Fos­sil skull chal­lenges his­tory of mod­ern hu­mans

The Prince George Citizen - - Front Page - Joel ACHEN­BACH

A skull frag­ment found in Greece has in­spired a star­tling hy­poth­e­sis about when our species first ar­rived in Europe and im­me­di­ately gen­er­ated ex­cite­ment and skep­ti­cism among ex­perts who study how and when Homo sapi­ens dis­persed from Africa.

Re­searchers say the fos­silized skull, found in the late 1970s in a cave in south­east Greece and stored since then in a museum, be­longed to an in­di­vid­ual with anatom­i­cally mod­ern fea­tures who lived about 210,000 years ago. If true, that would be ear­li­est ex­am­ple of Homo sapi­ens ever dis­cov­ered out­side the African con­ti­nent. The date also pre­cedes by a whop­ping 160,000 years the age of any Homo sapi­ens fos­sil pre­vi­ously found in Europe.

The bold claim, pub­lished Wed­nes­day in the jour­nal Na­ture, comes from a re­spected team of re­searchers, but it was met with cau­tion from a num­ber of other pa­le­oan­thro­pol­o­gists who were not in­volved in the re­search.

Dis­agree­ment is not un­usual for this field, in which hy­pothe­ses and con­jec­tures about hu­man pre­his­tory can emerge from a soli­tary jaw­bone or even a fin­ger.

Fos­sils are rare, dif­fi­cult to date and usu­ally frag­men­tary, and hu­man pre­his­tory is in­her­ently a misty nar­ra­tive.

The new study fo­cuses on the dam­aged re­mains of two skulls – named Apidima 1 and Apidima

2 – found just inches apart in a crevice. Ini­tially sci­en­tists as­sumed the skulls were of the same age be­cause they were found to­gether. But re­searchers re­cently used lab­o­ra­tory tech­niques that looked at the ra­dioac­tive de­cay of trace amounts of ura­nium in the spec­i­mens, and con­cluded that the in­di­vid­u­als came from dif­fer­ent eras. The tests in­di­cated that Apidima 1 is about 210,000 years old and Apidima 2 about 170,000 years old.

Those dates con­tained a shock­ing twist to the con­sen­sus about early hu­mans in Europe. The re­searchers used a va­ri­ety of meth­ods to model what the skulls would have looked like be­fore be­ing shat­tered and dis­torted across thou­sands of cen­turies. Apidima 2, the younger skull, looks clearly Ne­an­derthal, which fits nicely with the un­der­stand­ing that Ne­an­derthals – Homo ne­an­derthalen­sis – were the dom­i­nant early hu­mans in Europe in that pe­riod.

But the older skull, Apidima 1, doesn’t look like it be­longed to a Ne­an­derthal, the sci­en­tists found. It looks more like an early Homo sapi­ens, they re­port.

There’s not much to this skull – just part of the back of the cranium. But it has a rounded shape and other fea­tures that the re­searchers liken to early mod­ern hu­mans.

Such an early pres­ence of early mod­ern hu­mans in Europe is not im­plau­si­ble. Last year a dif­fer­ent team of re­searchers re­ported the dis­cov­ery in a cave in Israel of what they say is a Homo sapi­ens jaw­bone and teeth from an in­di­vid­ual that lived roughly 177,000 to 194,000 years ago. The new study pro­poses that the Le­vant and Turkey could have been mi­gra­tion routes for early mod­ern hu­mans to reach south­east Europe.

If this new in­ter­pre­ta­tion is cor­rect, the au­thors writer, Apidima 1 is “the ear­li­est known pres­ence of Homo sapi­ens in Eura­sia, which in­di­cates that early mod­ern hu­mans dis­persed out of Africa start­ing much ear­lier, and reach­ing much fur­ther, than pre­vi­ously thought.”

This dis­cov­ery also sug­gests that the early mod­ern hu­mans had con­tact with Ne­an­derthals, who went ex­tinct about 40,000 years ago, after a group of mod­ern hu­mans (of­ten re­ferred to as CroMagnons) had ar­rived in western Eura­sia in force.

An ex­traor­di­nary claim like this comes with in­her­ent chal­lenges. It’s es­sen­tially a sin­gle data point: one par­tial skull, dam­aged and dis­torted, with a “lack of ar­chae­o­log­i­cal con­text,” in the words of the new pa­per.

There’s noth­ing else: no stone tools, no burial signs, noth­ing to sug­gest mod­ern hu­man be­hav­ior. The claim would ob­vi­ously ben­e­fit from a sec­ond Homo sapi­ens fos­sil of sim­i­lar age some­where in that part of the world.

