One incredible ocean crossing may have made human evolution possible

https://theconversation.com/one-incredible-ocean-crossing-may-have-made-human-evolution-possible-157479

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April 29, 2021 11.12am EDT

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1. Nicholas R. LongrichSenior Lecturer in Evolutionary Biology and Paleontology, University of Bath

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Humans evolved in Africa, along with chimpanzees, gorillas and monkeys. But primates themselves appear to have evolved elsewhere – likely in Asia – before colonising Africa. At the time, around 50 million years ago, Africa was an island isolated from the rest of the world by ocean – so how did primates get there?

A land bridge is the obvious explanation, but the geological evidence currently argues against it. Instead, we’re left with a far more unlikely scenario: early primates may have rafted to Africa, floating hundreds of miles across oceans on vegetation and debris.

Such oceanic dispersal was once seen as far-fetched and wildly speculative by many scientists. Some still support the land bridge theory, either disputing the geological evidence, or arguing that primate ancestors crossed into Africa long before the current fossil record suggests, before the continents broke up.

But there’s an emerging consensus that oceanic dispersal is far more common than once supposed. Plants, insects, reptiles, rodents and primates have all been found to colonise island continents in this way – including a remarkable Atlantic crossing that took monkeys from Africa to South America 35 million years ago. These events are incredibly rare but, given huge spans of time, such freak events inevitably influence evolution – including our own origins.

Primate origins

Humans appeared in southern Africa between 200,000–350,000 years ago. We know we come from Africa because our genetic diversity is highest there, and there are lots of fossils of primitive humans there.

Our closest relatives, chimps and gorillas, are also native to Africa, alongside baboons and monkeys. But primates’ closest living relatives – flying lemurs, tree shrews and rodents – all inhabit Asia or, in the case of rodents, evolved there. Fossils provide somewhat conflicting evidence, but they also suggest primates arose outside of Africa.

Primates have differentiated over tens of millions of years. Nicholas R. Longrich/Wikimedia

The oldest primate relative, Purgatorius, lived 65 million years ago, just after the dinosaurs disappeared. It’s from Montana.

The oldest true primates also occur outside Africa. Teilhardina, related to monkeys and apes, lived 55 million years ago, throughout Asia, North America, and Europe. Primates arrived in Africa later. Lemur-like fossils appear there 50 million years ago, and monkey-like fossils around 40 million years ago.

But Africa split from South America and became an island 100 million years ago, and only connected with Asia 20 million years ago. If primates colonised Africa during the 80 million years the continent spent isolated, then they needed to cross water.

The continents 50 million years ago, when primates colonised Africa. Deeptimemaps, Author provided (No reuse)

Ocean crossings

The idea of oceanic dispersal is central to the theory of evolution. Studying the Galapagos Islands, Darwin saw only a few tortoises, iguanas, snakes, and one small mammal, the rice rat. Further out to sea, on islands like Tahiti, were only little lizards.

Darwin reasoned that these patterns were hard to explain in terms of Creationism – in which case, similar species should exist everywhere – but they made sense if species crossed water to colonise islands, with fewer species surviving to colonise more distant islands.

He was right. Studies have found tortoises can survive weeks afloat without food or water – they probably bobbed along until hitting the Galapagos. And in 1995, iguanas swept offshore by hurricanes washed up 300km away, very much alive, after riding on debris. Galapagos iguanas likely travelled this way.

Floating 800km from the Seychelles to Africa, this tortoise washed up on shore – covered in barnacles, but alive. Catharine Muir

The odds are against such crossings. A lucky combination of conditions – a large raft of vegetation, the right currents and winds, a viable population, a well-timed landfall – is needed for successful colonisation. Many animals swept offshore simply die of thirst or starvation before hitting islands. Most never make landfall; they disappear at sea, food for sharks. That’s why ocean islands, especially distant ones, have few species.

Rafting was once treated as an evolutionary novelty: a curious thing happening in obscure places like the Galapagos, but irrelevant to evolution on continents. But it’s since emerged that rafts of vegetation or floating islands – stands of trees swept out to sea – may actually explain many animal distributions across the world.

Rafting

Several primate rafting events are well established. Today, Madagascar has a diverse lemur fauna. Lemurs arrived from Africa around 20 million years ago. Since Madagascar has been an island since the time of the dinosaurs, they apparently rafted the 400 kilometre-wide Mozambique Channel. Remarkably, fossils suggest the strange aye-aye crossed to Madagascar separately from the other lemurs.

Even more extraordinary is the existence of monkeys in South America: howlers, spider monkeys and marmosets. They arrived 35 million years ago, again from Africa. They had to cross the Atlantic – narrower then, but still 1,500 km wide. From South America, monkeys rafted again: to North America, then twice to the Caribbean.

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Read more: Monkey teeth fossils hint several extinct species crossed the Atlantic

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But before any of this could happen, rafting events would first need to bring primates to Africa: one brought the ancestor of lemurs, another carried the ancestor of monkeys, apes, and ourselves. It may seem implausible – and it’s still not entirely clear where they came from – but no other scenario fits the evidence.

Several primate rafting events are well established. R.Blakey/Wikimedia, Author provided (No reuse)

Rafting explains how rodents colonised Africa, then South America. Rafting likely explains how Afrotheria, the group containing elephants and aardvarks, got to Africa. Marsupials, evolving in North America, probably rafted to South America, then Antarctica, and finally Australia. Other oceanic crossings include mice to Australia, and tenrecs, mongooses and hippos to Madagascar.

Oceanic crossings aren’t an evolutionary subplot; they’re central to the story. They explain the evolution of monkeys, elephants, kangaroos, rodents, lemurs – and us. And they show that evolution isn’t always driven by ordinary, everyday processes but also by bizarrely improbable events.

Macroevolution

One of Darwin’s great insights was the idea that everyday events – small mutations, predation, competition – could slowly change species, given time. But over millions or billions of years, rare, low-probability, high-impact events – “black swan” events – also happen.

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Read more: Black swans and other deviations: like evolution, all scientific theories are a work in progress

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Some are immensely destructive, like asteroid impacts, volcanic eruptions, and ice ages – or viruses jumping hosts. But others are creative, like genome duplications, gene transfer between multicellular species – and rafting.

The role rafting played in our history shows how much evolution comes down to chance. Had anything gone differently – the weather was bad, the seas rough, the raft washed up on a desert island, hungry predators waited on the beach, no males aboard – colonisation would have failed. No monkeys, no apes – no humans.

