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In China, paleontologists have announced a very important discovery of human fossils and artifacts. They have uncovered a large number of fossils of early relatives of modern humans in a cave. The remains are up to an amazing 300,000 years old. They have also found artifacts made by the hominids. This is allowing experts to have an unprecedented insight into human evolution and development in East Asia.
The fossils were unearthed by a team of leading Chinese experts during 15 years of excavations of a collapsed cave known as Hualongdong. The site is located in Dongzhi County, which is in Anhui Province. This cave was found when some researchers stumbled upon some fossils of an early mammal in 2004. A huge boulder at the entrance made excavation difficult but it may also have preserved the site over the millennia.
Features of the excavation site. ( Cai Yanjun, Yu Shuwen )
Finding the Fossils and Pleistocene Skull
ChinaPlus quotes Wu Xiujie, a member of the archaeological team, as saying, “in the cave, we not only have discovered a large number of ancient human fossils, but also a variety of evidence of ancient human behavior .”
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The experts found 30 fossils in total over the course of the dig. It is believed that these fragments date back to between 250,000 and 300,000 years ago. In 2006, the paleontologists uncovered a human bone and teeth, but many more fossils have been found since then. The remains are believed to be from 16 individuals. It appears that early humans inhabited the cave for a considerable period of time.
According to the Xinhua news agency, the finds in the cave also include the remains of ‘a human skull of the Middle Pleistocene period’. This is from at least a quarter of a million years ago and may even be older. The skull is very well-preserved and Xinhua reports that it has ‘a largely complete facial structure, most of the brain cranium, and one side of the mandible’.
Different types of ancient human fossils in contrast: A. Human fossil from Hualongdong Cave B. Peking Man fossil from Zhoukoudian site C. Fossil of Nanjing Homo erectus D. Human fossil found at the Dali Man site E. Human fossil found at Jinniushan Site F. Fossil of Maba Man. (Wu Xiujie )
The skull appeared to have belonged to a juvenile male and shows features that are similar to other types of humans found throughout the Pleistocene period in East Asia. A study of the skull would indicate that it had characteristics that prefigured the development of modern Asians .
To find a Pleistocene skull is remarkable and its well-preserved nature may even allow researchers to possibly reconstruct the facial appearance of the early human.
Skull fragments from the Chinese cave are put together to form a mostly complete Pleistocene skull. ( Wu Xiujie )
Evidence for Human Evolution in East Asia
The find is of international significance because. according to ChinaPlus, the ‘fossil evidence for human evolution in East Asia during the Pleistocene was often fragmentary and scattered’. This made it difficult for researchers to understand human evolution in the region during the era, unlike in areas such as Africa.
However, the finds in Hualongdong are allowing experts to better understand human evolution in East Asia . They have now established that there was a great deal of continuity in the evolution of humans in the period from 200,000 to over 300,000 years ago in East Asia. This was suspected for a long time but the find in the collapsed cave is confirming the theory.
Insight into Life in the Pleistocene
Also found at the site were some 100 stone objects that had been crafted by the people who once made the cave their home and these are mainly rudimentary tools, such as scrapers.
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The Chinese cave fossils and artifacts. ( Chinanews.com)
The dig also revealed the remains of up to 40 mammals. The artifacts and the animal remains are helping paleontologists to better understand the environment in which these early humans lived and how they managed to survive.
Those who have worked on the site believe that there are many exciting discoveries yet to be made. At present it is expected that the cave will be rated as a protected site to ensure it is preserved for further study. The findings from the research have recently been published in an American academic journal, the Proceedings of the National Academy of Sciences of the United States of America (PNAS).
300,000 year old skull reveals variation and continuity of early humans in Asia
A team of scientists led by LIU Wu and WU Xiujie from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) of the Chinese Academy of Sciences reported a new Middle Pleistocene human skull ever found in southeastern China, revealing the variation and continuity in early Asian humans. Their findings were published on April 30 in Proceedings of the National Academy of Sciences (PNAS).
Excavations in Middle Pleistocene cave deposits in southeastern China yielded a largely complete skull that exhibits morphological similarities to other East Asian Middle and Late Pleistocene archaic human remains, but also foreshadows later modern human forms.
Fossil evidence for human evolution in East Asia during the Pleistocene is often fragmentary and scattered, which makes evaluating the pattern of archaic human evolution and modern human emergence in the region complicated.
