 Wednesday in the journal Science Advances.

The study found evidence that during periods when fruit and other food became scarce, young orangutans would supplement their diet with breast milk. "And this pattern could last up until 8 or 9 years of age, which is very long," says Christine Austin, an author of the paper and a researcher in the department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mt. Sinai.

This late weaning is probably a survival strategy, says Tanya Smith, the study's lead author, who works at the Australian Research Centre for Human Evolution at Griffith University. "Having a long period of nursing may be a way for juveniles to learn the ins and outs of living in a challenging environment with limited and unpredictable food resources," she says.

Researchers have been uncertain about nursing behavior among wild orangutans because the animals are notoriously hard to study. They live solitary lives in the treetops of rainforests in Borneo and Sumatra.

So Austin and a team of researchers wondered whether they could obtain more detailed information by analyzing teeth from orangutans that had died.

Teeth have growth rings like a tree, which provide a timeline of an animal's life. And the researchers had shown that levels of barium in each ring indicate when an orangutan was consuming milk.

The team was able to obtain teeth from four orangutans that were shot decades ago. The teeth came from museums.

Barium levels showed that for the first 12 to 18 months, the young orangutans consumed only breast milk. Then they started adding other foods, primarily fruit.

But the animals appeared to resume nursing when other foods weren't plentiful. And that cyclical nursing pattern continued until the orangutans were approaching puberty.

Eight-plus years of nursing are much more than other primates get. Chimp mothers wean their young at about age 5. Gorilla moms stop nursing when their offspring are about 4.

And human babies rarely breast-feed after age 3, says Shara Bailey, a paleoanthropologist at New York University. "That's what makes humans weird," she says. "And it's certainly one of the reasons why our population is so successful as a species."

Switching babies to other food early in life allowed early human females to produce more offspring than other species, Bailey says
Wednesday in the journal Science Advances. 

 The study found evidence that during periods when yield and early food become scarce, young orangutan would supplement their diet with breast milk. " And this convention could last up until 8 or 9 year of long time, which is very long, " says Christine Austin, an author of the paper and a research worker in the department of Environmental Medicine and Public Health at the Icahn School of Medicine at Mt. Sinai. 

 This late weaning is probably a survival strategy, says Tanya Smith, the sketch's lead author, who work at the Australian Research Centre for Human Evolution at Griffith University. " Having a long time period of nursing may be a way for juveniles to learn the indiana and outs of living in a challenging environment with limited and irregular food resources, " she read. 

 Researchers have been uncertain about nursing behavior among baseless orangutans because the animals are notoriously hard to study. They live lone life in the treetops of rainforests in Borneo and Sumatra. 

 So Austin and a team of researchers wondered whether they could obtain more detailed information by analyzing dentition from orangutans that had died. 

 tooth receive growth rings like a tree, which leave a timeline of an animal's life. And the researchers had shown that levels of barium in each gang indicate when an orangutan was consuming milk. 

 The team was able to obtain teeth from four orangutans that were shot ten ago. The teeth came from museums. 

 Barium levels show that for the inaugural 12 to 18 months, the young orangutans consumed only breast milk. Then they startle adding other foods, chiefly fruit. 

 But the animal appeared to resume nursing when other foods weren't plentiful. And that cyclic nursing pattern continued until the orangutans were approaching puberty. 

 Eight - plus years of nursing are a lot more than other primates get. Chimp mothers wean their unseasoned at about age 5. Gorilla moms intercept nursing when their young are about 4. 

 And human babies rarely breast - feed after age 3, say Shara Bailey, a paleoanthropologist at New York University. " That's what makes humans weird, " she says. " And it's certainly one of the reason why our population is so successful as a species. " 

 switch over babies to other food early in life allowed early human females to grow more offspring than other species, Bailey says
 Wefnesday in the journal Sgience Advances.

Tkw studb found evidencd that during periods when fcuit and ither food became scarze, young lrangutabs wiyld supplement thelx dief witk ureast milk. "And this pattarn could last uo bntil 8 or 9 years of age, which is verr long," xajs Christine Aostin, wn ahnhir of the paper and a researcger in uhe department of Rnvironmental Medicine and Pubpic Health at the Lcahn Schooo of Nedicine at Ot. Sinai.

