Axolotl
According to legend, the axolotl is the Aztec god of fire and lightning, Xolotl, who disguised himself as a salamander to avoid being sacrificed. But these amphibians are impressive enough on their own.
Axolotls (pronounced ACK-suh-LAH-tuhl) can regenerate lost limbs and have a life cycle that allows them to stay 'young' their whole lives, a phenomenon called neoteny.
Their youthful traits include feathery gills sprouting from their heads like a mane, webbed feet, a dorsal fin that runs down the length of their body, and a tail.
Though they keep these external gills, adults also have functional lungs and can breathe through their skin. And as if being forever-babies didn't make them cute enough, they wear a permanent Mona Lisa smile.
A popular oddity
These cute critters have long fascinated the public, even more so when they were first brought from Mexico to Paris in 1864. Europeans across the continent began breeding them. That began a robust pet trade in the animals, which breed easily in captivity.
In the wild, they're mostly grayish-brown in color. Lighter colored specimens, especially those with white bodies and pink gills, are usually bred as pets.
Yet in most countries, axolotls cannot be traded across international borders, partly because of poaching concerns.
They're illegal to own in some parts of the United States for the same reason. Some are also concerned that they may escape captivity and interbreed with native salamanders.
Thanks to their regenerative abilities, axolotls are a common research subject for biologists. They can regrow lost or damaged limbs, hearts, spinal cords, and even parts of their brains—all without permanent scarring.
Since scarring prevents tissue from regenerating, finding out how and why axolotls don't scar could unlock human's ability to regenerate tissue. One study deciphered how the axolotl's molecules communicate to promote regeneration.
A 2025 study may have cracked the code. A particular enzyme and gene work with retinoic acid to grow the right body part in the right spot.
(Scientists may have found the key to amphibian regeneration.)
Axolotl reproduction and behavior
Axolotls are solitary creatures, but they reach sexual maturity at a year old. Their spawning season in the wild is in February. Males seek out females, possibly using pheromones, and perform a courtship 'hula' dance. He shakes his tail and lower body. She responds by nudging him with her snout.
The male then deposits spermatophores, or sperm packets, on the lake floor, which the female picks up with her cloaca, a body cavity, and fertilizes her eggs.
Females can lay up to a thousand eggs (though the average is about 300) on plant material or rocks, which protects them from predators. After two weeks, they hatch and, with no parental care, the larvae are off and swimming on their own.
There's a theory for why axolotls don't change appearance as adults. Because their native lakes never dry up, as is the case for many other water bodies, axolotls didn't have to trade in their aquatic traits, such as a tadpole-like tail, for terrestrial ones, such as legs.
(Axolotls and capybaras are TikTok famous—and that could be a problem.)
Axolotl habitat and diet
These lentic amphibians live and breed in Lake Xochimilco and Lake Chalco, located just south of Mexico City. During the day, axolotls hide from predators by burrowing in the mud or hanging out among aquatic plants.
They become active at night, when their sweet little smiles quickly turn into vacuum cleaners. Axolotls suck in their prey, which includes crustaceans, mollusks, insect eggs, and small fish. They may also suck up gravel, which can help grind up the food in their belly.
Conservation and threats
An assessment by the International Union for the Conservation of Species found that only 50 to a thousand axolotls are left in the wild. And their numbers are dropping.
They once inhabited the high-altitude lakes around Mexico City, but habitat degradation has limited them to a few inland canals in the area.
Further habitat loss from tourism and residential housing development, in addition to agricultural and industrial pollution, have drastically reduced the axolotl population. So has the introduction of tilapia and other invasive fish species, which eat baby salamanders and compete with adults for food.
The Mexican government, as well as many nonprofits, are trying to save Mexican axolotls, in part by restoring parts of their freshwater natural habitat and offering ecotourism for people to see the quirky salamanders in the wild.
For instance, Luis Zambrano, a leading axolotl researcher at the National Autonomous University of Mexico, is working with scientists and farmers to create chinampas, floating islands made of water plants, logs, and lake mud that help filter the polluted water.
Some travel companies offer tours of these gardens, whose proceeds support axolotl conservation efforts in the area.
(Here's how farmers and scientists are saving the axolotl in Mexico City.)