WU Xiujie and colleagues reported the recent discovery of most of a skull and associated remains dating to around 300,000 years ago in Hualong Cave (Hualongdong). The features of the Hualongdong fossils complement those of other East Asian remains in indicating a continuity of form through the Middle Pleistocene and into the Late Pleistocene.
In particular, the skull features a low and wide braincase with a projecting brow but a less prominent midface, as well as an incipient chin. The teeth are simple in form, contrasting with other archaic East Asian fossils, and its third molar is either reduced in size or absent.
According to the authors, the remains not only add to the expected variation of these Middle Pleistocene humans, recombining features present in other individuals from the same time period, but also foreshadow developments in modern humans, providing evidence for regional continuity.
Remains of Child From Mystery Human Species That Lived 300,000 Years Ago Discovered
Researchers have unearthed the remains of a young Homo naledi, the most recently discovered ancient human relative. The authors of the research article, published in PLOS ONE, say the find could improve our understanding of this mysterious species.
The findings belonging to an juvenile individual named DH7 are among the few pre-adult skeletal remains on the fossil record. The majority of those found are from adults, whose bones are tougher, less porous and more likely to survive the hundreds of thousands of years.
DH7's young age offers anthropologists a chance to study the development of young hominids. Bones from this particular individual were among a large collection found in the Dinaledi Chamber of the Rising Star Cave System in South Africa, dating to a period between 335,000 and 226,000 years ago, during the Late Middle Pleistocene.
Though the remains of DH7 are incomplete, they offer clues to how old the individual was when they died. DH7 displays a mix of maturity patterns&mdashspecifically, well-developed but unfused bones&mdashindicating the H. Naledi was a late juvenile. However, the exact age is harder to determine because the speed of maturation in the species is unknown.
If H. Naledi matured at the speed of earlier, more ape-like hominids, the maturity patterns suggest it is between 8 and 11 years old. But, the study's authors say, it is possible that it matured at a slower pace, similar to Homo sapiens and Neanderthals&mdashboth of which were roaming the planet 300,000 years ago. If that was the case, DH7 may have been as old as 15.
"There are very few pre-adult skeletons in the fossil record," Debra Bolter, Professor of Anthropology at Modesto Junior College in California, and Honorary Researcher, Evolutionary Studies Institute, University of Witwatersrand, South Africa, told Newsweek.
"The ability to associate the remains of an older juvenile H. naledi is a major break-through in paleoanthropology. Immature remains are critical for understanding how an extinct species matured," said Bolter.
"The pattern of skeletal maturation seen in the elements assigned to DH7 could be observed in humans and in other apes," Louise Humphrey, a researcher at the Natural History Museum in London, told Newsweek. "It does not exclude a slower, more human-like pace of development or an intermediate pace or a unique pace and pattern of development in Homo naledi, with subtle differences from both humans and other living apes."
She added: "Further research to establish an age at death from the dentition would provide greater insights into the timing of development in this species."
H. naledi is the most recently discovered member of the hominid family. The species, described in 2015, displays a mix of primitive and human-like features, with its hands, wrist and feet appearing more like Homo sapiens or Neanderthal, while its upper body and small brain size appear more primitive.
The bones found in the Rising Star Cave System date H. naledi to a period between 335,000 and 226,000 years ago, overlapping the arrival of modern humans. Neanderthals evolved approximately 400,000 years ago in Eurasia, while the first H. sapiens, or modern humans, emerged in Africa approximately 300,000 years ago.
These fossils place H. naledi relatively late on the evolutionary timeline, a fact that has confused paleontologists given their more primative characteristics akin to australopiths like the Australopithecus afarensi "Lucy." When they were first discovered, many expected the bones to be older and some academics have debated the use of the word "Homo" in their name.
Bolter is hopeful that future research could produce a more accurate reading on DH7's age, thus revealing whether the species was more ape-like or human-like in its maturation. Tooth microhistology, for example, may be used to calculate an age-at-death for immature remains from daily and weekly enamel secretions in a similar way to tree-ring dating.
"H. naledi stands out among other extinct hominin species because of its mixture of primitive australopith features, like a small brain and outwardly flared hip bones, in combination with human-like hands, feet and dentition, plus distinctive traits like heavily muscled thumbs," said Bolter.
"Future research will help us answer the developmental mysteries surrounding H. naledi, whether the pace of growing up and the pattern of dental-skeletal maturity are more primitive, are human-like, or some unique combination of the two."