It seems our ancestors beat odds that make Powerball lotteries seem like a safe bet. Had anything had gone differently, the evolution of life might look rather different than it does. At a minimum, we wouldn’t be here to wonder about it.

How new discoveries in west Africa could rewrite pre-history

https://qz.com/africa/1996308/what-do-we-know-about-human-evolution/

Archaeology in West Africa could rewrite the textbooks on human evolution.

By Eleanor Scerri

Independent Group Leader, Max Planck Institute for the Science of Human HistoryApril 17, 2021

Our species, Homo sapiens, rose in Africa some 300,000 years ago. The objects that early humans made and used, known as the Middle Stone Age material culture, are found throughout much of Africa and include a vast range of innovations.

Among them are bow and arrow technology, specialized tool forms, the long-distance transport of objects such as marine shells and obsidian, personal ornamentation, the use of pigments, water storage, and art. Although it is possible that other ancestors of modern humans contributed to this material culture in Africa, some of the earliest Middle Stone Age stone tools have been found with the oldest Homo sapiens fossils found so far.

The textbook view is that by around 40,000 years ago, the Middle Stone Age had largely ceased to exist in Africa. This was a milestone in the history of our species: the end of the first and longest lasting culture associated with humanity, and the foundation for all the subsequent innovations and material culture that defines us today.

Despite its central role in human history, we have little understanding of how the Middle Stone Age ended. Such an understanding could tell us how different groups were organized across the landscape, how they may have exchanged ideas and genes, and how these processes shaped the later stages of human evolution.

Unfortunately, vast swathes of Africa remain near complete blanks on the map when it comes to such deep prehistory, making it difficult to address these questions. Research has tended to focus on areas such as eastern Africa, where preservation is known to be high, understandably minimizing risks and maximizing gains. However, the emerging consensus that all of Africa played some role in human origins means that we can no longer afford to neglect vast regions of the continent if we want to reconstruct our evolution in a realistic framework.

For these reasons, my colleagues and I have been focusing on west Africa, one of the least well understood African regions for human evolution. And our recent work is validating earlier claims of a rich Middle Stone Age past.

New work in Senegal

In 2014, our work in Senegal led to the discovery of a site in the country’s north that suggested the Middle Stone Age ended there far more recently than the textbooks suggested. Several young dates in west Africa had been reported in the past, but the work was largely dismissed owing to problematic dating conducted before the present-day standards existed.

Dates from Ndiayène Pendao indicated that the site was around 12,000 years old. Yet the material culture was classically Middle Stone Age, without any Later Stone Age tools or production methods. In 2016 and 2018, we returned to the field to look for sites in different regions of Senegal and on different river systems, on tributaries of the Senegal and the Gambia. This is because sources of fresh water were critical to people in the past, just as they are to people today; river terraces also often offer excellent preservation conditions and are therefore good places to search for archaeological sites.

The site of Laminia on the Gambia had never been dated. We conducted a detailed assessment of its rock layers to obtain dating samples we could confidently link to the artifacts. The samples returned a date of 24,000 years ago for the site, which confirmed that a young Middle Stone Age was indeed present in the region.

The site of Saxomununya produced an even greater surprise. As the classically Middle Stone Age artifacts, such as retouched Levallois points, and ‘scrapers’, from this site were found upon and within a young terrace of the Falémé River, it was obvious that the site was relatively young. However, the date of 11,000 years ago took the youngest Middle Stone Age into the Holocene epoch, the period after the last major ice age. This was the first time such old material culture had been found in such recent times in Africa. It indicated that the results from Ndiayène Pendao were neither a fluke nor an error.

These results extend the last known occurrence of the Middle Stone Age by a staggering 20,000 years. At the same time, work by colleagues in Senegal also suggested an equally late first occurrence of the Later Stone Age at around 11,000 years—younger than in most other African regions.

Why did the Middle Stone Age last so long and why did the Later Stone Age arrive so late?

Population expansions

Part of the answer to the first question may lie in the fact that parts of west Africa appear to have been less affected by the extremes of repeated cycles of climate change. This may have created stable environmental conditions over a long period of time. As a result of such stability, a finely tuned toolkit that had worked well for millennia might not have needed to change, regardless of the social complexity of the people who made the tools.

The answer to the second question lies in the fact that this region of Africa was relatively isolated. To the north, it meets the Sahara Desert and to the east, there are the Central African rainforests, which were often cut off from the west African rainforests during periods of drought. However, around 15,000 years ago, there was a major increase in humidity and forest growth in central and western Africa. This may have linked different areas and provided corridors for dispersal of human populations. This may have spelled the end for humanity’s first and earliest cultural repertoire and initiated a new period of genetic and cultural mixing.

What is clear is that the long-held simple unilinear model of cultural change towards ‘modernity’ is not supported by the evidence. Groups of hunter-gatherers embedded in radically different technological traditions may have occupied neighboring regions of Africa for thousands of years, and sometimes shared the same regions. Long isolated regions, on the other hand, may have been important reservoirs of cultural and genetic diversity. This matches genetic studies and may have been a defining factor in the success of our species. Our findings are a reminder of the dangers of ignoring gaps on the map.

Fears of AI human-to-human transmission in Russia

https://www.poultryworld.net/Health/Articles/2021/3/Fears-of-AI-human-to-human-transmission-in-Russia-726023E/

Mar 24, 2021

The Russian Union of Poultry Producers (NUPP) has issued a statement ensuring customers that poultry products on the grocery shelves are safe for consumers despite the rising avian influenza (AI) fears.

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In late February, Russia reported the first case of bird flu (H5N8) being passed from birds to humans. 7 workers at a poultry farm in Russia’s south were infected with the H5N8 strain in an outbreak dating back to December 2020. This incident is believed to the first confirmed case of H5N8 poultry-to-human transmission in the world.Transmission of Avian influenza is on the minds of consumers, but test after test prove that meat is safe. Photo: Bert Jansen

On 12 March, Anna Popova, head of consumer health watchdog Rospotrebnadzor, raised concerns that the new AI strain could mutate further, leading to a possible human-to-human transmission. “The prediction that this could happen is deemed highly probable,” Popova said, adding that there is still time to prepare for the new threat and to develop new tests and a vaccine. “We want to be prepared for it and warn the entire global community that the danger exists,” she said.

