Nearly 40,000 years after disappearing from the planet, Neanderthals are having a moment. In recent years, tantalizing new evidence suggests that our primitive, heavy-browed cousins were chefs, jewelry-makers and painters. And what we are learning from the genetic clues they left behind—and the promise of what those clues will tell us about ourselves in the years ahead—won Swedish paleo-geneticist Svante Pääbo the 2022 Nobel Prize in medicine and physiology this fall.
The most recent discoveries, un-earthed in a Siberian cave, show why scientists are so excited. By Neanderthal standards, the Chagyrskaya Cave qualified as luxury housing. The two-chambered, cliffside cavity in Southern Siberia's Altai Mountains boasted a three-story-high limestone entrance overlooking a vast, green river valley, from which residents could easily have spotted herds of migrating bison, horses, reindeer and other tasty game, or just reveled in the cave's King of the World views. "It's the perfect place," says Bence Viola, a paleontologist at the University of Toronto, who studies ancient humans.
Which is why Viola, a jovial, thirty-something Hungarian-born scientist who describes field work as "camping with friends," wasn't surprised when a longtime Russian collaborator pulled a fossilized mandible in a plastic bag out of his shirt pocket one vodka-fueled evening at a conference in 2010, and boisterously declared: "I have a surprise for you!" Viola was able to confirm by sight that the remarkably well-preserved fossil, dug out of the recently discovered cave's entrance, had come from a Neanderthal.
Even so, Viola couldn't have predicted how rich an archeological haul Chagyrskaya would yield. So far, the 11-year excavation has produced a treasure trove of 90,000 stone tools, 300,000 bone fragments and, as Viola and Russian collaborators laid out in the journal Nature in October, rice-sized samples from some of the 80 confirmed Neanderthal bones. These are the remains of the world's first known Neanderthal family—at least 11 genetically connected individuals, including a father, his teenage daughter and their cousins, who all perished around the same time, probably from starvation.
These and other finds, together with advanced technology that's become available to paleontologists within the last decade, have smashed the popular conception of Neanderthals as hairy, primitive, knuckle-dragging cavemen who carried clubs and spoke in grunts. Neanderthals, we now know, were likely more intelligent, sophisticated and complicated than previously believed. Pääbo and other scientists have rapidly increased their understanding of Neanderthals—and, by way of contrast, exactly what it means to be a modern human.
Many different species of humans—or "hominids," in the language of scientists—got their start in Africa. Waves of migration starting about two million years ago spread hominids to Europe, the Middle East and beyond. Neanderthals made the trek 200,000 years ago, and modern humans followed about 60,000 years ago. We lived side-by-side for about 20,000 years—an astonishingly brief moment in evolutionary time—and then Neanderthals died out, leaving modern humans as the only remaining hominid on the planet.
"This last time, 60,000 years ago, when we came out into a brutal world that was already inhabited by other hominids, it took just a few ticks of the evolutionary clock and we were on every continent, had mastered every ecosystem, and were causing mass extinctions everywhere we went," says Richard Green, a biomedical engineer from the University of California at Santa Cruz. "Neanderthals didn't do that. Neither did any other hominid. You could say that demands an explanation. What were the genetic and biological changes that underlie this last final step toward the human condition?"
The more similarities scientists find between modern humans and Neanderthals, the closer they get to pinpointing what it was that allowed us to win the evolutionary competition against a crowded field of hominid rivals, including the especially sophisticated Neanderthals.
A key 2021 study by Green and colleagues found that very little of modern human DNA is different from Neanderthals'—only 1.5 to 7 percent, depending on which region of the world the comparison is made. One possibility is that this DNA explains our evolutionary success. Perhaps it endows the modern-human brain with the capacity to build a large, organized civilization, or emboldens us to take risks that helped us thrive in a hostile and uncertain world?
