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Did the loss of endogenous ascorbate propel the evolution of Anthropoidea and Homo sapiens?
Abstract
It has been previously theorized that free-radical reactions led to the first life on Earth, and their ability to randomly cause mutations may have subsequently led to the evolution of life. One of the most efficient free-radical quenchers is ascorbate, which most animals manufacture endogenously. It is generally believed that, approximately 25 million years ago, an ancestor of the Anthropoidea primate suborder, which includes Homo sapiens, lost the ability to produce its own ascorbate, and all descending species inherited this genetic defect. The first of three hypotheses presented here proposes that a genetic defect, caused by either free radicals or a virus, deleted the gene needed by Anthropoidea to manufacture endogenous ascorbate. The second hypothesis proposes that this evolutionary accident permitted large numbers of free radicals to remain metabolically unquenched. The third hypothesis proposes that the presence of these excessive free radicals increased the likelihood of free-radical-induced genetic mutations, and these mutations propelled the evolution of Anthropoidea, leading to Homo sapiens.
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Complete skull from Dmanisi- 1.78-million years old
"Scientists have unearthed a complete skull from Dmanisi, Republic of Georgia, which combines traits found in early Homo skulls from Africa. The 1.78-million-year-old find has a large brow typical of Homo erectus, the small brain of Homo habilis, and large teeth similar to Homo rudolfensis – all recognized as separate species in East Africa."
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Stone Tools Point to Mysterious Neighbor of Flores ‘Hobbit’
The sharp-edged stones were made at least 60,000 years before modern humans reached the island of Sulawesi—but who made them?
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Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada
Abstract
The timing of the first entry of humans into North America is still hotly debated within the scientific community. Excavations conducted at Bluefish Caves (Yukon Territory) from 1977 to 1987 yielded a series of radiocarbon dates that led archaeologists to propose that the initial dispersal of human groups into Eastern Beringia (Alaska and the Yukon Territory) occurred during the Last Glacial Maximum (LGM). This hypothesis proved highly controversial in the absence of other sites of similar age and concerns about the stratigraphy and anthropogenic signature of the bone assemblages that yielded the dates. The weight of the available archaeological evidence suggests that the first peopling of North America occurred ca. 14,000 cal BP (calibrated years Before Present), i.e., well after the LGM. Here, we report new AMS radiocarbon dates obtained on cut-marked bone samples identified during a comprehensive taphonomic analysis of the Bluefish Caves fauna. Our results demonstrate that humans occupied the site as early as 24,000 cal BP (19,650 ± 130 14C BP). In addition to proving that Bluefish Caves is the oldest known archaeological site in North America, the results offer archaeological support for the “Beringian standstill hypothesis”, which proposes that a genetically isolated human population persisted in Beringia during the LGM and dispersed from there to North and South America during the post-LGM period.
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The Hobbit: A Lineage More Ancient Than Once Thought?
But where, exactly, it came from has been a mystery. There were suggestions that it was simply a modern human subjected to dwarfism, but characteristics in its skeleton made it seem more like a Homo erectus relative.
But new research published in the Journal of Human Evolution suggests it may have branched off from the human lineage even earlier than that. Unlike previous studies, this study by researchers at the Australian National University focused on the entire skeleton. While the skull and lower jaw showed characteristics more in line with Homo erectus, the rest of the skeleton had characteristics not displayed at all by the Homo erectus that had more archaic features.
The researchers instead place the Homo floresiensis, often called the “Hobbit” for its short stature, as a cousin of the Homo habilis species. Homo habilis was one of the earliest modern human ancestors, and may, indeed, have been one of the missing links between chimps and humans. H. habilis maintained ape-like features even as its brain capacity increased and its jaw inched toward what we would consider human.
This raises another issue: It’s not known if Homo habilis was an early human or a late Australopithecus relative. The Australopithecus lineage were bipedal great apes that likely are a human ancestor, but still too primitive to be considered anything other than an extinct ape.
The Homo ergaster, a later human fossil between H. habilis and H. erectus may instead be the first “human” species, meaning that, if you’re of the school of thought that H. habilis is too primitive to be considered human, the Hobbit likely was, too.
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50,000 year old Siberian bones may be the ‘oldest Homo sapiens' outside Africa and Middle East
If the discovery in Buryatia is verified as being Homo sapiens, it will alter scientific thinking about the arrival of man in Siberia.
