Illustration of modern humans who lived in Europe about 45,000 years ago
Tom Björklund
Modern humans and Neanderthals interbred over a sustained period of around 7000 years, probably in the eastern Mediterranean. That is according to two studies that trace how these two hominins hybridised in unprecedented detail.
“The vast majority of the Neanderthal gene flow… occurred in a single, shared, extended period,” says Priya Moorjani at the University of California, Berkeley.
The studies confirm that modern humans acquired important gene variants by mixing with Neanderthals,…
More than just fossils show us how humans have evolved through time
Ivan M / Alamy Stock Photo
This is an extract from Our Human Story, our newsletter about the revolution in archaeology. Sign up to receive it in your inbox every month.
This month, Our Human Story turns 50 (months old). For the 50th instalment, I thought I would do something a little different: take stock of what’s happened, and look ahead. I emailed 10 researchers, asking them two questions:
What has been the biggest advance in human evolution of the past five years? This could…
A trackway of footprints thought to have been left by a Paranthropus boisei individual
Neil T. Roach
Preserved footprints in Kenya appear to record two different species of ancient humans walking over the same muddy lakeshore, probably within days of each other. It is one of the most dramatic demonstrations ever found that the world was once home to multiple hominin species living side by side.
“It’s really exceptional that we find this evidence for two different species walking across that surface,” says Kevin Hatala at Chatham University in Pittsburgh, Pennsylvania.
The footprints were found in 2021 in Koobi Fora, Kenya, near the eastern shore of Lake Turkana. They were first spotted by team member Richard Loki at the Turkana Basin Institute, says Hatala: “It was a team of Kenyans who were working there originally.”
Preserved in a dried-out layer of sand and silt, the team found a trackway consisting of 12 footprints (see image, above), evidently left by one individual walking in a straight line. There were also three isolated prints near the main group, seemingly made by three different individuals. The lack of signs of mud cracking or overprinting of tracks with others indicate that the prints were all made at about the same time. “These sites probably capture a window of time anywhere from minutes to a few days or so,” says Hatala.
The sediment has been dated to about 1.52 million years ago. The isolated tracks resemble those left by modern humans: the heel struck the ground first, then the foot rolled forwards before pushing off with the sole. Hatala and his colleagues suggest that these were made by Homo erectus, which are known to have lived in the area.
In contrast, the continuous trackway was made by a more flat-footed hominin. Hatala and his colleagues suggest this could have been Paranthropus boisei, another kind of hominin that lived in the region.
The fossil footprint on the left with a deeper heel imprint is thought to have been made by a Homo erectus, the more flat-footed one on the right by a Paranthropus boisei
Kevin Hatala/Chatham
“With footprints, you can never be 100 per cent sure who made them,” says Ashleigh Wiseman at University College London, who wasn’t involved in the study. However, H. erectus and P. boisei are the only hominins whose remains have been found preserved in the area, “so we can make an informed guess that it is those two”.
If the trackway really was made by a P. boisei individual, it shows that they walked bipedally, says Wiseman. While skulls, arm and leg bones have been attributed to Paranthropus, she says, “we have never found a skull in association with the rest of the skeleton”. That means we know little about their bodies apart from their heads, and their walking style has been a mystery. The trackway changes that: “It’s unequivocal evidence of walking on two legs.”
These two species were very different. H. erectus was one of the earliest members of our genus, Homo. They had larger brains than earlier hominins and became the first of the clade to travel outside Africa. In contrast, P. boisei were small-brained with large teeth and jaws, apparently adapted to eating chewy foods like grasses and sedges.
Hatala and his team then looked at other known footprints discovered in the same region and time period and found that they seemed to match either one species or the other. “We see a similar pattern at multiple other sites, and they might span more than 100,000 years,” he says. “It seems like these two species were coexisting on this same immediate landscape with one another for a very prolonged period of time.”
“We’re guessing that there was maybe low to neutral levels of competition between them, if they were able to coexist for more than 100,000 years,” says Hatala. Previous research has suggested the two ate different foods. Unlike P. boisei, H. erectus is thought to have eaten a varied diet that included hunting large animals.
“Both of them could carve out their own existence in this shared landscape,” says Hatala. Later, environmental shifts may have driven P. boisei to extinction, while the more adaptable H. erectus survived.
This is an extract from Our Human Story, our newsletter about the revolution in archaeology. Sign up to receive it in your inbox every month.
One hundred years ago, on 28 November 1924, anthropologist Raymond Dart opened a crate. It held a consignment of fossils from Taung, a quarry in South Africa, including a small skull that looked part-ape, part-human. Dart named it “Australopithecus africanus: The Man-Ape of South Africa”. It was the first Australopithecus specimen to be identified, and the first evidence that early humans evolved in…
There are few things more irritating in everyday life than getting something stuck between your teeth. Thankfully, we can reach for a toothpick – and it seems our ancient ancestors did the same. In fact, a fragment of a 1.2-million-year-old toothpick is perhaps the earliest direct evidence we have of hominins using plants as tools.
Our ancient ancestors probably made frequent use of implements made from plants. But finding evidence of this is extremely tough because botanical materials are so quick to rot away. This means the archaeological record of human tool use is deeply skewed towards the much hardier stone.
All this suggests that the origins of human technology could have been profoundly misunderstood.
Stone Age
The conventional view is it all started with the first stone tools and the dawn of the Stone Age over 3 million years ago. But what if, even before that, there was a botanical age, one based on woodworking and weaving of plant materials? For some researchers, it is absurd not to think that plants would be part of the story. “Perishable material culture is an essential element in our evolutionary past,” says Linda Hurcombe at the University of Exeter in the UK.