Concerns could impact consumption in Russia

Russian poultry farmers warned that concerns regarding the AI infection could impact poultry consumption in the country. In the statement, the NUPP ensured that, with all sanitary measures in place, the virus would not make it into the supply chain. Broiler meat and other poultry products are safe to eat when properly prepared. “No infected birds made it into the food chain, and consumers can remain confident in the safety of poultry meat. Safeguards are in place to ensure the safety of customers,” the NUPP said.

Russia reports first human infection of H5N8 bird flu
Russia has registered and reported the world’s first transfer of the H5N8 bird flu strain from birds to humans to the World Health Organization (WHO).

The workers at the farm where the AI outbreak was confirmed in December of 2020 likely got infected due to lack of compliance with sanitary regulations. “In the case of a recorded contamination of several employees of a small enterprise in February [when the poultry-to-human transmission was official confirmed], the theory is that safety measures were breached and the farm was non-compliant with veterinary and sanitary requirements by employees,” the NUPP said. Sergei Lakhtyukhov, chairman of NUPP, called AI in Russia “accidental and self-limiting”, adding that both market regulators and business unions are constantly monitoring the presence of AI to ensure the safety of customers.

Humans Share Genes With Weird Headless Creatures

Tim Childers  6 hrs ago

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New cross-country storm to bring more severe weatherFans Are Calling Out Khloé Kardashian’s Photoshopping in New Bikini Picture© Evans, et. al./Proceedings of the Royal Society B/Courtesy Christine Hall Researchers traced genes found in humans back to some of the earliest multicellular animals to roam Earth.

• Researchers traced genes found in humans back to some of the earliest multicellular animals to roam Earth.
• The 555-million-year old fossils belong to oceanic creatures that predate the Cambrian explosion.
• The animals may be the missing link between the first complex life forms on Earth and humans.

Peer back far enough into the fossil record and the evolutionary links between modern animals and ancient creatures become increasingly unclear. Although some of Earth’s first organisms lacked now-common features like heads, arms, and legs, researchers have traced back genes found in today’s animals—including humans—to some of the oldest complex multicellular creatures.

➡ Science is bad***. Let’s nerd out over it together.

Their research, published in the journal Proceedings of the Royal Society B, uses genetic analysis to link the appearance of 555-million-year-old fossils of simple oceanic critters to the genes found in complex modern-day animals. These findings could help biologists understand the evolution of the first animals on Earth during one of the most critical periods of the planet’s history.

The Cambrian explosion has long been considered the“big bang” of the evolution of life on Earth. During this period, beginning more than half a billion years ago, almost every major animal group inhabiting the planet today appeared in the fossil record over the span of a few million years.

But recent discoveries are leading scientists to believe the Ediacaran era, a brief period beginning 40 million years before the Cambrian explosion, may have been just as pivotal in the history of evolution. The Ediacaran period is marked by the emergence of the earliest known complex multicellular organisms on Earth. It’s also when scientists believe some of the defining characteristics of animals first took form.

“None of them had heads or skeletons,” study coauthor Mary Droser, Ph.D., a geology professor at the University of California, Riverside, said in a statement. She continued:

“Many of them probably looked like three-dimensional bath mats on the seafloor, round discs that stuck up. These animals are so weird and so different, it’s difficult to assign them to modern categories of living organisms just by looking at them, and it’s not like we can extract their DNA—we can’t.”

Lacking concrete DNA evidence, the researchers examined the appearance and likely behaviors of the animals that are clearly represented by genetic markers in modern animals. These markers include genes like SoxB2, which is believed to play a key role in the formation of an animal’s nervous system.

“The fact that we can say these genes were operating in something that’s been extinct for half a billion years is fascinating to me,” said study coauthor Scott Evans, Ph.D., a professor in the department of geosciences at Virginia Tech.

From more than 40 species identified from the Ediacaran period, the researchers picked four animals to study closely.© Evans, et. al./Proceedings of the Royal Society B/Courtesy Christine Hall (a,b) Kimberella quadrata (K) with frill or muscular foot (MF), proboscis (P) and associated scratch marks (SM); (c,d) Ikaria wariootia with wider end indicated by white stars and with associated trace fossil Helminthoidichnites; (e) Dickinsonia costata with white arrow indicating the direction of movement; and (f) Tribrachidium heraldicum.

The most iconic and largest of the bunch, the oval-shaped Dickinsonia, has been found to grow to almost a meter in length with a series of raised bands on its surface. Recently, scientists discovered Dickinsonia may have been capable of repairing itself from damage, showing the possibility of it having a primitive immune system.

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THE ORIGIN OF SPECIES

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The smallest critter, Ikaria, which Droser and her colleagues recently discovered, was about the size and shape of a grain of rice. It’s also one of the oldest bilaterians—an animal with two front and back openings connected by a gut—ever found. Scientists believe Ikaria was one of nature’s first scavengers, crawling using primitive muscles across the sea floor and eating organic matter.

The researchers also analyzed a teardrop-shaped animal called Kimberella, which may have scraped the ocean floor for food using a proboscis. Lastly, they studied Tribrachidium, a living ninja-star that the scientists, using computationational fluid mechanics simulations, believe used gravity to filter out particles of food falling into its spiral trap.

“Our work is a way to put these animals on the tree of life, in some respects,” Droser said.“And show they’re genetically linked to modern animals, and to us.”

Given their complexity, the researchers believe the animals likely had the genetic building blocks responsible for the formation of heads and sensory organs that could form a central nervous system. This includes genes like Hox, which are responsible for specifying the organization of parts of the body during development. However, the interaction between those building blocks wasn’t yet complex enough to create the concentrated nervous systems found in Cambrian-period animals.

In the future, the scientists hope to examine muscle development and perform functional studies to better understand this ancient period of animal evolution.

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Continued: Humans Share Genes With Weird Headless Creatures (msn.com)

How many early human species existed on Earth?

By Benjamin Plackett – Live Science Contributor 9 hours ago

It depends on your definition of human.

An Australopithecus skull(Image: © Jose A. Bernat Bacete via Getty Images)

We Homo sapiens didn’t used to be alone. Long ago, there was a lot more human diversity; Homo sapiens lived alongside an estimated eight now-extinct species of human about 300,000 years ago. As recently as 15,000 years ago, we were sharing caves with another human species known as the Denisovans. And fossilized remains indicate an even higher number of early human species once populated Earth before our species came along.