It's also possible that the differences are too minor to matter. If so, perhaps our good fortune came down to dumb luck—perhaps some simple twist of fate condemned Neanderthals to eventual extinction and allowed modern humans to thrive in their place. Under different circumstances, could Neanderthals have inherited the Earth instead of us? It's still a mystery, but the air is thick with new clues.
A Quick Exit
The branch of the evolutionary tree that would eventually give rise to Homo sapiens neanderthalensis diverged from what would eventually become modern humans (Homo sapiens sapiens) roughly 400,000 to 450,000 years ago—a few milliseconds in evolutionary time. When Neanderthals left Africa, they spread north as far as Wales, south to the Middle East, and all the way to the far southeastern edge of Siberia, near where Russia, Mongolia, China and Kazakhstan converge. They roamed across the vast steppes of Siberia, endured European ice ages and survived as a species for an impressive 350,000 years—far longer than modern humans have been around. Then, about 40,000 years ago, they disappeared and were not heard from again until the mid-19th century.
In 1856, miners working in a limestone quarry in the Neander Valley, south-west of Düsseldorf in Western Germany, dug up an ancient skull cap and skeletal bones buried two feet deep in a newly unearthed clifftop cave. The arm, thigh, hip, ribs and shoulder blade were far heavier than normal bones, suggesting they were fossilized remains. The skull cap consisted of a fossilized piece of cranium that cut off just below a distinctive eyebrow ridge—a hard-boned, protruding unibrow, which jutted out, like a pair of thick stone parentheses glued end-to-end.
From the beginning, it was widely assumed that Neanderthals were our lesser relatives—crude, unintelligent and far below us on the evolutionary ladder. In recent decades, however, experts have begun to reconsider what we thought we knew about our strange, animal-fur clad cousins and their role in human history.
"Over the past decade there has been a development towards recognizing that they were more like modern humans that we thought," Pääbo told Newsweek.
Recent bio-mechanical analyses have established beyond a doubt that Neanderthals walked upright like us, says Rebecca Wragg Sykes, an archeologist at the University of Liverpool, and author of the 2020 book Kindred: Neanderthal Life, Love, Death and Art, which aims to provide a definitive account of what we know about Neanderthals. They were slightly shorter than us and far stockier, ranging from about 4 feet 9 inches to 5 feet 6 inches in height and weighing 140 to 180 pounds. Those body proportions had less overall surface area, which would have made it easier to conserve body heat in the frigid climes outside Africa. Their skulls were longer, with a forehead that sloped forward, rather than falling at the 90 degree angle distinctive to the top of the modern human face. Scientists believe they had larger noses that would have warmed and moistened freezing, dry air on its way to the lungs. Larger eye sockets suggest their vision was suited to low light conditions.
"If you saw a Neanderthal from behind, I think you would just think it's a person," Wragg Sykes told Newsweek. "When they turned around to look at you, yes, you might think, 'wow, I've never seen anybody that looks like this.' But you would still have an interaction with a person looking back at you. So the idea that they are some kind of very ancient primitive thing just does not fit at all in how we place them in an evolutionary sense, never mind when we actually look at the archeological evidence."
In recent years, scientists have tracked anatomical bone profusions that are often connected to powerful muscles, analyzed the wear patterns on teeth, and used computer simulations to draw a number of other conclusions about Neanderthals that would have been impossible in previous generations. Neanderthals were likely right-handed, had powerful upper arms (the dominant side was between 25 percent and 60 percent more developed than the nondominant side). This, some suggest, gave them superhuman strength when they wielded spears while hunting. Dental markings suggest they used their teeth almost like a third hand, as a vice-like apparatus for clenching hides between their lips as they meticulously scraped them, using tools to fashion the hides into warm clothes.
We know they formed deep emotional attachments to one another. Early Neanderthals left more evidence that they interacted with one another and buried their dead than early Homo sapiens (though in some sites they butchered the dead and ate them—perhaps, as many have speculated, as part of the grieving process). The Chagyrskaya family revealed evidence of sophisticated social organizations. "The key insight is that females seem to move between groups rather than men," says Pääbo, who is director of the Max Planck Institute for Evolutionary Anthropology and was a co-author of the paper. "That is something that's shown in the paper for the first time in a clear way. And that begins to say something about a social organization."
