I've been researching on human
evolution for about 50 years.
And even ten or 15 years
ago, we had the view
that human evolution in
the last 500,000 years
was a relatively simple process,
that we had a gradual change
of species through time.
A species called Homo
heidelbergensis gradually
evolved to the Neanderthals
in Europe and Asia,
and it evolved to Homo
sapiens in Africa.
We now know this story is a
lot more complicated than that.
So here, we've got two
Neanderthal fossils
from Gibraltar.
And the one on the left,
from Forbes Quarry,
was the first Neanderthal I
ever looked at and studied.
And at that time, the
Neanderthals were actually
regarded as the direct
ancestors of modern humans,
and if we had a fossil
sequence in Europe,
we would see the Neanderthals
gradually evolving
into modern people.
We now know, in fact, that
the Neanderthals and us
are two separate lineages
from a common ancestor, which
generally has been regarded
as the species Homo
heidelbergensis.
And then, maybe
35,000 years ago, it
was thought that these
two species came together
in Europe, and very quickly,
the Neanderthals were completely
replaced by the modern humans.
We now know from DNA
evidence, including
even on some of these
Gibraltar Neanderthal fossils,
that actually the story is
more complicated than that.
By the year 2010,
scientists were
able to reconstruct whole
Neanderthal genomes.
And once those were examined
and compared with our own,
there was a big surprise.
It turned out that
most of us alive today
have an input of
about two per cent
Neanderthal DNA in our genomes.
And that means
our ancestors must
have mixed with Neanderthals,
interbred with them,
maybe 50,000 or
60,000 years ago.
So this idea that
Neanderthals were completely
replaced by modern humans has
been falsified by new science.
And even more remarkably,
both DNA and fossils
are contributing
to a re-evaluation
of the last 500,000 years
or so of our evolution.
So in particular, this
species, Homo heidelbergensis,
which has been regarded as
the common ancestor of us
and the Neanderthals, possibly
is too recent in time.
DNA evidence suggests
the common ancestor
may have lived further back.
And not only that, studying
the fossils themselves
suggests that this
species, Homo antecessor,
might actually
have a face that's
more like the common ancestor
of us and the Neanderthals.
And thus, the place of
heidelbergensis is in doubt.
What we can look forward to
in the next ten or 20 years
is both DNA evidence
and new fossil evidence
fleshing out many of these
empty areas of that tree,
and helping to unravel the
full story of our ancestry.
