Climate Change Did Not Cause the Demise of Neanderthals

Climate Change Did Not Cause the Demise of Neanderthals

On August 29th 2018 The Smithsonian Institute announced “Climate records gathered from stalagmites in Romanian caves show two extremely cold dry periods correspond with the disappearance of Neanderthals.” And now, a new study of stalagmites in Italy has announced that “ Homo neanderthalensis did not become extinct because of changes in climate.” What are we make of such an extreme, 180-degree about turn in the scientific community?

The study was published in Nature Ecology & Evolution by a joint team of researchers led by Andrea Columbu from the University of Bologna in Italy and scholars from the University of Innsbruck in Austria, where the isotopic analyses were carried out. The radiometric dating was conducted by researchers from Australia's University of Melbourne and China's Xi'an Jiaotong University , and the original stalagmite samples were collected with assistance from Grotte di Castellana , the Apulian Speleology Association.

The new study has based its findings on the analysis of samples taken from caves on the Murge karst plateau in Apulia, Italy.

Paleoclimatic Reconstruction Exposes Flaws in Climate Change Hypothesis

For a long time, the extinction of Homo neanderthalensis was attributed to Homo sapiens moving into their territories and extending their hunting activities to Neanderthals themselves. More recently a shift of perspective caused archaeologists to believe changes in climate brought about the demise of Neanderthals. But, after a detailed paleoclimatic reconstruction of the last ice age, which involved the analysis of stalagmites sampled from caves on the Murge karst plateau in Apulia, Italy, the new study concludes that this supposed climate change did not, in fact, occur in the western Mediterranean 42,000 years ago.

According to the research team, Neanderthals and Homo sapiens coexisted in this region for at least 3,000 years, from approximately 45,000 to 42,000 years ago. Samples extracted from stalagmites show that climate change, during this time span and in this area of Apulia, was “not particularly significant.” Andrea Columbu explains that this new research demonstrates a climate niche during the transition from Neanderthals to Homo sapiens, which leads to the conclusion that “it doesn't seem possible that significant climate changes caused the extinction of Neanderthals in Apulia”.

The field of paleoclimatic reconstruction based on stalagmite samples opens the door to a whole new world of discoveries and advances in understanding about the past. ( Charles R. Knight / Public domain )

Stalagmites as Paleoclimatic and Paleoenvironmental Archives

Thanks to what is the first ever paleoclimatic reconstruction of these early Neanderthal-occupied areas, the research team has managed to rebut the mainstream archaeological and paleontological hypothesis that claims that climate change was the cause of the demise of Neanderthals. The results gained from the analysis of stalagmite samples appear to prove that this thesis does not apply to the Neanderthals who inhabited the Mediterranean area as far back as 100,000 years ago.

Rising from the floor of Karst Caves , these stalagmites were formed over millions of years from drips of water from the cave ceiling. Jo De Waele, a research coordinator and professor at the University of Bologna, explains in Eureka Alert that stalagmites are “excellent paleoclimatic and paleoenvironmental archives” providing unquestionable evidence of the presence or absence of rain. The calcite in stalagmites is composed of carbon and oxygen isotopes which reveal soil conditions and how much it rained during their formation. When all this data had been assembled and interpreted with radiometric dating, the researchers discovered that Apulian stalagmites showed a consistent pace of dripping in the last and previous ice ages. This means, according to the paper, that “no abrupt change in climate happened during the millennia under investigation” that might have caused Neanderthals' extinction .

  • Top Ten Myths about Neanderthals
  • Neanderthals Died Out due to Inbreeding and Bad Luck
  • Ten Amazing Caves of the Ancient World

The question of what caused the demise of Neanderthals has been preoccupying scientists since the first Neanderthal remains were discovered in 1829 by the Dutch naturalist Philippe-Charles Schmerling in Belgium. ( Thilo Parg / CC BY-SA 3.0 )

So, What Did Cause the Demise of Neanderthals?

The research concludes that there was little variation in rainfall between 50,000 and 27,000 years ago, while the carbon isotopes show that the bio-productivity of the soil samples remained consistent during this period. If climate change did not occur in this part of the Mediterranean, then scientists “may rule out” the hypothesis that it is responsible for the extinction of Neanderthals . So, if it wasn’t climate change , what caused the demise of Neanderthals after coexisting with Homo sapiens for about three thousand years?

