Tag: human

Human brain size gene triggers bigger brain in monkeys

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Microscopy image of a section through one brain hemisphere of a 101 day- old ARHGAP11B-transgenic marmoset fetus. Cell nuclei are visualized by DAPI (white). Arrows indicate a sulcus and a gyrus. Credit: Heide et al. / MPI-CBG

The expansion of the human brain during evolution, specifically of the neocortex, is linked to cognitive abilities such as reasoning and language. A certain gene called ARHGAP11B that is only found in humans triggers brain stem cells to form more stem cells, a prerequisite for a bigger brain. Past studies have shown that ARHGAP11B, when expressed in mice and ferrets to unphysiologically high levels, causes an expanded neocortex, but its relevance for primate evolution has been unclear.

Researchers at the Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG) in Dresden, together with colleagues at the Central Institute for Experimental Animals (CIEA) in Kawasaki and the Keio University in Tokyo, both located in Japan, now show that this human-specific gene, when expressed to physiological levels, causes an enlarged neocortex in the common marmoset, a New World monkey. This suggests that the ARHGAP11B gene may have caused neocortex expansion during human evolution. The researchers published their findings in the journal Science.

The human neocortex, the evolutionarily youngest part of the cerebral cortex, is about three times bigger than that of the closest human relatives, chimpanzees, and its folding into wrinkles increased during evolution to fit inside the restricted space of the skull. A key question for scientists is how the human neocortex became so big. In a 2015 study, the research group of Wieland Huttner, a founding director of the MPI-CBG, found that under the influence of the human-specific gene ARHGAP11B, mouse embryos produced many more neural progenitor cells and could even undergo folding of their normally unfolded neocortex. The results suggested that the gene ARHGAP11B plays a key role in the evolutionary expansion of the human neocortex.

The rise of the human-specific gene

The human-specific gene ARHGAP11B arose through a partial duplication of the ubiquitous gene ARHGAP11A approximately five million years ago along the evolutionary lineage leading to Neanderthals, Denisovans, and present-day humans, and after this lineage had segregated from that leading to the chimpanzee. In a follow-up study in 2016, the research group of Wieland Huttner uncovered a surprising reason why the ARHGAP11B protein contains a sequence of 47 amino acids that is human-specific, not found in the ARHGAP11A protein, and essential for ARHGAP11B’s ability to increase brain stem cells.

Specifically, a single C-to-G base substitution found in the ARHGAP11B gene leads to the loss of 55 nucleotides from the ARHGAP11B messenger RNA, which causes a shift in the reading frame resulting in the human-specific, functionally critical 47 amino acid sequence. This base substitution probably happened much later than when this gene arose about 5 million years ago, anytime between 1.5 million and 500,000 years ago. Such point mutations are not rare, but in the case of ARHGAP11B its advantages of forming a bigger brain seem to have immediately influenced human evolution.


Wildtype (normal) and ARHGAP11B-transgenic fetal (101 days) marmoset brains. Yellow lines, boundaries of cerebral cortex; white lines, developing cerebellum; arrowheads, folds. Scale bars, 1 mm. Credit: Heide et al. / MPI-CBG

The gene’s effect in monkeys

However, it has been unclear until now if the human-specific gene ARHGAP11B would also cause an enlarged neocortex in non-human primates. To investigate this, the researchers in the group of Wieland Huttner teamed up with Erika Sasaki at the Central Institute for Experimental Animals (CIEA) in Kawasaki and Hideyuki Okano at the Keio University in Tokyo, both located in Japan, who had pioneered the development of a technology to generate transgenic non-human primates. The first author of the study, postdoc Michael Heide, traveled to Japan to work with the colleagues directly on-site.

They generated transgenic common marmosets, a New World monkey, that expressed the human-specific gene ARHGAP11B, which they normally do not have, in the developing neocortex. Japan has similarly high ethical standards and regulations regarding animal research and animal welfare as Germany does. The brains of 101-day-old common marmoset fetuses (50 days before the normal birth date) were obtained in Japan and exported to the MPI-CBG in Dresden for detailed analysis.

