The last days of the Neanderthals – National Geographic

The climate and early human societies were changing quickly during the fall of our closest evolutionary relative—and are big clues to the causes of their demise.Neanderthals (Homo neanderthalensis), are the human species that has attracted the most attention as our closest evolutionary relatives. The first fossils related to Neanderthals weren’t recognized as such until 1863, although they were discovered decades earlier. The ongoing intrigue should come as no surprise because, for a long time, Neanderthals were the model for the missing link between our own species, Homo sapiens, and the first apelike pre-human ancestors—but then they disappeared. This is the story of an extinction.In the past, Neanderthals were thought to be a European species that had disappeared without a trace. It was believed that their physical, intellectual, and technological “inferiority” had driven them to extinction, and that they were then replaced by the Cro-Magnons, early H. sapiens, who were also genuinely European. This progression fit in with 20th-century ideas about evolution, which was seen as an ascending process with H. sapiens at the peak. We were considered the species that had successfully completed the evolutionary process initiated millions of years ago.(What were Neanderthals really like—and why did they go extinct?)Today we know that human evolution was much more complex. Advances in research have overturned much of the old pejorative view of Neanderthals and undermined the idea that Europe was key to human evolution. We know now that modern humans and Neanderthals shared a common African ancestor less than 500,000 years ago (which, in evolutionary terms is the blink of an eye). Some have proposed Homo antecessor as that common ancestor of humans and Neanderthals, but this is far from generally accepted.For much of Homo sapiens’ existence, there were negligible physical differences between them and Neanderthals, and the cultural differences are archaeologically imperceptible. We have found that our distant cousins were as cognitively complex as we are. For a time we even interbred, successfully reproducing and giving rise to hybrid individuals that, in turn, reproduced as well.The inheritance of that interaction can be seen today: All humans now have 1 to 4 percent Neanderthal DNA in our genome.(You may have more Neanderthal DNA than you think.)The existence of so many similarities and the ability to hybridize have sparked debates for decades. Some researchers argue that H. sapiens and Neanderthals were actually members of a single species, which taxonomy—the classification of living beings—defines as a set of natural populations that are capable of interbreeding and producing fertile offspring. From this point of view, the Neanderthals would be a subspecies that evolved in Europe before being reabsorbed by the populations that arrived from Africa at the end of the Pleistocene (the long period of almost two million years that concluded when the last period of glaciation ended). Other scholars argue that the physical and genetic differences between the classic Neanderthals (those who lived from 200,000 years ago until their extinction) and the H. sapiens of the same period are still sufficient to keep each species in its own taxonomic box.But there’s something about the history of Neanderthals that continues to fascinate us: They became extinct. Neanderthals disappeared without a trace and were completely replaced by H. sapiens in every location they had inhabited for hundreds of thousands of years.Extinction is a natural part of biological evolution. It is estimated that 99.9 percent of all species that have ever existed have disappeared. So we must view the extinction of the Neanderthals as a natural historical process and not as an exception or a rarity.Many different factors are involved in natural extinction, the most common being competition between species and changes to ecosystems. These may be determining factors in the extinction of taxa or species when their populations face demographic and genetic problems, or they may not affect them at all when populations are in good health.Figures are difficult to come by when discussing human evolution, but here is an estimate: The Neanderthals became extinct around 40,000 to 37,000 years ago. According to the data currently available, we can safely say that there is no solid evidence that they lasted beyond this threshold. Now that we have a certainty, let’s move on to the nuances.To find out when an individual or a Neanderthal population lived and, therefore, when it disappeared, we use radiocarbon dating whenever possible. As a result of improvements in these techniques, some Neanderthals previously dated rather recently—such as those from Vindija (Croatia) at 28,000 years, or those from Spy (Belgium) at 30,000 years—are now dated more in accordance with the 40,000 to 37,000-year cutoff. However, some isolated populations were able to survive several millennia longer in certain regions. Ultimately, the very nature of radiometric dating will never give us a firm date for the extinction of Neanderthals but only a range of probability.From the viewpoint of biology and ecology, a species is considered extinct when its last individual dies. The popular image of the Neanderthals’ demise is a sequence in which a wandering, melancholic individual exhales his last breath in a mountain crevice while remembering his fellows who died before him. For a species to become extinct there obviously has to be a last individual, but nature works in a much more complex way. The affinity between Neanderthals and H. sapiens may have caused the last individuals to mix so that, rather than disappearing, the Neanderthals would have been diluted among the new African migrants.Before a taxon or species becomes extinct, it may be eradicated or