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Many recent articles maintain that a small percentages of Neanderthal genes (up to 2%) are found in modern non-African people. (I believe that currently there is insufficient genetic material from older hominids, such as H. erectus, to decode a genome).
My question is: how is it known the “Neanderthal genes” found in modern humans got there by way of interbreeding? What distinguishes those genes from genes that both species inherited from a common ancestor? After all, Neanderthals and H. Sapiens are over 99% genetically identical. How is it determined that gene A is found in both because it was from H. erectus, from which both evolved; but gene B was not already present in H. sapiens, so it must have arisen through interbreeding?
Although this question makes some false assumptions, it is fundamentally interesting as the methodology used is neither simple or easy to understand. It is not my area, but I have found it especially interesting to read the long 2010 Science paper by Green et al.. One really needs to read it for oneself (it is free view), but it is not a trivial undertaking.
False assumptions / misconceptions in the question
The main misconception in the question are:
- That it is necessary to know anything about the genome of H. erectus to make these conclusions. The methods used do not require this. (Although comparison with chimpanzee is sometimes used to give an indication of whether a genetic change occured in humans or Neanderthals.)
- That the similarities and differences under discussion relate to differences in complete genes - “but gene B was not already present in H. sapiens… ”. They do not, which makes the analysis more complex to follow.
Towards an explanation
Let me start by addressing the question “What distinguishes those genes (purported to have been acquired by H. sapiens from Neanderthals) from genes that both species inherited from a common ancestor?”. The answer relates to the absence of such genes from modern humans of African origin, and the fact that we know the general evolutionary relationship between neanderthals and modern humans (African and non-African) from a wealth of non-sequence paleontological evidence. This is shown in the diagram below, modified from a recent and recommended review by Nielsen et al. in Nature (2017).
Clearly any gene present in the common ancestor to humans and Neanderthals should be present in both African and European populations, unless it had been lost from the African population.
So if the analysis is not done by detecting gain/loss of individual genes, how is it done? Certainly not by overall percentage sequence similarity, because of the high overall similarity and the population variation. It is done by studying SNPs - single nucleotide polymorphisms - in particular genes.
For example, consider a gene that has only a single haplotype in Neanderthals, and originally had a single but different haplotype in humans. (This might determine something like eye colour, although this is not an actual example.) If the other haplotype were acquired by humans as a result of interbreeding, then the modern human population would contain both alleles. When you compared the relationship of the SNPs for this gene between different humans and between humans and Neanderthals you would find different results from those for a gene the variant of which had not been acquired by interbreeding. The acquired gene in humans would be more related to that in Neanderthals than non-acquired genes, but less related to that in other humans (because of its more recent appearance in the population and time for homogenization, I believe).
The African/non-African aspect is explained in the Science paper cited in my introduction, but there is a good visual diagram in a 2014 Nature paper by Sankararaman et al., the manuscript of which can be viewed freely in PMC through the US HHS.
(1) Sites where a panel of sub-Saharan Africans carries the ancestral allele and where the sequenced Neanderthal and the test haplotype (marked non-African) carry the derived allele are likely to be derived from Neanderthal gene flow; (2) Haplotype divergence patterns. Genomic segments where the divergence of the test haplotype to the sequenced Neanderthal is low while the divergence to a panel of sub-Saharan Africans is high are likely to be introgressed.
These papers contain a wide range of controls, including comparisons of different non-African population groups, and detailed discussion of alternative possibilities.
A final point of interest is that Sankararaman et al. examined some of the genes in which these SNPS suggest Neanderthal origin. They write:
“… genes involved in keratin filament formation and some other biological pathways are significantly enriched in Neanderthal ancestry in European populations, east-Asian populations, or both… . Thus, Neanderthal alleles that affect skin and hair may have helped modern humans to adapt to non-African environments.”
It would be scientifically dishonest not to mention some oddities. One is that the Green et al. paper suggested that gene flow had been uni-directional: from Neanderthals to humans, which is apparently unusual in interbreeding. However a more recent study (Kuhlwilm et al., 2016) shows some human gene flow into Eastern Neanderthals, although not into European Neanderthals. (Thanks to @iayork for pointing this out.). The other is that modern Asians appear to have more Neanderthal DNA than modern Europeans. (This is discussed in the paper already mentioned by Green et al.)