Mystery Population of Humans Were Living in Europe 210,000 Years Ago, Long Before Major Migration out of Africa
A human skull discovered in a Greek cave has been found to date back 210,000 years&mdashover 150,000 years before humans are believed to have first settled in Europe. The discovery suggests Homo Sapiens migrated out of Africa on multiple occasions before conquering the world.
The very first modern humans evolved in Africa around 350,000 years ago. They were preceded by a number of other Homo species&mdashincluding Homo Erectus and Neanderthals, both of which had left Africa hundreds of thousands of years earlier.
There are known to have been many waves of migration out of Africa over our history, starting from around 270,000 years ago. However, the most significant and sustained move into Asia, Europe and the rest of the world is thought to have started between 80,000 and 60,000 years ago.
In a study published by Nature, a team of researchers showed evidence that modern humans had reached Europe far, far earlier.
They analyzed two skulls that were found in the Apidima Cave cave in Greece in the late 1970s. Neither skull had ever been scientifically analyzed as they were fragmented and there was little context about their discovery.
One skull, known as Apidima 2, appeared to be a Neanderthal from its morphological features. CT scans confirmed this. Dating revealed it lived about 170,000 years ago.
Apidima 1, however, posed more of a problem. The team only had the back of the skull and it had both primitive and modern features. However, they were still able to create a 3D reconstruction of the skull&mdashto find it belonged to the species Homo Sapiens.
The discovery suggests there were at least two human species living at the site during the Middle Pleistocene&mdasha group of modern humans followed by a population of Neanderthals. "Our findings support multiple dispersals of early modern humans out of Africa, and highlight the complex demographic processes that characterized Pleistocene human evolution and modern human presence in southeast Europe," the scientists concluded.
Modern human migration out of Africa is a complicated picture&mdashand one that is becoming more complicated the bigger the fossil record gets. In 2017, scientists announced the discovery of Homo sapiens fossils in Morocco that dated back 300,000 years. This is far from the 'cradle of humanity' where it was thought our species first evolved, in southern and East Africa.
In an article about the latest discovery, Eric Delson, a paleoanthropologist not involved in the study, said the findings provide an insight into the "complex history of our species and our close relatives as these populations dispersed out of Africa&mdashfrom the early, unsuccessful dispersals to the migrations that eventually succeeded."
He said the Apidima fossils raise questions about what happened to this early Homo sapiens population that likely existed alongside Neanderthals. "Was it part of a population that was unable to compete successfully with Neanderthals, especially in the unstable climate of that time? Perhaps one or more times, the two species replaced each other as the main hominin group present in this region."
Eventually, modern humans replaced Neanderthals, with the latter going extinct about 40,000 years ago. "This evidence from Apidima, along with other discoveries, demonstrates that, on more than one occasion, modern humans kept pushing north and westwards from Africa and the Levant into Europe," Delson wrote. "Rather than a single exit of hominins from Africa to populate Eurasia, there must have been several dispersals, some of which did not result in permanent occupations by these hominins and their descendants."
Tidying Up the Muddle
Recent paleogenomics work has imposed some order on the muddle. By comparing DNA differences between lineages, researchers have estimated the timing of the evolutionary splits between modern humans, Neanderthals and Denisovans, which took place during the Mid-Pleistocene. Using this molecular clock dating approach, a 2017 Science paper reported that Homo sapiens diverged from the others around 520,000 to 630,000 years ago, and then the sister species Neanderthals and Denisovans split 390,000 to 440,000 years ago.
That timeline agrees with a 2016 genomic analysis of the
430,000 year old Sima fossils — the oldest human ancient DNA yet recovered. The sequences suggest the individuals belonged to the Neanderthal lineage after it split from Denisovans. It’s safe to classify the Sima hominins as Neanderthal ancestors.
But getting human DNA this old was a near miracle . The molecules survived because the cave keeps a cool 50 degrees Fahrenheit they were recovered because researchers put in extraordinary effort. The scientists salvaged just 0.1 percent of the Sima genome from one bone and tooth.
Ancient DNA won’t be found in most Mid-Pleistocene fossils, especially those from hot, tropical climates, harsh on biomolecules. Still, the dates we do have — divergences between H. sapiens , Neanderthals and Denisovans — provide a strong foundation for making sense of the muddle in the middle.
