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1 IHYPOTHESIS 11

Did Climate- Change • ..", &$ ,, m., ;4 +&

Do~m:!.tk-b&i'a,nd~,rt; ' . ' .' ".*$ P- V*TS. +,i -!/;

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9.. , @ -S ;riound 55,OOQwp wt dimate in Eurasia began ta,&nS wfl&:am-$&k.' b M md bck again in the span of &cad&. During the d w, i@ %&tsaW&da

. m l & t u n d m @ ~ ~ d e n v i r ~ a a w s d d t k e k a ~ ~ . ~ , , ~ ~ ~ w a i ~ w e y ~ ~ s a s c w n p a n E e d t h e s g ~ W i d e w & g ~ ~ d b i & . , f l u ~ t i ~ , a l l & d & ~ i n i s h e d ~ ~ r t d MM wfficient time t o h . -L&' .;: a p t zo to tkrrw-s. ) >

hiding suggests &at the answer involves a corn- plicad interplay of stresses.

A World in Flux One of the most informative new lines of evi- dence br ing on why the Neandertals died out is paledimate data. Scholars have known for some rime that Neandertals exper iend both glacial conditions and milder interglacial condi- tions during thejr long reign. In m y e a r s , haw- ever, analyses of isotopes trapped in primeval ice, ocean sdihmrs and pollen retrieved from such locales as Greenland, Venezuela and Italy have enabled investigators ro reconstruct a far fiiler-grained picrure of the c h t e shifts that occurred during a period knawo as oxygen iso- tope stage 3 (01s-3). Spanning the timF bemeen

34 SClE#TlFlC AMERlCAN . . .

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mad, Hardy s w m k tbatqhey w e ~ e a& to get the iab donewitbaur $lam. "You don% Itcod a g raph i t spocm to eat a grapetruit,* k ays. The* &at Neadmmds tadced b a g s

tqo,.srpms u d h l y in &of ~ r , ~ e s .

ieswith jewelry and

n N&al and modern ; 'human trehavior narrowing, many marchers -' . mmw Iooking m tabo!t differences in culture ,&I biology to explain why tb Ihndettals b t om "Wmenbg and highly ummbk cli- >wqma&kms would haw made canpaidon among bman gwups:all r4e more fierce," &ts prtlw~pologist Ka&m Harvan, a h at Max Hand. "la rhb context, even small ahantages would b m c cxcr~3mpmmm aad might spell tbedifhnce betweesl survival 1 rtnddarb"

Sqinges, for hi part, t h s o k that the mod- 1 erns.' somewhat wider range qf cultural a d a p -

cold rt bay. Neandertak meanwhile, left be- bind wsvch &pi of s m h g a n d a r e W by some to have bad more w d e l y assembled ap- pard and &dm as a -It.

N e a h l s and mockmsrnay have elso U- h d in the way they divvied up the chores

p u p ~~, In a paper pu blbhdin Cutvent A1kropolagy in 2006, archmdogim St~vcnL. Kuhn and M a y C. Stiner, both at th Univcrsiy of A r i m s , hypothesized &at rhQ varied diet of sly modern Eu-m w w k l have favored a division of l a h ia which mm hunted tb larger game and women collccd

u s r w l o n o f t h e M ~ k m e y h a v e b s ~ l a ~ p o f d ~ i n t h e B ~ h t m O t o r y o f

I GlbraW, where h archaic homlntds l v d as I

mentkyas 28,000 years ap. Gibraltar a d dta rest of the ,both Peninsula vnuld hnr had a I

' retad* mlld dlmtb a d sbundsnt fd r e 1 mms compdtgd with mwh of ke A$e@mp,

a mote reliable food supply and a safer d r o n - merit for rearing children, divisian d lbor could have tnaW modem h ~ ~ ~ p ~ to expand at the expense d & & W d e t t &

However the Neandehh shined their f d , they needed lofp,bt"*wdercaIs wen tbe W s of the ho- wrte,* says palman- rbmpoiagist &g&v&&o ofthe W m - G r c n tion-where to find drinking water in times of Foundii$$gnbHew Yo& City. A number of drought, fot instance. uLong-term survivorship stuf a aimid at Pstimacing Neanderml mta- gives the patential for bier d l network4 bolie mtes have concluded that these archaic and greater knowledge stoesp Stringer corn- horninids requhed significantly more &riesto ments. Among the shorter-lived N e a n d d in survive rhan the rmal moderns did. contrast, knowkdge was more likely ro h p -