'Dragon Man' claimed as potential new human species after analysis of China skull
The Harbinranium dates to at least 146,000 years old and a group of international researchers wrote in the journal The Innovation that phylogenetic analysis suggests it represents "a new sister lineage for Homo sapiens."
In a summary of one of three papers, the group wrote that the well-preserved artifact&aposs massive size and large cranial capacity fall in the range of modern humans but is combined with "a mosaic of primitive and derived characters."
"It differs from all the other named Homo species by presenting a combination of features, such as long and low cranial vault, a wide and low face, large and almost square orbits, gently curved but massively developed supraorbital torus, flat and low cheekbones with a shallow canine fossa, and a shallow palate with thick alveolar bone supporting very large molars," the group said, noting that the skull "advances" human understanding of several other less-complete fossils from China in the late Middle Pleistocene that had been interpreted as local "evolutionary intermediates" between Homo erectus and Homo sapiens.
The cranium nicknamed Dragon Man, which could be a new species of ancient human.
Upon closer examination, the scientists found that the Harbin cranium and other Middle Pleistocene Epoch human fossils from China formed a "third East Asian lineage, which is a part of the sister group of the H. sapiens lineage."
"Our analyses of such morphologically distinctive archaic human lineages from Asia, Europe, and Africa suggest that the diversification of the Homo genus may have had a much deeper timescale than previously presumed," they added. "Sympatric isolation of small populations combined with stochastic long-distance dispersals is the best fitting biogeographical model for interpreting the evolution of the Homo genus."
In additional commentary, the scientists suggested that one of the fossils they used called the Dali cranium – found in Shaanxi province and considered its own species, Homo daliensis – and another Hualongdong cranium should be referred to as Homo daliensis, the Harbin cranium&aposs "clear diagnostic features" differ from the Dali and Hualongdong crania.
The Harbin cranium, they said, has a sister-group relationship with Gansu province&aposs Denisovan Xiahe mandible.
"It is possible that both specimens belong to H. longi sp. nov. Further human fossils from the Middle Pleistocene of China and neighboring areas will test this idea," they pledged.
Denisovans, close relatives of Neanderthals, lived in Asia for hundreds of thousands of years, but scientists have only found small fossil traces of their existence. They are known to have interbred with Homo sapiens, as there were more than one species of hominin at the time.
Renderings of the Harbin cranium helped bring the male Homo longi, nicknamed "Dragon Man" -- after the Long Jiang, or Dragon River, in the Heilongjiang province – to life.
An artist's impression of what Dragon Man could have looked like.
The man was around 50 years old when he died.
The skull was allegedly found in mysterious circumstances almost 90 years ago, when a Chinese laborer working on a bridge over the Songhua River pulled it out of nearby sediment, according to the London Natural History Museum (NHM).
The man kept the Harbin cranium well hidden until shortly before his death in 2018, after which his family relocated the skull and donated it to the Geoscience Museum, Hebei GEO University and lead study author professor Qiang Ji.
The South China Morning Post reported Friday that the man had hidden it in order to protect it from the Japanese army.
In a lengthy statement posted to Twitter on Friday, NHM paleoanthropologistਊnd co-author of two of the three Dragon Man papers, Christopher Stringer, wrote that he had been invited to join Qiang Ji in 2019 and marveled at the preservation of the Harbin cranium.
"The cranium is almost intact, but with only one huge second molar preserved, and it is massive in size, with an endocranial volume of
1420 ml. It has a strong supraorbital torus and very broad upper face, nasal opening and palate, but in contrast the face is low in height with delicate cheekbones, and retracted under the cranial vault, more closely resembling Homo sapiens," he said.
"Nevertheless, the braincase is clearly archaic in profile - long, low and without the globular shape found in our species," Stringer continued. "However, the mastoid processes and large, and the back of the skull does not show the angulated occipital bone and strong transverse torus found in large H. heidelbergensis individuals. From the rear, the cranium is very broad and parallel-sided, lacking the upper parietal expansion found in H. sapiens and the almost spherical shape and suprainiac fossa found in most Neanderthals (Ni et al., 2021)."
Stringer pointed out that while palaeoanthropologists often use landmark-based analyses to measure overall similarities between compared human fossils, his colleagues&apos phylogenetic analyses employ mathematical techniques in order to establish branching diagrams of evolutionary relationships between species or organisms.