“We have one human species right now, and historically, that’s really weird,” said Nick Longrich, an evolutionary biologist at the University of Bath in the United Kingdom. “Not that far back, we weren’t that special, but now we’re the only ones left.”

So, how many early human species were there? 

Related: What’s the first species humans drove to extinction?CLOSEhttps://imasdk.googleapis.com/js/core/bridge3.435.0_en.html#goog_1361421722Volume 0% PLAY SOUND

When it comes to figuring out exactly how many distinct species of humans existed, it gets complicated pretty quickly, especially because researchers keep unearthing new fossils that end up being totally separate and previously unknown species.  

“The number is mounting, and it’ll vary depending on whom you talk to,” said John Stewart, an evolutionary paleoecologist at Bournemouth University in the United Kingdom. Some researchers argue that the species known as Homo erectus is in fact made up of several different species, including Homo georgicus and Homo ergaster.

“It’s all about the definition of a species and the degree to which you accept variation within a species,” Stewart told Live Science. “It can become a slightly irritating and pedantic discussion, because everyone wants an answer. But the truth is that it really does depend.”

What is a species?

The definition of a species used to be nice and simple: If two individuals could produce fertile offspring, they were from the same species. For example, a horse and a donkey can mate to produce a mule, but mules can’t successfully reproduce with each other. Therefore, horses and donkeys, though biologically similar, are not the same species. In recent decades, however, that simplicity has given way to a more complex scientific debate about how to define a species. Critics of the interbreeding definition point out that not all life reproduces sexually; some plants and bacteria can reproduce asexually. 

Others have argued that we should define species by grouping together organisms with similar anatomical features, but that method has weaknesses as well. There can be significant morphological variation between the sexes and even individuals of the same species in different parts of the world, making it a very subjective way of classifying life. 

Some biologists prefer to use DNA to draw the lines between species, and with advancing technology, they can do so with increasing precision. But we don’t have the DNA of every ancient human — the genome of Homo erectus, for instance, has never been sequenced, Live Science previously reported. 

The skulls of various human species  (Image credit: Shutterstock)

It gets even murkier when you consider that as much as 2% of the average European’s DNA comes from Neanderthals and up to 6% of the DNA of some Melanesians (Indigenous people from islands directly northeast of Australia in Oceania) comes from Denisovans. So, are we a separate species from these ancestors? 

“Some people will tell you that Neanderthals are the same species as us,” Stewart said. “They’re just a slightly different type of modern humans and the interbreeding is the proof, but again the definition of species has moved on from just interbreeding.”

Related: Why haven’t all primates evolved into humans?

After taking all of this into account, some experts have argued that the concept of a species doesn’t actually exist. But others say that, while a cast-iron definition of a species is almost impossible to achieve, it’s still worth the effort so that we can talk about evolution — including the evolution of our own species — in a meaningful way. 

So we muddle on, knowing that a species means different things to different people — which means, of course, that people will disagree on how many species of human have ever existed. It’s also a question of what constitutes a human. To answer this question, it helps to understand the word hominin, a large group that includes humans and chimps going back to their shared ancestor.

“The chimpanzee and us have evolved from a common ancestor,” Stewart said. If we decide that humans are everything that arrived after our split from ancient chimpanzees about 6 million to 7 million years ago, then it’s likely to be a diverse group. The Smithsonian National Museum of Natural History has listed at least 21 human species that are recognized by most scientists. Granted, it’s not a totally complete list; the Denisovans, for instance, are missing. Advertisementhttps://9b6cef199583258d1315a400200ee204.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

Those on the list include Homo sapiens, Neanderthals, the Indonesian hobbit-size people, Homo erectus and Homo naledi. The list also includes other species that existed closer in time to the common ancestor of humans and chimps, and so look more like chimpanzees than modern-day humans. Despite their looks, these species are still known as early humans. “You can’t go back 5 million years and expect them to look like us,” Stewart said.RELATED MYSTERIES

—When did humans discover how to use fire?

—How smart were Neanderthals?

—What if Neanderthals had not gone extinct?

If the Smithsonian says there are 21, then you can be sure the diversity is much greater, Stewart said. That’s because the list errs on the side of caution, picking the species that are close to universally recognized. For instance, the recently discovered dwarf human species Homo luzonensis, who is known from just a few bones unearthed in an Indonesian cave, is not included on the Smithsonian’s list.

Researchers also suspect there are many other fossilized species yet to be excavated. “The list has only ever grown and I don’t see why that will change,” Stewart said.

Originally published on Live Science.

https://www.livescience.com/how-many-human-species.html

IS A NEW HUMAN SPECIES EMERGING FROM AN UNDERGROUND CAVE?

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Most of us know by now that if anyone ever thinks “Neanderthal” is an insult, it’s probably true on both ends, because Homo sapiens interbred with Neanderthals. But is another human species hiding somewhere in our past?

Deep in the caves of Johannesburg, South Africa, many ancient human remains have been found. Lee Berger and his research team from the University of the Witwatersrand have found human bones that have survived thousands and thousands of years. They previously unearthed two new hominid species, and might have just stumbled on another one. Some of the many bone fragments scattered in Cave UW 105 stood out. These remains are unlike any from known hominids or modern humans — possibly an altogether different species.

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What began the quest to find out the identify of this mysterious human ancestor was a lower jaw fragment with just one tooth hanging on. Because it was initially piled up with bones and rubble from another excavation, it was set aside. Further investigation found between 100 and 150 pieces of ancient human bone. There were pieces of skulls, shoulder blades, teeth, and limb bones from at least four individuals, including an adult and two juveniles, that were out of place among known hominids.

Every time Berger and his team tried to make a connection between a known hominid species and the new bones they dug up, something didn’t fit. The closest they got was a molar found in Gondolin cave (shoutout to all you hardcore Tolkien fans out there who really know The Silmarillion). Even though the teeth looked similar to this molar, which belonged to Paranthropus Robusts, it was still not a match. P. Robustus appeared sometime between 1 and 2 million years ago. Its large, tough teeth had thick enamel and a strong jaw, thought to be ideal for tearing through plants that were otherwise difficult to chew.