Michael Heide explains: “We found indeed that the neocortex of the common marmoset brain was enlarged and the brain surface folded. Its cortical plate was also thicker than normal. Furthermore, we could see increased numbers of basal radial glia progenitors in the outer subventricular zone and increased numbers of upper-layer neurons, the neuron type that increases in primate evolution.” The researchers had now functional evidence that ARHGAP11B causes an expansion of the primate neocortex.

Ethical consideration

Wieland Huttner, who led the study, adds: “We confined our analyses to marmoset fetuses, because we anticipated that the expression of this human-specific gene would affect the neocortex development in the marmoset. In light of potential unforeseeable consequences with regard to postnatal brain function, we considered it a prerequisite—and mandatory from an ethical point of view—to first determine the effects of ARHGAP11B on the development of fetal marmoset neocortex.”

The researchers conclude that these results suggest that the human-specific ARHGAP11B gene may have caused neocortex expansion in the course of human evolution.

More information: “Human-specific ARHGAP11B increases size and folding of primate neocortex in the fetal marmoset” Science (2020). science.sciencemag.org/cgi/doi … 1126/science.abb2401

https://medicalxpress.com/news/2020-06-human-brain-size-gene-triggers.html

There Are Striking Similarities in The Way Bacteria And Humans Settle Into Colonies

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by CARLY CASSELLA

The way oral bacteria sets up shop in our mouths is not unlike how we humans settle into our cities, a new study has found.

There’s a reason bacteria are said to live in ‘colonies’, and the more we learn about how these tiny architects build their communities, the more familiar their behavior seems to us.

A new study following how multiple individual settlers develop into microcolonies has found growth patterns and dynamics that mirror our own urban inclinations.

“We take this ‘satellite-level’ view, following hundreds of bacteria distributed on a surface from their initial colonisation to biofilm formation,” says Hyun Koo from the University of Pennsylvania.

“And what we see is that, remarkably, the spatial and structural features of their growth are analogous to what we see in urbanisation.”

Just as in nature, bacteria in your mouth live in complex structures known as biofilms. In fact, 99.9 percent of prokaryotes live crammed together with millions of other neighbours in one of these settlements.

Biofilms are everywhere, but if they’re on your teeth, we refer to them as plaque. This dense and sticky deposit is hard to remove, thereby protecting resident microbes from environmental assaults, like toothpaste, floss or even antibiotics.

It builds up when several individual settlers develop into microcolonies, but exactly how this happens remains underexplored.

Using the oral bacterium Streptococcus mutans, researchers have shown that microbial cells settle at random and regardless of the surface type. Nevertheless, only a subset of colonisers actually begin clustering, expanding their scope “by amalgamating neighboring bacteria into densely populated microcolonies.”

“We thought that the majority of the individual bacteria would end up growing,” says Koo. “But the actual number was less than 40 percent, with the rest either dying off or being engulfed by the growth of other microcolonies.”

Once the clusters arise, something really curious happens: they begin to interact with one another, growing and organising into densely populated “micron-scale microcolonies that further expand and merge” to form a biofilm superstructure.

This sort of cooperation is interesting, as previous studies have reported bacterial competition in other species, especially when there was a scarcity of nutrients.

In this case, the nutrients only impacted the actual forming of the colonies. After that, “the individual microcolonies (distant or in close proximity) continued to grow without disruption until merging with each other, and the merged structures behaved and grew like a single new harmonised community,” the researchers write.

Only when more antagonistic foreign species were introduced did it affect that seemingly peaceful unit, and the growth of the microcolonies was lowered.

“These communities (microcolonies) can expand and merge with each other in a collaborative fashion, without competition between adjacent communities,” the authors conclude.

It’s the type of growth that indicates “communal behavior between microorganisms”, and it looks similar to human urbanisation, where some settlers stay static, while others grow into villages that further expand into densely-populated microcolonies or cities, which then merge into microbial megacities.

Of course, there are limits to this idea of bacterial urbanisation. The authors aren’t saying microbes build traffic signs, roads and supply lines, but the general idea is the same and it can not only help us tackle infections better, it might also help us build more sustainably.

“It’s a useful analogy, but it should be taken with a grain of salt,” Koo says. “We’re not saying these bacteria are anthropomorphic. But taking this perspective of biofilm growth gives us a multiscale, multidimensional picture of how they grow that we’ve not seen before.”