Experts have been pondering the question of why Neanderthals became extinct since the beginnings of anthropology. When asked, Stefano Benazzi, a palaeontologist at the University of Bologna who is cited in the University of Bologna release , explains that the primary reason Homo sapiens achieved supremacy over Neanderthals “had to do with technology.” In other words, Homo sapiens developed new hunting technologies that were “far more advanced than Neanderthals” leading to the eventual extinction of our most notorious relatives.


Neanderthals died out after Earth's magnetic poles flipped, causing a climate crisis 42,000 years ago, a study says

Earth saw a lot of commotion when its magnetic poles flipped 42,000 years ago.

Scientists have known about the flip since the late 1960s. Earth's magnetic poles aren't static — they're generated by electric currents from the planet's liquid outer core, which is constantly in motion. As of late, Earth's magnetic North pole has wandered considerably on a path toward northern Russia.

But for the most part, scientists didn't think the last pole flip had a major environmental impact. Sure, the planet's magnetic field got weaker, allowing more cosmic rays to penetrate the atmosphere, but plant and animal life wasn't known to have been greatly affected.

A new study now suggests a more dramatic phenomenon occurred: The additional cosmic rays may have depleted ozone concentrations, opening the floodgates for more ultraviolet radiation in the atmosphere. Shifting weather patterns may have expanded the ice sheet over North America and dried out Australia, prompting the extinction of many large mammal species. A solar storm, meanwhile, might have driven ancient humans to seek shelter in caves.

As competition for resources grew, our closest extinct human relative, Neanderthals, may have died out.

"It would have been an incredibly scary time, almost like the end of days," Chris Turney, an Earth scientist at the University of New South Wales, said in a video describing the new research.

Scientists have not come to agree on a definitive theory about why Neanderthals disappeared. Some research suggests their extinction happened naturally, as Neanderthals inbred with modern humans or the population became too small to hunt, mate, and raise children. Other scientists have posited that Neanderthals may have been out-competed for resources as modern humans started to populate Europe.

But it's probably no coincidence that Neanderthals died out following a major shift of Earth's magnetic poles, Turney's study suggests.

"It was only when you started talking between different areas of science, you could see the connections," his co-author, Alan Cooper, said. "Before that, none of the different fields had worked out 42 [42,000 years ago] was the key event."


Cold climates contributed to the extinction of the Neanderthals

Climate change may have played a more important role in the extinction of Neanderthals than previously believed, according to a new study.

Climate change may have played a more important role in the extinction of Neanderthals than previously believed, according to a new study published in the journal, Proceedings of the Natural Academy of Sciences.

A team of researchers from a number of European and American research institutions, including Northumbria University, Newcastle, have produced detailed new natural records from stalagmites that highlight changes in the European climate more than 40,000 years ago.

They found several cold periods that coincide with the timings of a near complete absence of archaeological artefacts from the Neanderthals, suggesting the impact that changes in climate had on the long-term survival of Neanderthal man.

Stalagmites grow in thin layers each year and any change in temperature alters their chemical composition. The layers therefore preserve a natural archive of climate change over many thousands of years.

The researchers examined stalagmites in two Romanian caves, which revealed more detailed records of climate change in continental Europe than had previously been available.

The layers of the stalagmites showed a series of prolonged extreme cold and excessively dry conditions in Europe between 44,000 and 40,000 years ago. They highlight a cycle of temperatures gradually cooling, staying very cold for centuries to millennia and then warming again very abruptly.

The researchers compared these palaeoclimate records with archaeological records of Neanderthal artefacts and found a correlation between the cold periods - known as stadials - and an absence of Neanderthal tools.

This indicates the Neanderthal population greatly reduced during the cold periods, suggesting that climate change played a role in their decline.

Dr Vasile Ersek is co-author of the study and a senior lecturer in physical geography in Northumbria University's Department of Geography and Environmental Sciences. He explained: "The Neanderthals were the human species closest to ours and lived in Eurasia for some 350,000 years. However, around 40,000 years ago - during the last Ice Age and shortly after the arrival of anatomically modern humans in Europe - they became extinct.

"For many years we have wondered what could have caused their demise. Were they pushed 'over the edge' by the arrival of modern humans, or were other factors involved? Our study suggests that climate change may have had an important role in the Neanderthal extinction."

