1,000 Years Ago, DNA Study Finds

English people are less genetically diverse today than they were in the days of the Vikings, possibly due to two deadly plagues that swept their country centuries ago, a new study says.

The study compared DNA from ancient and modern Englanders and found that the country has a smaller gene pool than it did a thousand years ago.E

The findings come in contrast to modern England's reputation as a cultural melting pot, where in many major cities you are as likely to hear Urdu (from India) or Yoruba (from Nigeria) being spoken on the streets as English.

"The findings were unexpected. Modern England is the result of centuries of mixing cultures, and so higher diversity was expected," said Rus Hoelzel, a geneticist from the Britain's University of Durham, who led the study.

Hoelzel and his colleagues obtained DNA samples from the skeletal remains of 48 ancient Britons who lived between A.D. 300 and 1000.

The researchers studied the mitochondrial part of the DNA, which is passed down from mothers to their children (see an overview of human genetics).

By comparing this DNA with that of thousands of people from various ethnic backgrounds living in England today, they found that genetic diversity was greater in the ancient population.

The team also compared the ancient DNA with samples from people living in continental Europe and the Middle East, and found a similar lack of genetic variety.

"Few of the modern populations were as diverse as our ancient sample," Hoelzel said, adding that his team analyzed 6,320 modern samples in all.....

 

[Oli]

That's 'cos we overwhelm everyone else's DNA and make 'em ENGLISH!

 

[iceaura]

There isn't necessarily all that much genetic diversity coming in with those immigrants. Humans are not as diverse as they are widespread, these days.

That said, measuring "diversity" is tricky. If 99% of your sample is one thing, and the other 1% is ten different things, do you have more diversity on hand than if ten different things are each 10% of your sample?

What is the the measue of diversity used?

 

[Orleander]

There isn't necessarily all that much genetic diversity coming in with those immigrants. Humans are not as diverse as they are widespread, these days.

That said, measuring "diversity" is tricky. If 99% of your sample is one thing, and the other 1% is ten different things, do you have more diversity on hand than if ten different things are each 10% of your sample?

What is the the measue of diversity used?

Umm, Vivkings?? I don't know. What do you mean measure?

 

[iceaura]

What do you mean measure?

I mean that if you have a claim of more or less of something, you probably have measured it somehow. How was the "diversity" measured? Diversity is hard to measure, because there is no intuitively obvious scale.

 

[Orleander]

This?

Hoelzel and his colleagues obtained DNA samples from the skeletal remains of 48 ancient Britons who lived between A.D. 300 and 1000.

The researchers studied the mitochondrial part of the DNA, which is passed down from mothers to their children (see an overview of human genetics).

By comparing this DNA with that of thousands of people from various ethnic backgrounds living in England today, they found that genetic diversity was greater in the ancient population.

 

[iceaura]

By comparing this DNA with that of thousands of people from various ethnic backgrounds living in England today, they found that genetic diversity was greater in the ancient population.

That doesn't say how they measured the "diversity".

It's like anything else measured - there has to be a scale, a yardstick, or in this case a formula. For example, Pielou's Diversity Index, or Shannon & Weaver's, (Google).

It's not that I don't believe them - it's quite plausible, as England has long had a lot of different kinds of people (the Romans brought soldiers from way south, the Mongols left genetics in the immigrants from the east, the Vikings brought northern - possibly even Lapp or Greenlander - genetics) and humans don't vary as much worldwide on average as they do locally in particular - but there is no info there on how they calculated the "diversity" they had on hand.

 

[Orleander]

does this article have what you are talking about?

 

[lucifers angel]

That's 'cos we overwhelm everyone else's DNA and make 'em ENGLISH!

this doesnt apply to me i am welsh

 

[Chatha]

There probably was no "England" 1000 years ago, it was probably just a space where people of all sorts came in and out. Then when England was formed, immigration obviously became regulated. A lot of reasons can be responsible for the diminished diversity. The crusades saw a huge export and loss of males, the black plague, and the obvious English colonial rule where English personels traveled and migrated to other parts of the world for days on end. But its still had for me to believe that England is less geneticaly diverse today with all its international business and culture.