The discovery was made in the Tunkinskaya Valley by Irkutsk scientists in 2016.
Older bones date to 50,000 years ago, younger ones at the same site to around 30,000 years ago, and they were found alongside tools and animal bones indicating these ancients were proficient hunters of cave lions, bison, horses and deer.
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2018: Hominid fossils in China from 2.1 million years ago.
Hominin occupation of the Chinese Loess Plateau since about 2.1 million years ago, Zhu et. al. 2018
Considerable attention has been paid to dating the earliest appearance of hominids outside Africa. The earliest skeletal and artifactual evidence for the genus Homo in Asia currently comes from Dmanisi, Georgia, and is dated to approximately 1.77–1.85 million years ago (Ma)1. Two incisors that may belong to Homo erectus come from Yuanmou, south China, and are dated to 1.7Ma2; the next-oldest evidence is an H. erectus cranium from Lantian (Gongwangling)—which has recently been dated to 1.63Ma3—and the earliest hominin fossils from the Sangiran dome in Java, which are dated to about 1.5–1.6Ma4. Artefacts from Majuangou III5 and Shangshazui6 in the Nihewan basin, north China, have also been dated to 1.6–1.7Ma. Here we report an Early Pleistocene and largely continuous artefact sequence from Shangchen, which is a newly discovered Palaeolithic locality of the southern Chinese Loess Plateau, near Gongwangling in Lantian county. The site contains 17 artefact layers that extend from paleosol S15—dated to approximately 1.26Ma—to loess L28, which we date to about 2.12Ma. This discovery implies that hominins left Africa earlier than indicated by the evidence from Dmanisi.
Also mentioned in The Atlantic, BBC
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The Hunt for the Ancient ’Hobbit’s’ Modern Relatives
A group of pygmies still lives near the cave where the short-statured Homo floresiensis was discovered. But they are not related.
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2018 - Earliest known hominin activity in the Philippines by 709 thousand years ago
Over 60 years ago, stone tools and remains of megafauna were discovered on the Southeast Asian islands of Flores, Sulawesi and Luzon, and a Middle Pleistocene colonization by Homo erectus was initially proposed to have occurred on these islands. However, until the discovery of Homo floresiensis in 2003, claims of the presence of archaic hominins on Wallacean islands were hypothetical owing to the absence of in situ fossils and/or stone artefacts that were excavated from well-documented stratigraphic contexts, or because secure numerical dating methods of these sites were lacking. As a consequence, these claims were generally treated with scepticism5. Here we describe the results of recent excavations at Kalinga in the Cagayan Valley of northern Luzon in the Philippines that have yielded 57 stone tools associated with an almost-complete disarticulated skeleton of Rhinoceros philippinensis, which shows clear signs of butchery, together with other fossil fauna remains attributed to stegodon, Philippine brown deer, freshwater turtle and monitor lizard. All finds originate from a clay-rich bone bed that was dated to between 777 and 631 thousand years ago using electron-spin resonance methods that were applied to tooth enamel and fluvial quartz. This evidence pushes back the proven period of colonization6 of the Philippines by hundreds of thousands of years, and furthermore suggests that early overseas dispersal in Island South East Asia by premodern hominins took place several times during the Early and Middle Pleistocene stages1,2,3,4. The Philippines therefore may have had a central role in southward movements into Wallacea, not only of Pleistocene megafauna7, but also of archaic hominins.
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Evidence man was in North America 30,000 years ago
The peopling of the Americas marks a major expansion of humans across the planet. However, questions regarding the timing and mechanisms of this dispersal remain, and the previously accepted model (termed ‘Clovis-first’)—suggesting that the first inhabitants of the Americas were linked with the Clovis tradition, a complex marked by distinctive fluted lithic points1—has been effectively refuted. Here we analyse chronometric data from 42North American and Beringian archaeological sites using a Bayesian age modelling approach, and use the resulting chronological framework to elucidate spatiotemporal patterns of human dispersal. We then integrate these patterns with the available genetic and climatic evidence. The data obtained show that humans were probably present before, during and immediately after the Last Glacial Maximum (about 26.5–19thousand years ago)2,3 but that more widespread occupation began during a period of abrupt warming, Greenland Interstadial1 (about 14.7–12.9thousand years before 2000)4. We also identify the near-synchronous commencement of Beringian, Clovis and Western Stemmed cultural traditions, and an overlap of each with the last dates for the appearance of 18now-extinct faunal genera. Our analysis suggests that the widespread expansion of humans through North America was a key factor in the extinction of large terrestrial mammals.