The study was published in Nature Communications.

https://www.sciencealert.com/bacteria-settle-into-complex-structures-just-like-humans-settle-into-cities

Unknown human relative discovered in Philippine cave, Homo luzonensis, that lived more than 50,000 years ago.

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Remains from Callao Cave in the Philippines, including a foot bone, belong to a new hominin species, Homo luzonensis.Credit: Rob Rownd, UP-ASP Film Inst.

The human family tree has grown another branch, after researchers unearthed remains of a previously unknown hominin species from a cave in the Philippines. They have named the new species, which was probably small-bodied, Homo luzonensis.

The discovery, reported in Nature on 10 April1, is likely to reignite debates over when ancient human relatives first left Africa. And the age of the remains — possibly as young as 50,000 years old — suggests that several different human species once co-existed across southeast Asia.

The first traces of the new species turned up more than a decade ago, when researchers reported the discovery of a foot bone dating to at least 67,000 years old in Callao Cave on the island of Luzon, in the Philippines2. The researchers were unsure which species the bone was from, but they reported that it resembled that of a small Homo sapiens.

Further excavations of Callao Cave uncovered a thigh bone, seven teeth, two foot bones and two hand bones — with features unlike those of other human relatives, contends the team, co-led by Florent Détroit, a palaeoanthropologist at the National Museum of Natural History in Paris. The remains come from at least two adults and one child.

“Together, they create a strong argument that this is something new,” says Matthew Tocheri, a palaeoanthropologist at Lakehead University in Thunder Bay, Canada.

Hominin history
H. luzonensis is the second new human species to be identified in southeast Asia in recent years. In 2004, another group announced the discovery3 of Homo floresiensis — also known as the Hobbit — a species that would have stood just over a metre in height, on the Indonesian island of Flores.

But Détroit and his colleagues argue that the Callao Cave remains are distinct from those of H. floresiensis and other hominins — including a species called Homo erectus thought to have been the first human relative to leave Africa, some 2 million years ago.


Seven hominin teeth, including molars and premolars, were found in Callao Cave.Credit: Callao Cave Archaeology Project

The newly discovered molars are extremely small compared with those of other ancient human relatives. Elevated cusps on the molars, like those in H. sapiens, are not as pronounced as they were in earlier hominins. The shape of the internal molar enamel looks similar to that of both H. sapiens and H. erectus specimens found in Asia. The premolars discovered at Callao Cave are small but still in the range of those of H. sapiens and H. floresiensis. But the authors report that the overall size of the teeth, as well as the ratio between molar and premolar size, is distinct from those of other members of the genus Homo.

The shape of the H. luzonensis foot bones is also distinct. They most resemble those of Australopithecus — primitive hominins, including the famous fossil Lucy, thought not to have ever left Africa. Curves in the toe bones and a finger bone of H. luzonensis suggest that the species might have been adept at climbing trees.


Curves in the toe bones of H. luzonensis may have been adaptations for climbing.Credit: Callao Cave Archaeology Project

The researchers are cautious about estimating H. luzonensis’ height, because there are only a few remains to go on. But given its small teeth, and the foot bone reported in 2010, Détroit thinks that its body size was within the range of small H. sapiens, such as members of some Indigenous ethnic groups living on Luzon and elsewhere in the Philippines today, sometimes known collectively as the Philippine Negritos. Men from these groups living in Luzon have a recorded mean height of around 151 centimetres and the women about 142 centimetres.

The right fit
Researchers are split on how H. luzonensis fits into the human family tree. Détroit favours the view that the new species descends from a H. erectus group whose bodies gradually evolved into forms different from those of their ancestors.

“You get different evolutionary pathways on islands,” says palaeontologist Gerrit van den Bergh at the University of Wollongong in Australia. “We can imagine H. erectus arrives on islands like Luzon or Flores, and no longer needs to engage in endurance running but needs to adapt to spend the night in trees.”

But, given the species’ similarities to Australopithecus, Tocheri wonders whether the Callao Cave dwellers descended from a line that migrated out of Africa before H. erectus.

Genetic material from the remains could help scientists to identify the species’ relationship to other hominins, but efforts to extract DNA from H. luzonensis have failed so far. However, the bones and teeth were dated to at least 50,000 years old. This suggests that the species might have been roaming southeast Asia at the same time as H. sapiens, H. floresiensis and a mysterious group known as the Denisovans, whose DNA has been found in contemporary humans in southeast Asia.