Remarkably, recent research shows that Neanderthals had some skill in the kitchen, modifying their food in complex ways to make it more palatable. Researchers at the University of Liverpool took microscopic pieces of burned, carbonized food found in and around ancient Neanderthal fire pits and, using an electron micrograph, bombarded it with electrons. By measuring the amount of energy reflected back, they determined the molecular composition of the charred crumbs. Then they compared the measurements to reference samples of food items accumulated over decades in fields that study more modern examples of cooking practices. Many of the fragments consisted of multiple plant components and seeds with "distinct flavor profiles," some of which might even make those eating them sick if not properly processed by soaking, pounding, or combining them with other items, says Ceren Kabukcu, the archaeobotanical scientist who co-authored a paper published in November in the scientific journal Antiquity.
"It's almost like what we consider today to be a recipe," Kabukcu told Newsweek. "Food is not just providing calories and energy but is part of a culinary repertoire. It suggests to me that there's a cultural complexity associated with the way they hunted and gathered."
Neanderthals, we now know, also used fire and cooking to create synthetic materials that could be used to make better tools and weapons. By analyzing chemical traces from sediments around fire, scientists have demonstrated that Neanderthals manufactured a primitive type of glue, known as birch tar, often found in North American indigenous populations, according to Wragg Sykes. The glue was likely used to add handles to tools, she says.
"You have to cook it out of birch and in order to make that process work. You have to manage your fire very carefully," Wragg Sykes says. "You can't let too much oxygen in or it doesn't work."
All of this suggests a high degree of intelligence. So what then sets modern humans apart?
Our Differences
Although it's still too early to make any concrete conclusions, new evidence offers tantalizing clues. The fossil record suggests Neanderthals had well-developed brains. While human brains are an estimated four times larger than that of chimpanzees, our closest living relatives, ancient hominid skulls suggest the brains of our ancestors began to expand dramatically about 2 million years ago, and reached the size of modern humans 600,000 years ago—some 200,000 years before we split from Neanderthal. Although the shape of the modern human brain differs from Neanderthals—ours is more spherical, their more elongated—the two versions are roughly equivalent in overall size.
Green, Pääbo and other researchers have also begun to use the tools of molecular biology. By consulting maps of the human genome and what's known about the function of various regions, Pääbo has made a list of the 30,000 genetic differences between Neanderthal and modern human genes that he considers most likely to have made a functional difference. Green, in his lab, has his own list.
Many parts of the genome that differ "tend to be enriched for genes and specifically genes that are expressed in neural tissue," says Green. This is "an indication that our neural development and perhaps cognitive function is just different than Neanderthals'."
To understand those differences, Pääbo, Green and many other laboratories are using cutting edge technologies to grow "brain organoids," colonies of neurons in dishes derived from DNA and stem cells, which have the capacity to develop into many different cell types, such as neurons. Scientists culture human brain cells and then tweak them, using the gene editing technology CRISPR-Cas9, to be more like the brain cells of Neanderthals. Then they observe what impact that tweak has on the development of the brain cells.
In 2017, a neurobiology group Pääbo frequently collaborates with identified a mutation unique to humans on a gene that becomes active in the developing human cortex, especially the frontal lobe—an area of the brain thought to be associated with expressive language, creativity, working memory and executive functions. Earlier this year in the journal Science, they published an intriguing study suggesting the mutation seems to cause stem cells to produce more neocortical neurons, a change that would allow our ancestors to produce extra neurons in the frontal lobes of the brain—a finding Paabo describes as "very exciting to me." Another recent paper found that other mutations in humans seem to allow neurons to develop with fewer genetic mistakes, which ensure that more will survive during development.
