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Neanderthal Dna Partially Sequenced

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Neanderthal DNA partially sequenced


Nov. 16, 2006

Courtesy Lawrence Berkeley National Laboratory

and World Science staff


Sci­en­tists have writ­ten out a small frac­tion of the Ne­an­der­thal ge­net­ic code, us­ing it to map out when the stocky hu­man cousins di­verged from our own spe­cies.


The sci­en­tists al­so con­clud­ed that Ne­an­der­thals mat­ed lit­tle if at all with the fore­bears of mod­ern hu­mans—con­tra­dict­ing an­oth­er re­cent study, and adding a new page to a de­bate that has seen flip-flopping con­clu­sions in re­cent years.






A­nal­y­sis of ge­no­mic DNA from fos­sil­ized Ne­an­der­thal bones in­di­cat­ed that Ho­mo sapi­ens and Ho­mo ne­an­derthalen­sis last shared a com­mon an­ces­tor about 700,000 years ago, sci­en­tists say. The two ho­minids split in­to in­to sep­a­rate spe­cies around 400,000 years ago, they add. (Cour­te­sy LBL)




Ne­an­der­thals are the clos­est hom­i­nid rel­a­tives of mod­ern hu­mans. The two spe­cies co-existed in Eu­rope and west­ern Asia as late as 30,000 years ago.


Sci­en­tists with the U.S. Energy De­part­ment’s Law­rence Ber­k­e­ley Na­tion­al La­b­o­ra­to­ry in Ber­k­e­ley, Ca­lif., and the Joint Ge­nome In­s­ti­tute in Wal­nut Creek, Ca­lif. se­quenced DNA from Ne­an­der­thal fos­sils.


The re­sults indicate their genomes were at least 99.5-percent iden­ti­cal to ours, the re­search­ers said. Based on these ear­ly find­ings, the spe­cies shared a com­mon an­ces­tor about 700,000 years ago, wrote the in­ves­t­i­ga­tors in the Nov. 17 is­sue of the re­search jour­nal Sci­ence.


Un­til now, knowl­edge of Ne­an­der­thals came from “lim­ited num­ber of bony re­mains and as­so­ci­at­ed ar­ti­facts that are avail­a­ble in hard-to-ac­cess mu­se­um col­lec­tions and field sites,” said Ed­ward Ru­bin, di­rec­tor of the in­sti­tute and of the laboratory’s Ge­nomics Di­vi­sion, and lead au­thor of the stu­dy.


That will change, he added. “In the near fu­ture, an­thro­pol­o­gists will be able to de­vel­op hy­pothe­ses about our ex­tinct an­ces­tors through the scan­ning of bil­lions of base pairs of DNA se­quences avail­a­ble on the web.” A base pair is a “let­ter” of ge­net­ic code.


In 1856, a par­tial hom­i­nid ske­l­e­ton turned up at the Feld­ho­fer Cave in Ger­ma­ny’s Ne­an­der Val­ley. The ske­l­e­ton would be dubbed Ne­an­der­thal Man. It gen­er­at­ed pub­lic cu­ri­os­i­ty and sci­en­tif­ic de­bate that con­tin­ue today.




Artist's concept of a Neanderthal. (Courtesy Science)


In the late 1990s, sci­en­tists be­gan using ge­net­ic tech­nol­o­gy to study Ne­an­der­thals. Re­search led by Svan­te Pääbo, now of the Max Planck In­sti­tute for Ev­o­lu­tion­ary An­thro­pol­o­gy in Leip­zig, Ger­ma­ny, found that Ne­an­der­thals were cousins rath­er than an­ces­tors of mod­ern hu­mans.


In the new work, Ru­bin and col­leagues ex­tracted the DNA in the thigh bone of a 38,000-year-old male Ne­an­der­thal from Vin­dija, Cro­a­tia. They re­cov­ered 65,250 base pairs of Ne­an­der­thal DNA, out of a to­tal of an es­t­i­mat­ed three bil­lion base pairs.


Com­par­ing Ne­an­der­thal to hu­man and chim­pan­zee ge­n­omes showed that in ma­ny places the Ne­an­der­thal code matched chimp DNA but not hu­ma­n, Ru­bin said. “This ena­bled us to cal­cu­late for the first time when in pre-history Ho­mo sapi­ens and Ho­mo ne­an­derthalen­sis [Ne­an­der­thals] co­a­lesced to a sin­gle ge­n­ome,” he added.


The analysis found that the com­mon ge­net­ic an­ces­tor of Ne­an­der­thal and mod­ern hu­mans lived about 706,000 years ago, he con­ti­nued. This would be the time when the two line­ages began to diverge, the re­search­ers said; the fi­nal split, though, came some 330,000 years lat­er.


Ru­bin and his col­leagues said they also shed new light on the long-stand­ing ques­tion of wheth­er Ne­an­der­thals and hu­mans mat­ed dur­ing the thou­sands of years the two spe­cies co­hab­i­tated parts of Eu­rope. Some sci­en­tists have sug­gested that rath­er than die out, Ne­an­der­thals as a spe­cies were bred out of ex­ist­ence by the over­whelm­ing pop­u­la­tions of Ho­mo sapi­ens.


Sa­id Ru­bin, “While una­ble to de­fin­i­tive­ly con­clude that in­ter­breed­ing be­tween the two spe­cies of hu­mans did not oc­cur, anal­y­sis... sug­gests the low like­li­hood of it hav­ing oc­curred at any apprecia­ble lev­el.”


Past Ne­an­der­thal gene stud­ies were based on so-called mi­to­chon­dri­al DNA, ge­net­ic ma­te­ri­al that lies out­side the cell nu­cle­us, Ru­bin said. This type tends to stay better-pre­served, he added, but pro­vides lim­it­ed in­for­ma­tion be­cause the vast ma­jor­i­ty of the ge­nome is in the nu­cle­us. His stu­dy fo­cused on this “nu­cl­ear” DNA.


“If you want to un­der­stand how traits like lan­guage and cog­ni­tion are en­cod­ed, you have to study nu­cle­ar DNA,” said James Noo­nan of the Berke­ley Lab and Joint Ge­nome In­sti­tute, a mem­ber of the re­search team.

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