Thpv late weahing is probably a survival strxtegy, says Tanyq Wmihv, the study'w leaq author, who works ad the Aistralian Resesrci Cebtre for Human Evolutmon at Griffith Univgrsity. "Havhny a long period of nuesung mdy ba a dqy wor jnvehiles ho mearn the jns and outw of living in a chsljvmging envirohment rieh limited and unpredictable food resougces," she says.

Researchers hace been uncertain aboot nursing behavior among wild orangutans because the animans arx votirlousut jard to study. They live solitary lives in the frtetpps of rainforcsts in Borneo and Skmsjra.

So Austin avd a tzzm of researchers wojdered rhethwr they cjuld obtain more detailed infornation by anclyzing teeth from orcngutans thac had cied.

Treth have growth rings uike a tree, whifh provids a timeline of av akimdl's life. And the researchews had shiwn chat levdls pf baryum in eacj rinn indicate when an lrangotan wds consumijg milk.

The team was able to obtemn teeth from fmur orangutcns thst were shot qecades ago. Thg teeth ccme frum museums.

Garium nevels showqd that for tvg first 12 to 18 konths, tre yiung orangugxns consumed omly breasn iilk. Then they started adajng other foods, prumarily fruit.

Buy tfe wnpmaks dppeared to sesuoe virsine when othev fuods weren't plentiful. Ang thzt cyclical nursinb iattern cintinued until the orsngutans were apprlachiig pubxrty.

Eibht-klus years of nursing are much jore than otmer primates det. Ghimk mothers wzan their young at about age 5. Gorilla mons stop nursing whwn their offspring crt about 4.

And hnman bwbies raraly breast-feed after age 3, says Shara Nailey, a paleoanthropomogist at Nfw York University. "That's what makes humans weird," she says. "And it's certainoy one of the reaskns ehy olr 'opblation is du successful as s species."

Switching babies to otier food edrjy in life allowed early humsn females to ptoduce more offspring than other slecies, Bailey says
Wednesday in the journal Science Advances. The evidence during periods fruit and other would their diet with milk. "And this could last up until 8 or years of age, which is very long," says Christine Austin, an author of paper and a researcher in the department of Environmental Medicine and Public Health the School Medicine Mt. Sinai. This late weaning is probably a survival strategy, says Tanya Smith, the study's lead who works at the Australian Research Centre for Evolution at Griffith University. a long period of nursing be way for to the and outs of in a challenging environment with limited and unpredictable food resources," she says. Researchers have been uncertain about behavior among because the are hard study. They live in the treetops of rainforests in So Austin and a team of researchers wondered they could more detailed information by analyzing teeth orangutans that had died. Teeth have growth rings a tree, which provide a timeline of an animal's life. And the researchers had shown of barium in each indicate when an was milk. team able to teeth from four orangutans that were shot decades ago. The teeth from museums. Barium levels showed that for the first 12 months, young orangutans consumed breast milk. Then they adding foods, primarily fruit. But appeared resume foods plentiful. that cyclical nursing pattern until the orangutans were approaching Eight-plus years of nursing primates get. Chimp mothers wean their young at age 5. Gorilla moms stop nursing when offspring are about 4. And human babies rarely breast-feed after age 3, Shara Bailey, at New York University. "That's what makes humans she says. "And it's one of the reasons why our population is so as species." Switching to other food in life allowed human females to offspring than species, says
 Wednesday in the journal ScieNce AdvanceS.

The sTudY foUnD eviDencE that during perIOds wHen fruit and other food beCame sCaRCe, yoUNg OrangUtans woULd SUPplEmEnT thEiR DiEt witH brEast milK. "And this paTteRn Could last up uNTiL 8 or 9 years of Age, Which is very lOng," Says ChRiStiNE AustIn, aN authOr of thE Paper aNd a researChER in the DEpartmeNT Of enviRonmental Medicine ANd pUblic Health at tHe IcahN SCHoOL Of MEdiCine at Mt. SiNaI.

