The ancestral lines of Neanderthals and modern humans split about 800,000 years ago, making them our closest relatives on the hominid family tree. Neanderthals inhabited ice age Europe and parts of the Middle East before going extinct 30,000 years ago. A team of researchers led by geneticist Svante Pääbo at the Max Planck Institute in Leipzig, Germany announced last week that they had completed a draft sequence of the genome of Neanderthal humans. Eager evolutionary biologists believe that comparing the Neanderthal genome with our own will throw considerable light on the genetic changes that gave us our big brains, language, and the ability to create culture.
Once the Neanderthal genome is complete, could it then be used to clone an actual Neanderthal? Harvard University biologist George Church thinks so. He told The New York Times that a Neanderthal could be brought to life using present technology for about $30 million. How? Church would modify a modern human genome so that its DNA matches the Neanderthal version. To avoid ethical problems, Church tells the Times, this Neanderthal genome would not be inserted into a human cell but instead into a chimpanzee cell. This chimp cell would be reprogrammed to an embryonic state, and then introduced into a chimpanzee's womb where it would develop into a Neanderthal infant.
But does this avoid ethical problems? Hardly.
Assuming that cloning is safe, would it be ethical to clone a human being? The short answer is yes. Clones are basically delayed twins—and there is nothing inherently immoral about twins. Recent polls, however, show that most Americans still oppose the use of cloning to create human babies. In addition, some religious traditions believe that human cloning is immoral. So I suspect that the proposal to use chimpanzee cells to clone a Neanderthal is an attempt to do a kind of ethical end-run around this "yuck factor" reaction to human cloning. In this case, researchers could argue that they are cloning a different species, not a human being.
But there is another problem with Church's plan to use chimpanzee cells: Neanderthals are human beings, too. The ancestral lineage that led to both Neanderthals and modern humans diverged from the chimpanzee line nearly 6 million years ago. If it is possible to clone Neanderthals using chimpanzee cells, it would also be possible to clone humans the same way. One would insert a human genome taken from, say, a skin cell, into an enucleated chimpanzee egg and then install that egg in a chimpanzee's womb where it would develop. The only genetic difference from a normal human would be that the clone's mitochondria (tiny intracellular power plants that have their own small genomes) would be chimp rather than human. Neanderthal mitochondrial DNA has around 200 differences from human mitochondrial genomes whereas chimpanzee mitochondrial DNA has about 1500 differences. I fear that using chimpanzee cells to clone Neanderthals would likely be taken as an indication from the outset that they are in some sense subhuman, and thus less worthy of moral respect.
But let's set that worry aside and assume that scientists are able to produce healthy Neanderthal clones. What rights would they have? One way to approach the question is to ask if Neanderthals would be able to make and keep moral commitments. One significant clue that they might have this ability is the fact their genomes have the same version of the FOXP2 gene that we do. Our variant of that gene is necessary for articulate speech. The human (both modern and Neanderthal) FOXP2 gene differs from that found in chimps and most other primates by two changes in its genetic sequence. The fact that Neanderthals carried the same version means that it is possible that they could talk and might have been able to make and keep promises. If Neanderthals had this ability it strongly suggests that they would merit the same moral consideration that we give to our fellow human beings. If they can speak, there's a good chance that they can also demand rights.
Archaeological evidence also indicates that Neanderthals behaved in ways similar to modern humans. They controlled fire, wore clothing, made and used tools, and buried their dead. In addition, they physically developed in much the same way as we do. Like modern humans, Neanderthal infants were born with relatively large brains and took a long time to mature into adults. Some researchers believe that modern humans and Neanderthals could interbreed. Does the future hold inter-species nuptials?
Less happily, what if meeting a Neanderthal evokes an "uncanny valley" experience? Many people experience unease or even revulsion in the presence of robots or other facsimiles that look and act almost, but not quite, human. Higher primates such as chimpanzees and orangutans can also induce such uncanny feelings. We won't know if Neanderthals dwell in the uncanny valley until they have been cloned.
Unlike the characters portrayed in Jean Auel's novel The Clan of the Cave Bear, newly resurrected Neanderthals are unlikely to be in the grip of hereditary memories, but they might still have significant intellectual and behavioral differences from us. For instance, they might express a different range of emotions or lack mathematical reasoning skills. The rights they would be accorded would depend on those differences. We do, after all, limit the rights and responsibilities of children and of people whose intellectual deficits make it difficult for them to tell right from wrong. On the other hand, we also have a greater duty to take care of children and adults with diminished mental and moral capacities.
So what if we bring back Neanderthals and it turns out that their intellectual capacities are so dissimilar from ours that they cannot cope successfully with modern life? Should we control their fertility so that they go extinct again? This comes uncomfortably close to the eugenic arguments used to justify sterilizing people who were deemed mentally defective in the 20th century. Or perhaps Neanderthals could be placed in reservations where they would be allowed to develop without further interference from modern humans. Would this be akin to confining them to a zoo?
One science fiction trope says that it is impossible for two intelligent species to evolve simultaneously on the same planet since one would inevitably out-compete the other. This may have happened on our planet. Neanderthals disappeared around the same time that modern humans began to move into their territory. New research suggests that our ancestors killed them off. Perhaps we should use modern science to resurrect Neanderthals in order to right an ancestral wrong.
Just because these moral conundrums cannot be answered in advance is not a good enough reason to preclude future efforts to clone Neanderthals. The only way to find out what rights Neanderthals should have is to bring them back into our world.
Ronald Bailey is Reason magazine's science correspondent. His book Liberation Biology: The Scientific and Moral Case for the Biotech Revolution is now available from Prometheus Books.