Fascinating facts about axolotls
(Learn how Mexican nuns are helping to save axolotls.)
See axolotls in the wild According to legend, this 'water monster' was a god who disguised himself as a salamander to avoid sacrifice. Nowadays, it is critically endangered in the wild because of the pollution and urban sprawl that threaten its habitat in the Mexican Basin.
Is it OK to have an axolotl as a pet?
You can legally own one from a reputable breeder, supplier, or rescue organization. Some states in America prohibit owning even legally obtained exotic pets or require a permit. Axolotls bred in captivity are typically pink or white, instead of brown. —World Wildlife Fund
Why can't you touch axolotls?
In general, you should not touch or handle axolotls unnecessarily. Their delicate skin is permeable, which means anything from natural oils to soap residue can cause harm. Additionally, their bodies are primarily made of cartilage, making them highly vulnerable to injury. —Environmental Literacy Council
Do axolotls live in the U.S.?
They are not native to the United States. They are endemic to southern Mexico City, in Xochimilco and Chalco Lakes. —The Natural History Museum U.K.
Why did my axolotl turn into a salamander? It is extremely rare for wild axolotls to turn into salamanders. Environmental changes can cause a transformation and certain genetic traits can make some animals more prone to metamorphosis.
In captivity, iodine or thyroid hormones can induce metamorphosis. However, doing so can cause stress and shorten the life of these fragile creatures, leading to ethical questions. Experts strongly discourage inducing metamorphosis. —Environmental Literacy Council
Do axolotls have teeth?
Yes, they have small, underdeveloped teeth. However, they eat by sucking in food. —PBS
This story originally published on September 10, 2010. It was updated on June 17, 2025.
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The Hill
03-08-2025
- The Hill
What still causes the plague in the US?
(NEXSTAR) — Northern Arizona recently recorded its first pneumonic plague-related death since 2007. Early last year, Oregon saw its first case of the bubonic plague since 2015. Person-to-person spread of the plague hasn't been seen in more than 100 years in the U.S., but cases occasionally pop up. So what causes them? The plague cases reported in the U.S. today are not exactly the same as those seen in medieval Europe. Between 1347 and 1352 alone, it's estimated that the plague caused the deaths of at least 25 million Europeans. Rats aboard a ship from the Crimea and Asia that docked in Sicily are blamed for bringing the bubonic plague into Europe. Once fleas ran out of host rodents in Europe – those that lacked resistance to the plague also died – they sought out humans. Fungus labeled 'urgent threat' by CDC is spreading rapidly, hospital study finds Eventually, those who were sick or at risk of carrying the plague were isolated and put into quarantine, much like guidance issued during the COVID pandemic. A vaccine in the late 19th century, improved sanitation, better health practices and modern antibiotics have been credited with helping to stop the spread of the plague when it pops up. The U.S. now sees about seven cases annually, on average, according to estimates from the Centers for Disease Control and Prevention. The World Health Organization says most human cases over the last three decades have been in Africa. When cases do occur in the U.S., they're primarily in the West, with most reported in New Mexico and Arizona. Cases have also appeared within the region of southern Oregon, far western Nevada, and California. U.S. cases are, most often, bubonic. There are three main forms of the plague: bubonic (the most common during Europe's Black Death), septicemic, and pneumonic. Generally speaking, plague is brought on by the Yersinia pestis bacterium, with humans and mammals being affected. 'Quiet cracking' is the newest term for a workplace problem — and it's 'pretty pervasive,' expert says The three types of plague present with different symptoms and are caused by different things. Bubonic plague is caused by the bites of fleas that are mostly found on rodents. Symptoms of bubonic plague, the Cleveland Clinic explains, include a sudden high fever; chills; headaches; pain in the abdomen, arms, and legs; and large, swollen lymph nodes that can leak pus. While the bacteria will multiply in the lymph node where it entered the body, it's capable of spreading to other parts of the body if not treated with antibiotics. Septicemic plague has similar symptoms to bubonic plague, including fever, chills, extreme weakness, pain in the abdomen, shock, and the possibility of bleeding into the skin and other organs, the CDC explains. This form of plague can develop from untreated bubonic plague as well as from the handling of infected animals. Should a person with bubonic or septicemic plague go without treatment, and the bacteria reach their lungs, they can develop pneumonic plague. A person can also get pneumonic plague from breathing in 