Using organoids, Green has identified a single genetic change in Neanderthals that when applied to human genes causes brain morphology to "go haywire." To him, this suggests he is interfering with an important process essential to normal brain development, which likely involves many other genes.
Understanding precisely what other genes he has interfered with—and precisely how they may have caused behavioral or cognitive changes that separated modern humans from Neanderthals—will likely take years. In the meantime, whether these changes are related to abstract thought or some other quality remains a matter of intense speculation.
Viola is skeptical that genetics will ever solve the mystery of why we were able to outcompete our Neanderthal cousins. (He is, after all, a trained archeologist, not a geneticist). In fact, he believes that the survival of modern humans over Neanderthals might not be due to genetic differences at all. "The DNA tells us a lot, but I don't think it will explain what really happened," he says.
He notes that small groups of hominids—like the Neanderthals—are likely extremely vulnerable to extinction. External factors like a natural disaster, a spate of bad weather or a pandemic can easily wipe out the entire population. The earliest humans in Europe, he notes, are not related to present day Europeans or even to Europeans who were there 10,000 years later. Despite all their neural bells and whistles, they were powerless in the face of the external challenges that killed them off.
"I think that we really can't overestimate the importance of luck," he says. "We know that a lot of modern populations who are genetically identical to us have been unsuccessful. They colonized areas and they just died off."
Our Equals?
Viola is not yet ready to rule out the possibility that, had Neanderthals survived instead of us, they might have reached the same level of sophistication. In recent years, archeological evidence has emerged in Neanderthal sites suggesting at least the beginning of that most human of human characteristics: the capacity for symbolic, complex thought, and at least rudimentary communication through the use of symbols.
In 2010, archeologists working in Southeastern Spain reported they had identified cockle and scallop shells found in two caves dating back 50,000 years (10,000 years before humans arrived), with what appeared to be man-made holes in them, along with traces of decorative red pigments, suggesting Neanderthals might have put painted shells on string and worn them as jewelry. Archeologists have found an eagle talon with a mix of pigment on it. Some have suggested they decorated themselves with feathers.
Some objects, bone and at least one stone appear to have been altered with crude markings, engravings or sizing lines. Paul Pettitt, professor of paleolithic archaeology at Durham University, says spots of red colored pigments, clearly used as paints, have been found in open air Neanderthal campsites dating back a quarter of a million years. Even a conservative interpretation of this evidence suggests they had a rudimentary grasp of nonverbal communication, he says, and thus, perhaps, the stirrings of symbolic thought and imagination.
"Parsimoniously, the best interpretation of this is that they were coloring their bodies in one way or another to add emphasis to however else they were communicating 'Don't mess with me, I'm big and strong and colored in red," he says. "And for the last 20 years or so, we've recognized that they were decorating their bodies. That's fairly uncontroversial."
Notably, the pigments, we now know, were even used for primitive cave art. In 2018 Pettitt and collaborators analyzed strange wall paintings made from red pigments found in three caves in Spain, a series of dots, lines, a rectangle and several dozen hand stencils, which he suggests were made by placing a hand against the wall and spitting wet pigment at it. By dating other cave materials found nearby in three caves in Spain, they estimated some of them to be 65,000 years old, well before modern humans arrived. At the time, one expert described this as "major breakthrough in the field of human evolution," telling Nature magazine that it "makes the case for a radical retelling of the human story, in which the behavior of modern humans differs from the Neanderthals by the narrowest of margins."
"In these caves they seem at the very least to be starting to use pigments to extend a message off their bodies and onto the cave walls, which is an external medium," Pettitt told Newsweek. "And this I think could be a very important cognitive crossroads in which you cease entirely dealing with each other face to face in the here and now and have the possibility of extending your messaging to each other in space and time by making it permanent on a wall."
This, he says, along with evidence of Neanderthals that died deep in caves—caves which they would have no other reason to explore than curiosity—"makes us think that there's something more going on there."