pushed out of one of its natural ranges (e.g., because of changes in climate), thus greatly reducing the territory in which it can be found. Species may even be in a state of functional extinction, in which populations are not viable in the long term becuase of their small size. Recent analysis of DNA from a Neanderthal fossil found in the Mandrin Cave in France’s Rhône Valley reveals that the individual belonged to a hitherto unknown Neanderthal lineage, a tiny community that had remained in genetic isolation from other Neanderthals for some 50,000 years. The ability of these populations to survive isolated for so long shows how extraordinarily resilient they were.Before their final extinction, their populations were probably pushed out of most of their ranges, and they must have become isolated in separate groups with no gene flow between them.Genomic studies of Neanderthals from the caves of El Sidrón (Asturias, Spain), Vindija (Croatia), Mezmaiskaya (Caucasus), and Altai (Siberia) show that the last populations had very low genetic diversity. That means that they were small and very closed groups with cases of inbreeding. So, although some individuals may have interbred with other human species, by the end, most Neanderthal populations and subpopulations were physically and genetically isolated, and therefore functionally extinct. It is estimated that this process could have taken up to five millennia, between 42,000 and 37,000 years ago.(Ancient DNA reveals new twists in Neanderthal migration.)Although Neanderthals were once thought to have been exclusively European, their fossils have been found as far east as the Chagyrskaya and Denisova Caves in Altai (Siberia) and in the Bawa Yawan shelter in the Zagros Mountains (Iran).Certain stone tools allow us to conjecture that Neanderthals may have extended into East Asia and were very common in Central Asia. Therefore, it would be more correct to speak of a Eurasian taxon.(How a molar, jawbone, and pinkie are rewriting human history.)However, the last Neanderthal fossils or Mousterian archaeological sites, as the typical Neanderthal culture is called, come from the southern half of Europe. The Iberian Peninsula plays a fundamental role here. It is clear that Neanderthals spent their final centuries in sunny Andalusia, but when exactly they went extinct is a matter of debate. Studies carried out at Boquete de Zafarraya Cave (Málaga, Spain) in 2003 and Gorham’s Cave (Gibraltar) in 2006 yielded very recent dates, ranging between 33,000 and 28,000 years ago. These findings have since been questioned. It cannot be stated with certainty that these sites are less than 40,000 years old.Other Iberian sites south of the Ebro River—such as Cueva Antón and Sima de las Palomas (Murcia, Spain), Gruta da Oliveira (Portugal), and some levels of Gorham’s Cave—continue to provide relevant data to argue that if the Iberian Peninsula was not the last place where Neanderthals survived, it was the last in western Europe. However, it would not be strange if, in the near future, we found other populations like those in the Iberian Peninsula in Siberia and even farther east.(Why did Neanderthals and humans bury their dead? Scientists have a new theory.)One of the most important questions in paleoanthropology is why the Neanderthals became extinct. The reality is that we do not know for sure, but there are several hypotheses. A vast amount of time elapsed from the emergence of Neanderthals to their extinction. During the 350,000 or so years of this human species’ existence, the climate changed drastically dozens of times and did so on a global scale. This means that during the more than 13,000 generations of Neanderthals, places like the British Isles went from having sunny summers and mild winters to being buried under tons of ice.We know that Neanderthals lived through at least 10 major climatic oscillations known as interglacial and glacial periods with stadial (secondary advance of glaciers) and interstadial (recession or standstill of glaciers) periods. Local research indicates that southern Europe, not only the Mediterranean peninsulas but also the northern shore of the Black Sea and the Caucasus, were unaffected by extreme conditions at the coldest times. These areas acted as refuges to which flora and fauna had retreated before the advance of the ice. Once the ice receded, they returned to colonize their former ranges in renewed abundance.(Neanderthal teeth reveal intimate details of daily life.)Neanderthals were just pieces on the great ecosystem chessboard, and their range expanded and contracted in step with climate changes.Molecular and archaeological data tell us that there were several moments of splendor in which Neanderthals colonized territories to the north and east, perhaps going as far as Mongolia and China. A notable wave of expansion began from 130,000 years ago, and another from 60,000 years ago, in part due to mild climate periods. But the second expansion wave was relatively short-lived: Starting 55,000 years ago, a series of extreme, erratic, and very short climate events happened that made conditions completely unpredictable. Sometimes the changes occurred on a human scale and are believed to have had a terrible impact on Neanderthal populations, which entered a period of great uncertainty.If Neanderthals had adapted to more or less harsh climate periods dozens of times, did an unpredictable climate make them disappear? Perhaps not by itself. However, it is believed that climate was one of the main factors that pushed this species toward extinction.The climate was not only chaotic during oscillations; there were also successive tremendously cold pulses caused by the Heinrich and Dansgaard-Oeschger climatic events—a massive iceberg discharge and abrupt warming then a slow cooling of the Earth, respectively. As far as we know, these hominins did not develop technology that