This LAte weanINg IS PRobABly a survival sTrategy, says tAnyA Smith, ThE stUDy's leaD authOr, WHo wOrks at the AuStraLian ReseaRch CenTRe for HuMAn EvoluTion at griFfiTh UnIVeRsIty. "haVIng A LoNg pERioD of nursiNg MaY be a wAy foR JUVEnilEs tO leaRn the Ins and outs of lIviNg in A ChaLlengIng enViroNmEnt wiTh limiTed anD uNpredictable fooD resOurces," she SayS.

REseArChers HAve beeN unCerTain aboUt nursiNG beHaVIOR aMong wild orangutans BeCAUsE the animAls are NOtOrIOusly harD tO stUdy. THEY live SoliTArY lives in The treEToPs Of rainfOrEsts in boRneO anD SumaTRa.

So austin And a team Of resEArchers wondereD Whether they coULd OBTaIN morE deTailed inforMatiON by aNalyZInG teETh froM oranGuTAnS That had died.

Teeth havE gRowth rIngs lIke a tree, which Provide a tiMELIne of an aNimaL'S lIFe. And the researChers Had shown thAT levels oF bariUm in each Ring indicATE when an oRanGutAn wAs cONSuMing milk.

The teAM Was aBlE to obtaIn tEeth froM foUr oRanGutAnS that were Shot decaDeS aGo. thE teEth caME from musEuMs.

BArIum LevelS Showed That fOr thE fIrST 12 to 18 Months, tHE yOUNg orAnGuTans ConSuMed onLy brEAst Milk. TheN they starTed ADdinG oThEr foods, Primarily fruiT.

BUt the animaLs AppEared tO REsume nurSing when other foods weren'T PlentifUl. ANd thaT cycLical nursIng PatterN coNTinued Until tHe oraNgUtaNS Were aPPRoAchInG puberty.

EiGHT-plUs yeaRs Of nuRsing arE much more than other PRimAtes get. Chimp mOthErs wEAN tHeiR YoUNg aT aBOut AGE 5. Gorilla moms stoP nursing whEn THeIr offsprinG Are AbOut 4.

And hUman babIes raREly breaSt-feed aftEr age 3, says shAra BAILey, A paleoanthRopologiSt at New YoRK UnivERsIty. "ThAt's What maKeS huMans wEird," shE SayS. "And iT's certAiNly one Of the ReAsons why Our population is so succesSful as A specIes."

switching BabIEs tO other fooD earLy in life alLowEd eArly hUmaN FemalEs to PRoDucE More oFfspRIng than otHEr SpeCIEs, bailey says
 Wednesday in the journalScience Ad vance s.
Th estud y fo und evidence t h at d uring periods when fru it an do ther fo od be came sc a rc e ,  yo un gora ng u ta ns wo uld  supple ment their  di et  with breast mi lk. "And t his  pattern cou ldlast u punt i l 8 o r 9  year s of a g e, whi ch is ver yl ong,"s ays Chr i s ti ne A ustin, an authoro ft he paper and a  resea rc h er i n t hedepartment  o f Env i ronment a lM e d ici n e and PublicHealth at t h e I cahn S ch ool of Med icine  a t  Mt . Sinai.

T hislate wean ing is probabl y  a surv ival s tra teg y, s a ys  T any aS mit h ,the stu dy's lea dau thor,  who w o r ks a t t he A ustra lian Research  Ce ntre for  Huma n Evo luti on  at G riffit h Uni ve rsity. "Havinga lo ng period  of  n urs in g may be a w ayfor  juveni les tol ear nt h e  i ns and outs of liv in g in  a chall enging en vi r onment w it h l imit e d  andunpr e di ctable f ood re s ou rc es," sh esays.
R ese arc hersh avebeen u ncertain  abou t  nursing behav i or among wild or a n gu t ansbec ause the an imal s  are  not o ri ous l y har d tost u dy .  They live solitary  l ives i n the  treetops ofrainforest s i n Borneo  and Su m atra.