Perhaps the most intriguing and tantalizing possible suggestion that Neanderthals had the capacity for symbolic thought comes from deep within a cave in Southwest France, where explorers in the 1990s discovered an odd semicircular wall of stacked stalagmites. In 2016, researchers dated the find to about 176,000 years ago. The site, a little less than a quarter of a mile inside the cave, can only be reached through a narrow passage that requires, in places, crawling on all fours. The find consists of six man-made structures, composed of about 400 large pieces of stalagmite arranged in semi-circles, which researchers believe were once stacked on top of one another to form rudimentary walls, within which fires were likely built (most of the materials are partially burned).
"However we look at this enigmatic structure, it is very odd," Pettitt says. "We cannot explain it in any prosaic way. It doesn't need to be there, in a physical sense, and it must represent something about this intellectual curiosity that's now becoming so evident for those Neanderthals. The more we gain new data, the closer they become to us cognitively and behaviorally."
Green and Pääbo, however, dismiss the idea that it is simply luck that allowed modern humans to prevail over Neanderthals. They say the suddenness with which the species that became modern humans surged out of Africa and innovated in new ways suggests there was something about them that gave them an insurmountable advantage.
"For eons there were never more than a few hundred thousand early hominids at any one time in history," Pääbo says. "Their technologies changed quite slowly over time. They spread like other mammals. They didn't deliberately cross water unless they saw land on the other side. Then modern humans arrived at least 70,000 years ago. And things started to change."
The technology used by early humans around 100,000 years ago does not differ markedly from that of Neanderthals at the time. But then at some point between 50,000 and 100,000 years ago, there was an "almost exponential acceleration of how cultures develop," he says. Although we overlapped with Neanderthals for at least 10,000 years, they soon disappeared.
"The technology looked very similar wherever you looked—western Europe or Central Asia," Pääbo says. "But then with modern humans, it begins to change so rapidly that the technologies become regionalized—an expert can look at a tool and immediately say, 'this must come from southern Europe,' 'this must come from the Middle East.' That is new."
He believes the most likely explanation for modern human dominance has to do with their ability to form bigger groups, or more efficiently trade ideas than Neanderthals. He says he finds it hard to imagine that between 70,000 or 100,000 years ago, a new mutation spread that suddenly made everybody "smarter." But he could imagine that if we had a "propensity for developing bigger social groups and bigger societies" that over "a few 10,000 years" humans could outcompete Neanderthals.
Small group living, he notes, "was the situation probably with all early humans. It's the modern humans that are special here. Something changed with us."
"I would tend to think that Neanderthals individually may have been as smart as us," Pääbo says. "But my gut feeling would be there's something with sociality that allows modern humans to form bigger groups or be better in manipulating each other's worldview—traits necessary to form bigger societies, which may have many consequences, more innovation, for example. But this is really speculation."
The success of modern humans might come down to more than just our ability to interact with others. "Modern humans are crazy in ways others were not," he says "How many people must have sailed out on the Pacific and just perished before one found Easter Island? Right now we're going to Mars. Apparently, we have to go to Mars. We can't stop exploring. And of course it's culture, but it also feels to me that there is some biological basis for that, which makes this culture possible."
Pettitt, the archeologist, believes modern humans, as a species, may simply be a better "explorer of imaginary worlds." Growing evidence that we may have been able to grow more neurons in the frontal areas of the brain would support this theory.
Green believes all these things might be true. "I think we were masters of language and communication in a way that they weren't," he says. "If you think about how much you know personally and how much of that was communicated to you by others through written or spoken language, none of us individually does anything really. We stand on the shoulders of those who have gone before us and were kind enough to write things down. If Neanderthals were deficient even a little bit in that way compared to humans, then of course we win."
There's a long way to go until we find out. The field of human developmental biology still does not understand the genetic underpinnings of language and communication, he says. Our best hope lies in collecting more evidence in genetic gold mines like Chagyrskaya Cave. And perhaps a bit of luck.
Correction (1/5/2023): Paul Pettitt's name was misspelled in an earlier version. It has been corrected.