“Island southeast Asia appears to be full of palaeontological surprises that complicate simple scenarios of human evolution,” says William Jungers, a palaeoanthropologist at Stony Brook University in New York.

https://www.nature.com/articles/d41586-019-01152-3?utm_source=Nature+Briefing&utm_campaign=669ddc32b9-briefing-dy-20190411&utm_medium=email&utm_term=0_c9dfd39373-669ddc32b9-44039353

Scientists have found that our big toe was one of the last parts of the foot to evolve

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As our early ancestors began to walk on two legs, they would also have hung about in trees, using their feet to grasp branches. They walked differently on the ground, but were still able to move around quite efficiently. The rigid big toe that eventually evolved gives efficient push-off power during walking and running.

The findings have been published in the journal Proceedings of the National Academy of Sciences.

In this new study, scientists made 3D scans of the toe bone joints from living and fossil human relatives, including primates such as apes and monkeys, and then compared them to modern day humans.

They overlaid this information onto an evolutionary tree, revealing the timing and sequence of events that produced the human forefoot.

The main finding is that the current shape of the bones in the big toe, or “hallux” in anatomical language, must have evolved quite late in comparison with the rest of the bones that they investigated.

In an interview with the BBC, lead author of the study Dr Peter Fernandez, from Marquette University in Milwaukee, said: “Our ability to efficiently walk and run on two feet, or be ‘bipedal’, is a crucial feature that enabled humans to become what they are today. For everything to work together, the foot bones first had to evolve to accommodate the unique biomechanical demands of bipedalism”.

He then said: “The big toe is mechanically very important for walking. In our study, we showed that it did not reach its modern form until considerably later than the other toes.”

When asked whether the rigid big toe evolved last because it is most or least important, Dr Fernandez commented: “It might have been last because it was the hardest to change. We also think there was a compromise. The big toe could still be used for grasping, as our ancestors spent a fair amount of their time in the trees, before becoming fully committed to walking on the ground.”

He added: “Modern humans have increased the stability of the joint to put the toe in an orientation that is useful for walking, but the foot is no longer dextrous like an ape.”vvvv

The reason that our ancestors stood upright and then walked on two feet is still a mystery, but there are plenty of ideas. Scientists think that walking may have evolved, either because it freed our hands to carry tools, or because climate change led to a loss of forests, or that overhead arms can be used to support walking on two legs along thin branches.

Studies such as this new one show that early human ancestors must have able been to walk upright for millions of years, since the 4.4 million year old fossil Ardipithecus ramidus, but that they did not fully transition to a modern walk until much later, perhaps in closer relatives within our own group, Homo.

This new study, alongside other work, now confirms that early walking humans, or “hominins” still used their feet to grasp objects.

Dr William Harcourt-Smith from City University of New York, who was not involved in this study, said: “They are suggesting that one of the earliest hominins, Ardipithecus, was already adapting in a direction away from the predicted morphology of the last common ancestor of chimps and modern humans, but not ‘towards’ modern humans. To me this implies that there were several lineages within hominins that were likely experimenting with bipedalism in different ways to each other.”

Professor Fred Spoor, an expert in human anatomy at the Natural History Museum, London said: “It was a bit of shock when hominins were found that have a grasping, or opposable, big toe, as this was thought to be incompatible with effective bipedalism. This work shows that different parts of the foot can have different functions. When a big toe is opposable, you can still function properly as a biped.”

The scientists involved say that this work shows that early hominin feet had a mixed and versatile set of functions. Becoming human was not a giant step, but a series of gradual changes, with some of the last and arguably most important changes being made to big toes. Peter Fernandez said that they would like to conduct similar analyses on the remaining bones of the forefoot, in order to fully characterise the changes involved in the evolution of bipedal walking.

https://www.bbc.co.uk/news/science-environment-45183651

Humans may have developed advanced social behaviours and trade 100,000 years earlier than previously thought.

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Olorgesailie Basin: the dig site spans an area of 65 square kilometres

This is according to a series of papers published today in Science.

The results come from an archaeological site in Kenya’s rift valley. “Over one million years of time” is represented at the site, according to Rick Potts from the Smithsonian Institution, who was involved in the studies.