Now, we are finally getting a clearer view of this lost age. New techniques are making it possible to find traces of plant-based tools that would otherwise have been missed. And by studying the way modern primates use plants,…
The genus Citrus refers to a group of flowering shrubs and trees
liv friis-larsen / Alamy
This is an extract from Our Human Story, our newsletter about the revolution in archaeology. Sign up to receive it in your inbox every month.
One of the most important factors in the evolution of humans and other hominins is their relationship with food, and how it has changed over the millennia.
There are some foods that we can barely imagine living without, but that are quite recent additions to our diet. Take wheat, which we use to make bread, pasta, cake and…
As frightening as monsters are, they have always captivated us. From chimeras and hydras to bunyips and golems, creatures have emerged from our imaginations throughout history and across cultures. Today, they explode onto our cinema screens with incredible regularity. Given how scary monsters can be, it seems paradoxical that we keep making them. In fact, they are actually very important to us, and are deeply rooted in our evolutionary history and psychology.
Monsters are the fantastical descendants of our co-evolution with predatory animals: they are wired into our neurocircuitry. Snakes, for example, were some of our ancestors’ first deadly…
Ancient humans are said to have evolved to leave the trees, where our primate ancestors lived, in favour of open grassy savannahs – but we may have this idea wrong
The invention of the printing press helped the distribution of information
Justin Sullivan/Getty Images
Nexus Yuval Noah Harari (Fern Press, out 10 September)
Reading Nexus is a strange experience. The quality of the text lurches up and down: one minute you are reading something incisive, the next you are wading through banalities.
Its author, Yuval Noah Harari, is a medieval historian most famous for his book Sapiens, a whistlestop history of humanity from the Stone Age to the present day. Its central thesis is that humans came to dominate the planet because we can believe in things that only…
A humerus fragment excavated at Mata Menge in Flores, Indonesia
Yousuke Kaifu
Hominins living on an Indonesian island 700,000 years ago were even smaller than Homo floresiensis, the so-called hobbits that lived on the same island much more recently. Newly analysed fossils may represent the hobbits’ ancestors – but the evolutionary story of these small-bodied hominins is still shrouded in mystery.
Fossils of H. floresiensis were first discovered in 2003 in Liang Bua cave on the island of Flores. The hobbit bones date from between 90,000 and 50,000 years ago.
In 2016, Yousuke Kaifu at the University of Tokyo and his colleagues uncovered hominin remains from Mata Menge, an open-air site further east on Flores that was once a riverbed. The remains are about 700,000 years old and include part of a skull, a piece of jawbone and six teeth, all unusually small for a hominin.
The obvious interpretation was that the Mata Menge hominins were the ancestors of the hobbits. But because the remains were so fragmentary, it wasn’t possible to be confident.
Kaifu and his colleagues have now described three new remains from Mata Menge: two teeth and, crucially, a piece of an upper arm bone, or humerus. With this limb bone, “we could finally determine the body size,” says Kaifu.
Unfortunately, the humerus isn’t complete: the shaft is snapped. To determine exactly how far along the break occurred, the team looked for key markers, including a groove that supports a nerve and the attachment point for a muscle. Using these clues, they determined that the bone had broken about halfway along – enabling them to estimate its total length as between 20.6 and 22.6 centimetres.
There are telltale features of the microstructure of the bone that confirm it is from an adult. Extrapolating from the humerus to the entire body, the team estimates the Mata Menge hominin was between 93 and 121 cm tall, with a best estimate of 100 cm. That is a little shorter than the H. floresiensis specimens from Liang Bua, which Kaifu says were at least 6 cm taller – and would make it the smallest adult hominin ever found.
The findings point to a likely explanation for the evolution of H. floresiensis, says Kaifu. It has long been suspected that the species was descended from large-bodied hominins called Homo erectus, which are the first hominin species known to have lived outside Africa – including on Java in Indonesia about a million years ago. “I’m almost sure that they are derived from those populations,” says Kaifu. This is because of similarities between the teeth from Mata Menge and those of H. erectus from Java, and the close proximity of the dates and locations.
The suggestion is that a small population of H. erectus reached Flores, possibly by accident, and lived there in isolation. They must have then evolved a smaller body size within 300,000 years, says Kaifu. “They were small early and then they remained small for a long, long time,” he says.
It’s common for island-dwelling animals to shrink through evolution, because food resources are limited and the lack of large predators means there’s no advantage to being bulky. In line with this, Flores was home to dwarf elephants and other species that had shrunk over many generations.
Argue points out that the Mata Menge teeth don’t look especially similar to the H. floresiensis teeth from Liang Bua. For instance, a molar from Mata Menge has five pointed “cusps”, while H. floresiensis molars have four. “There’s no clear indication of anyone evolving into anyone else,” she says, and it’s not clear why the later H. floresiensis would have evolved slightly larger bodies than their Mata Menge ancestors. Furthermore, “there’s no evidence for Homo erectus from the island.”
For these reasons, Argue says we shouldn’t assume that the Mata Menge hominins are the ancestors of the hobbits. “I would be considering another hypothesis, that the Mata Menge hominins are a new unknown species.” If island life could cause one hominin population to evolve smaller bodies, it could do so twice, she suggests.
In 2017, Argue and her colleagues compared H. floresiensis with other hominins and concluded that their closest known relatives weren’t H. erectus, but instead an older species called Homo habilis, which is only known from Africa. On this basis, they proposed that H. floresiensis actually evolved in Africa, from the same ancestral population that gave rise to H. habilis. Later, some of them migrated east, ending up on Flores. Argue says we probably need more fossils to resolve the question of the hobbits’ origins.