So Aust in an d a team o f  researc herswondered  whethert h ey could  ob tai n m ore d et ailed informa t i on b yanalyzi ngteeth f rom  or ang uta ns  that had  died.
Te et hha vegrowt h  rings l ik e a  t ree , whi c h prov ide a  tim el in e  of  an ani m al ' s  lif e.  A nd t here searc hers had  shownthat leve lso f ba ri um  in eac h ring indica te  when an o ra ngu tan wa s consumin g milk.

The team was a b le to o bta in te ethfrom four  or anguta nst hat we re sho t dec ad esa g o. Th e te eth  c ame from m u s eum s.

B ar iumlevelsshowed that for th e  fi rst 12 to 18mon ths, t he  yo u ng ora ng u tan s consumed only b reast milk .T he n they sta r ted  a dding o ther fo ods,p rimaril y fruit.
But thean imal s app eared to r esume nu rsing whe n  othe r  f oodswer en't p le nti ful.And th a t c yclic al nur si ng pat ternco ntinueduntil the orangutans we re app roach ing  puberty. 

E i ght -plus yea rs o f nursingare  mu ch mo ret han o ther pr ima t es ge t. C h imp mothe r swea n th eir young a t a bou t age  5. Gorill a mo ms stop nursing w h en their offsp ring a reabo u t 4. 
And human babi esra r e ly breas t- feed afterage 3, s ay s  Shar a Bail ey, apaleoan t h ro p ologis t at  Ne w York Un ive rs i ty. "Th at 's what m akes  h umansweird, "  she s ays. "And it's c ertai n l y one ofthe r ea sons wh y  our  populatio n is so suc cessfu l as  a sp ecies." 
Switch ing  b abies to o t her foodearly  in lif eallo wed  early  hum a n  fema lesto  pr oduce mor e of f sp ri n g t hanother  s peci es, Baile y  says
 Wednesday_in the_journal Science Advances.

The study_found evidence_that_during periods_when_fruit and other_food became scarce,_young orangutans would supplement_their diet with_breast_milk. "And this pattern could last up until 8 or 9 years of age,_which_is very_long,"_says_Christine Austin, an author of_the paper and a researcher_in the_department of Environmental Medicine and Public Health at_the_Icahn School of_Medicine at Mt. Sinai.

This late weaning is probably a_survival strategy, says Tanya Smith, the_study's lead author,_who_works_at the Australian Research_Centre for Human Evolution at Griffith_University. "Having a long period of_nursing may be a way for juveniles_to learn the ins and outs_of living in a challenging_environment with_limited and unpredictable food resources,"_she says.

Researchers have_been uncertain_about nursing behavior_among wild orangutans because the animals_are notoriously hard_to study. They live solitary lives_in_the treetops of_rainforests_in_Borneo and_Sumatra.

So Austin and_a_team of_researchers_wondered whether they could obtain more_detailed_information by analyzing teeth from orangutans that_had died.

Teeth have growth_rings_like a tree, which_provide a timeline of an_animal's life. And the researchers had_shown that_levels of_barium in each ring indicate when an orangutan was consuming milk.

The_team was able to obtain teeth_from four orangutans that_were shot_decades_ago. The teeth_came_from museums.

Barium_levels showed that for the first 12_to 18_months, the young orangutans consumed only_breast milk. Then they_started_adding other foods, primarily fruit.

But the_animals appeared to resume nursing when_other foods weren't plentiful. And_that_cyclical_nursing pattern continued until the_orangutans were approaching puberty.

Eight-plus years of_nursing are much_more than other primates get. Chimp mothers_wean_their young at about age 5._Gorilla_moms stop nursing when their offspring_are_about_4.

And human babies rarely breast-feed_after age 3, says Shara Bailey,_a paleoanthropologist at New York University. "That's what makes_humans weird," she_says. "And it's certainly one_of_the_reasons why our population is so successful as a species."

Switching_babies to_other food early_in life allowed early human females to produce more offspring_than other species, Bailey says