Tracing a DNA Trail
The skeleton, dubbed "Naia" (an ancient Greek name related to water nymphs) by her discoverers, belonged to a teenage girl who fell more than 100 feet to her death nearly a half mile inside an elaborate network of karst caves that were largely dry at the end of the Pleistocene. Divers who found Naia in the cave on Mexico's Yucatán Peninsula named her watery grave Hoyo Negro ("Black Hole" in Spanish).
Chatters described Naia's face as narrow with wide-set eyes and a low, prominent forehead a low, flat nose and outward-projecting teeth—"about the opposite of what Native Americans look like today." To see those features coupled with genetic markers indicating a common lineage with Native Americans is highly significant.
"This is the first time that we have genetic data from a skeleton that exhibits these distinctive skull and facial features," said Deborah Bolnick, an anthropological geneticist at the University of Texas at Austin and one of the study's co-authors.
The find from Hoyo Negro comes on the heels of the recent genomic sequencing of the 12,600-year-old remains of an infant found at the Anzick Clovis site in Montana, which also revealed a shared ancestry with Native Americans.
Genetic analyses of modern Native Americans indicate they descend from a founding population that originated in Asia. They were isolated from other population groups for several thousand years somewhere in or near the region known as Beringia, a broad swath of land that reached from Siberia to Alaska during the last glacial maximum.
It was there that this founding population developed its unique genetic markers. But until the Anzick discovery, little genetic data had been available from Paleoamerican skeletal specimens, leaving their relationship to Native Americans poorly understood.
The genetic data from the Anzick find is superior to that of Hoyo Negro's because it was derived from mitochondrial and nuclear DNA, providing a much more comprehensive lineage history than mitochondrial DNA alone, which traces only maternal lineages. But the downside of Anzick is that the specimen itself is much less complete: just four bones and the braincase portion of a cranium.
Michael Waters, director of the Center for the Study of First Americans at Texas A&M University in College Station, said the Anzick and Hoyo Negro finds complement one another.
"Now we've got two specimens, both from a common ancestor that came from Asia," he said. "Like Hoyo Negro, the Anzick genome shows that Paleoamericans are genetically related to native peoples, so the latter cannot be a replacement population. Their differences have to be a result of evolutionary change. What drove that change, we don't know."
Materials and Methods
The human paleontological analysis is based on the morphological and morphometric analysis of the original HLD human fossils (SI Appendix, Table S7), using standard osteometric variables (52, 53) (SI Appendix, Tables S9 and S11). The original observations not outlined here are included in SI Appendix, sections 6–8 and Tables S9–S13. The analyses of the site structure and the lithic assemblage are included in SI Appendix, section 1. All remains referred to in this study are available in the Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing. The comparative HLD faunal representation is included in SI Appendix, Table S1. The U-series dating methods are included in SI Appendix, section 2 and the detailed results included in SI Appendix, sections 5 and 6.
Here were two clearly distinct species, separated by up to 700,000 years of evolution, yet the remnants of their sexual proclivities are captured in the DNA of the majority of people alive today. What’s more, it soon emerged that our ancestors weren’t only getting it on with Neanderthals.
Just as Pääbo was finishing sequencing the Neanderthal genome, a parcel landed on his desk. It contained a tiny fragment of a finger bone from the Altai mountains in Siberia. The piece was 30,000 to 50,000 years old and was thought to be from another Neanderthal. His team was in for a big surprise. The DNA analysis revealed an entirely new group of archaic humans, now dubbed the Denisovans, which split from a common ancestor with Neanderthals some 500,000 years ago.
Once again, comparisons with modern human genomes showed that the two interbred. Genetic studies reveal this to have happened in Eurasia. They also show that Denisovans ranged from Siberia to South-East Asia, and that at least one of their genes helps modern Tibetans to live at high altitude. The idea that our ancestors hybridised with other hominins was once dismissed. Now it was starting to look as though they would mate with anything vaguely human.
Denisovans are nearly ghosts: we have that one finger bone and a few molars as a physical testament to their existence, but no more. Then in 2016, a true ghost emerged from the genomes of 44 individuals who lived in the Middle East between 14,000 and 3400 years ago. Their DNA held genetic markers indicative of a distinct group of ancient H. sapiens based in the region more than 45,000 years ago. The members of this population are now known as Basal Eurasians, and they present a conundrum. Their DNA, which is still found in modern Europeans, shows none of the telltale signs of interbreeding with Neanderthals. This came as a surprise because ancestral humans mated with Neanderthals very soon after leaving Africa 60,000 years ago in the migration that was to give rise to all people of non-African heritage alive today.