'droplets coughed out by another person or animal with pneumonic plague,' according to the CDC. Like other forms of plague, a person infected with pneumonic plague may develop a fever, headache, weakness, and pneumonia, with the latter developing 'rapidly.' While bubonic and septicemic plague may take a few days to set in, the incubation period for pneumonic plague may be just over a day, the CDC reports. It's the only form that can be spread person-to-person, and it is considered the most serious form of the disease. Between 2020 and 2023, the CDC reported 15 human plague cases were reported. Of those, three died. As the Cleveland Clinic explains, plague has to be treated with antibiotics as quickly as possible — taking antibiotics within 24 hours of symptoms gives you 'the best chance of getting better.' You could begin feeling better within a week or two, as long as you receive treatment, according to health experts. Regardless of the type of plague, about 90% survive with quick treatment. Untreated, 'plague is nearly always fatal,' the Cleveland Clinic said. Health officials have not said how the Arizona resident who died earlier this year of the pneumonic plague became infected. Oregon's case of bubonic plague last year was believed to be brought on by a pet cat. In recent years, Colorado has reported a cat testing positive for septicemic plague and a cat, two prairie dog colonies, and a squirrel testing positive for bubonic plague. Infected fleas are largely to blame for plague cases that occur in the U.S. today, but the handling of infected animals – like cats, rabbits, rats, mice, and squirrels, according to New York's Department of Health – has also been known to lead to the plague. To avoid getting the plague, it's recommended that you take steps to avoid flea bites. That includes wearing bug spray with DEET and clearing up spaces outside where the wild animals fleas love may live. It's also important to speak with your veterinarian about preventing fleas on your pets. Your pets should also not be allowed to roam outdoors freely if you live in an area prone to the plague.
National Geographic
22-07-2025
- National Geographic
The first Europeans weren't who you might think
Genetic tests of ancient settlers' remains show that Europe is a melting pot of bloodlines from Africa, the Middle East, and today's Russia. Three waves of immigrants settled prehistoric Europe. The last, some 5,000 years ago, were the Yamnaya, horse-riding cattle herders from Russia who built imposing grave mounds like this one near Žabalj, Serbia. DANUBIAN ROUTE OF YAMNAYA CULTURE PROJECT, NATIONAL SCIENCE CENTER, POLAND Photographs by Rémi Bénali This story appears in the August 2019 issue of National Geographic magazine. The idea that there were once 'pure' populations of ancestral Europeans, there since the days of woolly mammoths, has inspired ideologues since well before the Nazis. It has long nourished white racism, and in recent years it has stoked fears about the impact of immigrants: fears that have threatened to rip apart the European Union and roiled politics in the United States. Now scientists are delivering new answers to the question of who Europeans really are and where they came from. Their findings suggest that the continent has been a melting pot since the Ice Age. Europeans living today, in whatever country, are a varying mix of ancient bloodlines hailing from Africa, the Middle East, and the Russian steppe. (Modern Europe's Genetic History Starts in Stone Age) The evidence comes from archaeological artifacts, from the analysis of ancient teeth and bones, and from linguistics. But above all it comes from the new field of paleogenetics. During the past decade it has become possible to sequence the entire genome of humans who lived tens of millennia ago. Technical advances in just the past few years have made it cheap and efficient to do so; a well-preserved bit of skeleton can now be sequenced for around $500. The result has been an explosion of new information that is transforming archaeology. In 2018 alone, the genomes of more than a thousand prehistoric humans were determined, mostly from bones dug up years ago and preserved in museums and archaeological labs. In the process any notion of European genetic purity has been swept away on a tide of powdered bone. Analysis of ancient genomes provides the equivalent of the personal DNA testing kits available today, but for people who died long before humans invented writing, the wheel, or pottery. The genetic information is startlingly complete: Everything from hair and eye color to the inability to digest milk can be determined from a thousandth of an ounce of bone or tooth. And like personal DNA tests, the results reveal clues to the identities and origins of ancient humans' ancestors—and thus to ancient migrations. The horsemanship the Yamnaya brought to Europe lives on in their native region. A rider at the Zaporizhzhya Cossack Museum on Ukraine's Khortytsya Island demonstrates the acrobatic skills that made the Cossacks such feared warriors from the 1400s on. Three major movements of people, it now seems clear, shaped the course of European prehistory. Immigrants brought art and music, farming and cities, domesticated horses and the wheel. They introduced the Indo-European languages spoken across much of the continent today. They may have even brought the plague. The last major contributors to western and central Europe's genetic makeup—the last of the first Europeans, so to speak—arrived from the Russian steppe as Stonehenge was being built, nearly 5,000 years ago. They finished the job. In an era of debate over migration and borders, the science shows that Europe is a continent of immigrants and always has been. 