"These methods were applied to 95 representative fossils and over 600 metrical and morphological traits, and the analyses revealed 3 main clades of later Pleistocene humans: H. sapiens, H. neanderthalensis and a group containing Harbin and other Chinese fossils such as Dali, Jinniushan and Xiahe," he said.
In doing so, what was "surprising" to Stringer was that the Harbin clade – a grouping that includes a common ancestor and all the descendants of that ancestor – was first linked to Homo sapiens and not Homo neanderthalensis.
Stringer said while he believes the Harbin group warrants a distinct species name, he would "prefer to place the Harbin and Dali fossils together as H. daliensis" and considers the Harbin cranium as a "possible Denisovan."
"But these differences of opinion should not deflect from a remarkable new piece in the jigsaw of human evolution, a fossil that will continue to add important information for many years to come," he concluded.
How is it known that Homo sapiens and Homo neanderthalensis interbred? - Biology
Making sense of ancient hominin DNA
May 2010, update added in July 2010 and August 2015
|The Siberian cave where a 40,000 year old pinky bone was found.|
Based on the sequences of mitochondrial DNA extracted from the pinky bone, Neanderthal fossils, and modern humans, the researchers built a phylogenetic tree that shows how all the different sequences are likely related to each other and how recently they descended from a common ancestor. This sort of phylogeny is called a gene tree. It shows the relationships among genes not necessarily the relationships among species. The gene tree showed that known human and Neanderthal mitochondrial DNA sequences were more closely related to each other than either was to the new sequence from the fossil. Does this mean that the finger bone comes from a new species? Maybe. Maybe not.
If the mitochondrial gene tree turns out to be an accurate indicator of species relationships, it might indeed mean that X-woman is a new species. But it's also possible that X-woman represents a species distinct from humans and Neanderthals just not a new species. For example, X-woman might be a member of the species Homo erectus. So far, scientists have not extracted any DNA from known Homo erectus fossils, so we can't figure this out by looking at X-woman's genetic sequence. Existing evidence suggests that Homo erectus spread from Africa into Europe and Asia 1.9 million years ago and was unlikely to have lived in Siberia 40,000 years ago when X-woman lived. However, if we are wrong about where and when Homo erectus (or other known hominin species) lived, X-woman could represent one of these more familiar species.
However, it's also possible that X-woman's mitochondrial gene tree doesn't accurately reflect the evolutionary history of the X-woman species (whatever that species might be). This is because species trees and gene trees don't always match up. To understand how this can happen, you need to think of species as populations made up of many different individuals:
- At any point in time, there are likely to be many different versions of a gene in the population.
- However, some gene versions may be ancient and may have hung around in the population for a long time.
- Sometimes these gene versions are so old that they are actually more closely related to a gene version found in a separate species than they are to other gene versions in the same population.
For example, some humans have immune system gene versions that are more closely related to chimpanzee immune system gene versions than they are to other human versions. That's just because these gene versions are extremely old and have stuck around in both human and chimp populations since our two lineages split from one another six million years ago, not because the humans carrying those genes are more closely related to chimps than to other humans. In this case, the gene tree and species tree don't match. It's a bit like if you and your cousin both inherited brown eyes from your grandmother, but your sibling inherited blue eyes from your grandfather. Does this mean that you are more closely related to your cousin than your sibling? Of course not. The genes that control eye color are just a few out of tens of thousands of genes and if you could look at all of those genes, instead of just one or a few, they would show that you are more closely related to your sibling.
So, with all these possible explanations for X-woman's unusual mitochondrial DNA, how do we know which is best? We need more evidence. The discovery of new fossils that provide better anatomical information would help us figure out whether or not X-woman belonged to a species we already know about. Unfortunately, that would require a stroke of good luck. So far, scientists have not found any additional fossils, beyond the pinky bone, that could help us. Fortunately, that bone has yet more evidence imbedded in it. The researchers who sequenced its mitochondrial DNA are currently working to extract and sequence nuclear genes from the bone. Since an individual's nuclear genes come from all its ancestors not just a single, maternal lineage this information should give us a much better understanding of how X-woman herself not just her mitochondrial DNA is related to humans and Neanderthals. Stay tuned for further updates!