What makes this even more complicated is that evolution can take unexpected turns. Ghosts of the past can return during different evolutionary phases. Powerful teeth and jaws as found in P. Robustus are often thought to be a primitive human trait, but define “primitive.” Homo Naledi, one of the two species discovered by Berger and his team, lived around 250,000 years ago, but its skull was not much larger than a chimpanzee’s and looks deceptively more primitive than its age suggests.

“[Homo Naledi’s] humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur,” Berger said in a study published in eLife after the discovery of this species.

The problem with the teeth of the unknown species goes further than archaeological stereotypes. Both its front and back teeth were large, compared to only the back teeth of P. Robustus, and the bones from the rest of its body were much slimmer. Most hominids with huge teeth also had robust bones to match. However, the other species discovered by Berger, Australopithicus sediba, also had a juxtaposition of features. Some of its teeth resembled those of more primitive species of Australopithicus while others were closer to Homo sapiens. The narrow upper chest of A. sediba also channeled its Australopithicus ancestors while its broader lower chest was a step forward towards becoming human.

The difference in so-called “primitive” and more evolved features could have something to do with how ancient hominids adapted to their environments. Though H. Naledi lived much later than other species with relatively small skulls, this part of its morphology may have given it an advantage where it lived. The same could be said of the teeth of the yet-unknown species that seem to be mismatched to its bones. While these hominids may have needed teeth that could withstand the wear and tear of tough plants and possibly meat, the rest of their environment might have not demanded a bulky body for survival.

Finding out the fossil’s age may reveal something more, so nobody evolve any more until those results are in.

What’s the biggest group of animals ever recorded on Earth?

By Emma Bryce – Live Science Contributor 2 days ago

For these gregarious animals, ‘alone time’ is a fantasy.

• https://www.livescience.com/largest-group-of-animals.html
• Also see: https://www.livescience.com/first-human-caused-animal-extinction.html

Wildebeests have large herd sizes, but they’re not the largest animal group ever recorded.(Image: © James Warwick)

In early 2020, ornithologist Noah Strycker found himself walking amongst several thousand chinstrap penguins on Elephant Island, a remote blip of snow-covered rock just off the Antarctic Peninsula. He was there to carry out a census of the island’s penguin colony, which hadn’t been properly surveyed since 1970. “I’ll never forget the sight, sound, and…smell,” joked Strycker, a graduate student at Stony Brook University in New York, as well as a professional bird watcher, and author.

The survey that he and his colleagues eventually produced revealed that chinstrap penguin numbers are in decline. But despite this, this species actually forms the biggest colony of penguins on Earth – gathering in the millions in some Antarctic locations. But counting these animals doesn’t daunt Strycker, who has actually developed something of a hobby for this task. 

It started a few years ago when he found himself pondering how many starlings were contained in the magical murmurations that these birds form, and which swell and undulate across the evening sky in many parts of the world. “They are quite beautiful. It almost looks like smoke,” Strycker told Live Science. “And it just gets you wondering, how many of them are there?” The answer, he discovered, was that there are roughly 1 million in the average murmuration, all soaring and swooping in unison. That discovery spurred Strycker on to answer an even more ambitious question: beyond birds, what’s the biggest group of animals ever recorded on Earth?

Related: What’s the first species humans drove to extinction?CLOSEhttps://imasdk.googleapis.com/js/core/bridge3.432.0_en.html#goog_1844543049Volume 0% PLAY SOUND

Answering this question takes us to some very interesting places — back into the past, up into the sky, down into the ocean and sweeping across desert plains. It offers magnificent proof of the abundance of animal life on Earth, but it also points to humanity’s role in reducing — and, unexpectedly, increasing it too.

Thousands, millions, billions

When Strycker embarked upon his unusual quest, he shared his discoveries in his book called “The Thing with Feathers: The Surprising Lives of Birds and What They Reveal About Being Human” (Penguin Random House, 2014). As the title suggests, birds are high contenders for the title of most numerous group. At 1 million per flock, starling numbers are jaw-droppingly high – but they’re easily outnumbered by chinstrap penguins, which can reach 2 million on the South Sandwich Islands off Antarctica. 

But those charismatic penguins fall far behind the red-billed quelea: this small species that can gather in single flocks of several million over savannah and grassland areas in sub-Saharan Africa — so huge that they seem to roar as they pass overhead. “I think they’re considered now to be the most abundant species of bird in the world. And they do make very large flocks in the millions — tens of millions, maybe hundreds of millions,” Strycker said. Their explosive success as a species may be helped by agriculture’s spread: these birds consume grass seeds, but they’ll also settle for fields of cultivated grain. As such, they’re loathed by embattled farmers who lose huge shares of barley, buckwheat and sorghum harvests to these birds every year.

Quelea are so numerous that observers say it can take five hours for a flock to pass overhead. But here is where this species yields to an even more populous bird that once was abundant across American skies: the passenger pigeon. “There are stories of people standing there and watching a single flock of passenger pigeons fly over them for hours or days at a time, which is crazy!” Strycker said. One gathering in 1866 was recorded as 1 mile (1.6 kilometers) wide and 300 miles (482 km) long, and was estimated to contain about 3.5 billion birds, based on the number of pigeons per square mile and extrapolated across the size of the flock. Of course, that was before hunting drove this successful species to extinction. 

So surely with that grand tally, this pigeon of yore takes the prize for most populous creature on Earth? Not so fast: there are quite a few other contenders to consider still. 

Related: Why are there so many pigeons?

Shifting our gaze down from the skies, and into the ocean’s depths, there are records of fish species — specifically Atlantic herring — gathering in schools that exceed 4 billion, Strycker explains in his book — the passenger pigeon’s closest contender for the reigning title so far. Other species don’t come close to the numbers tallied up so far — but they’re still so impressive to behold that they deserve a mention. These include migratory mammals like springbok and wildebeest in southern Africa that have, in the past, gathered in herds exceeding 1 million, forming vast processionals that march across the sun-beaten savanna for weeks. These are further outstripped by their winged mammalian cousins: in Texas, there’s a single cave that’s home to more than 20 million Mexican free-tailed bats, whose closely-packed bodies transform the cave’s interior into a rippling, writhing mass.

Yet there’s one animal whose enormous gatherings leave all these other contenders behind in a trail of dust. (Or rather, a trail of decimated vegetation and ravaged crops.)