The researchers believe that modern humans survived these cold stadial periods because they were better adapted to their environment than the Neanderthals.

Neanderthals were skilled hunters and had learned how to control fire, but they had a less diverse diet than modern humans, living largely on meat from the animals they had successfully pursued. These food sources would naturally become scarce during colder periods, making the Neanderthals more vulnerable to rapid environmental change.

In comparison, modern humans had incorporated fish and plants into their diet alongside meat, which supplemented their food intake and potentially enabled their survival.

Dr Ersek said the research team's findings had indicated that this cycle of "hostile climate intervals" over thousands of years, in which the climate varied abruptly and was characterised by extreme cold temperatures, was responsible for the future demographic character of Europe.

"Before now, we did not have climate records from the region where Neanderthals lived which had the necessary age accuracy and resolution to establish a link between when Neanderthals died out and the timing of these extreme cold periods," he said, "But our findings indicate that the Neanderthal populations successively decreased during the repeated cold stadials.

"When temperatures warmed again, their smaller populations could not expand as their habitat was also being occupied by modern humans and this facilitated a staggered expansion of modern humans into Europe.

"The comparable timing of stadials and population changes seen in the archaeologic and genetic record suggests that millennial-scale hostile climate intervals may have been the pacesetter of multiple depopulation-repopulation cycles. These cycles ultimately drew the demographic map of Europe's Middle-Upper Paleolithic transition."

The Impact of climate change on the transition of Neanderthals to modern humans in Europe study involved academics from the universities of Northumbria (UK), Cologne (Germany) and South Florida, Tampa (USA) together with experts from the Institute of Speleology (Romania), the International Atomic Energy Agency (Austria), and the Max Planck Institute for Evolutionary Anthropology (Germany).

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.


Climate Change Did Not Cause the Demise of Neanderthals - History

Why is Homo neanderthalensis gone while Homo sapiens have bent the world to our will?

In recent years, there has been speculation that climate change wiped out Neanderthal people, or interbreeding with us, since many of us have DNA shared by Neanderthals (we also share 60 percent of our DNA with a banana) but a new paper affirms the earliest belief about survival of the fitter, commonly called survival of the fittest competition between Cro-Magnon and Neanderthal. And Neanderthals lost.

Cro-Magnon became a common name for homo sapiens when the first fossil to be recognized as belonging to our own species was discovered in 1868 at the Cro-Magnon archaeological site outside Les Eyzies, France. Homo neanderthalensis, commonly called Neanderthals, were identified from a find in the west German Neandertal Valley 12 years earlier. The narrative immediately sprang up that they were precursor 'cave men' to us in a straight evolutionary line but now it is recognized that they were a separate branch.

In the 20th century extinction hypotheses for the end of Neanderthals gave way to climate shifts but that is tricky because 90,000 of every 100,000 years in recent geological history have been ice ages, so Neanderthals survived at least three worse than the one they died during. Then there was speculation that they never went extinct at all, but just became part of us.

They died off too quickly for either of those to be plausible, which leaves the thing we do best competition and war.

A new paper attempts to do what many have tried in the past numerically quantify the drivers of Neanderthal extinction. Like all simulators, they use equations to create scenarios for how both Neanderthals and Homo sapiens as the landscape began to emerge from the last ice age. Since there was no agriculture, they competed for the same limited food resources. Like any good story, a few fell in love with each and had happy or perhaps tragic lives, but because we know how the scenario ends - Neanderthal was doomed - there are at least some reasonable parameters. And their model says modern man out-competed neanderthals.


The decline is too rapid to be anything but getting beat.

There could be other factors, of course. Europe gave the New World smallpox and the New World sent back syphilis. It is possible that neanderthals were wiped out by some kind of viral plague, the same way bees get wiped out by varroa mites and cause Colony Collapse Disorder as it spreads through managed hives.

But resource competition seems most likely, according to their simulation, and that would mean better tools. If modern man had better tools for hunting, they also had better tools for fighting. There are few instances were man or any other animal found itself hungry and did not fight for scarce food. While total war is not an evolutionary mandate, struggle is.

It could be that the first species we sent into extinction was our biological cousin.