Hominid en&etics expert Karen Stendel- pear, be suhtisxs. Numbers of the Univmsiry of Wismnsh-Mad- More clues tp why &e Ncandertals faded ism hae determind. for example, that the en- - away may come Eroma~aiyskof the Neandertai mgetic coat of Iocomation was 32 prcmt higher gcoome, the fuI1 sequence of which is due out

. I in Neandertals than in anatomically modern this year. But answers are likely to be slow to humans, thanks to the a d a i c homhids' budy surfam, because scimth know so little about build a d sbr t shinbones, which would have the functional s i g n h x e of mosc region~of the s h o d theit stride. In m s of daily energy MORE T modem genome, neva mind the Neandertal needs, 'thc Meandcrtals would haye required -0 d om. *We're a long way from being able to mad -&ween 10 0 and 35 0 calories more what the [NeandertaIj genome is telbg us," than modam b i n the game climates, ac- Ok~BatomesCMnmonLate Stiinger says. Still, future analyses a u l d con- cording ro a model developed by An+ W. ~~~H~~~~~ ccivably pinpint &tiye or mefabolii differ- Froehle ofthe U ~ Y ~ of California, San Di- * h w e o f - ences between thetwa p u p a , for example, and ego, and Steven E. Cbu&l of Duke Universi- U a VoI. 101, No. 30, - vide a morcd&itive answer to the question ty. Modern buornr, lm, might have outcorn- t 0 8 9 5 - 1 ~ ; J*27, m a a,$ - -

whether Ncandertals and modem interbred. peted Ntandcrtals simply by virtue of being

Rapid Ealoglcal Turnorrer and tts Tk Stone Age whodunit is far from solved.

more fuel-efiicnt: using less energy for base- on Heanderthal and Othrr But r e s e a d m are convesging an one conclu- line functions meant that modems could devote H"- ~opula~kns, crive fin- sion: regardless of whether climate or ~ m p e r i - more energy ro producing and ensuring the and b& 5. Canibn in Tnnds In Ecdo- tion with modcras, or some combination there- survival of their young. wadEumrubbn, Vol, 22, Nu. 4, of, was tbe prime mover in the dedine of the Ne-

One more distinction berween Neandermls pages 213-222; . ---- 2007. andertals, the precise factors governing the and moderas destrves mention, one that wuld North: An AfrlEanlrt Per- extinction of individual populations of these ar- t have enhanced modern survival in important on shaie horninids almost certainly varied from ways. Research lcd by Rsshsl Clrpari of Cco- Nmndemulr b y h d m MU-. group m group. Some may haw perished h a m

I

i tml Michigan University has shown that around m W . w n i n f i m lt* disease, orhers from inbreeding. "Each vatley ; 30,000 years ago, the number of modern hu- EbnedbPau' may tell io own story," Finlayson remarks.

Melametal. M 4 ) o M W ImiWtc -, mans who lived to be old enough to %grand- -, As for the last known Neandertals, the ones parents began to skyrocket. ~ x a c ? ' l ~ what c ~ ~ ~ ~ o o who l i d in Gibraltar's reaside cavcs some spurred this increase in longevity is uncertain, - 28,000 years ago, Fialsyson is certain that they

? but the change had two key consequences. First, ~ e d h a l Ex~loltatlmof Ma- did not spend their days competing wirh mod- - people had more reproductive yean, thus in- rhe ''braharm = '. erns, because modems setm not ro have settled ; Swinger et al. In of the

i creasing their fertility potmtial. Second, they N ~ ~ ~ ~ ~ ~ - ~ &em until thousands of years after the Nean-

d had more time over which to q u i r e specialized vol, 105, N~ 3, - t4314-,4324; -1s were gone. The rest of ttPeir story, how- bwledge and pass it on to the next genera- septmh23,

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Mysteries of &st,

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A Way to R e d m .Drug Side Effects