A gathering swarm

In East Africa earlier this year, a veil of insects swept across the sky, forming a mass of spiky legs and fluttering wings that spanned nearly 930 square miles (2,400 square km). “It was literally like a black blanket that went over the clouds. It was difficult to even see the clouds,” said Emily Kimathi, a researcher at the International Center of Insect Physiology and Ecology in Kenya. 

That swarm was composed of desert locusts, a species that turns up in huge numbers sporadically in East and North Africa, as well as parts of the Middle East and South Asia. That particular event was the largest swarm seen in the Horn of Africa in 25 years. Experts estimate that locusts swarm at a density of about 50 million per 0.3 square miles (1 square km), so that means the single 2020 throng would have contained roughly 200 billion locusts, said Kimathi, who studies the desert locust. “[The species] can increase up to 20 times its population in a span of three months.” 

What Kimathi is concerned about is how much more frequent — and larger — these swarms could become. The desert locust needs two things to thrive: heat, and moisture, which is crucial for the eggs to hatch from the desert sands. And fortuitously for locusts, climate change is increasing these conditions across their vast range. “These areas are getting more arid, and when they do receive the rainfall, it’s torrential rain,” Kimathi said. “These conditions are becoming more frequent. And so these areas are becoming more favorable for locusts to breed.”Advertisement

Related: What makes grasshoppers swarm?

In this case, the gathering of gregarious animals isn’t just a spectacle to behold; a voracious swarm of locusts can decimate farmers’ crops in a matter of hours, ruining livelihoods and increasing food insecurity for millions. 

Kimathi is trying to tackle this enormous challenge in her research. In a recent study published in July in the journal Scientific Reports, she used meteorological data, paired with information on the breeding patterns of desert locusts, to develop models that identify precise geographical locations across the region where species are most likely to breed in the future. She’s hoping her findings will inform early-warning systems that countries can use to predict where locusts will breed, so they can be intercepted before eggs hatch and take to the skies in ever-growing swarms. 

Two-hundred billion is an eye-popping number. But a clue from history suggests that locust swarms can grow much more numerous, given the perfect conditions. In 1875, an amateur meteorologist named Albert Child stood, bewitched, as locusts whizzed across the sky in a swarm that ultimately cloaked a large portion of the western United States. The species was the Rocky Mountain locust, and Child estimated the swarm covered an area of 198,000 square miles (512,800 square km). 

This historical event became known as ‘Albert’s Swarm’, and based on Child’s estimates, it was thought to contain not millions, not billions, but trillions of insects. Three-and-a-half trillion, to be exact. And that, in fact, is thought to be the largest number of animals in a group ever recorded by a human. Rocky Mountain locusts have since gone extinct — but their historic flight offers us a cautionary look at those other swarms, gathering across the planet today.

Will we ever know?

It’s overwhelming to contemplate what several trillion locusts looks like. But, take a breath, because there’s one final contender on our list — if we go with a slightly more liberal definition of what a ‘group’ entails. That’s because beneath the Earth’s surface, we find creatures that gather in colonies so vast, it’s almost inconceivable that they form a unit. 

This is the Argentine ant, which was unintentionally introduced from South America to Europe about 100 years ago. This industrious creature has formed the world’s largest known continuous colony: a behemoth that stretches 3,700 miles (6,000 km) underground across vast swathes of Europe. The stretch is made up of several hundred nests that each contain billions of ants — so it’s likely that the whole system collectively contains trillions. But getting to a closer estimate has proven elusive: the task of counting these insects may simply be too challenging.RELATED MYSTERIES

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This underscores the difficulty of answering this deceptively simple question, of what animal forms the biggest group. “It seems like such a quantifiable question, and yet the more you dig down into it, the harder it becomes to define what do you mean by a ‘group’. It’s so difficult to estimate large concentrations,” Strycker said. And what’s more, as the case of the locusts reveals, “The more you dive into it, the more you can’t answer that question without talking about ourselves,” he said. The boom and bust of animal populations isn’t something we can separate from human influence. 

Maybe the important thing is that contemplating the sheer abundance of life on Earth — and the roles humans play in making it fall, and rise — will help us do a better job of protecting it. 

Originally published on Live Science.

Having kids increases global warming.

But don’t blame the parents…

https://www.theguardian.com/lifeandstyle/2020/dec/13/having-kids-increases-global-warming-but-dont-blame-parents

Eva Wiseman

When world leaders get serious about reducing carbon emissions, we can raise families determined to improve the planet’s future

Family time: ‘In a conversation like this the stakes are so high that the largest reasons for having children – love, hope – can be dismissed in an inch of ink.’ Photograph: Alamy Stock PhotoSun 13 Dec 2020 03.00 EST

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When I had my daughter I felt like the first person to have a baby; now I’ve had my son, I feel like I might be the last. An academic study into how young people factor climate change into their reproductive choices makes for dark reading, with 96% “very or extremely” concerned about their potential children in a climate-changed world. For some the concern is so severe they’ve decided not to have children at all. “I can’t in good conscience bring a child into this world and force them to try to survive what may be apocalyptic conditions,” one 27-year-old woman said.Advertisement

More shocking even, were the 6% of parents who confessed to feeling remorse about having children. One 42-year-old father painted a Goya-like picture of his children’s adult life, “a hot-house hell, with wars over limited resources, collapsing civilisation, failing agriculture, rising seas, melting glaciers, starvation, droughts, floods, mudslides and widespread devastation”. After reading this, I put the kettle on and had a small cup of tea and waited until my hands stopped shaking. Bloody hell. Literally, bloody hell. Man, I feel for that dad, singing his children to sleep before curling up on the landing and rocking, slowly. As well as pressing upon one of my archipelago of dready bruises, his quote made me consider the intellectual compromises required in order to have a baby.

There are the physical details – a person growing inside you – which, at the beginning especially, are so unlikely they feel more akin to a metaphor or fable than science. There is the naming of the child, a task better suited to a god, who at least would not be burdened with class prejudice or negative associations with snotty classmates. There is the folding of tiny empty vests, the fantasies of their talents. And then, the stories one must tell themselves to stave off the terrors that come free with every child. Terrors including but not limited to: the child rolling off the sofa, going hungry, being bullied or, at the far end of the continuum, being drowned aged 38 in a town-sized mudslide. This catastrophising leads to such things as the purchase of knee-pads or, in the case of this 42-year-old dad, terrible, terrible regret.

