Translator: Behdad Khazaeli Reviewer: Hélène Vernet
Hello everyone.
So, I'm going to talk today about migration and movement,
and particularly people moving into the British Isles in the past.
And if we think about past migrations into Britain,
we probably first off might have some ideas about the 20th century,
people coming from the Caribbean, from east Africa,
or from India, or Pakistan, or places like that.
And if we have to go back a bit further in time,
of course we've got people like the Normans, Romans or the Vikings.
But despite the fact that we've noticed quite a lot of people
who have moved into Britain at different times,
I don't think we really think of ourselves as a migrant nation.
We think of ourselves more outside as an island nation.
But what about if we go back really a long way,
we really go back far in time beyond the time
when there is any notion of a Britain or an England,
beyond any kind of english language,
in fact beyond written history at all.
In fact, we can go so far back in time
that Britain is actually not even an island at all.
It's still joined to the continent, still part of the Eurasian landmass.
So that's what I want to talk to you about today,
about Britain in prehistory, and the prehistory of migration here.
So we're going to take a big jump back in time,
but I can't do that with you all in one go.
So we are going to take little jumps first.
We are going to jump back to the late Victorian period,
and we're going to start off here.
Here, we start in Somerset at Cheddar Gorge.
It is here during the last decades of the 19th century,
that this guy, Richard Cox Gough,
discovered and excavated and blasted out
a series of caves that he made into a major tourist attraction or a showcase.
But it's actually a year after Richard died
that the really big discovery was made,
the one we're actually interested in.
So that discovery was made in December, 1903,
and it was made by Richard's son, Arthur, who was digging a drainage ditch
to try to combat the seasonal flooding that they had in the caves.
They tended to make all their big discoveries in the winter
because that's when there weren't any tourists around.
So workmen who were working on the cave
actually blasted out and uncovered
the skeleton of an adult male.
And rather quickly, this skeleton made big news.
Experts of the day said that perhaps it was the body of the first Englishman,
and that he was of extreme importance,
that he was at least 40,000 years old
and perhaps as much as 80,000 years old.
Well, that's not entirely true.
What we actually know today is that "Cheddar Man," as he became known,
Is actually about 10,000 years old,
but he is still certainly very important.
He's extremely important for a number of reasons.
Firstly because he is the only near-complete skeleton
that we have from that kind of time period.
He is also important because he's the only one
where we have a complete skull or near-complete skull.
And here is the skull, in this rather post-setting
with the two brothers, William and Arthur, staring at it.
They seem to be enjoying themselves
which is what I really like about this picture.
(Laughter)
So what else do we know about Cheddar Man?
Well, he's definitely a man.
And that has been the subject of a little bit debate over the years
because he has a rather gracile and slender skeleton.
He was probably in his early twenties when he died;
he was buried deliberately, it seems,
and he was buried on his own.
Today, he looks something like this.
This guy has been better assembled,
and you can see him at the Natural History Museum.
He is on display a couple of galleries away from where my office is.
So, we've worked on Cheddar Man
and a number of other individuals over the years
and built together quite a large complex project
exploring the history of the British Isles.
And one of the things that came up as the result of that project
was the opportunity to take part in a channel 4 documentary
where we were going to explore Cheddar Man and his history
to build up more of a story about him.
So that was good because we already had quite a lengthy project
working on the history of the British Isles,
but what the people who put the documentary together
wanted to know about
was something a little bit more complicated, more detailed,
and that was about his appearance,
about his skin color, hair color and eye color.
And what we were able to do for them was to supply that information.
We passed it on to the people who made the reconstruction.
Well, they came back with this,
an individual with a rather small face compared to the overall size of his head,
with blue eyes, dark curly hair,
and obviously with dark skin.
And that was a surprise for some people,
for most of the people I talked to actually.
And most of them actually seem to think that this was rather cool.
People who saw the show generally quite enjoyed it.
We weren't particularly surprised by this
because similar information had already been generated by a group,
a couple of year previously,
looking at different skeletons around Europe of a similar kind of age.
They had already identified that dark skin
was practically normal for people about 10,000 years ago.
But what we've been able to do
was better quantify exactly how dark that was.
And we've done that using a tool borrowed from forensic sciences.
Some people didn't think that this was very cool.
Some people I think were expecting to see something a little bit more like this,
which is the results of the previous reconstruction.
Both reconstructions are obviously quite different,
but they do share one feature at least
which is this rather wispy facial hair.
And I'm surprised about that because there's really no evidences either way,
from the archeological genetic data, that would tend to actually suggest that.