The most-likely explanation is that soon after that migration, a group of humans became isolated while the rest bumped into and mated with Neanderthals. “If you like, it’s a third branch,” says Chris Stringer of the Natural History Museum in London – a branch that is distinct from the humans who had stayed in Africa and the ones who were gradually spreading out across Eurasia, Australia and eventually into the Americas. Because there are no known fossils belonging to Basal Eurasians, it is impossible – for now – to say why they were isolated. Perhaps it was just down to where they settled, far from other groups. Or maybe they developed cultural differences. Either way, these ghosts didn’t mix with the rest of humanity for millennia – long enough to evolve distinct genetic markers.
The Basal Eurasian research showed that rich insights into human history can be gleaned from DNA alone. But, like the Neanderthal and Denisovan studies, it relied on obtaining DNA from fossils, something that remains a huge challenge. DNA degrades with time, so it takes special fossils and special skills to extract it from very old bones, particularly ones that have spent thousands of years buried in hot climates. However, in the mid-2000s, geneticists were already discussing another approach. Among others, Jeffrey Wall, now at the University of California, Los Angeles, and Vincent Plagnol, now at University College London, suggested that it might be possible to spot signs of extinct populations in the DNA of modern humans, simply by using clever statistics.
The broad idea is that all DNA is subject to random mutations that accumulate over millennia and are passed down from generation to generation. By looking at mutation patterns in modern populations, it is possible to spot segments that don’t match the usual H. sapiens pattern. These are presumed to come from populations that evolved separately from our own species for thousands of years before mating with humans. Statistical modelling can then produce estimates of when the two groups mated and how different the other population was from our ancestors.
The past few years have seen several attempts to refine these methods and apply them to Africa – the birthplace of our species and the setting for a slice of our history that we know very little about. This new research has revealed the presence of at least one ancient ghost on the continent.
Prehistoric Polar Bear vs Cave Bear
these are my two favorite bears, shame they are both extinct. or is it that the Prehisotric Polar Bear is the same as the current but a smaller version.
anyway, who would win a fight?
Nov 01, 2009 #2 2009-11-01T16:01
Nov 01, 2009 #3 2009-11-01T18:07
Nov 01, 2009 #4 2009-11-01T20:17
Nov 01, 2009 #5 2009-11-01T20:22
If we pick up the largest for both, then the fight would be close.
Also keep in mind that prehistoric polar bears were more brown bear like than the modern version.
Nov 01, 2009 #6 2009-11-01T23:44
Nov 02, 2009 #7 2009-11-02T01:06
Nov 02, 2009 #8 2009-11-02T08:22
so it was more brown bear in color? did it also had the huge claws and canines that came with the brown bear species i currently see right now?
also, where has my FAST REPLY button went? i dont see it, i always have to go advance or reply from someone's post
Nov 03, 2009 #9 2009-11-03T04:39
Yes, they were originally more brown bear evolving to Polar Bear. More to come on both bears (I'm pretty sure you will like).
Nov 03, 2009 #10 2009-11-03T14:32
Evolution of Polar BearsThe fossil transitions leading to our knowledge of development of the Polar Bear species are very well documented. Bear fossils change through time i.e., as higher levels of sediments and sedimentary rocks are examined, more recent fossils are found. For most of the transitions from one species to another, there is a well characterized series of transitional specimens leading right across the species "boundaries" Kurten (1976). Somewhere during the mid-Pleistocene period (roughly 100,000 to 250,000 years ago), a number of brown (same as grizzly) bears (Ursos arctos) probably became isolated by glaciers. many probably perished on the ice however, they apparently did not all disappear. Some survived due to the fact that "organisms vary" (Steve Gould's terminology and logic is used here), that is, every litter of grizzly's has a variation in coat thickness, coat color etc. which imparted a slight evolutionary advantage to some indivials of each litter. These successful individuals underwent an apparent rapid (rapid, probably because of the small population, and extreme selection pressure) series of evolutionary changes in order to survive (note they were not necessarily "better" in any absolute sense, or on any absolute "bear" scale of perfection - they were simply more in keeping with their new environment than their siblings). Today, polar bears are adapted to their harsh northern environment.
Hecht (in Chaline, 1983) describes polar bear evolution: the first "polar bear", Ursus maritimus tyrannus, was essentially a brown bear subspecies, with brown bear dimensions and brown bear teeth. Over the next 20,000 years, body size reduced and the skull elongated. As late as 10,000 years ago, polar bears still had a high frequency of brown-bear-type molars. Only recently have they developed polar-bear-type teeth.