News update, July 2010
As described above, one possible explanation for X-woman's divergent mitochondrial DNA sequence is that it came from an earlier episode of breeding between different early hominin species. Before this summer, the evidence for mating between humans and Neanderthals was equivocal at best and the most revealing line of evidence, mitochondrial DNA sequences from several different Neanderthals, suggested that, even if some Neanderthals and humans had interbred, those Neanderthal genes are no longer around. Modern human populations carry no trace of Neanderthal DNA . or so we thought, before we had any nuclear DNA from Neanderthals to study.
In May 2010, an international team of researchers announced that the Neanderthal nuclear genome they'd just sequenced contained a surprise: Neanderthals' nuclear DNA is more similar to the DNA of modern Europeans and Asians than it is to the DNA of modern Africans! The most likely explanation for this observation is that Neanderthals interbred with the ancestors of Europeans and Asians, possibly when both species lived together in the Middle East and that Neanderthals didn't interbreed with the ancestors of modern Africans. The researchers also revealed that many genes from these episodes of interbreeding are still around today. People of European and Asian descent probably share between 1 and 4% of their DNA with Neanderthals! Though this is a significant portion of the genome, it may have resulted from relatively few interbreeding events. After all, at the time these events occurred, the human population was expanding out of Africa and increasing in population size. Genes from just a few interbreeding events may have surfed to relatively high frequencies as the population grew.
So what does this new discovery tell us about X-woman? It still doesn't indicate whether she represents a new hominin species, but it does highlight the fact that interbreeding among early hominin species happened and that the genetic divisions between species are not always neat. It also emphasizes how informative nuclear DNA can be. The same team that worked on the Neanderthal genome is currently at work on X-woman's nuclear genome. Stay tuned to find out if her nuclear DNA is as unique as her mitochondrial DNA and whether this reveals anything more about interspecies breeding between early hominins!
The first migrations out of Africa
Click to enlarge image Toggle Caption
About 2 million years ago, the first of our ancestors moved northwards from their homelands and out of Africa.
Why did it take so long to leave Africa?
The extensive arid environments of northern Africa and the Middle East were a major barrier blocking movement out of Africa. Before they could spread out of Africa, our ancestors needed to develop physical and mental capabilities that would enable them to survive in these harsh environments where food and fresh water were highly seasonal resources.
Who left Africa first?
Homo ergaster (or African Homo erectus) may have been the first human species to leave Africa. Fossil remains show this species had expanded its range into southern Eurasia by 1.75 million years ago. Their descendents, Asian Homo erectus, then spread eastward and were established in South East Asia by at least 1.6 million years ago.
However, an alternate theory proposes that hominins migrated out of Africa before Homo ergaster evolved, possibly about 2 million years ago, prior to the earliest dates of Homo erectus in Asia. These hominins may have been either australopithicines or, more likely, an unknown species of Homo, similar in appearance to Homo habilis. In this theory, the population found at Dmanisi represent a missing link in the evolution of Homo erectus/Homo ergaster. Perhaps too, the evolution of Homo ergaster occurred outside of Africa and there was considerable gene flow between African and Eurasian populations.
This theory has gained more support in recent years due to DNA research. Evidence from a genetic study indicates an expansion out of Africa about 1.9 million years ago and gene flow occurring between Asian and African populations by 1.5 million years ago. More physical evidence is needed from key areas in Eurasia such as Iran, Afghanistan and Pakistan, but politics is currently making this difficult.
What made it possible to leave Africa?
While there is some debate about whether Homo ergaster was the first of our ancestors to leave Africa, they did possess the physical and cultural attributes that would have aided dispersal through the arid environments of northern Africa and the Middle East. These attributes included:
- a modern body shape with an efficient striding gait suited to travelling over long distances, although smaller statures are represented in the remains from Dmanisi
- a sufficiently developed intelligence to cope with unfamiliar environments, although did not require a brain size much bigger than Homo habilis, with an average brain size of 610cc
- improved technology to aid subsistence (Oldowan-style tools or Mode1 Technology have been found at sites in Dmanisi, Georgia, and northern China, both dating to 1.7 million years old)
- a diet that included more meat and which increased the food supply options in seasonally arid environments
Who left Africa next?
