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Home , Continent, Denisovan, Homo erectus, Homo heidelbergensis, Peking Man, Xujiayao

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THE finds in are challenging ideas about the evolution of modern and our closest relatives.

n the outskirts of , a small BY JANE QIU government is setting up a US$1.1-million mountain named Dragon laboratory at the IVPP to extract and sequence Hill rises above the surround- spread around the globe — and relegated ancient DNA. Oing sprawl. Along the northern side, a path to a kind of evolutionary cul-de-sac. The investment comes at a time when palaeo­ leads up to some fenced-off that draw But the tale of has haunted anthropologists across the globe are starting to DEAGOSTINI/GETTY 150,000 visitors each , from schoolchildren generations of Chinese researchers, who have pay more attention to Asian and how to grey-haired pensioners. It was here, in 1929, struggled to understand its relationship to they relate to other early hominins — creatures that researchers discovered a nearly complete modern humans. “It’s a story without an end- that are more closely related to humans than ancient skull that they determined was roughly ing,” says Xinzhi, a palaeontologist at the to chimps. Finds in China and other parts of half a million old. Dubbed Peking Man, Chinese Academy of Sciences’ Institute of Ver- Asia have made it clear that a dazzling variety of it was among the earliest remains ever tebrate and once roamed the continent. And uncovered, and it helped to convince many (IVPP) in Beijing. They wonder whether the they are challenging conventional ideas about researchers that humanity first evolved in Asia. descendants of Peking Man and fellow members the evolutionary of humanity. Since then, the central importance of Peking of the species died out or evolved “Many Western scientists tend to see Asian Man has faded. Although modern dating into a more modern species, and whether they fossils and artefacts through the prism of what methods put the fossil even earlier — at up to contributed to the gene pool of China today. was happening in and ,” says 780,000 years old — the specimen has been Keen to get to the bottom of its people’s Wu. Those other continents have historically eclipsed by discoveries in Africa that have ancestry, China has in the past decade stepped drawn more attention in studies of human evo- yielded much older remains of ancient human up its efforts to uncover evidence of early lution because of the antiquity of fossil finds relatives. Such finds have cemented Africa’s sta- humans across the . It is reanalysing there, and because they are closer to major tus as the cradle of humanity — the place from old fossil finds and pouring tens of millions palaeoanthropology research institutions, he which modern humans and their predecessors of dollars a year into excavations. And the says. “But it’s increasingly clear that many Asian