 

[Zephyr]

Mitochondrial DNA is passed on without recombination since it comes only from the mother. It may be affected by this:

http://en.wikipedia.org/wiki/Muller's_ratchet

The article mostly talks about irreversible deleterious mutations, but I wonder if it couldn't result in less diversity over time too. If you go back far enough - only along the female line - a lot of people must share some matriarch or other :shrug:

 

[Idle Mind]

It comes down to timing. The individuals were taken from sample humans between 300AD and 1000 AD. This was a very hectic time in Britain. Rome had finished it's withdrawal by the year 410 AD, which left Britain open to invasion by peoples expanding from the European continent (Jutes, Danes, Saxons, Angles, etc) and the Celts from Ireland as well as Berbers and other travellers from Northern Africa, although I'm not sure how long they lingered because of the dramatic climate difference. Few of these cultures even spoke the same language, let alone interbred with one another.

So we have the Roman people who remained, all the 'invading' peoples and the local British that were there before the Roman occupation. It likely would have taken centuries before the people all started coming together and mixing culturally and genetically. However, now that these people have lived together for over a millenium, they have thoroughly mixed and are thus less diverse.

If they had taken samples from people in an earlier time frame (say prior to Roman occupation), who knows? Perhaps the current population would show a higher diversity.

 

[Fraggle Rocker]

There probably was no "England" 1000 years ago, it was probably just a space where people of all sorts came in and out.

There was definitely an Angle Land 1,000 years ago. King Arthur may be a myth and England had not necessarily coalesced into a single administrative entity under a single ruler, but that section of Britannia was home to an "Anglisc" people who spoke Old English--or Anglo-Saxon as we now call it, the language of the Beowulf saga. Just a few years later, in 1066, the Normans invaded, conquered and occupied England and began intermarrying with the English people.

If they had taken samples from people in an earlier time frame (say prior to Roman occupation), who knows? Perhaps the current population would show a higher diversity.

For sure. Prior to the Roman conquest, the southern part of Britannia was occupied by Brythonic people--the Celtic tribes of the British Isles as opposed to those of the mainland like the Iberians. They were close relatives of the Gaels of Ireland. I'm not sure whether the ancestors of the Welsh, Cornish and other surviving Celts of Britannia had even become separate peoples yet, or just remote regions all speaking dialects of the same Celtic language. At this point their genetic diversity must have been very low.

The Romans brought some of their DNA into the gene pool, but they did not really establish a huge colony on Britannia. It was after they left that the real waves of immigration began. England had become an outpost of Roman civilization, an attractive destination for Neolithic people seeking to make their fortune by hard work, plunder, or other means. Norsemen came and settled, but Germanic tribes (Angles, Saxons and Jutes) came to conquer. They did the same thing to the "British" that the Arabs did to the "Egyptians": marginalized the natives, took over their country, and commandeered their name. However, the new name "Angle Land" came into being in parallel with the old name "Britain."

During this period the Irish began migrating to what is now Scotland, displacing the Picts who lived there--a pre-Indo-European tribe that we know very little about--and establishing Gaelic as its language.

Then in 1066 a second wave of Norsemen invaded--after first invading France, establishing a colony there, and taking a French form of their name: Normans and Normandy. These Normans were of mixed Norse and French ancestry, and the French themselves were a mixture of the original Germanic Franks in the north of France and the Celtic Gauls in the south.

So this was probably the point in history at which England's genetic diversity was the greatest: The time between the Norman Invasion and Chaucer. Original native Brythonic with probably a bit of Pict, an infusion of Roman, a smattering of Scandinavian, a massive inflow of several Germanic tribes, some Irish by way of Scotland, then an invasion of Norman French carrying their own olio of DNA. From this point on the population had a chance to stabilize and was subject to the forces noted above, which worked to limit diversity.