After the first early dispersals out of Africa, various other groups of early humans spread out of Africa as their populations grew. These dispersals were not regular or constant but instead occurred as waves of dispersal during periods with favourable climatic and environmental conditions.
These waves of dispersal out of Africa included movements eastward across southern Asia more than one million years ago and movements into western Europe within the last 900,000 years. Movements back into Africa also occurred.
Modern human migrations
More recently, modern humans began their dispersal out of Africa. This dispersal appears to have taken two forms - irregular occupation of the Levant and nearby sites by small populations and then migration on a mass scale.
The oldest known Homo sapiens fossils outside of Africa come from caves in Israel - Misliya (about 180,000 years old), Skhul (about 90,000 years old) and Qafzeh (about 120,000 years old). These probably represent populations that intermittently occupied the region and it is unlikely that there was direct evolutionary continuity between the Misliya and later Skhul/Qafzeh peoples. Genetic studies also support the idea of earlier dispersals of modern humans out of Africa starting from about 220,000 years ago.
There is also evidence in the form of stone tools that indicate the possibility that earlier dispersals reached beyond the Levant. Stone tools have been found in India dating to about 74,000 years old, in Yemen dating to between 70,000 and 80,000 years old, and in the United Arab Emirates dating to about 80,000 years old. Some of these tools resemble African Middle Stone Age technology, others are more like those used by Neanderthals in Europe and Homo sapiens and Neanderthals in the Levant. No human remains were found with the tools, but as Neanderthals have not been found in these regions, it is assumed the makers were modern humans.
Most experts conclude, from genetic and material evidence, that migration on a mass scale only occurred within the last 60,000 years or so.
By 100,000 years ago, humans had dispersed and diversified into at least four species. Our own species, Homo sapiens, lived in Africa and the Middle East, Homo neanderthalensis lived in Europe, and Homo floresiensis in southern Asia. DNA from human remains in Denisova cave, Russia, indicates a fourth species was also still extant when Homo sapiens was migrating through southern Asia about 60,000 years ago. Modern Melanesians have about 4% of this DNA. The species is unknown, but may be late surviving Homo heidelbergensis or a yet-to-be-discovered species. This diversity disappeared about 28,000 years ago, however, and only one human species now survives.
In short, cooking was another factor involved in the brain development and cognitive abilities of our ancestors, allowed energy savings to digest and chew food, decreased masticatory apparatus, allowed the young become earlier independent from their breast-feeding mothers (who could mate more often), improved immune system… Even improved social skills: left more free time so they could dedicate it to other tasks, such as cooperation to keep the fire, planning the collection or capture of food, distribution of food in the group acoording to range and health of individuals… intelligence enhanced cooking techniques, which in turn enhanced the intelligence, in an infinite wheel that still exists today.
Aside from physical differences in the skeleton, researchers have also tracked clues of behavioral changes from archaic to modern humans. From the anthropology of our species today, we know that we practice a very complex version of culture, with many layers to our language, art, social organization, and technology, among other areas. Did cultural complexity increase gradually or quickly with the first modern humans? This question is being actively investigated. A major obstacle to answering this question is that it is hard to define and measure cultural complexity. Since we cannot directly observe humans of the distant past, we have to infer these measures of human behavior from other types of evidence. Two particularly illuminating areas are archaeology and the analysis of reconstructed brains.
Archaeology tells us much about the behavioral complexity of past humans by interpreting the significance of material culture. In terms of evolved advanced culture, items created with an artistic flair, or as a decorative piece, speak of some abstract thought process (Figure 12.4). The demonstration of difficult artistic techniques and technological skills hints at social learning and cooperation as well. For example, most of your skills were taught to you by a more experienced person, upon which you’ve developed your own style with practice. Some day you may pass on what you know to someone else using language to convey your knowledge. The same process is believed to have happened with early modern humans in areas such as toolmaking and craftwork, producing the sophisticated material culture that we can now study. According to paleoanthropologist John Shea (2011), one way to track the complexity of past behavior through artifacts is by measuring the variety of tools found together. The more types of tools constructed with different techniques and for different purposes, the more modern the behavior. Turning this view to ourselves, think of all of the tools we have available to us today at a typical hardware store and the cumulative knowledge they represent. This idea of measuring past behavior is promising, but researchers are still working on an archaeological way to measure cultural complexity that is useful across time and place.
