After years of anticipation, the Neanderthal genome has been sequenced. It's not quite complete, but there's enough for scientists to start comparing it with our own.
According to these first comparisons, humans and Neanderthals are practically identical at the protein level. Whatever our differences, they're not in the composition of our building blocks.
However, even if the Neanderthal genome won't show scientists what makes humans so special, there's a consolation prize for the rest of us. Most people can likely trace some of their DNA to Neanderthals.
"The Neanderthals are not totally extinct. In some of us they live on a little bit," said Max Planck Institute evolutionary geneticist Svante Pääbo.
It took four years for Pääbo's team to assemble a working sequence from DNA in the bones of three 38,000-year-old Neanderthal women, found in Croatia's Vindija Cave. The sequence, published May 6 in Science, covers about 60 percent of the entire genome.
Though much remains unfinished, researchers were able to compare the Neanderthal genome to the human at 14,000 protein-coding gene segments that differ between humans and chimpanzees. Researchers link these proteins to changes in humans' cognitive development, physiology and metabolism.
At all but 88 of those hot spots, Neanderthals were no different than us. The differences are so slight that the researchers suspect them to be functionally irrelevant. If more genomes could be compared, there might be no differences at all.
Changes in the biology of humans and our close caveman ancestors may be a result not of simple genetic changes, but of evolution in how humans use our genes, turning them on and off at different times and places.
That type of evolution won't be easy to study by looking at a few ancient fossils.
"There are a lot of aspects of differences between species that can't be solely obtained from DNA sequence," said University of Michigan genetic anthropologist Noah Rosenberg, who wasn't involved in the study. "But at the same time, the DNA sequence is a good place to start."
Such studies will occupy scientists for years to come. In the meantime, the researchers produced a more immediately stirring result. They compared the Neanderthal genome to genomes of five people from China, France, Papua New Guinea, southern Africa and western Africa. Among non-Africans, between one and four percent of all DNA came from Neanderthals.
On a functional level, the DNA was no different from our own, but bore telltale molecular marks of Neanderthal heritage.
Many studies have posited a Neanderthal-human inbreeding. In 1999, researchers discovered a 25,000-year-old girl with mixed features. Population geneticists have found historical patterns of genetic influx so sudden that breeding with Neanderthals seems the most plausible explanation. But studies like those have not proved conclusive.
For people of African descent disappointed that they lack Neanderthal ancestry, Pääbo gave solace.
"It's totally possible that inside Africa, there was a contribution from other archaic humans that we don't know about," he said. "We shouldn't take these results as saying that only people outside Africa have caveman biology."
Images: 1. Neanderthal sculpture by John Gurche./ Photographed by Chip Clark, Smithsonian. 2) Neanderthal bone fragments./Max Planck Institute.
See Also:
- DNA Reveals New Hominid Ancestor
- Roll the Genetic Dice Twice and We Might Be Neanderthals
- Lucy 2.0: Famous Fossil Hominid Goes Digital
- Possible New Human Ancestor Discovered
Citations: "Targeted Investigation of the Neandertal Genome by Array-Based
Sequence Capture." By Hernán A. Burbano, Emily Hodges, Richard E. Green, Adrian W. Briggs, Johannes Krause, Matthias Meyer, Jeffrey M. Good, Tomislav Maricic, Philip L.F. Johnson, Zhenyu Xuan, Michelle Rooks, Arindam Bhattacharjee, Leonardo Brizuela, Frank W. Albert, Marco de la Rasilla, Javier Fortea, Antonio Rosas, Michael Lachmann, Gregory J. Hannon, and Svante Pääbo. Science, Vol. 328 No. 5979, May 6, 2010.
"A Draft Sequence of the Neandertal Genome." By Richard E. Green, Johannes Krause, Adrian W. Briggs, Tomislav Maricic, Udo Stenzel, Martin Kircher, Nick Patterson, Heng Li, Weiwei Zhai, Markus Hsi-Yang Fritz, Nancy F. Hansen, Eric Y. Durand, Anna-Sapfo Malaspinas, Jeffrey D. Jensen, Tomas Marques-Bonet, Can Alkan, Kay Prüfer, Matthias Meyer, Hernán A.Burbano, Jeffrey M.Good, Rigo Schultz, Ayinuer Aximu-Petri, Anne Butthof, Barbara Höber, Barbara Höffner, Madlen Siegemund, Antje Weihmann, Chad Nusbaum, Eric S. Lander, Carsten Russ, Nathaniel Novod, Jason Affourtit, Michael Egholm, Christine Verna, Pavao Rudan, Dejana Brajkovic, Željko Kucan, Ivan Gušic, Vladimir B. Doronichev, Liubov V. Golovanova, Carles Lalueza-Fox, Marcodela Rasilla, Javier Fortea, Antonio Rosas, Ralf W. Schmitz, Philip L. F. Johnson, Evan E. Eichler, Daniel Falush, Ewan Birney, James C. Mullikin, Montgomery Slatkin, Rasmus Nielsen, Janet Kelso, Michael Lachmann, David Reich, Svante Pääbo. Science, Vol. 328 No. 5979, May 6, 2010.
Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.