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New Species of Ancient Human Found in Philippines
At the northern tip of the Philippine island of Luzon lies Callao Cave, an expansive, seven-chamber limestone warren. In April, researchers reported in the journal Nature that they’d uncovered the bones of a now-extinct, previously unknown human species near the far end of the first chamber. The discovery adds to growing evidence that human evolution and dispersal out of Africa is much more complicated than scientists once thought — and that we’re just starting to understand Southeast Asia’s role in that story.
“There is no reason why archaeological research in the Philippines couldn’t discover several species of hominin,” Philip Piper, an archaeologist at the Australian National University who coauthored the new research, said in a statement. “It’s probably just a matter of time.”
In 2007, Piper and an international team of researchers discovered a foot bone in Callao Cave that belonged to a member of the genus Homo, though they were unable to determine which species.
Remains preserved in Callao Cave include several teeth with traits that established the individuals belonged to the genus Homo — but also raised questions about their evolution. (Credit: Callao Cave Archaeology Project)
Researchers continued to excavate the cave, eventually unearthing more bones — plus seven teeth — from three individuals who lived at least 50,000 years ago. That date would mean they were alive at the same time as Neanderthals, Denisovans and our own species, as well as Homo floresiensis, short and small-brained ancient humans who lived in Indonesia.
The Callao Cave bones have a unique combination of primitive and modern human traits, leading the researchers to classify them as an entirely new species: Homo luzonensis.
The seven teeth found were of particular interest to the researchers. Oddly small molars are similar in shape to those of H. sapiens. However, they also have features that resemble the molars of H. erectus, a much earlier human species that dispersed out of Africa about 2 million years ago. And parts of the premolars of H. luzonensis resemble those of H. floresiensis.
Meanwhile, the curved shape of the toe and finger bones of H. luzonensis look like those of australopiths, human predecessors that lived some 3 million years ago. That means H. luzonensis likely spent some of its time climbing in trees — even though other Homo species were ground-dwellers by this point.
The discovery of H. luzonensis on an island that was never connected to mainland Asia, and which would have required a significant sea crossing to reach, adds to the mystery surrounding the latest addition to our family tree.
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Sulawesi art: Animal painting found in cave is 44,000 years old
A painting discovered on the wall of an Indonesian cave has been found to be 44,000 years old.
The art appears to show a buffalo being hunted by part-human, part-animal creatures holding spears and possibly ropes.
Some researchers think the scene could be the world's oldest-recorded story.
The findings were presented in the journal Nature by archaeologists from Griffith University in Brisbane, Australia.
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Fossil find suggests Homo erectus emerged 200,000 years earlier than thought
These discoveries, combined, have led scientists to set Homo erectus‘ emergence at about 1.8 million years ago – with the oldest known record coming from Dmanisi, Georgia and an important slightly later record from the East African Rift valley.
But our new discovery in South Africa’s Cradle of Humankind, which has just been published in Science, suggests that Homo erectus actually emerged 200 000 years earlier than we thought. We were part of a team from South Africa, Australia, Italy and the US that discovered a Homo erectus cranium which has since been dated to almost 2 million years ago.
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Two-million-year-old skull of human 'cousin' unearthed
Australian researchers say the discovery of a two-million-year-old skull in South Africa throws more light on human evolution.
The skull was a male Paranthropus robustus, a "cousin species" to Homo erectus - a species thought to be direct ancestors of modern humans.
The two species lived around the same time, but Paranthropus robustus died out earlier.
The research team described the find as exciting.
"Most of the fossil record is just a single tooth here and there so to have something like this is very rare, very lucky," Dr Angeline Leece told the BBC.
The researchers, from Melbourne's La Trobe University, found the skull's fragments in 2018 at the Drimolen archaeological site north of Johannesburg.
It was uncovered just metres away from a spot where a similarly aged Homo erectus skull of a child was discovered in 2015.