These doom-tinged prophesies are not unique to those with climate anxiety – they are baked into parenthood

Which is not to say it’s irrational. All signs, yes, lead to horrible devastation, and indeed, it is a good idea for a child to wear protective clothing when careening on their scooter down a bumpy hill. But these doom-tinged prophesies are not unique to those with climate anxiety – they are baked into parenthood. Ask any group of childless young people today if they want kids and many of the reasonable ones will say no, partly because it is no longer taboo to be honest about wanting to keep your independence, and live a beautiful life of freedom with the responsibility of only your own arse to wipe, and partly because until one has a child, such a thing remains abstract and completely bananas. It is a trick question, grounded in the privilege of choice. There are thousands of reasons not to have kids – the fact that the world is ending is simply one of them.

I do not begrudge for a second these people choosing to remain childless either in an attempt to save the planet, or for fear of the child having to live through its death rattle. It is entirely sensible – in fact there are few rational reasons to have a child. But I do feel uneasy about the load of responsibility and sacrifice placed on to individuals, rather than companies or countries.

The problem for those surveyed is that having kids increases global warming. But if our polluting industries and the governments that support them limited their energy use, the children themselves would not cause such harm. If world leaders made serious changes, actively reducing carbon emissions and the use of fossil fuels, the basic needs of children, like staying warm or even travelling abroad, need not be so impactful.

In a conversation like this the stakes are so high that the largest reasons for having children – love, hope – can be dismissed in an inch of ink. But, well, maybe that’s for the best.

Because, of course, the choice to procreate and care for a stranger for the rest of your life, to carry them first in your belly and then on your back and then in every line on your face is a mad and objectively silly idea. And yet, some people will continue to do it in the same way that they will continue to fall in love. This is what humans do. And each child’s future will always be uncertain, because that is the nature of future. But we know that humans adapt, because we’ve seen ourselves adapt.

In the same way that having a baby makes a person suddenly aware of steps a buggy can’t manage, so it can radicalise them, creating a family determined to improve their planet’s future. To have a baby is to indulge in an ancient form of magical thinking, where fairytales are made flesh. Where all terrors must be swallowed and their stones spat out, clean now, and ready to plant.

Our Solar System Is Going to Totally Disintegrate Sooner Than We Thought

A white dwarf star after ejecting its mass to form a planetary nebula. (ESO/P. Weilbacher/AIP)SPACE

MICHELLE STARR29 NOVEMBER 2020

https://www.sciencealert.com/our-solar-system-is-going-to-totally-disintegrate-sooner-than-we-thought

Although the ground beneath our feet feels solid and reassuring (most of the time), nothing in this Universe lasts forever.

One day, our Sun will die, ejecting a large proportion of its mass before its core shrinks down into a white dwarf, gradually leaking heat until it’s nothing more than a cold, dark, dead lump of rock, a thousand trillion years later.

But the rest of the Solar System will be long gone by then. According to new simulations, it will take just 100 billion years for any remaining planets to skedaddle off across the galaxy, leaving the dying Sun far behind.

Astronomers and physicists have been trying to puzzle out the ultimate fate of the Solar System for at least hundreds of years.

“Understanding the long-term dynamical stability of the solar system constitutes one of the oldest pursuits of astrophysics, tracing back to Newton himself, who speculated that mutual interactions between planets would eventually drive the system unstable,” wrote astronomers Jon Zink of the University of California, Los Angeles, Konstantin Batygin of Caltech and Fred Adams of the University of Michigan in their new paper.

But that’s a lot trickier than it might seem. The greater the number of bodies that are involved in a dynamical system, interacting with each other, the more complicated that system grows and the harder it is to predict. This is called the N-body problem.

Because of this complexity, it’s impossible to make deterministic predictions of the orbits of Solar System objects past certain timescales. Beyond about five to 10 million years, certainty flies right out the window.https://fe8833891bcc1430155e90abe75eaac5.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

But, if we can figure out what’s going to happen to our Solar System, that will tell us something about how the Universe might evolve, on timescales far longer than its current age of 13.8 billion years.

In 1999, astronomers predicted that the Solar System would slowly fall apart over a period of at least a billion billion – that’s 10^18, or a quintillion – years. That’s how long it would take, they calculated, for orbital resonances from Jupiter and Saturn to decouple Uranus.

According to Zink’s team, though, this calculation left out some important influences that could disrupt the Solar System sooner.

Firstly, there’s the Sun.

In about 5 billion years, as it dies, the Sun will swell up into a red giant, engulfing Mercury, Venus and Earth. Then it will eject nearly half its mass, blown away into space on stellar winds; the remaining white dwarf will be around just 54 percent of the current solar mass.

This mass loss will loosen the Sun’s gravitational grip on the remaining planets, Mars and the outer gas and ice giants, Jupiter, Saturn, Uranus, and Neptune.https://fe8833891bcc1430155e90abe75eaac5.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

Secondly, as the Solar System orbits the galactic centre, other stars ought to come close enough to perturb the planets’ orbits, around once every 23 million years.

“By accounting for stellar mass loss and the inflation of the outer planet orbits, these encounters will become more influential,” the researchers wrote.

“Given enough time, some of these flybys will come close enough to disassociate – or destabilise – the remaining planets.”

With these additional influences accounted for in their calculations, the team ran 10 N-body simulations for the outer planets (leaving out Mars to save on computation costs, since its influence should be negligible), using the powerful Shared Hoffman2 Cluster. These simulations were split into two phases: up to the end of the Sun’s mass loss, and the phase that comes after.

Although 10 simulations isn’t a strong statistical sample, the team found that a similar scenario played out each time.

After the Sun completes its evolution into a white dwarf, the outer planets have a larger orbit, but still remain relatively stable. Jupiter and Saturn, however, become captured in a stable 5:2 resonance – for every five times Jupiter orbits the Sun, Saturn orbits twice (that eventual resonance has been proposed many times, not least by Isaac Newton himself).https://fe8833891bcc1430155e90abe75eaac5.safeframe.googlesyndication.com/safeframe/1-0-37/html/container.html

These expanded orbits, as well as characteristics of the planetary resonance, makes the system more susceptible to perturbations by passing stars.

After 30 billion years, such stellar perturbations jangle those stable orbits into chaotic ones, resulting in rapid planet loss. All but one planet escape their orbits, fleeing off into the galaxy as rogue planets.