But that is perhaps their only shared feature actually.
So those people, who didn't think it was very cool,
were a bit surprised,
and they made their surprise known on social media,
as you might expect.
And actually things got rather heated there, and you can look at that.
Right now I don't really want to go into too much detail about it.
But here's one of the sort of slightly odd events that happened there,
one of my childhood heroes indirectly ...
(Laughter)
... indirectly congratulating me on having upset some people.
So that was a little bit weird actually.
And that went on for a while.
So, what became clear to us was something rather disappointing.
As I've already said to you, we had spent quite a bit of time
getting a pretty good understanding
of what the population history of British Isles actually looks like.
So how do you get from someone like this to people in the audience today?
I mean Cheddar Man obviously not Billy Bragg!
So that's what I'm going to go through now,
what we're going to have a look at.
Okay, but before we can do that
we have to work out how exactly we're going to look at that information.
We really have a lot of data here.
The human genome has 3.2 billion base pairs
and I can't just keep flashing that up
because we'd run out of time quite quickly.
So what we need to do is find a way of crunching those data down
and just pulling out the most important and interesting parts of it.
And the method that we often use just to get a handle on the data initially
is called the "principal components analysis,"
and that's what I'm going to show you here.
So these are genome data that has been squashed down onto something
that looks a bit like a graph or a plot.
And so individuals who are close together are genetically similar to each other,
regardless of where they might happen to come from.
So let's start here with Cheddar Man.
But all alone, like he was in Gough's cave,
he's not actually doing much for us, he's not telling us very much.
So let's put on the other five individuals from Britain,
from which we have very small amounts of genome sequenced data,
and see what happens.
What happens then is that they all plot together quite neatly.
Despite the fact that we have individuals here from Scotland,
Wales and southwest England,
they actually all look quite similar to each other.
Let's expand the search a bit more across the rest of Europe.
What we have here are some more individuals.
The ones in blue are older individuals,
slightly older ones from slightly earlier time periods.
The ones in that kind of dark red color are of a similar age.
And these are samples that have been taken
from Spain, Hungary, Germany,
Sweden, Luxembourg, all sorts of places including Britain.
And what you see is that the British ones
kind of bridge the gap between the earlier and later ones.
But there's still not much of a picture here.
Where we do get a bit of a surprise is if we jump forward in time a bit more.
Okay, so what we have here,
about 4000 years after Cheddar Man died,
is that something quite surprising happened in Britain,
and that's the origins of farming.
So the first farmers had arrived in Europe several thousands years earlier.
They had arrived in Greece.
They are the red folks on that plot.
They'd made they way across Europe over several millennia
and eventually arrived in Britain
where we have the grey individuals on the plot.
What you can see there about those grey people
is that we have two important things to get out of this.
They are genetically extremely different
to the hunter-gatherers that were in Britain at that time.
And they entirely replaced them,
a complete replacement of the population.
Now it's always tempting at these points to think of some kind of vast horde
arriving and committing some kind of genocidal act
on the people, the peaceful hunter-gatherer people.
We don't have any evidence for that at all.
So what we think in fact is quite plausible
is that there were actually remarkably few people
in the British Isles at this time.
[Farmers] arrive and just take over.
And they can easily take over the country.
What is even more surprising
is that a very similar thing happens about 1300 years later.
A second genetically very distinct group arrives in the British Isles.
These are the so-called "Beaker people" who are called that
because of the distinctive ceramic vessels that they're often buried with.
These Beaker people were also genetically very different
and seem to completely replace the Neolithic people there,
the farmers that were there before.
And this, it seems,
is the last major population replacement that we can detect
at the resolution that we can work with at the moment, with ancient DNA data.
So if we bring up now the modern population across Europe,
you can see that those Beaker people sit pretty much
on top of current British Isles populations
and, in fact, the populations of northwestern Europe continents
in a bit of smear across there as well.
Okay, so what can we draw from this?
What do we really have to conclude here?
One of the things that I realized
some time after we've done this work and the documentary show
was that for some people who are upset
by the way we had reconstructed Cheddar Man,
the issue was one of population continuity.
We had challenged that notion that they had
that there was a long-term population continuity in Britain.
And that's very much not what the data seem to be saying.
The history and the prehistory of Britain
is one where populations are under a series of replacements.
The other thing that you can also draw from this data
is about migration and our modern day concerns about mass migration
and how it affects society.
What you can see here is that the scale of migration today,
despite the advent of globalization and mass transportation,
is nothing like the kind of migrations that we must have had in the past
that have led to these very large-scale replacements.
Thanks very much.
(Applause)