'The people who live in a place today are not the descendants of people who lived there long ago,' says Harvard University paleogeneticist David Reich. 'There are no indigenous people—anyone who hearkens back to racial purity is confronted with the meaninglessness of the concept.' Yamnaya artifacts from their homeland in Russia and Ukraine include a four-foot-tall anthropomorphic stela from 3000 B.C. featuring axes and horses. YAVORNITSKY NATIONAL HISTORICAL MUSEUM, DNIPROPETROVSK, UKRAINE Thirty-two years ago the study of the DNA of living humans helped establish that we all share a family tree and a primordial migration story: All people outside Africa are descended from ancestors who left that continent more than 60,000 years ago. About 45,000 years ago, those first modern humans ventured into Europe, having made their way up through the Middle East. Their own DNA suggests they had dark skin and perhaps light eyes. Europe then was a forbidding place. Mile-thick ice sheets covered parts of the continent. Where there was enough warmth, there was wildlife. There were also other humans, but not like us: Neanderthals, whose own ancestors had wandered out of Africa hundreds of thousands of years earlier, had already adapted to the cold and harsh conditions. The first modern Europeans lived as hunters and gatherers in small, nomadic bands. They followed the rivers, edging along the Danube from its mouth on the Black Sea deep into western and central Europe. For millennia, they made little impact. Their DNA indicates they mixed with the Neanderthals—who, within 5,000 years, were gone. Today about 2 percent of a typical European's genome consists of Neanderthal DNA. A typical African has none. As Europe was gripped by the Ice Age, the modern humans hung on in the ice-free south, adapting to the cold climate. Around 27,000 years ago, there may have been as few as a thousand of them, according to some population estimates. They subsisted on large mammals such as mammoths, horses, reindeer, and aurochs—the ancestors of modern cattle. In the caves where they sheltered, they left behind spectacular paintings and engravings of their prey. DNA recovered from ancient teeth and bones lets researchers understand population shifts over time. As the cost of sequencing DNA has plummeted, scientists at labs like this one in Jena, Germany, have been able to unravel patterns of past human migration. MAX PLANCK INSTITUTE FOR THE SCIENCE OF HUMAN HISTORY About 14,500 years ago, as Europe began to warm, humans followed the retreating glaciers north. In the ensuing millennia, they developed more sophisticated stone tools and settled in small villages. Archaeologists call this period the Mesolithic, or Middle Stone Age. In the 1960s Serbian archaeologists uncovered a Mesolithic fishing village nestled in steep cliffs on a bend of the Danube, near one of the river's narrowest points. Called Lepenski Vir, the site was an elaborate settlement that had housed as many as a hundred people, starting roughly 9,000 years ago. Some dwellings were furnished with carved sculptures that were half human, half fish. Bones found at Lepenski Vir indicated that the people there depended heavily on fish from the river. Today what remains of the village is preserved under a canopy overlooking the Danube; sculptures of goggle-eyed river gods still watch over ancient hearths. 'Seventy percent of their diet was fish,' says Vladimir Nojkovic, the site's director. 'They lived here almost 2,000 years, until farmers pushed them out.' In Sweden, ancient rock carvings (enhanced with modern red paint) echo cultural shifts brought by migrants—starting with hunter-gatherers who came from Africa in the Ice Age and followed retreating glaciers north. Their DNA is still prevalent, especially in southern Baltic countries. Over millennia, migrating humans have used the Danube River, seen here at a narrow gorge between Serbia and Romania, as a highway from the Fertile Crescent into the heart of Europe. The site of Lepenski Vir, nearby in Serbia, was a haven for fishing hunter-gatherers—until farmers took over around 6000 B.C. The Konya Plain in central Anatolia is modern Turkey's breadbasket, a fertile expanse where you can see rainstorms blotting out mountains on the horizon long before they begin spattering the dust around you. It has been home to farmers, says University of Liverpool archaeologist Douglas