I founded Science 2.0® in 2006 and since then it has become the world's largest independent science communications site, with over 300,000,000 direct.


Results

We first used average demographic rates extracted from the literature on hunter-gatherer humans and great apes as the average for a random draw. These rates were converted into annual rates (Table 1 column “Survival”) to parameterize the projection matrix and then to simulate population trajectories over a time period of 10,000 yrs (Fig 2A).

After few iterations the model converged to nearly asymptotic dynamics, and the average of the 10,000 simulated trajectories of the total Neanderthal population size and of the three subpopulations (A, B and C) stayed quite stable with a generation time of 25 yrs. With these demographic parameter values, the extinction probability over the 10,000 yrs was relatively low (P = 0.2) for the whole population and for the Westernmost subpopulations (A and B). The extinction probability for the Eastern subpopulation C, which happens to be the smallest too, was higher, reaching P = 0.6 (Table 2, column “Survival”).

We report the outcome of 10,000 simulated trajectories and the decrease in reproduction rate of primiparous women required for the extinction of Neanderthals in 10,000, 6,000 and 4,000 yrs.

We then successively decreased the value for the fertility rates of young females, initially set at 0.1415 (Table 1 column “Survival”) in each subpopulation A, B, and C. We found that by slightly altering the reproduction of young females to 0.1376 (-2.7%) in each subpopulation, the average total population size of Neanderthals fell below the threshold of 5,000 individuals within less than 10,000 yrs (Fig 2B). We tabulated the average time to extinction and probability of extinction for this model in Table 2 column “Demise in 10,000 yrs”. As expected from the imposed changes in demographic parameters, subpopulations did not become extinct at the same time, with the easternmost population (C) collapsing first, followed by the Northern subpopulation (B) and then the Southern subpopulation (A). We obtained comparable but more dramatic results when the fertility rate of younger women was further reduced to 0.1345 (-5%: Fig 2C, Table 2 column "Demise in 6,000 yrs") and even more when lowered to 0.1300 (-8%: Fig 2D, Table 2 column "Demise in 4,000 yrs"). Note that the models we proposed differ in the fertility rate of the younger females only as it adopted different values for each subpopulation each year. The difference between "stable" and "demise" fertility values is minimal, but large enough to bring about the disappearance of the Neanderthals over a period of between 10,000 and 4,000 yrs, without the need to take into account changes in survival rates.

Then we analyzed the effect of the reduction in survival (and consequently the increase in mortality) of infants (<1 y.o.). Starting again from the values of the demographic stability of the population (Table 1 column “Survival”), we decreased the survival rate and found that a decrease of 5% in the survival rate (0.6850) every year, holding the other parameters unchanged, led to an extinction of the population in 20 yrs. For the time to extinction of Neanderthals to match 10,000 yrs, we had to reduce survival by only 0.4% (0.7171) (Fig 3A), while a reduction by 1% (0.7128) causes an extinction in almost 6,000 yrs. We finally explored the possible effects of a disease transmitted by sapiens or of a conflict that would have substantially affected survival rates of adults: from the parameters of the "Survival" model reducing adult survival by 10% (keeping all other parameters identical), the whole Neanderthal population became extinct extremely fast (Fig 3B).

Parameters used in the simulation are shown in Table 1 “Survival”, reducing young infants survival by 0.4% (Fig 3A) or reducing adult survival by 10% (Fig 3B).


Why did the Neanderthals die out?

T he puzzle is one of the greatest surrounding our species. On a planet that bristled with different types of human being, including Neanderthals and the Hobbit-like folk of Flores, only one is left today: Homo sapiens.

Our current solo status on Earth is therefore an evolutionary oddity – though it is not clear when our species became Earth's only masters, nor is it clear why we survived when all other versions of humanity died out. Did we kill off our competitors, or were the others just poorly adapted and unable to react to the extreme climatic fluctuations that then beset the planet?

These key issues are to be tackled this week at a major conference at the British Museum, in London, called When Europe was covered by ice and ash. At the meeting scientists will reveal results from a five-year research programme using modern dating techniques to answer these puzzles.

In particular, researchers have focused on the Neanderthals, a species very close in physique and brain size to modern humans. They once dominated Europe, but disappeared after modern humans emerged from our African homeland around 60,000 years ago. The question is: why?