That last, lonely planet sticks around for another 50 billion years, but its fate is sealed. Eventually, it, too, is knocked loose by the gravitational influence of passing stars. Ultimately, by 100 billion years after the Sun turns into a white dwarf, the Solar System is no more.

That’s a significantly shorter timeframe than that proposed in 1999. And, the researchers carefully note, it’s contingent on current observations of the local galactic environment, and stellar flyby estimates, both of which may change. So it’s by no means engraved in stone.

Even if estimates of the timeline of the Solar System’s demise do change, however, it’s still many billions of years away. The likelihood of humanity surviving long enough to see it is slim.

Sleep tight!

The research has been published in The Astronomical Journal.

Neanderthals And Humans Were at War For Over 100,000 Years, Evidence Shows

The Saint-Césaire Neanderthal skull suffered a blow that split the skull. (Smithsonian Institution)HUMANS

NICHOLAS R. LONGRICH, THE CONVERSATION3 NOVEMBER 2020

Around 600,000 years ago, humanity split in two. One group stayed in Africa, evolving into us. The other struck out overland, into Asia, then Europe, becoming Homo neanderthalensis – the Neanderthals. They weren’t our ancestors, but a sister species, evolving in parallel.

Neanderthals fascinate us because of what they tell us about ourselves – who we were, and who we might have become. It’s tempting to see them in idyllic terms, living peacefully with nature and each other, like Adam and Eve in the Garden.

If so, maybe humanity’s ills – especially our territoriality, violence, wars – aren’t innate, but modern inventions.

Biology and palaeontology paint a darker picture. Far from peaceful, Neanderthals were likely skilled fighters and dangerous warriors, rivalled only by modern humans.

Top predators

Predatory land mammals are territorial, especially pack-hunters. Like lions, wolves and Homo sapiens, Neanderthals were cooperative big-game hunters. These predators, sitting atop the food chain, have few predators of their own, so overpopulation drives conflict over hunting grounds. Neanderthals faced the same problem; if other species didn’t control their numbers, conflict would have.

This territoriality has deep roots in humans. Territorial conflicts are also intense in our closest relatives, chimpanzees. Male chimps routinely gang up to attack and kill males from rival bands, a behaviour strikingly like human warfare.

This implies that cooperative aggression evolved in the common ancestor of chimps and ourselves, 7 million years ago. If so, Neanderthals will have inherited these same tendencies towards cooperative aggression.

All too human

Warfare is an intrinsic part of being human. War isn’t a modern invention, but an ancient, fundamental part of our humanity. Historically, all peoples warred. Our oldest writings are filled with war stories. Archaeology reveals ancient fortresses and battles, and sites of prehistoric massacres going back millennia.

To war is human – and Neanderthals were very like us. We’re remarkably similar in our skull and skeletal anatomy, and share 99.7 percent of our DNA.

Behaviourally, Neanderthals were astonishingly like us. They made fire, buried their dead, fashioned jewellery from seashells and animal teeth, made artwork and stone shrines. If Neanderthals shared so many of our creative instincts, they probably shared many of our destructive instincts, too.

Violent lives

The archaeological record confirms Neanderthal lives were anything but peaceful.

Neanderthalensis were skilled big game hunters, using spears to take down deer, ibex, elk, bison, even rhinos and mammoths. It defies belief to think they would have hesitated to use these weapons if their families and lands were threatened. Archaeology suggests such conflicts were commonplace.

Prehistoric warfare leaves telltale signs. A club to the head is an efficient way to kill – clubs are fast, powerful, precise weapons – so prehistoric Homo sapiens frequently show trauma to the skull. So too do Neanderthals.

Another sign of warfare is the parry fracture, a break to the lower arm caused by warding off blows. Neanderthals also show a lot of broken arms. At least one Neanderthal, from Shanidar Cave in Iraq, was impaled by a spear to the chest.

Trauma was especially common in young Neanderthal males, as were deaths. Some injuries could have been sustained in hunting, but the patterns match those predicted for a people engaged in intertribal warfare- small-scale but intense, prolonged conflict, wars dominated by guerrilla-style raids and ambushes, with rarer battles.

The Neanderthal resistance

War leaves a subtler mark in the form of territorial boundaries. The best evidence that Neanderthals not only fought but excelled at war, is that they met us and weren’t immediately overrun. Instead, for around 100,000 years, Neanderthals resisted modern human expansion.

The out-of-Africa offensive. (Nicholas R. Longrich)

Why else would we take so long to leave Africa? Not because the environment was hostile but because Neanderthals were already thriving in Europe and Asia.

It’s exceedingly unlikely that modern humans met the Neanderthals and decided to just live and let live. If nothing else, population growth inevitably forces humans to acquire more land, to ensure sufficient territory to hunt and forage food for their children.

But an aggressive military strategy is also good evolutionary strategy.

Instead, for thousands of years, we must have tested their fighters, and for thousands of years, we kept losing. In weapons, tactics, strategy, we were fairly evenly matched.

Neanderthals probably had tactical and strategic advantages. They’d occupied the Middle East for millennia, doubtless gaining intimate knowledge of the terrain, the seasons, how to live off the native plants and animals.

In battle, their massive, muscular builds must have made them devastating fighters in close-quarters combat. Their huge eyes likely gave Neanderthals superior low-light vision, letting them manoeuvre in the dark for ambushes and dawn raids.

Sapiens victorious

Finally, the stalemate broke, and the tide shifted. We don’t know why. It’s possible the invention of superior ranged weapons – bows, spear-throwers, throwing clubs – let lightly-built Homo sapiens harass the stocky Neanderthals from a distance using hit-and-run tactics.

Or perhaps better hunting and gathering techniques let sapiens feed bigger tribes, creating numerical superiority in battle.

Even after primitive Homo sapiens broke out of Africa 200,000 years ago, it took over 150,000 years to conquer Neanderthal lands. In Israel and Greece, archaic Homo sapiens took ground only to fall back against Neanderthal counteroffensives, before a final offensive by modern Homo sapiens, starting 125,000 years ago, eliminated them.

This wasn’t a blitzkrieg, as one would expect if Neanderthals were either pacifists or inferior warriors, but a long war of attrition. Ultimately, we won. But this wasn’t because they were less inclined to fight. In the end, we likely just became better at war than they were.

Nicholas R. Longrich, Senior Lecturer in Evolutionary Biology and Paleontology, University of Bath.