There are also signs of developments in toolmaking technologies.

Environmental change may have been a key influence in this evolution of early Homo sapiens in the region of the Olorgesailie dig site.


The world turned upside down

Early humans were in the area for about 700,000 years, making large hand axes from nearby stone, explained Dr Potts.

“[Technologically], things changed very slowly, if at all, over hundreds of thousands of years,” he said.

Then, roughly 500,000 years ago, something did change.

A period of tectonic upheaval and erratic climate conditions swept across the region, and there is a 180,000 year interruption in the geological record due to erosion.

It was not only the landscape that altered, but also the plant and animal life in the region – transforming the resources available to our early ancestors.

When the record resumes, the way of life of these early humans has completely changed.

“The speed of the transition is really remarkable,” Dr Potts said. “Sometime in that [gap] there was a switch, a very rapid period of evolution.”

The obsidian road

New tools appeared at this time – small, sharp blades and points made from obsidian, a dark volcanic glass.

This technology marks the transition to what is known as the Middle Stone Age, explained Dr Eleanor Scerri from the University of Oxford.

Rather than shaping a block of rock, into a hand axe, humans became interested in the sharp flakes that could be chipped off. These were mounted on spears and used as projectile weapons.

Where 98% of the rock previously used by people in the Olorgesailie area had come from within a 5km radius, there were no sources of obsidian nearby.

People were travelling from 25km to 95km across rugged terrain to obtain the material, and “interacting with other groups of early humans over that time period”, according to Dr Potts.

This makes the site the earliest known example of such long distance transport, and possibly of trade.


(l to r) Hand axes, obsidian sharps and colour pigments discovered at the site

There is additional evidence that the inhabitants, who would likely have lived in small groups of 20-25 people, also used pigments like ochre. It is unclear whether these were merely practical or had a ritual social application.

Dr Marta Mirazon Lahr from the University of Cambridge said that being able to “securely date” the continuous occupation of the site using argon techniques on volcanic deposits “makes Olorgesailie a key reference site for understanding human evolution in Africa during [this period]”.

Human origins

Dr Scerri, who was not involved in the studies, emphasised that they are valuable in implying that “Middle Stone Age technology emerged at the same time in both eastern and northwestern Africa.”

Prof Chris Stringer from the Natural History Museum agrees.

“This makes me think that the Middle Stone Age probably already existed in various parts of Africa by 315,000 years ago, rather than originating in one place at that time and then spreading,” he said.

While the behaviours exhibited at the Kenya site are characteristic of Homo sapiens, there are as yet no fossils associated with this time period and location.

The oldest known Homo sapiens fossils were discovered in Morocco, and are dated to between 300,000 and 350,000 years old.

http://www.bbc.com/news/science-environment-43401157

Scientists Extract DNA From Ancient Humans Out of Cave Dirt

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by Jason Daley

Fiinding bones from early humans and their ancestors is difficult and rare—often requiring scientists to sort through the sediment floor of caves in far-flung locations. But modern advances in technology could completely transform the field. As Gina Kolta reports for The New York Times, a new study documents a method to extract and sequence fragments of hominid DNA from samples of cave dirt.

The study, published this week in the journal Science, could completely change the type of evidence available to study our ancestral past. Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, collected 85 sediment samples from seven archeological sites in Belgium, Croatia, France, Russia and Spain, covering a span of time from 550,000 to 14,000 years ago.

As Lizzie Wade at Science reports, when the team first sequenced the DNA from the sediments, they were overwhelmed. There are trillions of fragments of DNA in a teaspoon of dirt, mostly material from other mammals, including woolly mammoth, woolly rhinoceroses, cave bears and cave hyenas. To cut through the clutter and examine only hominid DNA, they created a molecular “hook” made from the mitochondrial DNA of modern humans. The hook was able to capture DNA fragments that most resembled itself, pulling out fragments from Neanderthals at four sites, including in sediment layers where bones or tools from the species were not present. They also found more DNA from Denisovans, an enigmatic human ancestor found only in single cave in Russia.

“It’s a great breakthrough,” Chris Stringer, anthropologist at the Natural History Museum in London tells Wade. “Anyone who’s digging cave sites from the Pleistocene now should put [screening sediments for human DNA] on their list of things that they must do.”