Baird, since the first days of farming. For more than a decade Baird has been excavating a prehistoric village here called Boncuklu. It's a place where people began planting small plots of emmer and einkorn, two ancient forms of wheat, and probably herding small flocks of sheep and goats, some 10,300 years ago, near the dawn of the Neolithic period. Within a thousand years the Neolithic revolution, as it's called, spread north through Anatolia and into southeastern Europe. By about 6,000 years ago, there were farmers and herders all across Europe. It has long been clear that Europe acquired the practice of farming from Turkey or the Levant, but did it acquire farmers from the same places? The answer isn't obvious. For decades, many archaeologists thought a whole suite of innovations—farming, but also ceramic pottery, polished stone axes capable of clearing forests, and complicated settlements—was carried into Europe not by migrants but by trade and word of mouth, from one valley to the next, as hunter-gatherers who already lived there adopted the new tools and way of life. But DNA evidence from Boncuklu has helped show that migration had a lot more to do with it. The farmers of Boncuklu kept their dead close, burying them in the fetal position under the floors of their houses. Beginning in 2014, Baird sent samples of DNA extracted from skull fragments and teeth from more than a dozen burials to DNA labs in Sweden, Turkey, the U.K., and Germany. Many of the samples were too badly degraded after spending millennia in the heat of the Konya Plain to yield much DNA. But then Johannes Krause and his team at Germany's Max Planck Institute for the Science of Human History tested the samples from a handful of petrous bones. The petrous bone is a tiny part of the inner ear, not much bigger than a pinkie tip; it's also about the densest bone in the body. Researchers have found that it preserves genetic information long after usable DNA has been baked out of the rest of a skeleton. That realization, along with better sequencing machines, has helped drive the explosion in ancient DNA studies. Excavations at the 10,300-year-old site of Boncuklu in Turkey have revealed that people were living there during the transition to farming. The person buried here under the floor of a home likely would have farmed small plots of domesticated wheat, and may have herded goats and sheep, while continuing to forage. The Boncuklu petrous bones paid off: DNA extracted from them was a match for farmers who lived and died centuries later and hundreds of miles to the northwest. That meant early Anatolian farmers had migrated, spreading their genes as well as their lifestyle. They didn't stop in southeastern Europe. Over the centuries their descendants pushed along the Danube past Lepenski Vir and deep into the heart of the continent. Others traveled along the Mediterranean by boat, colonizing islands such as Sardinia and Sicily and settling southern Europe as far as Portugal. From Boncuklu to Britain, the Anatolian genetic signature is found wherever farming first appears. Those Neolithic farmers mostly had light skin and dark eyes—the opposite of many of the hunter-gatherers with whom they now lived side by side. 'They looked different, spoke different languages … had different diets,' says Hartwick College archaeologist David Anthony. 'For the most part, they stayed separate.' A woman harvests wheat by hand near Konya, Turkey. Farmers from Anatolia brought agriculture to Europe starting nearly 9,000 years ago. Within a few millennia, farmers and herders dominated most of the continent. Across Europe, this creeping first contact was standoffish, sometimes for centuries. There's little evidence of one group taking up the tools or traditions of the other. Even where the two populations did mingle, intermarriage was rare. 'There's no question they were in contact with each other, but they weren't exchanging wives or husbands,' Anthony says. 'Defying every anthropology course, people were not having sex with each other.' Fear of the other has a long history. About 5,400 years ago, everything changed. All across Europe, thriving Neolithic settlements shrank or disappeared altogether. The dramatic decline has puzzled archaeologists for decades. 'There's less stuff, less material, less people, less sites,' Krause says. 