Chatty Red-Haired Neanderthals?
New DNA evidence reveals that Neanderthals had genes for speech and red hair
November 09, 2007
Using DNA from bones like these,
scientists have found that
Neanderthals may have been able
to speak and that some had
Imagine trying to describe an entire culture based on a few skeletons. Now imagine that those bones are 40,000 years old. Sounds pretty tricky, huh?
But scientists in Spain and Germany are starting to do just that. These scientists are studying Neanderthals, a group of human-like creatures that lived in Europe and western Asia starting half-a-million years ago. They overlapped for a bit with the ancestors of modern-day humans. And it's our ancestors who probably made the Neanderthals go extinct 30,000 years ago.
Since the discovery of the first Neanderthal skeletons in Germany in the mid-19th century, most of what we know about these creatures has been based on fossils. From skeletal remains, we know they were short and had a large forehead and nose. From carved stones found near these skeletons, we know that they used tools for everyday work and for fighting.
But researchers wanted to know more. What did these Neanderthals really look like? How did they interact with each other? Could they talk like we do?
Scientists are beginning to figure these things out by looking at Neanderthals' DNA. Recently, they found that Neanderthals may have been able to talk to each other. And that at least a couple Neanderthals were redheads.
DNA can reveal this kind of information because it's the genetic blueprint for all living things. Just like looking at a blueprint can tell us about a building we've never seen, looking at a living creature's DNA can help tell us what the creature looked like. It can even give us clues to how it acted or whether it could speak.
Two years ago, researchers in Germany and the United States discovered intact DNA in a 40,000-year-old Neanderthal bone found in Croatia. They were able to recover a piece of DNA that was over a million letters (nucleotides) long. Despite some of the scary Neanderthal pictures you've seen, their DNA was 99.5% identical to ours!
Armed with these one million nucleotidesand a million questions to answer, scientists began trying to figure out what Neanderthals were really like.
One burning question about Neanderthals is whether they could talk. By looking at fossils, scientists think that Neanderthals had the bones necessary for speech, including a special bone called the hyoid bone that helps the tongue move.
But could Neanderthals actually talk to each other? To figure this out, a group of scientists led by Svante Pääbo looked at a gene called FOXP2.
We know FOXP2 is an important gene for human speech because some people have a broken version of the FOXP2 gene and they have all sorts of trouble speaking. They can't control the movements of their mouth and tongue and they have problems understanding sentences and using correct grammar. (Click here to learn more.)
To see what the Neanderthal FOXP2 gene looked like, scientists studied a Neanderthal bone from Vindija Cave in Croatia. Because it had been buried in the ground for 40,000 years, this bone didn't have very much DNA left in it. To get around this problem, the scientists used a technique called polymerase chain reaction, or PCR.
PCR is just like photocopying DNA: it lets scientists make many copies of a specific piece of DNA starting from just a single copy. And once they have these copies, scientists can figure out the sequence of the DNA.
Using PCR, scientists found that the Neanderthal FOXP2 gene looked just like the human FOXP2 gene!
It turns out there are two differences in the FOXP2 gene between chimpanzees and humans. Scientists think this might help explain why humans can talk and chimps can't. And Neanderthals have the two human differences in their version of FOXP2.
Of course, there are many other genes involved in speech, so having a human-looking FOXP2 gene doesn't necessarily mean that Neanderthals could talk. But at the very least, Neanderthals were more likely to talk than chimpanzees!
Extreme Makeover: Redheaded Neanderthals
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.
The MC1R 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 gene!
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.
- Did Neanderthals and humans interbreed?
- Contamination issue
- Inconsistencies in Neanderthal Genomic DNA Sequences