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Homo Erectus Is 200,000 Years Older Than Previously Thought
For eight years, a crunched cranium protruded from an excavation pit in South Africa’s Drimolen Cave. Archaeologists ignored the fossil, assuming it to be a baboon, until they swept up pieces that had crumbled free in 2015. Early on, the remains looked more human than monkey.
Jesse Martin and Angeline Leece, researchers at Australia’s La Trobe University, jigsaw-puzzled together more than 150 bone bits, each no bigger than a quarter. Some were so fine that light shone through. Analysis confirmed the fossil wasn’t baboon. Then, in 2018, another skull surfaced at the Drimolen site, and chronometric dating placed both craniums around 2 million years old. The researchers published their big news in Science this April: Based on skull shape, the second cranium belonged to Paranthropus robustus, a Lucy-like relative with jumbo molars. The first came from Homo erectus — a species thought to have originated 200,000 years later in East Africa.
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Mystery ancestor mated with ancient humans. And its 'nested' DNA was just found.
Today's humans carry the genes of an ancient, unknown ancestor, left there by hominin species intermingling perhaps a million years ago.
The ancestor may have been Homo erectus, but no one knows for sure — the genome of that extinct species of human has never been sequenced, said Adam Siepel, a computational biologist at Cold Spring Harbor Laboratory and one of the authors of a new paper examining the relationships of ancient human ancestors.
The new research, published today (Aug. 6) in the journal PLOS Genetics, also finds that ancient humans mated with Neanderthals between 200,000 and 300,000 years ago, well before the more recent, and better-known mixing of the two species occurred, after Homo sapiens migrated in large numbers out of Africa and into Europe 50,000 years ago. Thanks to this ancient mixing event, Neanderthals actually owe between 3% and 7% of their genomes to ancient Homo sapiens, the researchers reported.
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Massive human head in Chinese well forces scientists to rethink evolution
“The important thing is the third lineage of later humans that are separate from Neanderthals and separate from Homo sapiens.”
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Fossil footprints show humans in North America more than 21,000 years ago
The footprints, the earliest firm evidence for humans in the Americas, show that people must have arrived here before the last Ice Age.
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Experts Name New Species of Human Ancestor
An international team of researchers, led by University of Winnipeg palaeoanthropologist Dr. Mirjana Roksandic, has announced the naming of a new species of human ancestor, Homo bodoensis. This species lived in Africa during the Middle Pleistocene, around half a million years ago, and was the direct ancestor of modern humans.
The Middle Pleistocene (now renamed Chibanian and dated to 774,000-129,000 years ago) is important because it saw the rise of our own species (Homo sapiens) in Africa, our closest relatives, and the Neanderthals (Homo neanderthalensis) in Europe.
However, human evolution during this age is poorly understood, a problem which paleoanthropologists call “the muddle in the middle”. The announcement of Homo bodoensis hopes to bring some clarity to this puzzling, but important chapter in human evolution.
The new name is based on a reassessment of existing fossils from Africa and Eurasia from this time period. Traditionally, these fossils have been variably assigned to either Homo heidelbergensis or Homo rhodesiensis, both of which carried multiple, often contradictory definitions.
“Talking about human evolution during this time period became impossible due to the lack of proper terminology that acknowledges human geographic variation” according to Roksandic, lead author on the study.
Recently, DNA evidence has shown that some fossils in Europe called H. heidelbergensis were actually early Neanderthals, making the name redundant. For the same reason, the name needs to be abandoned when describing fossil humans from east Asia according to co-author, Xiu-Jie Wu (Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, China).
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Child fossil find in South Africa sheds light on enigmatic hominids
Fossils found deep in a South African cave formed part of a hominid child's skull, apparently left on an alcove by fellow members of her species 250,000 years ago, scientists said on Thursday.
These remains are the first of a child's skull. No other bones were found, not even a jawbone, and the skull showed no signs of damage—as from a carnivore's attack.
Death ritual?
The researchers speculate that other members of the species may have set the skull there, for reasons that could be linked to rituals around the dead, Berger said.
He has proposed such a line of thinking for explaining the entire Homo naledi site, as a site for ritual burials.
If further evidence supports that theory, it would mark a dramatic rethinking about the human odyssey.
Until now, the earliest known hominid rituals associated with death date back to 50,000-100,000 years ago, he said.
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