So how did the DNA get there? The researchers can’t say exactly, but it wouldn’t be too difficult. Humans shed DNA constantly. Any traces of urine, feces, spit, sweat, blood or hair would all contain minute bits of DNA. These compounds actually bind with minerals in bone, and likely did the same with minerals in the soil, preserving it, reports Charles Q. Choi at LiveScience.

There’s another—slightly scarier—option for the DNA’s origins. The researchers found a lot of hyena DNA at the study sites, Matthias Meyer, an author of the study tells Choi. “Maybe the hyenas were eating human corpses outside the caves, and went into the caves and left feces there, and maybe entrapped in the hyena feces was human DNA.”

The idea of pulling ancient DNA out of sediments is not new. As Kolta reports, researchers have previously successfully recovered DNA fragments of prehistoric mammals from a cave in Colorado. But having a technique aimed at finding DNA from humans and human ancestors could revolutionize the field. Wade points out that such a technique might have helped produce evidence for the claim earlier this week that hominids were in North America 130,000 years ago.

DNA analysis of sediments might eventually become a routine part of archeology, similar to radio carbon dating, says Svante Pääbo, director of the Evolutionary Genetics department at the Max Planck Institute for Evolutionary Anthropology, in the press release. The technique could also allow researchers to start searching for traces of early hominids at sites outside of caves.

“If it worked, it would provide a much richer picture of the geographic distribution and migration patterns of ancient humans, one that was not limited by the small number of bones that have been found,” David Reich, Harvard geneticist tells Kolta. “That would be a magical thing to do.”

As Wade reports, the technique could also solve many mysteries, including determining whether certain tools and sites were created by humans or Neanderthals. It could also reveal even more hominid species that we have not found bones for, creating an even more complete human family tree.

Read more: http://www.smithsonianmag.com/smart-news/new-technique-pulls-ancient-human-dna-out-cave-soil-180963084/#5gzaxagh8RYmlP6s.99

Neanderthals Likely Built These 176,000-Year-Old Underground Ring Structures

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By Taylor Kubota

About 40,000 years before the appearance of modern man in Europe, Neanderthals in southwestern France were venturing deep into the earth, building some of the earliest complex structures and using fire.

That’s according to new research that more precisely dated bizarre cave structures built from stalagmites, or mineral formations that grow upward from the floor of a cave. Scientists discovered about 400 stalagmites and stalagmite sections that were collected and stacked into nearly circular formations about 1,100 feet (336 meters) from the entrance of Bruniquel Cave, which was discovered in 1990.

Dating these formations to a time when Neanderthals, but not modern humans, were present in Eurasia, makes the finding the oldest directly dated constructions attributed to Neanderthals, according to Marie Soressi, an archaeologist at Leiden University in the Netherlands, who wrote a News and Views article in the same issue of the journal Nature in which the original study is published.

Dating bone
Soot stains, heat fractures and burnt material, including bone, point to the likelihood that these circles were used to contain fires back in the day.

In 1995, some of the burnt bone was dated using carbon-14 dating, a technique that measures the ratio of carbon-14 to carbon-12; that ratio indicates about how long an organism has been dead. It was found to be 47,600 years old — the maximum age carbon-14 dating can attain.

More recently, lead author Jacques Jaubert, of the University of Bordeaux in France, and his colleagues revisited this site, with more advanced surveying and dating technology. Through a technique called uranium-series dating, which relies on the breakdown of uranium to thorium, they were able to estimate when the stalagmites were broken and moved into the circular formations. They found the installations are approximately 176,500 years old (give or take 2,000 years).

Human-made structures
These structures are “among the oldest known well-dated constructions made by humans,” Jaubert and his colleagues wrote in their research paper published yesterday (May 26) in the journal Nature.

Evidence of a human-made structure exists in Olduvai Gorge in Tanzania, dated at over 1 million years old. But this has not been studied extensively, Jaubert said. He added there is similarly little information about a Homo erectus campsite in Bilzingsleben, Germany (about 400,000 years old), early shelters in Terra Amata, France (about 400,000 years old), and the bone and stone materials found in France’s Lazaret cave (around 170,000 years old). Researchers have credited Neanderthals with making a building out of mammoth bone in Ukraine. They believe this is about 40,000 years old.

