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In a paper published Feb. 19 in the skill journal Nature , two paleoanthropologists reason that some recently discovered hierarch dodo may not be as human as everyone mean . While the authors maintain thathumans did , of course , germinate from apes , their contentions highlight the difficulty of using 7 - million - twelvemonth - old bone fragments to tack together thefull story of human evolution .
The fossils in head — corresponding to species namedOrrorin tugenensis , Sahelanthropus tchadensisandArdipithecus ramidus — have all made newspaper headline in late years forfilling in gapsin the evolution from emulator to humans . Though they ’ve been hailed as remnants of some of our early hominin antecedent , paleoanthropologists Bernard Wood of George Washington University and Terry Harrison of New York University say they ’re probably just non - hominin ape bones .
" The problem is that a phone number of lineament that have been identified as being related to humans may be interpreted in different way , " Harrison toldLife ’s Little Mysteries , a babe site to LiveScience .
For example , all that has been bump ofSahelanthropus , the quondam genus widely conceive to have been a hominin , is a 7 - million - year - old partial skull . And yet , from its shape , paleoanthropologists have concluded that the specimen must havewalked upright . " The position of its foramen magnum"—the spot where the encephalon connects to the spinal anaesthesia cord—“has historically been reason to be colligate with bipedalism , " enunciate Harrison . " However , we see from comparative physical body that that ’s not always the cause . "
In 2008,Orrorin , the second - oldest say hominin , was also argue to be bipedal in an article in Science by William Jungers at Stony Brook University and his colleagues . But Harrison and Wood argue thatOrrorinmight not have walked upright either .
And of the renowned 4.4 - million - year - oldArdipithecuspartial skeleton found in 2009 , Harrison aver , " It ’s a remarkable find . It ’s really unbelievable to have such an sometime frame of a potential human ascendent . But we would reason it seems to look like many of the forms of the apes we have seen from that period . "
Skepticism regarding these famous primate fossil finds seems to call into question the rigor of the scientific operation within the field of palaeoanthropology . Wood ’s and Harrison ’s paper certainly makes one wonder : Are these isolated incidents of misinterpretation followed by medium ballyhoo , or does the problem diffuse the whole branch of science ? Is the human evolutionary fossil record a crapshoot ?
" No , " tell Harrison . There are reasons why this outgrowth of scientific discipline may seem messier than most , he said , but all things view , it is doing exceedingly well .
One in a million
" In science , there are always divergence in interpretation and debate . It takes a long time for an answer to emerge . But it takes even longer with historical sciences – ones that do n’t countenance experiment , " Harrison said .
" These were species that live millions of years ago in one small region in Africa . " What ’s more , Harrison explained , the mintage in interrogation had small population . " So there are only isolated examples around today , and it ’s hard for people to respond to a paper when it occur out because they do n’t have the original material . Slowly , more scientist get a hazard to look at the specimen , and the debate continues and finally gets resolved . "
Finding the right age of fossil is also problematical . " There are spectaculartechniques to date excavation sites , but there are limits to what you’re able to apply them on , " Harrison said . " Argon - atomic number 18 dating is really precise , for example , but it need the presence of volcanic rocks and you ca n’t rule those everywhere . Cave site are particularly concentrated to date . Carbon-14 date kicks in for anything up until 40,000 years ago but before that is treacherous . "
An added trouble , as Harrison and Wood point out in their newspaper , is the occurrence of homoplasy – a situation where the traits of two species have evolved to look like , as counterbalance to await similar because of a tight genetic relationship .
Jungers , the paleoanthropologist who pen aboutOrrorin ’s bipedalism , agrees with the Nature generator on that fussy tip . " Homoplasy is a real trouble in the study of the dodo record , whether we ’re talking about humans or other groups , " Jungers told Life ’s Little Mysteries . " It ’s a complicating factor that a law of similarity does n’t inevitably imply shared ancestry or a particularly close family relationship . That take - house message is skillful for everybody in the field to keep in the back of their nous . "
conceive all those difficulty , Harrison and Jungers both described our understanding of human origins as surprisingly well - developed . " Because we pass the most fourth dimension and money excavating sites we know will be best for find hominin fossils , the human fossil record is one of the best know of any , " say Harrison .
According to Jungers , the issues raised in the new Nature theme ought not to be over - generalized . " The human dodo record is one of the best in biota . That ’s one of the reasons multitude can nitpick over its ok point . “By the time modernistic humans evolved 200,000 yr ago , the dodo evidence they leave behind behind is extensive , and from 50,000 to 60,000 year ago on , our ascendent will fogy over a large neighborhood of the world . But the phonograph record is quite substantial going back much far into the past .
" The undisputable human ancestral record starts around 4.2 million yr ago . Only the details are left to be shape out , " Harrison said .
" That ’s pretty practiced go . "
This clause was put up byLife ’s Little Mysteries , a sister land site to LiveScience .