"A major problem in understanding what happened when modern humans appeared in Europe has concerned the dates for our arrival," said Professor Chris Stringer, of the Natural History Museum, London. "It was once thought we appeared in Europe around 35,000 years ago and that we coexisted with Neanderthals for thousands of years after that. They may have hung on in pockets – including caves in Gibraltar – until 28,000 years ago, it was believed."

In other words, there was a long, gradual takeover by modern humans – an idea that is likely to be demolished at this week's conference, Stringer said. Results from the five-year research programme, Reset (Response of humans to abrupt environmental transitions), will show that modern humans arrived much earlier than previously estimated and that Neanderthals expired earlier than we thought. Careful dating of finds across Europe suggest Homo sapiens could have reached Europe 45,000 years ago. Five thousand years later, Neanderthals had largely disappeared.

"Previous research on Neanderthal sites which suggested that they were more recent than 40,000 years old appears to be wrong," said Stringer. "That is a key finding that will be discussed at the conference."

Using radiocarbon technology to date remains that are 40,000 years old has always been tricky. Radioactive carbon decays relatively quickly and after 40,000 years there will only be a tiny amount left in a sample to measure. The tiniest piece of contaminant can then ruin dating efforts.

However, scientists have set out to get round these problems. At Oxford University, scientists led by Tom Higham have developed new methods to remove contamination and have been able to make much more precise radiocarbon dating for this period. In addition, Reset researchers have used evidence of a devastating eruption of the Campi Flegrei volcano west of Naples 39,000 years ago.

Recent studies have shown this eruption was much more destructive than previously recognised. More than 60 cubic miles of ash were blasted into the atmosphere and covered a vast area of eastern Europe, North Africa and western Asia. This layer gives scientists a precise means of dating for this period and, combined with the new radiocarbon dating, shows there seem to be no Neanderthal sites anywhere in Europe 39,000 years ago, a date 10,000 years earlier than previous estimates. It is a significant shift in our thinking about our nearest evolutionary cousins.

Some researchers have even suggested that Campi Flegrei – the biggest volcanic eruption in Europe for more than 200,000 years – would have had a catastrophic impact. Vast plumes of ash would have blotted out the sun for months, or possibly years, and caused temperatures to plummet. Sulphur dioxide, fluoride and chloride emissions would have generated intense falls of acid rain. Neanderthals may simply have shivered and choked to death.

The Campi Flegrei eruption not only gives us a date for the Neanderthals' disappearance, it may provide us with the cause of their extinction, though Stringer sounds a note of caution.

"Some researchers believe there is a link between the eruption and the Neanderthals' disappearance. But I doubt it," he said. "From the new radiocarbon dating and the work carried out by Reset scientists, it looks as if the Neanderthals had probably already vanished. A few may still have been hanging around, of course, and Campi Flegrei may have delivered the coup de grace. But it would be wrong to think the eruption was the main cause of the Neanderthals' demise."

So what did kill off the Neanderthals? Given the speed at which they seem to have disappeared from the planet after modern humans spread out of Africa, it is likely that Homo sapiens played a critical role in their demise. That does not mean we chased them down and killed them – an unlikely scenario given their muscular physiques. However, we may have been more successful at competing for resources, as recent research has suggested.

Eiluned Pearce and Robin Dunbar of Oxford University recently worked with Stringer and compared the skulls of 32 Homo sapiens and 13 Neanderthals, finding the latter had eye sockets that were significantly larger. These larger eyes were an adaptation to the long, dark nights and winters of Europe, they concluded, and would have required much larger visual processing areas in Neanderthal skulls.

By contrast, modern humans, from sunny Africa, had no need for this adaptation and instead they evolved frontal lobes, which are associated with high-level processing. "More of the Neanderthal brain appears to have been dedicated to vision and body control, leaving less brain to deal with other functions like social networking," Pearce told BBC News.

This point is stressed by Stringer. He said: "Neanderthal brains were as big as modern humans' but the former had bigger bodies. More of their brain cells would have been needed to control these larger bodies, on top of the added bits of cortex needed for their enhanced vision. That means they had less brain power available to them compared with modern humans."

Thus our ancestors possessed a fair bit of enhanced cerebral prowess, even though their brains were no bigger than Neanderthals'. How they used that extra brain power is a little trickier to assess, though most scientists believe it maintained complex, extended social networks. Developing an ability to speak complex language would have been a direct outcome, for example.