“In any case, there are many examples of concentrations [of] remains, hearths, lithic [stone] workshops, faunal structures … but never the structures of this magnitude. And in this deep cave context!” Jaubert wrote in an email to Live Science. Before the Bruniquel Cave discovery, the cave paintings of Chauvet, France, were the oldest evidence of cave use by humans or human ancestors. Those date back a mere 38,000 years.

The amazing Bruniquel Cave
The Bruniquel Cave is located on private property, overlooking the Aveyron Valley, near a tributary of the Tarn. This area is rich in Paleolithic sites (dated to about 2.6 million to 10,000 years ago). Near the entrance is another important paleontological site of a similar age or potentially older, Jaubert said. The cave has a narrow entrance and is 33 to 49 feet (10 to 15 meters) wide, 13 to 23 feet (4 to 7 m) high, and — as far as anyone knows — 1,581 feet (482 m) long.

When the cave was first discovered, speleologists (people who study caves) meticulously preserved its natural formations, which aside from the stalagmite circles, include translucent flowstone, an underground lake and calcite rafts, or thin sheets of calcite that formed on the surface of the lake. Calcite is a rock-forming mineral found in limestone and marble. The speleologists also took care to keep Bruniquel’s bone remains and dozens of bear hibernation hollows in pristine condition. A thick layer of calcite had coated all the structures, making dating techniques difficult to perform.

For the next two decades, very few people visited the cave, Jaubert said. He thinks part of this may have been due to the death of the original researcher, archaeologist Francois Rouzaud. Additionally, he said the cave is challenging to access, not only physically but also because it is on private property and there are many conditions that need to be met in order for the owners and the French Ministry of Culture to authorize new research.

In 2013, using 3D-surveying equipment and magnetic measurements that record anomalies caused by heat, researchers were able to map both the stalagmite structures and the burnt remnants. Stalagmite arrangements of this scale are unprecedented, so the research team created the term “speleofacts” to describe each piece of stalagmite used in the structures. They estimate there were about 400 speleofacts total, with a combined weight of between 2.3 and 2.6 tons (2.1 and 2.3 metric tonnes) and a combined length of 367 feet (112 m). Jaubert said the stalagmites were the only raw material available for building in the cave.

Social Neanderthals
Until now, Neanderthals were “presumed by the scientific community not to have ventured far underground, nor to have mastered such sophisticated use of lighting and fire, let alone to have built such elaborate constructions,” according to a statement by the National Center for Scientific Research.

“This type of construction implies the beginnings of a social organization: This organization could consist of a project that was designed and discussed by one or several individuals, a distribution of the tasks of choosing, collecting and calibrating the speleofacts, followed by their transport (or vice versa) and placement according to a predetermined plan,” wrote the researchers in the Naturearticle. The researchers also said this process would have required adequate lighting and determined that the fires in the cave were likely used as light sources.

Given their distance from the cave entrance and daylight, the team said it was unlikely the circles were used as shelters. They didn’t rule out the possibility that they could have been used for technical purposes, such as water storage, or religious or ceremonial purposes. Jaubert said the next steps in studying the cave will include further examination of the structures, a more extensive survey of the cave’s interior to uncover any additional archaeological remains, and a closer look at the cave’s entrance.

The find has added extensively to scientists’ knowledge of Neanderthal social organization and human cave dwelling in prehistory, the researchers said. Even so, they added, the question remains: What were the structures used for?

– See more at: http://www.livescience.com/54906-neanderthals-built-bizarre-underground-ring-structures.html?#sthash.zM2MKLXT.dpuf

New 3 million year old human-like species discovered in South Africa indicates ritualistic behavior and symbolic thought, which were not previously considered possible earlier than 200,000 years ago.

On By A.P.In archeology, evolution, Science1 Comment

By

by Pallab Ghosh
Science correspondent, BBC News, Johannesburg

Scientists have discovered a new human-like species in a burial chamber deep in a cave system in South Africa. The discovery of 15 partial skeletons is the largest single discovery of its type in Africa.

The researchers claim that the discovery will change ideas about our human ancestors.

The studies which have been published in the journal Elife also indicate that these individuals were capable of ritualistic behaviour.

