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http://www.world-science.net/othernews/060...y-afarensis.htm

 

“Lucy’s Baby”: pre-human fossil dazzles scientists

 

Sept. 20, 2006

Special to World Science

 

Re­search­ers say they’ve unearthed the pos­sib­ly most com­plete known fos­sil of a fore­bear of hu­mans: a ba­by of the same spe­cies as the famed “Lu­cy” fos­sil found in 1974.

 

Human-like be­low the waist, ape-like above, the tot is a “once-in-a-lifetime” find, said Ethi­o­pi­an pa­le­oan­thro­po­lo­gist Ze­re­se­nay Al­em­se­ged, who led the sci­en­tif­ic team cre­d­ited with the dis­cov­er­y.

 

dikika-baby.JPG

 

De­scribed as the skull of an Aus­tra­lo­pi­the­cus afa­ren­sis ba­by, this meas­ures about 12 cm (5 inches) from the bot­tom of the chin to the top of the head ver­ti­cal­ly. (Cour­te­sy Ze­re­se­nay Al­em­seged; © Au­tho­r­i­ty for Re­search and Con­ser­va­tion of Cul­tur­al He­r­i­ta­ges).

 

 

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The find re­vived me­m­o­ries of “Lu­cy,” be­lieved to be a fe­male in her mid-20s and hailed, when dis­cov­ered, as the most com­p­lete known ske­l­e­ton of a pre-hu­man ho­m­i­nid. A ho­m­i­nid is a spe­cies on the hu­man branch of the ev­o­lu­tion­a­ry tree.

 

The new spe­ci­men, dubbed “Lu­cy’s ba­by” by some—though it’s ac­tu­al­ly thought to have lived a bit ear­li­er than Lu­cy—is like­wise caus­ing a stir over its splen­did con­di­tion.

 

That, sci­en­tists say, makes it a trea­s­ure trove of ad­di­tio­n­al clues to hu­man ori­gins.

 

Years ago, Lu­cy, in many re­search­ers’ view, over­turned a wide­spread as­sump­tion: that our an­ces­tors evolved in­tel­li­gence first and up­right walk­ing la­ter. She was seen to re­fute that be­cause her bones sug­ges­ted at least some up­right-walk­ing abi­l­i­ty, yet a small, ape-like brain.

 

This helped re­vive a no­tion pro­posed by Charles Dar­win: that up­right move­ment spurred brain evo­lu­tion by free­ing hands for tool use. Hence­forth, suc­cess in the bat­tle for sur­vi­val would de­pend on ever-bet­ter tool use, and the brains to en­able it.

 

Like Lucy, the new­found child shows the marks of a spe­cies able to walk up­right, re­search­ers said; it also of­fers more clues to the ev­o­lu­tion of that skill, and of the brain and speech. It’s a “mine of in­for­ma­tion about a cru­cial stage in hu­man ev­o­lu­tion­ary his­to­ry,” wrote pa­le­o­bi­o­lo­gist Ber­nard Wood of George Wash­ing­ton Uni­ver­si­ty in Wash­ing­ton, D.C., in a com­men­tary in the Sept. 21 is­sue of the re­search jour­nal Na­ture.

 

The sci­en­tists cred­ited with the find de­s­c­ribed it in ano­ther pa­per in the same is­sue. They es­ti­mat­ed that the in­fant died at age three, pos­si­bly in a flood that al­so bur­ied it in peb­bles and sand, help­ing pre­serve it.

 

afarensis-motherbaby.JPG

 

Artist's conception of a mo­ther and child Aus­tra­lo­pi­the­cus afaren­sis. Ad­ult fe­males of the spe­cies were some 3½ feet tall, judg­ing from the "Lucy" spe­ci­men.

 

 

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Lu­cy and the ba­by, which date to slight­ly more than three mil­lion years ago, are far from the old­est known mem­bers of the hu­man fam­i­ly.

 

That dis­tinc­tion be­longs to the chimp-sized Sa­he­lan­thro­pus tchaden­sis or “Toumai Man,” es­ti­mat­ed as sev­en mil­lion years old and found in Cen­tral Af­ri­ca four years ago.

 

But Lu­cy and the tot—said to re­p­re­sent a lat­er spe­cies, Aus­tra­lo­pi­the­cus afaren­sis—would be part of a burst of hom­i­nid di­ver­si­ty noted in the fossil re­cord from four to two mil­lion years ago.

