Some Neanderthals may
have been redheads too.
OK, so we think Neanderthals may have been able to talk. But what did they look like? We can't figure this out completely, because we don't know enough about the genes involved. But one gene we do know a lot about is the one that causes red hairMC1R
gene contains the instructions for making a protein that sits on the outside of pigment-producing cells called melanocytes. Part of its job is to make sure there's a certain balance of pigments in the hair and skin. (Click here
to learn more.)
People with certain mutations (DNA changes) in their MC1R
gene have a buildup of red pigment, and they end up with red hair and fair skin. Neanderthals lived during the Ice Age, so having fair skin might have been an advantage, since it would help the body absorb sunlight to help make vitamin D. (Click here
to learn more.)
Just like with FOXP2
, scientists used PCR to make copies of the MC1R
gene from Neanderthal DNA. This time they used two Neanderthal fossils, one from Italy and one from Spain. After reading the sequence of the DNA, they found that both of these fossils had mistakes in their MC1R
And just like the broken MC1R
genes found in modern-day humans, when scientists put the broken Neanderthal MC1R
gene into cells in a Petri dish, the Neanderthal MC1R
gene couldn't tell the cells to produce the right balance of pigments. After doing some number crunching, the scientists estimated that at least 1 percent of Neanderthalsand maybe many morehad red hair.
It's hard to draw conclusions about the number of redheaded Neanderthals from just two fossils. After all, we don't know whether other Neanderthals had mistakes in their MC1R
gene. But this is our first glimpse into what some Neanderthals really looked like.
And there's one more interesting twist to the red hair story. It turns out that modern humans with red hair have different mutations in the MC1R
gene than these two Neanderthals did. This is further evidence that Neanderthals and modern humans didn't interbreed
when they were living together in Europe 50,000 years ago.
With the help of modern genetic technology, the DNA in those 40,000-year-old bones is helping us get to know our Neanderthal neighbors a little bit better.
Are you sure that's Neanderthal DNA?
In the next year, scientists hope to finish reading the entire DNA sequence of a Neanderthal. This would help us learn more about what Neanderthals looked like, how they acted, and how similar they were to us.
But studying Neanderthal DNA is trickier than you might imagine. A huge problem is contamination with modern-day human DNA. So the big question is how do you know you're really looking at Neanderthal DNA?
Because DNA breaks down over time, fossils only contain tiny traces of DNA. And almost everythingfrom our hands to our lab gloves to our test tubeshas modern human DNA on it. So when we use PCR to make copies of Neanderthal DNA, we might be copying our own DNA, too. And because humans and Neanderthals share 99.5% of their DNA, it's tough to tell whether this contamination has occurred.
So how have scientists been getting around this problem? First, they're very careful. The fossils are removed from the ground using extra-clean equipment and are immediately frozen so they don't get contaminated.
Second, scientists look at sequences they know to be different in Neanderthals and humans, based on previous research. For example, there's a special type of DNA called mitochondrial DNA, and there are pieces of mitochondrial DNA that are very different in Neanderthals and humans. The same goes for chunks of the Y chromosome and several other chromosomes.
Scientists can look at the sequence of these pieces of DNA in their Neanderthal fossils. If the sequences match the known Neanderthal sequences, the scientists are safe. But if they find some modern human sequence, then they know there's been some contamination.
And finally, as in most things, two heads are better than one. If several labs examine each fossil sample and come up with the same sequence, it's much more likely that the sequence is truly Neanderthal sequence.