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The reconstructed materials cannot fit knows what they are because they ’t seem want everything to come from China.” skull of Peking Man, into the traditional to fit into any categories we know.” Chinese researchers reject such allegations. the fossil that launched narrative of human The fossils’ transitional characteristics have “This has nothing to do with nationalism,” says discussions of .” prompted researchers such as Stringer to Wu. It’s all about the evidence — the transitional origins in China. , lump them with H. heidelbergensis. Because fossils and archaeological artefacts, he says. a palaeoanthro- the oldest of these forms, two skulls uncov- “Everything points to continuous evolution in pologist at the Natural History Museum in ered in Yunxian in Hubei province, date back China from H. erectus to modern human.” London, agrees. “Asia has been a forgotten 900,000 years1,2, Stringer even suggests that But the continuity-with-hybridization model continent,” he says. “Its role in human evolu- H. heidelbergensis might have originated in is countered by overwhelming genetic data tion may have been largely under-appreciated.” Asia and then spread to other continents. that point to Africa as the wellspring of mod- But many researchers, including most ern humans. Studies of Chinese populations EVOLVING STORY Chinese palaeontologists, contend that the show that 97.4% of their genetic make-up is In its typical form, the story of Homo sapiens materials from China are different from Euro- from ancestral modern humans from Africa, starts in Africa. The exact details vary from one pean and African H. heidelbergensis fossils, with the rest coming from extinct forms such telling to another, but the key characters and despite some apparent similarities. One nearly as and Denisovans5. “If there had events generally remain the same. And the title complete skull unearthed at Dali in Shaanxi been significant contributions from Chinese is always ‘Out of Africa’. province and dated to 250,000 years ago, has H. erectus, they would show up in the genetic In this standard view of human evolu- a bigger braincase, a shorter face and a lower data,” says Li Hui, a population geneticist at tion, H. erectus first evolved there more cheekbone than most H. heidelbergensis speci- Fudan University in . Wu counters that than 2 million years ago (see ‘Two routes for mens3, suggesting that the species was more the genetic contribution from archaic hominins human evolution’). Then, some time before advanced. in China could have been missed because no 600,000 years ago, it gave rise to a new spe- cies: , the oldest remains of which have been found in Ethiopia. About THE EVOLUTIONARY TALE IN ASIA IS MUCH MORE 400,000 years ago, some members of H. hei- INTERESTING THAN PEOPLE REALIZED. delbergensis left Africa and split into two branches: one ventured into the Middle and Europe, where it evolved into Neander- Such transitional forms persisted for DNA has yet been recovered from them. thals; the other went east, where members hundreds of thousands of years in China, Many researchers say that there are ways became — a group first discov- until species appeared with such modern traits to explain the existing Asian fossils without ered in in 2010. The remaining popu- that some researchers have classified them as resorting to continuity with hybridization. lation of H. heidelbergensis in Africa eventually H. sapiens. One of the most recent of these is The Zhirendong hominins, for instance, could evolved into our own species, H. sapiens, about represented by two teeth and a lower jawbone, represent an exodus of early modern humans 200,000 years ago. Then these early humans dating to about 100,000 years ago, unearthed from Africa between 120,000 and 80,000 years expanded their range to 60,000 years in 2007 by IVPP palaeoanthropologist Liu Wu ago. Instead of remaining in the in the ago, where they replaced local hominins with and his colleagues4. Discovered in Zhirendong, , as was thought previously, these a minuscule amount of interbreeding. a in Guangxi province, the jaw has a clas- people could have expanded into , A hallmark of H. heidelbergensis — the sic modern-human appearance, but retains says Michael Petraglia, an archaeologist at the potential common ancestor of Neanderthals, some archaic features of Peking Man, such as University of Oxford, UK. Denisovans and modern humans — is that a more robust build and a less-protruding chin. Other evidence backs up this hypothesis: individuals have a mixture of primitive and Most Chinese palaeontologists — and a few excavations at a cave in Daoxian in China’s modern features. Like more archaic lineages, ardent supporters from the West — think that Hunan province have yielded 47 fossil teeth H. heidelbergensis has a massive brow ridge and the transitional fossils are evidence that Peking so modern-looking that they could have no chin. But it also resembles H. sapiens, with Man was an ancestor of modern Asian people. come from the mouths of people today. But its smaller teeth and bigger braincase. Most In this model, known as multiregionalism the fossils are at least 80,000 years old, and per- researchers have viewed H. heidelbergensis — or continuity with hybridization, hominins haps 120,000 years old, Liu and his colleagues or something similar — as a transitional form descended from H. erectus in Asia interbred reported last year6. “Those early migrants between H. erectus and H. sapiens. with incoming groups from Africa and other may have interbred with archaic populations Unfortunately, fossil evidence from this parts of Eurasia, and their progeny gave rise to along the way or in Asia, which could explain period, the dawn of the human race, is scarce the ancestors of modern east Asians, says Wu. Zhirendong people’s primitive traits,” says and often ambiguous. It is the least under- Support for this idea also comes from arte- Petraglia. stood episode in human evolution, says Russell facts in China. In Europe and Africa, stone Another possibility is that some of the Ciochon, a palaeoanthropologist at the Univer- tools changed markedly over time, but homi- Chinese fossils, including the Dali skull, rep- sity of Iowa in Iowa City. “But it’s central to our nins in China used the same of simple resent the mysterious Denisovans, a species understanding of humanity’s ultimate origin.” stone instruments from about 1.7 million years identified from Siberian fossils that are more The tale is further muddled by Chinese fossils ago to 10,000 years ago. According to Gao than 40,000 years old. Palaeontologists don’t analysed over the past four decades, which cast Xing, an archaeologist at the IVPP, this sug- know what the Denisovans looked like, but doubt over the linear progression from African gests that local hominins evolved continuously, studies of DNA recovered from their teeth and H. erectus to modern humans. They show that, with little influence from outside populations. indicate that this ancient population con- between roughly 900,000 and 125,000 years ago, tributed to the genomes of modern humans, east Asia was teeming with hominins endowed POLITICS AT PLAY? especially Australian Aborigines, New with features that would place them somewhere Some Western researchers suggest that there is Guineans and — suggesting that between H. erectus and H. sapiens, says Wu. a hint of nationalism in Chinese palaeontolo- Denisovans might have roamed Asia. “Those fossils are a big mystery,” says gists’ support for continuity. “The Chinese — María Martinón-Torres, a palaeoanthropol- Ciochon. “They clearly represent more they do not accept the idea that H. sapiens ogist at University College London, is among advanced species than H. erectus, but nobody evolved in Africa,” says one researcher. “They those who proposed that some of the Chinese