would enable them to survive in Arctic biomes; there was never evidence resembling adaptability like that of the Inuit. This feature may be of vital importance in understanding Neanderthal extinction in the context of those times of extreme cold.While different Neanderthal populations adapted to Mediterranean ecosystems— where it seems they diversified their diet to include an important contribution of vegetables; small animals, such as birds, rabbits, and turtles; and even marine resources—in northern Europe a much more austere way of life prevailed.There they depended on large herbivores, which were diminishing with the glacial cycles. Often, especially in cold periods, the Neanderthals of the European plains depended heavily on the meat of one or two main prey, such as bison in Mauran or reindeer in the Jonzac rock-shelter (both in France). The animal remains consumed at the sites do not indicate there were famines or shortages in these areas during the latest occupation. However, the more specialized a predator is—and the Neanderthals were exactly that—the easier it is to slide down the slope of extinction when the climatic situation worsens and the number of possible prey decreases.The middle of the Marine Isotope Stage 3 interglacial (about 45,000 years ago) produced an erratic climate that worsened from time to time. Neanderthal populations divided into small isolated groups, while a new human lineage of more recent African origin was timidly beginning to establish itself in the lower Danube Basin, coming from Africa or Asia.It was not the first time that Neanderthals and H. sapiens coexisted, as between 100,000 and 55,000 years ago both species had lived alongside one another without apparent conflict in the Near East.Many researchers argue that competition for resources and territory between the ancient settlers of Europe and the newcomers was the key element in tipping the balance against the Neanderthals.Although archaeologists do not see too many differences between Neanderthals and H. sapiens in terms of technology, diet, or how they occupied the territory, the first migrant H. sapiens who arrived in Europe brought Upper Paleolithic cultures with them. These included aspects that may have been of great importance in adapting to a world in crisis: needles for sewing elaborate clothing, harpoons for fishing and hunting aquatic animals, spear-throwers for long-distance hunting, and, above all, an impressive panoply of ornaments that indicate the existence of complex networks for long-distance exchange between groups.Coexistence has been documented through hybrid fossils. These include Oase 1 from the Pestera cu Oase (Romania), a jaw with a mixture of traits from H. sapiens and Neanderthals; and fossils from Bacho Kiro Cave (Bulgaria), which had one grandparent from each species just six to 10 generations before their birth. It has also been proposed that the transitional cultures between the Middle and Upper Paleolithic, such as the Châtelperronian, may have been the product of an exchange of ideas between the two human groups, which coexisted for at least three millennia in most of Europe.Perhaps the reproductive strategy was enough for modern humans to ecologically displace Neanderthals. Neanderthals may have devoted much effort to raising few children, an ecological strategy that favors specialized predators that live in balance with the environment. By contrast, newly arrived H. sapiens would have had more opportunistic ecological strategies, in which little effort was invested in the raising of large numbers of offspring, even if they had a relatively low probability of surviving into adulthood. Since small differences in the mortality rates of competing populations led to the extinction of the less competitive one, H. sapiens could have displaced other hominins in their global expansion.(World’s oldest cave art found—and Neanderthals made it.)What seems to be ruled out is aggressive confrontation: There is not a shred of evidence that H. sapiens deliberately “exterminated” Neanderthals. This is not a dichotomy between two homogeneous and differentiated human species. Both groups were diverse culturally and (most likely) phenotypically (that is, in their external appearance.)In some places and in some populations, they must not have differed too much. Nevertheless, contact between the two populations in Europe was likely sporadic. The extinction process of the European Neanderthals happened over an extended period of more than 5,000 years. The structure of Neanderthal populations (small, highly inbred groups), their reproductive strategies, their place in ecosystems, climate chaos, and the reduction in their main prey all created a discouraging panorama. Even large volcanic eruptions and meteorite impacts have been proposed as events that complicated matters for them.Perhaps if H. sapiens had not been expanding out of Africa, Neanderthal populations would have recolonized all of Eurasia in the following interglacial period for the umpteenth time from their refuges in southern Europe. Maybe they would have lasted many millennia longer. We will never know.Our species expanded around the globe at a speed never seen before and to areas that had never been visited by other hominins. In addition to the Neanderthals, H. sapiens met other humans of different species along the way: Denisovans in Central Asia, Homo luzonensis in the Pacific, Homo floresiensis in Southeast Asia, and surely others yet to be discovered.If, after 160 years of studying Neanderthals, we still do not have a definitive answer about their extinction, the path to understanding the disappearance of other human species appears equally long, and no less fascinating.Copyright © 1996-2015 National Geographic SocietyCopyright © 2015-2025 National Geographic Partners, LLC. All rights reserved

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