'Without some major event, it's hard to explain.' But there's no sign of mass conflict or war. After a 500-year gap, the population seemed to grow again, but something was very different. In southeastern Europe, the villages and egalitarian cemeteries of the Neolithic were replaced by imposing grave mounds covering lone adult men. Farther north, from Russia to the Rhine, a new culture sprang up, called Corded Ware after its pottery, which was decorated by pressing string into wet clay. The State Museum of Prehistory in Halle, Germany, has dozens of Corded Ware graves, including many that were hastily rescued by archaeologists before construction crews went to work. To save time and preserve delicate remains, the graves were removed from the ground in wooden crates, soil and all, and stored in a warehouse for later analysis. Stacked to the ceiling on steel shelves, they're now a rich resource for geneticists. Bones and artifacts some 7,700 years old found at Aktopraklik, a Neolithic village in northwestern Turkey, offer clues to the early days of agriculture. DNA extracted from the skulls of people buried here has helped researchers trace the spread of early farmers into Europe. BURSA CITY MUSEUM, TURKEY Corded Ware burials are so recognizable, archaeologists rarely need to bother with radiocarbon dating. Almost invariably, men were buried lying on their right side and women lying on their left, both with their legs curled up and their faces pointed south. In some of the Halle warehouse's graves, women clutch purses and bags hung with canine teeth from dozens of dogs; men have stone battle-axes. In one grave, neatly contained in a wooden crate on the concrete floor of the warehouse, a woman and child are buried together. When researchers first analyzed the DNA from some of these graves, they expected the Corded Ware folk would be closely related to Neolithic farmers. Instead, their DNA contained distinctive genes that were new to Europe at the time—but are detectable now in just about every modern European population. Many Corded Ware people turned out to be more closely related to Native Americans than to Neolithic European farmers. That deepened the mystery of who they were. Masked figures at the annual carnival in Ottana, a village on the Italian island of Sardinia, act out human mastery over animals, a theme dating to the early days of domestication. DNA of Europe's first farmers still dominates the genes of modern Sardinians. One bright October morning near the Serbian town of Žabalj, Polish archaeologist Piotr Włodarczak and his colleagues steer their pickup toward a mound erected 4,700 years ago. On the plains flanking the Danube, mounds like this one, a hundred feet across and 10 feet high, provide the only topography. It would have taken weeks or months for prehistoric humans to build each one. It took Włodarczak's team weeks of digging with a backhoe and shovels to remove the top of the mound. Standing on it now, he peels back a tarp to reveal what's underneath: a rectangular chamber containing the skeleton of a chieftain, lying on his back with his knees bent. Impressions from the reed mats and wood beams that formed the roof of his tomb are still clear in the dark, hard-packed earth. 'It's a change of burial customs around 2800 B.C.,' Włodarczak says, crouching over the skeleton. 'People erected mounds on a massive scale, accenting the individuality of people, accenting the role of men, accenting weapons. That's something new in Europe.' It was not new 800 miles to the east, however. On what are now the steppes of southern Russia and eastern Ukraine, a group of nomads called the Yamnaya, some of the first people in the world to ride horses, had mastered the wheel and were building wagons and following herds of cattle across the grasslands. They built few permanent settlements. But they buried their most prominent men with bronze and silver ornaments in mighty grave mounds that still dot the steppes. By 2800 B.C, archaeological excavations show, the Yamnaya had begun moving west, probably looking for greener pastures. Włodarczak's mound near Žabalj is the westernmost Yamnaya grave found so far. But genetic evidence, Reich and others say, shows that many Corded Ware people were, to a large extent, their descendants. Like those Corded Ware skeletons, the Yamnaya shared distant kinship with Native Americans—whose ancestors hailed from farther east, in Siberia. Within a few centuries, other people with a significant amount of Yamnaya DNA had spread as far as the British Isles. In Britain and some other places, hardly any of the farmers who already lived in Europe survived the onslaught from the east. In what is now Germany, 'there's a 70 percent to possibly 100 percent replacement of the local population,' Reich says. 'Something very dramatic happens 4,500 years ago.' Until then, farmers had been thriving in Europe for millennia. They had settled from Bulgaria all the way to Ireland, often in complex villages that housed hundreds or even thousands of people. Volker Heyd, an archaeologist at the University of Helsinki, Finland, estimates there were as many as seven million people in Europe in 3000 B.C. In Britain, Neolithic people were constructing Stonehenge. To many archaeologists, the idea that a bunch of nomads could replace such an established civilization within a few centuries has seemed implausible. 