Kurten (1976) describes bear transitions: "From the early Ursus minimus of 5 million years ago to the late Pleistocene cave bear, there is a perfectly complete evolutionary sequence without any real gaps. The transition is slow and gradual throughout, and it is quite difficult to say where one species ends and the next begins. Where should we draw the boundary between U. minimus and U. etruscus, or between U. savini and U. spelaeus? The history of the cave bear becomes a demonstration of evolution, not as a hypothesis or theory but as a simple fact of record." He adds, "In this respect the cave bear's history is far from unique."
Ursus minimus (Pliocene) First little bear, with very bearlike molars, but still had the first premolars and slender canines. Shows gradual tooth changes and increase in body size as the ice age approached. Gave rise to the modern black bears (U. americanus & U. thibetanus), which haven't changed much since the Pliocene, and also smoothly evolved to the next species, U. etruscus: Ursus etruscus (late Pliocene) A larger bear, similar to our brown bear but with more primitive dentition. Molars big & square. First premolars small, and got smaller over time. Canines stouter. In Europe, gradually evolved into:
Ursus savini (late Pleistocene, 1 Ma) Very similar to the brown bear. Some individuals didn't have the first premolars at all, while others had little vestigial premolars. Tendency toward domed forehead. Slowly split into a European population and an Asian population.
U. spelaeus (late Pleistocene) The recently extinct giant cave bear, with a highly domed forehead. Clearly derived from the European population of U. savini, in a smooth transition. The species boundary is arbitrarily set at about 300,000 years ago.
U. arctos (late Pleistocene) The brown ("grizzly") bear, clearly derived from the Asian population of U. savini about 800,000 years ago.. Spread into the Europe, & to the New World.
This hominid may have shared Earth with humans
The skull of this adult male hominid was unearthed in an underground cave. Members of his Homo naledi species may have roamed what is now South Africa as recently as 236,000 years ago, claim the authors of a new study.
A humanlike species with some fairly ancient skeletal traits appears to have lived in southern Africa close to 300,000 years ago, a new study concludes. If true, this species would have been around at about the time humans emerged. This raises the surprising possibility that both our species and this other hominid might have coexisted.
The newly studied fossils come from a species that has been dubbed Homo naledi. Two years ago, this species achieved worldwide acclaim as perhaps being a pivotal player in the evolution of our genus, Homo. That earlier cache of H. naledi bones had appeared to be quite old. Estimates had put them at between 900,000 and 1.8 million years old.
Explainer: How a fossil forms
Both those old fossils and the newfound ones come from the same Rising Star cave network in South Africa. They were just found in different underground chambers. The newer bones somehow ended up in the network’s Dinaledi Chamber some 236,000 to 335,000 years ago. That’s the conclusion of an international research team. Lee Berger headed the group. He’s a paleoanthropologist in South Africa at the University of the Witwatersrand in Johannesburg. Geoscientist Paul Dirks of James Cook University in Townsville, Australia, directed the team’s dating effort.
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Their group shared its findings in a trio of papers published May 9 in eLife.
As interesting as their new, younger age for H. naledi is, it does not solve two important puzzles: When did this species first emerge and when did it die out?
What the new fossils show
Researchers used two methods to try and date the new fossils. For instance, they measured the levels of uranium and other radioactive elements in three H. naledi teeth. They also assessed damage to the teeth caused by those elements over time. In addition, the scientists used the radioactive elements to date a thin sheet of rock that had been deposited just above the fossils by water flowing through the cave.
BODY PLAN A partial Homo naledi skeleton unearthed in South Africa is about as complete as Lucy’s famous partial skeleton. Lucy, an Australopithecus afarensis, lived in East Africa about 3.2 million years ago. H. naledi lived perhaps 300,000 years ago, scientists say, although this new partial skeleton remains undated. Wits Univ., J. Hawks
A second new paper describes 131 newly discovered H. naledi fossils found in a second underground cave, dubbed Lesedi Chamber. It’s within the Rising Star cave network. This work, by Berger’s group, was led by John Hawks. He’s a paleoanthropologist at the University of Wisconsin–Madison.
The bones come from at least three individuals. They include some from an adult male. Although all of his bones are not there, the share that’s present is comparable in completeness to those of Lucy. She’s a 3.2-million-year-old human ancestor found in East Africa. She belonged to the species Australopithecus afarensis (Aw-STAHL-oh-pith-ih-kus AF-ur-REN-sis). In each case, only about 40 percent of each skeleton has turned up.