 

This is thought to re­flect some of the rich ev­o­lu­tion­a­ry ex­per­i­men­ta­tion that na­ture tossed up on the way to pro­duc­ing our spe­cies, Ho­mo sapi­ens. Ho­minids of that pe­ri­od are col­lec­tive­ly called Aus­tralo­p­iths. Which line­age led to us is un­known, though.

 

The new­found bun­dle of bones, found like Lu­cy in the Ethi­o­pi­an de­sert, was also a fe­male, and lived about 3.3 mil­lion years ago, its disco­verers said. Lu­cy is thought to have lived 3.2 mil­lion years ago.

 

“The most im­pres­sive dif­fer­ence be­tween them is that this ba­by has a face,” said team lead­er Ze­re­se­nay (E­thi­o­pi­ans’ first names are their for­mal names.) This face gave away the spe­cies, added Ze­re­se­nay, of the Max Planck In­sti­tute for Ev­o­lu­tion­ary An­thro­pol­o­gy in Leip­zig, German­y.

 

Al­so un­like Lu­cy—nick­named after a Beat­les song—the ba­by has fin­gers, a foot and a tor­so. Tooth struc­tures clued re­search­ers in to its rough age and its sex, they said, while the se­di­ments that had trapped it re­vealed its time period.

 

The tot helps ex­p­lain how A. a­fa­ren­sis blurred ape-hu­man bound­aries, Ze­re­se­nay said: her shoul­der blades re­sem­ble a young go­ril­la’s, sug­gest­ing she could climb trees, but her thigh bone is an­gled like hu­mans’, im­ply­ing good up­right walk­ing abil­i­ty. Members of the spe­cies seem to have been for­ag­ing, up­right walk­ers, ca­pa­ble of “climb­ing trees when nec­es­sar­y, es­pe­cial­ly when they were lit­tle,” he said.

 

Ze­re­se­nay first led a band of fos­sil hunters in­to Ethi­o­pi­a’s Dikika re­gion in 1999, re­search­ers re­counted. Pun­ish­ing heat, flash floods, ma­lar­i­a, wild beasts and oc­ca­sion­al shootouts be­tween ri­val eth­nic groups plague the zone.

 

On a shade­less De­cem­ber day the next year, the sci­en­tists re­called, they hunt­ed un­der a pound­ing sun for the prize that had elud­ed them—our ape-like fore­bears. Team mem­ber Tilahun Ge­bre­se­lassie then spot­ted the tot’s face, no big­ger than a mon­key’s, peer­ing out from a dusty slope.

 

Tucked be­neath it in hard sand­stone were more bones, the whole bun­dle of them no big­ger than a can­te­loupe, one fin­ger still curled in a ti­ny grasp, re­search­ers said. Ze­re­se­nay found a rare ex­am­ple of a hy­oid bone, a throat struc­ture lat­er cru­cial to hu­man speech, he said. This of­fers a glimpse of the ev­o­lu­tion of the voice box, which un­der some the­o­ries is in­t­er­wo­ven with that of speech.

 

Ze­re­se­nay spent the next five years scratch­ing away rock from the skel­e­ton with a den­tist’s drill, ac­cord­ing to mem­bers of his team.

 

What killed the ba­by is un­clear. But it seems the an­cient Awash Riv­er rap­id­ly bur­ied the body in a flood, the sci­en­tists said, pre­serv­ing rare de­tails such as a full set of both milk teeth and un­e­rupt­ed adult teeth. The brain cast will help reveal “wheth­er our ear­li­est an­ces­tors grew their brains in the uniquely hu­man way,” said a mem­ber of the re­search group, Fred Spoor of Uni­ver­si­ty Col­lege Lon­don.

 

One of her hu­manlike knees was com­plete with a knee­cap no big­ger than a dried pea, re­search­ers said. But her up­per bod­y, like Lu­cy’s, had many ape­like fea­tures: small brain, nose flat like a chim­p’s, face pro­ject­ing for­ward. Her two com­plete shoul­der blades are the first found from an aus­tralo­p­ith, Ze­re­se­nay said; an­a­lyz­ing their func­tion “will be among the ex­cit­ing chal­lenges that we will face.”

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What an awesome find she is. One question to anyone who knows: do other primates have kneecaps?

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Alrighty then. I barely know my ass from my hands when it comes to anatomy. That is a cool site Rev, thanks for sharing and answering my stupid question.

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Alrighty then. I barely know my ass from my hands when it comes to anatomy. That is a cool site Rev, thanks for sharing and answering my stupid question.

 

That's fine. I'm glad I could help.

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