Figure 12.4 Carved ivory figure called the Lion-Man of the Hohlenstein-Stadel. It dates to the Aurignacian culture, between 35 and 40 kya. What does this artifact suggest about the culture and technical skill of its artist?
The interpretation of brain anatomy is another promising approach to studying the evolution of human behavior. When looking at the body of work on this topic in modern Homo sapiens brains, researchers found a weak association between brain size and test-measured intelligence (Pietschnig et al. 2015). This means that there are more significant factors that affect tested intelligence than just brain size. Additionally, they found no association between intelligence and biological sex. Since the sheer size of the brain is not useful for weighing intelligence, paleoanthropologists are instead investigating the differences in certain brain structures. The differences in organization between modern Homo sapiens brains and archaic Homo sapiens brains may reflect different cognitive priorities that account for modern human culture. Researchers (e.g., Bruner 2010) have hypothesized that the expanded frontal and parietal lobes in the globular modern human braincases mean that we can do more complex thinking regarding memory and social ability than the Neanderthals could. In contrast, the Neanderthal brain prioritized the visual regions where the occipital bun was located, with fewer neurons in the frontal area for complex thinking. As with the archaeological line of research in the preceding paragraph, this is a very active area of investigation. New discoveries will refine what we know about the human brain and apply that knowledge to studying the distant past.
Taken together, the cognitive abilities in modern humans may have translated into an adept use of tools to enhance survival. The ability to process a new environment, adapt to it with innovative technology, and pass on that knowledge may be the key behind the success of modern Homo sapiens. Researchers Patrick Roberts and Brian A. Stewart call this concept the generalist-specialist niche : Our species is an expert at living in a wide array of environments, with populations culturally specializing in their own particular surroundings (Roberts and Stewart 2018). The next section tracks how far around the world these skeletal and behavioral traits have taken us.
In historic discovery, scientists find human ancestor that interbred with ancient humans
Researchers found a new hominin, which are species regarded as human, directly ancestral to humans or very closely related to humans, and it is called the Nesher Ramla homo. It lived in the eastern Mediterranean in modern day Israel and Arabia.
Some 120,000 years ago when the Nesher Ramla homo lived, Homo sapiens lived in the same landscape, as did Neanderthals, who were living throughout Eurasia, or the continental area comprising all of Europe and Asia, Business Insider reported.
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The Nasher Ramla homo were capable of doing the same things as the other hominins and lived close by the other two groups, and researchers say they interbred.
"They lived together and interacted with another," Rachel Sarig, senior researcher at Dan David Center for human evolution and biohistory research, told Insider.
“They were hunter-gatherers living in small groups, hunting animals like rhinos, horses, and deer," she said. "[They are] not very different in their abilities from other groups."
Sarig and her colleagues also noticed a new jaw bone, chunks of skull and a tooth that was found in the Nesher Ramla sinkhole in Israel.
A distinctive feature about the Nasher Ramla homo is that it did not have a chin, but had a flatter, squatter head compared to the other hominins, and it could be a “pre-Neanderthal” of some kind.
The Neanderthal and Homo sapiens interbred with the Nesher Ramla homo, and two new studies published in Science show that Nesher Ramla homo helped influence the shaping of their looks and their lives.
This could answer a genetic missing link: It could explain how Neanderthals got genes from Homo sapiens before the latter species arrived in Europe.
Evidence from the sinkhole also suggests that the three hominins also shared techniques in making flint tools.
Scientists Discover Bones of An ‘Unknown’ Type of Human
Researchers have discovered fossils of a human species previously unknown to science. These remains are not of modern-day humans, and the researchers have named the Homo-type they belong to as the “Nesher Ramla Homo-type” — christened after the place in Israel where the fossils were discovered.
Reportedly, remnants of the species — skull fragments and a lower jaw with teeth that are about 120,000 to 140,000 years old — were discovered as early as 2010. However, the process of cleaning the fossils, reconstructing them, and analyzing them took well over a decade. Finally, two papers detailing the discovery of the species were published in the Science journal today.
“The discovery of a new type of Homo is of great scientific importance,” said Israel Hershkovitz from the department of anatomy and anthropology at Tel Aviv University, who led one of the studies.