'How the hell would these pastoral, decentralized groups overthrow grounded Neolithic society, even if they had horses and were good warriors?' asks Kristian Kristiansen, an archaeologist at the University of Gothenburg in Sweden. A clue comes from the teeth of 101 people living on the steppes and farther west in Europe around the time that the Yamnaya's westward migration began. In seven of the samples, alongside the human DNA, geneticists found the DNA of an early form of Yersinia pestis—the plague microbe that killed roughly half of all Europeans in the 14th century. Unlike that flea-borne Black Death, this early variant had to be passed from person to person. The steppe nomads apparently had lived with the disease for centuries, perhaps building up immunity or resistance—much as the Europeans who colonized the Americas carried smallpox without succumbing to it wholesale. And just as smallpox and other diseases ravaged Native American populations, the plague, once introduced by the first Yamnaya, might have spread rapidly through crowded Neolithic villages. That could explain both their surprising collapse and the rapid spread of Yamnaya DNA from Russia to Britain. 'Plague epidemics cleared the way for the Yamnaya expansion,' says Morten Allentoft, an evolutionary biologist at the Natural History Museum of Denmark, who helped identify the ancient plague DNA. But that theory has a major question: Evidence of plague has only just recently been documented in ancient Neolithic skeletons, and so far, no one has found anything like the plague pits full of diseased skeletons left behind after the Black Death. If a plague wiped out Europe's Neolithic farmers, it left little trace. Whether or not they brought plague, the Yamnaya did bring domesticated horses and a mobile lifestyle based on wagons into Stone Age Europe. And in bringing innovative metal weapons and tools, they may have helped nudge Europe toward the Bronze Age. When construction of Stonehenge began about 3000 B.C., Britain was inhabited by Neolithic farmers. A millennium later, when it was finished, the Neolithic population had been replaced by descendants of the Yamnaya—perhaps because the latter carried plague. That might not have been the Yamnaya's most significant contribution to Europe's development. Their arrival on the continent matches the time linguists pinpoint as the initial spread of Indo-European languages, a family of hundreds that includes most languages spoken from Ireland to Russia to the northern half of India. All are thought to have evolved from a single proto-Indo-European tongue, and the question of where it was spoken and by whom has been debated since the 19th century. According to one theory, it was the Neolithic farmers from Anatolia who brought it into Europe along with farming. Another theory, proposed a century ago by a German scholar named Gustaf Kossinna, held that the proto-Indo-Europeans were an ancient race of north Germans—the people who made Corded Ware pots and axes. Kossinna thought that the ethnicity of people in the past—their biological identity, in effect—could be deduced from the stuff they left behind. 'Sharply defined archaeological cultural areas,' he wrote, 'correspond unquestionably with the areas of particular people or tribes.' The north German tribe of proto-Indo-Europeans, Kossinna argued, had moved outward and dominated an area that stretched most of the way to Moscow. Nazi propagandists later used that as an intellectual justification for the modern Aryan 'master race' to invade eastern Europe. Partly as a result, for decades after World War II the whole idea that ancient cultural shifts might be explained by migrations fell into ill repute in some archaeological circles. Even today it makes some archaeologists uncomfortable when geneticists draw bold arrows across maps of Europe. 'This kind of simplicity leads back to Kossinna,' says Heyd, who's German. 'It calls back old demons of blond, blue-eyed guys coming back somehow out of the hell where they were sent after World War II.' Yet ancient DNA, which provides direct information about the biology of ancient humans, has become a strong argument against Kossinna's theory. First, in documenting the spread of the Yamnaya and their descendants deeper and deeper into Europe at just the right time, the DNA evidence supports the favored theory among linguists: that proto-Indo-Europeans migrated into Europe from the Russian steppe, not the other way around. Second, together with archaeology it amounts to a rejection of Kossinna's claim that some kind of pure race exists in Europe, one that can be identified from its cultural artifacts. All Europeans today are a mix. The genetic recipe for a typical European would be roughly equal parts Yamnaya and Anatolian farmer, with a much smaller dollop of African hunter-gatherer. But the average conceals large regional variations: more 'eastern cowboy' genes in Scandinavia, more farmer ones in Spain and Italy, and significant chunks of hunter-gatherer DNA in the Baltics and eastern Europe. 'To me, the new results from DNA are undermining the nationalist paradigm that we have always lived here and not mixed with other people,' Gothenburg's Kristiansen says. 'There's no such thing as a Dane or a Swede or a German.' Instead, 'we're all Russians, all Africans.' From his base in Berlin, Andrew Curry writes about archaeology and other subjects. Rémi Bénali lives near Arles, France, where he photographed a Roman boat for the April 2014 issue.
