Photograph: Reconstruction by Kennis & Kennis/Photograph by Joe McNally National Geographic October 2008

Neanderthals, an intelligent and resilient human species, lived in Eurasia for some 200,000 years. Then about 28,000 years ago the last of them died. No one knows exactly what led to their extinction, but it was probably a combination of factors, including climate change and the arrival of modern humans in the region, around 45,000 years ago.

Since Neanderthals and modern humans overlapped for some 15,000 years, many wonder if they ever interbred. It's possible. But DNA studies show that Neanderthals were indeed a separate species, and no trace of Neanderthal DNA has been found in humans today. Yet Neanderthals had some genes that are similar to those in humans but evolved separately. Studying DNA from Neanderthals found in Spain and Italy, scientists isolated a form of a pigmentation gene called MC1R, indicating that some Neanderthals would have had red hair, pale skin, and possibly freckles, though the gene is unlike the one in red-haired people today. Scientists also found that Neanderthals had a gene that's necessary for speech and language, FOXP2, though this one is identical to the gene in modern humans. No one knows if they could speak like us, but they at least had the genetic capacity for speech.

By the end of this year scientists will have completely mapped the three-billion-letter sequence of the Neanderthal genome. The Neanderthal is the closest prehistoric relative of the modern human—our genes differ by just 0.5 percent—and by mapping the genome, scientists hope to learn more about modern human evolution and brain development, including how we picked up key traits such as walking upright and developing complex languages. Neanderthals are believed to have been relatively sophisticated but lacking the higher reasoning functions of modern humans. "By having Neanderthal [genome], we'll really be able to home in on the small percentage of differences that gave us higher cognitive abilities," says Jonathan Rothberg, one of the scientists involved in the mapping. "Neanderthal [genome] is going to open the box. It's not going to answer the question, but it's going to tell where to look to understand all of those higher cognitive functions."

Hall, Stephen S. "Last of the Neanderthals." National Geographic (October 2008), 34-59.

Green, Richard, and others. "Analysis of One Million Base Pairs of Neanderthal DNA." Nature (November 16, 2006).

Lalueza-Fox, Carles, and others. "Neandertal Evolutionary Genetics; Mitochondrial DNA Data From the Iberian Peninsula." Molecular Biology and Evolution (February 2, 2005).

Moulson, Gier. "Neanderthal Genome Project Launches." MSNBC, July 20, 2006.

Noonan, James, and others. "Sequencing and Analysis of Neanderthal Genomic DNA." Science (November 17, 2006).

Virtual Paleoanthropology

In the process of obtaining data from scarce early hominid fossils, scientists often have to damage the fossils. So to gain large amounts of information without causing harm, scientists are turning to virtual paleoanthropology, using CT scans and computers to create complete 3-D models of fossils. Fossils are often incomplete, sometimes just fragments, but computers can make them complete, by adding data based on external and internal anatomical clues. For example, if a skull is found with just half of the face intact, the other half can be filled in using a mirror image of the existing one.

Once a complete computer-generated fossil is created, it can be converted into a physical specimen, or hard copy, using rapid prototyping techniques. The most accurate replication technology available is stereolithography, which builds objects by depositing consecutive thin layers of resin, wax, or other materials. This 3-D “printing” process resembles that of building topographical models by piling on layers of cardboard.

Being able to create complete 3-D virtual fossils, both on the computer and as a hard copy, allows scientists to see features that before were merely speculative. This enables them to make morphological comparisons between Neanderthals and modern humans or other human species. It also allows precise quantitative analysis of inaccessible internal structures such as middle and inner ears. Comparisons of fossil data can also be made with living humans, which can shed light on issues such as growth and development, skeletal and dental maturation, and evolution of the brain.

"Computer Assisted Paleoanthropology and the Neanderthals." University of Zurich.

"3D Morphometrics." Max Planck Institute, Department of Human Evolution.

"How Stereolithography Works." How Stuff Works.

Other Resources
"El Sidron site." Biology Online.

Evolution of Modern Humans.

Finlayson, Clive. "Biogeography and Evolution of the Genus Homo." TRENDS in Ecology and Evolution (August 2005).

Green, Richard, and others. "Analysis of One Million Base Pairs of Neanderthal DNA." Nature (November 16, 2006).

Hall of Human Ancestors, Smithsonian Institution.

Hublin, Jean-Jacques. "The New Neandertal: Virtual Fossils and Real Molecules Are Changing How We View Our Enigmatic Cousin." Archaeology (July/August 2005).

Kreger, C. David. " Homo Neanderthalensis. "

"Neanderthal Genome Sequencing Yields Surprising Results and Opens a New Door to Future Studies." Science Daily (November 16, 2006).

Rosas, Antonio, and others. "Paleobiology and Comparative Morphology of a Late Neandertal Sample From El Sidron, Asturias, Spain." PNAS, December 19, 2006.

Shreeve, James. The Neandertal Enigma. William Morrow and Company, 1995.

Stringer, Chris. Homo Britannicus: The Incredible Story of Human Life in Britain. Allen Lane, 2006.

Trinkaus, Erik, and Pat Shipman. The Neandertals: Of Skeletons, Scientists, and Scandal. Vintage Books, 1992.

Other National Geographic Resources

Gore, Rick. "The Dawn of Humans: Neandertals." National Geographic (January 1996).

Gore, Rick. "Dawn of Humans: People Like Us." National Geographic (July 2000).

Shreeve, James. "Greatest Journey." National Geographic (March 2006).

Last updated: August 26, 2008