Having extended networks of clans would have been a considerable advantage in Europe, which was then descending into another ice age. When times got hard for one group, help could be sought from another. Neanderthals would have less backup. This point is supported by studies of the flints used for Neanderthal tools. These are rarely found more than 30 miles from their source. By contrast, modern humans were setting up operations that saw implements transported 200 miles.

Cultural life became increasingly important for humans. Research by Tanya Smith of Harvard University recently revealed that modern human childhoods became longer than those of Neanderthals. By studying the teeth of Neanderthal children, she found they grew much more quickly than modern human children. The growth of teeth is linked to overall development and shows Neanderthals must have had a much reduced opportunity to learn from their parents and clan members.

"We moved from a primitive 'live fast and die young' strategy to a 'live slow and grow old' strategy and that has helped make humans one of the most successful organisms on the planet," said Smith. Thus Neanderthals – who already lived in sparse, small populations across Europe – were fundamentally ill-equipped to deal with the newcomers who had arrived from Africa.

"There may not have been a single cause of Neanderthal extinction," said Stringer. "They may have disappeared in different regions for different reasons, but the background cause is clear. They didn't have the numbers."


Animals

These steppes supported enormous herbivores such as mammoth, mastodon, giant bison and woolly rhinoceros, which were well adapted to the cold. These animals were preyed upon by equally large carnivores such as saber toothed cats, cave bears and dire wolves.

The latest glacial retreat began the Holocene Epoch. In Europe and North America the mammoth steppes were largely replaced by forest. This change in climate and food resources began the extinction of the largest herbivores and their predators. However climate change was not the only factor in their demise a new predator was making itself known.


Why Did Humans Prevail?

NEW YORK — One hundred thousand years ago, several humanlike species walked the Earth. There were tribes of stocky Neanderthals eking out an existence in Europe and northwest Asia, and bands of cave-dwelling Denisovans in Asia. A diminutive, hobbitlike people called Homo floresiensis inhabited Indonesia. What were essentially modern humans roamed Africa.

Then, about 60,000 years ago, a few thousand of those humans migrated out of Africa. As they slowly moved into new territories over the course of generations, they encountered the Neanderthals, the Denisovans and the hobbit people — all of whom descended from hominin groups that had left Africa during prior waves of migration. DNA analysis shows the humans interbred with these strangers, but other details of the encounters are lost to history. One thing is clear: only humans remain.

Why did we prevail? A panel of experts discussed their latest interpretations of genetic and fossil evidence Saturday (June 2), at the fifth annual World Science Festival here in New York. Humanity's success, they said, appears to be a "revenge of the nerds" story of global proportions.

First, although Neanderthals had as big a brain as anyone, the shapes of their fossilized skulls indicate humans had slightly larger frontal lobes, said Chris Stringer, a paleoanthropologist at the Natural History Museum in London. That brain region controls decision-making, social behavior, and such uniquely human tendencies as creativity and abstract thought. Meanwhile, Neanderthals were broader and stronger than us, with especially powerful upper bodies, and their robustness made them better adapted to Europe's cold climate. "In a sense, we're wimps," Stringer said. "Physically, we didn't have any advantage over the Neanderthals — quite the opposite."

This would suggest brains won out over brawn, and that rather than destroying our enemies in some epic battle, our ancestors may simply have been savvier survivors, steadily growing our numbers while our burlier brethren met their demise.

Braininess helped us broaden our diets, for example. We had smaller teeth than Neanderthals, suggesting we put some of those superior abstract thinking skills toward processing food (such as pounding cooked yams), which would have conferred a major survival advantage. "The more processing you do before it goes in your mouth, the more energy you save," Stringer said. "If you want your kids to survive, you can process the food for them as well."

Ancient hunting tools such as snares and fishing nets suggest we may also have been more efficient hunter-gatherers. "Modern humans had technology that allowed them to get a more consistent, reliable and balanced diet," said Alison Brooks, an anthropologist at George Washington University. [Top 10 Technologies that Changed the World]

Another handy cognitive capacity allowed the rapid spread of new technologies, as well as the sharing of knowledge and information relevant for survival: We were — and clearly still are — adept social networkers. According to Brooks, excavations of ancient human settlements in Africa have turned up stashes of stone tools located as many as 100 kilometers from where the stones were quarried, implying the presence of a sophisticated and multidirectional trade network. "You're seeing a completely different approach to social organization in modern humans … than we're seeing in the Neanderthals," Brooks said. "Neanderthals simply did not do this."