Yahoo
19-07-2025
- Yahoo
Endurance athletes that carry Neanderthal genes could be held back from reaching their peak
When you buy through links on our articles, Future and its syndication partners may earn a commission. Scientists have uncovered a genetic variant, inherited from Neanderthals, that may limit athletic performance. The mutation is thought to affect roughly 8% of modern-day Europeans and influences the activity of a key enzyme in the production of energy in skeletal muscle. In a study published July 10 in the journal Nature Communications, researchers analyzed more than 2,700 individuals, which revealed that those who carried the Neanderthal gene variant were half as likely to become top athletes as those without the variant. The variant was found in up to 8% of present-day Europeans, 3% of Native Americans and 2% of South Asians, while it was absent in Africans, East Asians and African-Americans. "Since modern humans mixed with Neanderthals around 50,000 years ago, particularly in Europe and Western Asia, non-African populations today carry about 1–2% Neanderthal DNA," Dominik Macak, the study's first author and Doctoral Student at Max-Planck-Institute for Evolutionary Anthropology, told Live Science in an email. While the Neanderthal variant is not linked with any major health issues, its impact on the body's ability to produce energy during intense exercise could lead to reduced athletic performance in endurance and power sports, the researchers say. During exercise, cells gain energy by breaking down a molecule called adenosine triphosphate (ATP), often described as our body's "batteries". One way that our body creates ATP, particularly during intense exercise, is by turning two molecules of adenosine diphosphate (ADP) into one molecule of ATP and one of adenosine monophosphate (AMP). The ATP produced by this reaction is used to power energetic processes in our cells, while the AMP byproduct is removed by an enzyme called AMPD1. It's this enzyme that is impaired in those with the Neanderthal gene variant, the researchers found. To test the impacts of this gene variant, scientists recreated the Neanderthal version of the AMPD1 enzyme in the lab. They found that it was 25% less active than the enzyme produced in humans with other variants of the gene. Next, they genetically engineered mice to express the altered AMPD1 and found that the enzyme was up to 80% less active than the non-Neanderthal variant. RELATED STORIES — East Asians who can digest lactose can thank Neanderthal genes — Papua New Guineans, genetically isolated for 50,000 years, carry Denisovan genes that help their immune system, study suggests — Viking DNA helps reveal when HIV-fighting gene mutation emerged: 9,000 years ago near the Black Sea The researchers then analyzed the prevalence of the gene among elite athletes and non-athletes. They found that 4% to 14% of athletes carried this genetic variant, while 9% to 19% of non-athletes had the variant. Carrying just one copy of the Neanderthal gene (out of the two copies inherited from parents) led to a 50% lower probability of achieving elite athletic status, the data suggested. Those that carry the Neanderthal gene may struggle with more extreme exercise because the impaired enzyme will allow AMP to build up in their muscles, making it harder for them to produce ATP as fast as their cells need. However, having the Neanderthal gene variant is unlikely to affect most people's daily activities, where energy is obtained by other means. It is only during endurance sports or in exercises that demand muscular power that carriers might be at a slight disadvantage, the researchers said. But how might this variant have impacted the Neanderthals themselves? "It's very unlikely that this single genetic variant played a role in the extinction of the Neanderthals," Macak said. "We find it in both early and later Neanderthal individuals, suggesting it was stably present over thousands of years. Additionally, some modern humans today carry mutations that disrupt the AMPD1 protein entirely, often without any major health issues. So, while the gene affects muscle metabolism, it likely wasn't a decisive factor in their ability to survive."