Berger and Hawk’s team named the newfound partial skeleton of the male “Neo.” It means gift in Sesotho. That’s a language spoken in South Africa.
No signs indicate that predatory animals or streams carried H. naledi corpses into the caves. As such, Berger’s group says the Lesedi Chamber discoveries support their controversial suggestion that H. naledi deliberately placed bodies of its dead into the cave’s chambers.
Remains from both underground chambers display the same distinctive skeletal features. These include relatively small, orange-sized brains and curved fingers like those of a Homo species that lived around 2 million years ago. In addition, the skeletal remains have wrists, hands, legs, feet and body sizes comparable to those of Neandertals and humans. Taken together, the researchers argue, the newfound bones all belong to H. naledi, not some other Homo species.
A narrow path took cave explorers to the Lesedi Chamber in this cave system. Homo naledi fossils found here came from at least three individuals. These included an adult male, named Neo. A neighboring passageway connects to the Dinaledi Chamber, where H. naledi fossils were first unearthed a few years earlier. MARINA ELLIOTT/WITS UNIV.
When did H. naledi evolve?
Despite the relatively young age of the new fossils, their features have ancient-looking characteristics. Indeed, Berger and his colleagues propose in a third new paper, these traits suggest H. naledi originated near the root of the Homo genus. That likely would have been 2 million years ago or more. This would make the South African species a possible ancestor or close relative of H. erectus, which dates to around that time. The oldest Homo fossils date to 2.8 million years ago in East Africa.
But there’s also another possibility, Berger’s group says. Perhaps H. naledi evolved just a few hundred thousand years ago. Then it would be most closely related to early H. sapiens or other Homo species that may have inhabited southern Africa back then. A relatively late origin for H. naledi would suggest it evolved from larger-brained ancestors, the researchers say. That would be unusual: Scientists had argued for a long while that the hominid brain only became larger as Homo species evolved.
But that proposed scenario has some parallels to Indonesia’s Homo floresiensis, better known as “hobbits.” These short hominids, whose remains date to between about 100,000 and 60,000 years ago, had chimp-sized brains. And, like H. naledi, they had some skull features resembling early Homo species. Hobbits either evolved smaller brains or retained small brains after splitting from a much older Homo species in Africa.
It’s unclear how H. naledi might have survived in Africa alongside larger-brained Homo species, perhaps even early members of our own. Occasional interbreeding in southern Africa — similar to what occurred later in Eurasia among H. sapiens, Neandertals and Denisovans — might have benefited H. naledi, Berger’s team says.
DNA analysis could help clarify H. naledi’s evolutionary status. So far, researchers have yet to test the newfound fossils for DNA or to try to generate firm age estimates for them.
“My intuition is that Homo naledi points to a diversity of African Homo species that once lived south of the equator,” Hawks says. It’s unlikely Homo evolution in Africa proceeded in a straight line here, from one species to the next, he adds.
What other scientists think
Some paleoanthropologists who have just learned of the new reports interpret the new findings differently.
An “astonishingly young” age for a Homo species with several ancient-looking features suggests H. naledi was the sole survivor of a group of much older, closely related species, argues Chris Stringer. He works in England at the Natural History Museum in London. H. naledi probably made some of the many stone tools found at southern African sites, he adds. A number of these sites hosted no hominid bones but date to around 300,000 years ago.
Despite Berger’s claims, Stringer doubts this species disposed of its dead deep within a pitch-black, hard-to-navigate cave system. Keep in mind, he notes, this creature had a brain size close to that of a gorilla. Moreover, the controlled use of fire for torches would likely also have been needed.
Berger’s team plans to excavate near openings to the Rising Star cave system. The researchers will be looking for any signs of stone tools and use of fire.
However complex H. naledi’s behavior may have been, ancient aspects of its anatomy rule it out as a direct ancestor of H. sapiens, says Donald Johanson. A codiscoverer of Lucy, Johanson now works at Arizona State University in Tempe. Our species originated in East Africa, he notes. Researchers generally place that evolutionary turning point at between 200,000 and 300,000 years ago. Says Johanson: “The Rising Star Cave hominids, much like the hobbits, evolved in isolation and have no relevance to the origins of humankind.”
Yet even a largely isolated H. naledi population might have interbred now and again with other Homo species in southern Africa, says Fred Smith. He works at Illinois State University in Normal. The relatively recent Homo evolution “is far more complex than has generally been thought,” he says.