“Even though they lived so long ago… [they] can tell us a fascinating tale, revealing a great deal about their descendants’ evolution and way of life,” Hershkovitz said, adding that the discovery will enable us to “make new sense of previously found human fossils, add another piece to the puzzle of human evolution, and understand the migrations of humans in the old world.”
Researchers believe the Nesher Ramla people were a large population in the region, and lived there at least about 400,000 to 100,000 years ago. In fact, they may even have interbred with Homo sapiens — the species to which modern-day humans belong — during the time they were around.
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Interestingly, the Nesher Ramla people were found buried 25 feet into the ground — among bones of horses and deer, and also stone tools. “It was a surprise that archaic humans were using tools normally associated with Homo sapiens. This suggests that there were interactions between the two groups,” said Yossi Zaidner from the Hebrew University at Jerusalem, who led the other study.
The jaw bone that was discovered had very large teeth and no chin, and the skull, too, was found to be flat. Researchers ran three-dimensional analyses on the fossils to rule out possibilities of them belonging to known Homo species.
They believe it is possible the Nesher Ramla people were ancestors to the Homo neanderthalensis, or Neanderthals, who are known to be the modern human’s “closest extinct human relative.” If that turns out to be true, the discovery might alter our geographical understanding of the origin of Neanderthals.
“The oldest fossils that show Neanderthal features are found in Western Europe, so researchers generally believe the Neanderthals originated there. However, migrations of different species from the Middle East into Europe may have provided genetic contributions to the Neanderthal gene pool during the course of their evolution,” Rolf Quam, an anthropologist from Binghamton University in the U.S., who was involved in one of the studies, said in a statement.
The discovery could also explain how Neanderthals’ populations have been found to carry the DNA of Homo sapiens before the two had even crossed paths — the answer could, perhaps, lie in the interbreeding of Homo sapiens and the Nesher Ramla people.
“This is a complicated story, but what we are learning is that the interactions between different human species in the past were much more convoluted than we had previously appreciated,” Quam noted.
50,000 to 60,000 Years Ago: Genes and Climate Reconstructions Show a Migration Out of Africa
A digital rendering of a satellite view of the Arabian Peninsula, where humans are believed to have migrated from Africa roughly 55,000 years ago
All living non-Africans, from Europeans to Australia’s aboriginal people, can trace most of their ancestry to humans who were part of a landmark migration out of Africa beginning some 50,000 to 60,000 years ago, according to numerous genetic studies published in recent years. Reconstructions of climate suggest that lower sea levels created several advantageous periods for humans to leave Africa for the Arabian Peninsula and the Middle East, including one about 55,000 years ago.
“Just by looking at DNA from present day individuals we’ve been able to infer a pretty good outline of human history,” Akey says. “A group dispersed out of Africa maybe 50 to 60 thousand years ago, and then that group traveled around the world and eventually made it to all habitable places of the world.”
While earlier African emigres to the Middle East or China may have interbred with some of the more archaic hominids still living at that time, their lineage appears to have faded out or been overwhelmed by the later migration.
14. Red Deer Cave people
The Red Deer Cave People were the most recent known prehistoric population that do not resemble modern humans. Fossils dated between 14,500 and 11,500 years old were found in Red Deer Cave and Longlin Cave in China. Having a mix of archaic and modern features, they are tentatively thought to be a separate species of humans that became extinct without contributing to the gene pool of modern humans. Evidence shows large deer were cooked in the Red Deer Cave, giving the people their name.
Fossils of the Red Deer Cave people were radiocarbon dated between 14,500 and 11,500 years of age, using charcoal found in the fossil deposits. During the period the Red Deer Cave people lived, all other prehistoric human species such as Neanderthals were thought to have died out. The Red Deer Cave humans would therefore be more recent than Homo floresiensis(dubbed “Hobbits”) dated to 13,000 years ago.
In spite of their relatively recent age, the fossils exhibit features of more primitive humans. The Red Deer Cave dwellers had the following distinctive features that differ from modern humans: flat face, broad nose, jutting jaw with no chin, large molars, prominent brows, thick skull bones, and moderate-size brain. Although the physical features of the Red Deer Cave people suggest that they may be a previously undiscovered species of prehistoric human, the scientists who discovered them are reluctant to classify them as a new species