Why didn't they? Such activities would have required the ability to communicate in great detail, which raises an important question in terms of the other hominins' demise: Were Neanderthals, Denisovans and Homo floresiensis capable of language, and if so, how well-developed was their system of communication? "If they could talk, then perhaps that's not the reason why we beat them, but if they couldn't, it's an obvious reason," said Ed Green, a genome biologist at the University of California, Santa Cruz, and a member of the team that sequenced the Neanderthal genome in 2010 using DNA from fossils. "If you think about all the things that you know, and calculate how much of that you figured out yourself versus what was told to you, it's obvious how important speech and language is and being able to communicate." [The Original Human Language Like Yoda Sounded]

Neanderthals probably did have some form of language. They appear to have had a gene that is crucial to language in humans, and they buried their dead, which seems too complex an idea to have arisen among a tribe of mutes. But Brooks argues they may have lacked the vocal cords necessary for complex communication. "The sounds they made would have been a little bit less distinct" — somewhat like the speech of a 2-year-old, she said. That would imply they communicated in small groups, but not with others in a network they simply wouldn't have been able to make sense of individuals with different accents.

Strangely coinciding with human beings' ability to cooperate is our tendency to be extremely aggressive. That, too, may have helped us prevail. "William James said 'history is a bloodbath.' And we should see that as a powerful generating force for what we are," said the Harvard evolutionary biologist E.O. Wilson. "If that trait is specific to our species as opposed to those competitors that fell before us, that could explain a lot."

Some combination of these cognitive and behavioral advantages led us to out-compete the other hominins, setting us on our uncontested path to world domination. "It's the really big brain 'Revenge of the Nerds' story," Green said. "There are 7 billion of us and maybe 100,000 of the most populous great apes. We've not only crowded out all the other hominin forms, but we're also on our way to crowding out all the other great apes."

In fact, we're so darn smart, we're in a bit of a pickle. "Our biggest danger right now is really our success," Green said. "We're taxing the world in a way that's never been done before, and so hopefully we're smart enough to figure out a solution to that problem."

This story was provided by Life's Little Mysteries, a sister site to LiveScience. Follow Natalie Wolchover on Twitter @nattyover. Follow Life's Little Mysteries on Twitter @llmysteries, then join us on Facebook & Google+.


Why did the Neanderthals die out?

We once lived alongside Neanderthals, but interbreeding, climate change, or violent clashes with rival Homo sapiens led to their demise.

Asked by: Joe Adams, London

Until around 100,000 years ago, Europe was dominated by the Neanderthals. But by 28,000 years ago, the last of them had vanished from their final hold-out in Gibraltar, having apparently lost out to modern humans (Homo sapiens) arriving from Africa.

Various explanations have been suggested. A popular theory is that they gradually interbred with the new arrivals, and their genes just faded out. Studies of DNA extracted from Neanderthal fossils have so far failed to produce a definitive answer: some researchers claim the DNA is too different from that of humans to permit interbreeding, while others disagree. Another theory is that they fell victim to climate change. There’s evidence for dramatic ‘cold snaps’ around 25,000-40,000 years ago – roughly coinciding with the extinction of the Neanderthals. But some palaeontologists claim that the physical build and clothing of Neanderthals suggest they were able to cope with the conditions.

They may, however, have found themselves in a violent struggle for resources, losing out to the cunning of Homo sapiens. And of course, the real cause of their disappearance may have been some combination of all of the above.

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.


‘Blue screen of death’ for dinosaurs

The research team from Imperial College London, the University of Bristol and University College London combined geological markers of climate, powerful mathematical models, and the climate features—such as rainfall and temperature—that each species of dinosaur needed to thrive. They then mapped where these conditions would still exist in a world after either an asteroid strike or massive volcanism.

“In this study we add a modelling approach to key geological and climate data that shows the devastating effect of the asteroid impact on global habitats,” said co-author Dr Philip Mannion, from University College London. “It produces a blue screen of death for dinosaurs.”