On that, Berger and his colleagues agree.
anatomy (adj. anatomical) The study of the organs and tissues of animals. Or the characterization of the body or parts of the body on the basis of its structure and tissues. Scientists who work in this field are known as anatomists.
Australopithecus An extinct genus of hominids that lived in East Africa from about 4 million to 2 million years ago.
behavior The way something, often a person or other organism, acts towards others, or conducts itself.
colleague Someone who works with another a co-worker or team member.
corpse The body of a dead human.
Denisovans An ancient humanlike population whose existence is known only from a few fossils discovered in a cave in Siberia.
diversity (in biology) A range of different life forms.
DNA (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions.
element (in chemistry) Each of more than one hundred substances for which the smallest unit of each is a single atom. Examples include hydrogen, oxygen, carbon, lithium and uranium.
equator An imaginary line around Earth that divides Earth into the Northern and Southern Hemispheres.
Eurasia That part of the globe covered by Europe and Asia.
evolutionary An adjective that refers to changes that occur within a species over time as it adapts to its environment.
evolve (noun evolution) To change gradually over generations, or a long period of time. In living organisms, the evolution usually involves random changes to genes that will then be passed along to an individual’s offspring. These can lead to new traits, such as altered coloration, new susceptibility to disease or protection from it, or different shaped features (such as legs, antennae, toes or internal organs
fossil Any preserved remains or traces of ancient life. There are many different types of fossils: The bones and other body parts of dinosaurs are called “body fossils.” Things like footprints are called “trace fossils.” Even specimens of dinosaur poop are fossils. The process of forming fossils is called fossilization.
genus (plural: genera) A group of closely related species. For example, the genus Canis — which is Latin for “dog” — includes all domestic breeds of dog and their closest wild relatives, including wolves, coyotes, jackals and dingoes.
hobbit Nickname given to Homo floresiensis, a small-bodied hominid species whose fossils have turned up only on the island of Flores, in Indonesia. The small-brained folk lived in isolation there until at least 18,000 years ago.
hominid A primate of an animal family that includes humans and their ancient relatives known only from fossils.
Homo A genus of species that includes modern humans (Homo sapiens). All had large brains and used tools. This genus is believed to have first evolved in Africa and over time evolved and radiated throughout the rest of the world.
Homo erectus An extinct species of hominid that lived in Africa and Eurasia between about 1.9 million and 70,000 years ago.
Homonaledi An extinct human relative of unknown age. The bones of this species were found in a cave system in South Africa, beginning in 2013.
Neandertal A species (Homo neanderthalensis) that lived in Europe and parts of Asia from about 200,000 years ago to roughly 28,000 years ago.
network A group of interconnected people or things.
paleoanthropologist A scientist who studies ancient humans and hominid biology, also the behavior and evolution of hominids evolved. This field is based on the analysis of fossils, remnants, artifacts or markings created or used by hominids.
population (in biology) A group of individuals from the same species that lives in the same area.
radioactive An adjective that describes unstable elements, such as certain forms (isotopes) of uranium and plutonium. Such elements are said to be unstable because their nucleus sheds energy that is carried away by photons and/or and often one or more subatomic particles.
scenario An imagined situation of how events or conditions might play out.
skull The skeleton of a person’s or animal’s head.
species A group of similar organisms capable of producing offspring that can survive and reproduce.
trait A characteristic feature of something. (in genetics) A quality or characteristic that can be inherited.
uranium The heaviest naturally occurring element known. It’s called element 92, which refers to the number of protons in its nucleus. Uranium atoms are radioactive, which means they decay into different atomic nuclei.
Journal: P.H.G.M. Dirks et al. The age of Homo naledi and associated sediments in the Rising Star Cave, South Africa. eLife . Published online May 9, 2017. doi: 10.7554/eLife.24231.002.
Journal: J. Hawks et al. New fossil remains of Homo naledi from the Lesedi Chamber, South Africa. eLife . Published online May 9, 2017. doi: 10.7554/eLife.24232.002.
Journal: L.R. Berger et al. Homo naledi and Pleistocene hominin evolution in subequatorial Africa. eLife . Published online May 9, 2017. doi: 10.7554/eLife.24234.001.
About Bruce Bower
Bruce Bower has written about the behavioral sciences for Science News since 1984. He writes about psychology, anthropology, archaeology and mental health issues.
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