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In the standard model of human origins (left panels), multiple waves of making a push in that direction. Qiaomei Fu, a TWO ROUTES FOR hominins left Africa in succession and spread around Eurasia over the past palaeogeneticist who did her PhD with Pääbo, 2 million years. A di erent model (right) suggests that early emigrants from Africa established a source population in the Middle East. This gave rise to returned last year to establish a lab to HUMAN EVOLUTION many transitional species that spread to Europe, east Asia and Africa. extract and sequence ancient DNA at the IVPP. One of her immediate goals is to see whether some of the Chinese fossils belong to the mys- AFRICAN ORIGIN 1.8 million ya terious group. The prominent Homo erectus evolved in teeth from will be an early target. “I Africa and had dispersed 1.7 million ya think we have a prime suspect here,” she says. into Asia by 1.8 million years ago (ya). HOMO ERECTUS FUZZY PICTURE 1.5 million to 0.9 million ya Despite the different interpretations of the Chinese fossil record, everybody agrees that the evolutionary tale in Asia is much more OUT OF AFRICA ALTERNATIVE MODEL interesting than people appreciated before. But the details remain fuzzy, because so few NEANDERTHALS DENISOVANS NEANDERTHALS DENISOVANS researchers have excavated in Asia. by 430,000 ya by 430,000 ya When they have, the results have been TRANSITIONAL startling. In 2003, a dig on in FORMS 9 SOURCE 900,000– turned up a diminutive hominin , POPULATION 125,000 ya which researchers named TRANSITIONAL FORMS and dubbed the hobbit. With its odd assort- 900,000 – ment of features, the creature still provokes HOMO HOMO 125,000 ya HEIDELBERGENSIS HEIDELBERGENSIS debate about whether it is a dwarfed form of 600,000 ya 600,000 ya H. erectus or some more primitive lineage that made it all the way from Africa to and lived until as recently as 60,000 years Homo heidelbergensis or other transitional Homo erectus descendants in the ago. Last month, more surprises emerged from forms evolved into Neanderthals and Middle East give rise to various Denisovans. Hominins in China with hominin groups in Europe Flores, where researchers found the remains mixtures of archaic and modern features and east Asia, as as to of a hobbit-like hominin in rocks about may have derived from H. heidelbergensis. Homo heidelbergensis in Africa. 700,000 years old10. Recovering more fossils from all parts of Asia will clearly help to fill in the gaps. Many 45,000 ya 45,000 ya palaeoanthropologists also call for better 120,000– 120,000– 60,000 ya 80,000 ya 80,000 ya access to existing materials. Most Chinese 120,000– fossils — including some of the finest speci- 60,000 ya 80,000 ya mens, such as the Yunxian and Dali skulls — are accessible only to a handful of Chinese MODERN HUMANS MODERN HUMANS palaeontologists and their collaborators. “To Descended from African 60,000 ya Descended from Middle 60,000 ya make them available for general studies, with H. heidelbergensis Eastern source population. replicas or CT scans, would be fantastic,” says Stringer. Moreover, fossil sites should be dated much more rigorously, preferably by multiple Modern humans emerged in Africa about Modern humans evolve in Africa from methods, researchers say. 200,000 years ago and reached the Middle East H. heidelbergensis or another hominin by 120,000–80,000 years ago. Later waves of derived from the Middle East, and they But all agree that Asia — the largest modern humans spread through Europe and Asia. disperse to Eurasia in multiple waves. continent on — has a lot more to offer in terms of unravelling the human story. “The hominins were Denisovans. She worked with of modern humans. Their descendants mostly centre of gravity,” says Petraglia, “is shifting IVPP researchers on an analysis7, published settled in the Middle East, where the eastward.” ■ last year, of a fossil assemblage uncovered was favourable, and then produced waves of at Xujiayao in Hebei province — including transitional hominins that spread elsewhere. Jane Qiu is a writer in Beijing. partial jaws and nine teeth dated to 125,000– One Eurasian group went to Indonesia, another 1. Li, T. & Etler, D. A. Nature 357, 404–407 (1992). 100,000 years ago. The molar teeth are massive, gave rise to Neanderthals and Denisovans, and 2. Vialet, A. et al. Comptes Rendus Palevol. 9, 331–339 with very robust roots and complex , a third ventured back into Africa and evolved (2010). reminiscent of those from Denisovans, she says. into H. sapiens, which later spread through- 3. Wu, X. & Athreya, S. Am. J. Phys. Anthropol. 150, A third idea is even more radical. It emerged out the . In this model, modern humans 141–157 (2013). 4. Liu, W. et al. Proc. Natl Acad. Sci. USA 107, when Martinón-Torres and her colleagues evolved in Africa, but their immediate ancestor 19201–19206 (2010). compared more than 5,000 fossil teeth from originated in the Middle East. 5. Hu, Y. et al. Preprint at http://arxiv.org/ around the world: the team found that Eurasian Not everybody is convinced. “Fossil inter- abs/1404.7766 (2014). specimens are more similar to each other than pretations are notoriously problematic,” says 6. Liu, W. et al. Nature 526, 696–699 (2015). 8 7. Xing, S., Martinón-Torres, M., Bermúdez de Castro, to African ones . That work and more recent Svante Pääbo, a palaeogeneticist at the Max J. M., Wu, X. & Liu. W. Am. J. Phys. Anthropol. 156, interpretations of fossil skulls suggest that Eura- Planck Institute for Evolutionary Anthro- 224–240 (2015). sian hominins evolved separately from African pology in Leipzig, Germany. But DNA from 8. Martinón-Torres, M. et al. Proc. Natl Acad. Sci. USA 104, 13279–13282 (2007). ones for a long stretch of time. The researchers Eurasian fossils dating to the start of the 9. Brown, P. et al. Nature 431, 1055–1061 (2004). propose that the first hominins that left Africa human race could help to reveal which story 10. van den Bergh, G. D. et al. Nature 534, 245–248 1.8 million years ago were the eventual source — or combination — is correct. China is now (2016).

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