The species, which has been named naledi, has been classified in the grouping, or genus, Homo, to which modern humans belong.

The researchers who made the find have not been able to find out how long ago these creatures lived – but the scientist who led the team, Prof Lee Berger, told BBC News that he believed they could be among the first of our kind (genus Homo) and could have lived in Africa up to three million years ago.

Like all those working in the field, he is at pains to avoid the term “missing link”. Prof Berger says naledi could be thought of as a “bridge” between more primitive bipedal primates and humans.

“We’d gone in with the idea of recovering one fossil. That turned into multiple fossils. That turned into the discovery of multiple skeletons and multiple individuals.

“And so by the end of that remarkable 21-day experience, we had discovered the largest assemblage of fossil human relatives ever discovered in the history of the continent of Africa. That was an extraordinary experience.”

Prof Chris Stringer of the Natural History Museum said naledi was “a very important discovery”.

“What we are seeing is more and more species of creatures that suggests that nature was experimenting with how to evolve humans, thus giving rise to several different types of human-like creatures originating in parallel in different parts of Africa. Only one line eventually survived to give rise to us,” he told BBC News.

I went to see the bones which are kept in a secure room at Witwatersrand University. The door to the room looks like one that would seal a bank vault. As Prof Berger turned the large lever on the door, he told me that our knowledge of very early humans is based on partial skeletons and the occasional skull.

he haul of 15 partial skeletons includes both males and females of varying ages – from infants to elderly. The discovery is unprecedented in Africa and will shed more light on how the first humans evolved.

“We are going to know everything about this species,” Prof Berger told me as we walked over to the remains of H. naledi.

“We are going to know when its children were weaned, when they were born, how they developed, the speed at which they developed, the difference between males and females at every developmental stage from infancy, to childhood to teens to how they aged and how they died.”

I was astonished to see how well preserved the bones were. The skull, teeth and feet looked as if they belonged to a human child – even though the skeleton was that of an elderly female.
Its hand looked human-like too, up to its fingers which curl around a bit like those of an ape.

Homo naledi is unlike any primitive human found in Africa. It has a tiny brain – about the size of a gorilla’s and a primitive pelvis and shoulders. But it is put into the same genus as humans because of the more progressive shape of its skull, relatively small teeth, characteristic long legs and modern-looking feet.

“I saw something I thought I would never see in my career,” Prof Berger told me.

“It was a moment that 25 years as a paleoanthropologist had not prepared me for.”

One of the most intriguing questions raised by the find is how the remains got there.

I visited the site of the find, the Rising Star cave, an hour’s drive from the university in an area known as the Cradle of Humankind. The cave leads to a narrow underground tunnel through which some of Prof Berger’s team crawled in an expedition funded by the National Geographic Society.

Small women were chosen because the tunnel was so narrow. They crawled through darkness lit only by their head torches on a precarious 20 minute-long journey to find a chamber containing hundreds of bones.

Among them was Marina Elliott. She showed me the narrow entrance to the cave and then described how she felt when she first saw the chamber.

“The first time I went to the excavation site I likened it to the feeling that Howard Carter must have had when he opened Tutankhamen’s tomb – that you are in a very confined space and then it opens up and all of a sudden all you can see are all these wonderful things – it was incredible,” she said.

Ms Elliott and her colleagues believe that they have found a burial chamber. The Homo naledi people appear to have carried individuals deep into the cave system and deposited them in the chamber – possibly over generations.

If that is correct, it suggests naledi was capable of ritual behaviour and possibly symbolic thought – something that until now had only been associated with much later humans within the last 200,000 years.

Prof Berger said: “We are going to have to contemplate some very deep things about what it is to be human. Have we been wrong all along about this kind of behaviour that we thought was unique to modern humans?

“Did we inherit that behaviour from deep time and is it something that (the earliest humans) have always been able to do?”

Prof Berger believes that the discovery of a creature that has such a mix of modern and primitive features should make scientists rethink the definition of what it is to be human – so much so that he himself is reluctant to describe naledi as human.

Other researchers working in the field, such as Prof Stringer, believe that naledi should be described as a primitive human. But he agrees that current theories need to be re-evaluated and that we have only just scratched the surface of the rich and complex story of human evolution.

http://www.bbc.com/news/science-environment-34192447