“Of course it would be lovely to find more,” said lead au­thor Ka­te­rina Har­vati of Eber­hard Karls Univer­sity of Tub­in­gen, in Ger­many, in a con­fer­ence call with re­porters. “We in­tend to try to look.” Sev­eral pa­le­on­tol­o­gists who read the pa­per came away skep­ti­cal. Rick Potts, di­rec­tor of the hu­man ori­gins pro­gram at Smith­so­nian’s Na­tional Museum of Nat­u­ral His­tory, said the new claim is a “one-off” with a date sig­nif­i­cantly dif­fer­ent from what has been pre­vi­ously doc­u­mented. That doesn’t mean it’s wrong, though.

“Of course there’s got to be a time when you find the first one. But we don’t know yet un­til we find mul­ti­ple ex­am­ples of this,” he said.

Me­lanie Lee Chang, a Portland State Univer­sity evo­lu­tion­ary bi­ol­o­gist who spe­cial­izes in hu­man evo­lu­tion, echoed that sen­ti­ment: “Right now it is an out­lier. It could be that there are whole lot of spec­i­mens in cab­i­nets that peo­ple haven’t looked at in a while and will go back and rein­ter­pret like this. But I’m not will­ing to sign on to all of their con­clu­sions here.”

John Hawks, a Univer­sity of Wis­con­sin pa­le­oan­thro­pol­o­gist, said ge­netic ev­i­dence has shown that Ne­an­derthals had genes from African an­ces­tors some­time be­fore 200,000 years ago, and thus “find­ing a skull that might be that age that has clearly what seems like African mod­ern hu­man fea­tures make a lot of sense.”

But he also sounded a cau­tion­ary note. It’s odd, he said, that two skulls of such dif­fer­ent ages were found right next to one another. The re­searchers be­lieved the fos­sils were washed into a crevice and then were em­bed­ded in sed­i­ments that hard­ened about 150,000 years ago. Said Hawks,

“This is a weird sce­nario to have two hu­man skulls that are next to each other that are so dif­fer­ent in age, and it makes me want more ev­i­dence.”

One co-au­thor of the Na­ture pa­per, Chris Stringer of the Nat­u­ral His­tory Museum of Lon­don, ac­knowl­edged that this is a “chal­leng­ing new find” for which skep­ti­cism is ap­pro­pri­ate ini­tially.

“We don’t have the frontal bone, browridge, face, teeth or chin re­gion, any of which could have been less ‘mod­ern’ in form,” he said in an email. But he said the team tested their re­con­struc­tion ef­forts in mul­ti­ple ways and that the fos­sil “cer­tainly shows the high and rounded back to the skull that is typ­i­cal only of H. sapi­ens.”

He said it would be help­ful to find stone tools as­so­ci­ated with Homo sapi­ens. “If we have in­ter­preted the Apidima ev­i­dence cor­rectly, the hand­i­work of th­ese early H. sapi­ens must be present else­where in the Euro­pean record,” he said.

All peo­ple alive to­day ap­pear to have de­scended from an an­ces­tral group in Africa that lived roughly 70,000 years ago. “Both the fos­sil ev­i­dence and ge­nomic ev­i­dence of mod­ern day hu­mans still sug­gest that the per­ma­nent suc­cess of Homo sapi­ens be­yond the African con­ti­nent is maybe 70,000 years old,” Potts said.

But the finer de­tails of hu­man pre­his­tory, in­clud­ing the fate of groups that dis­persed but ap­par­ently died out, have got­ten more com­pli­cated with each new dis­cov­ery. There was not a sin­gle, lin­ear evo­lu­tion of hu­mans – which was the pre­sump­tion among pa­le­oan­thro­pol­o­gists just half a cen­tury ago – but rather many ho­minid species that co­ex­isted for mil­lions of years be­fore a sin­gle species re­placed ev­ery­one else.

UNIVER­SITY OF TUE­BIN­GEN IM­AGE BY KA­TE­RINA HAR­VATI VIA AP

This im­age pro­vided by the Univer­sity of Tue­bin­gen in Ger­many shows the Apidima 1 par­tial cranium fos­sil, right, with a piece of rock still at­tached. A dig­i­tal re­con­struc­tion shows a side view, left, and a pos­te­rior view, mid­dle. The rounded shape of the Apidima 1 cranium is a unique fea­ture of mod­ern hu­mans and con­trasts sharply with Ne­an­derthals and their an­ces­tors.

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