How This Decade of Archaeology Changed What We Know About Human Origins

Artist’s reconstruction of A. anamensis, based on the discovery of a nearly complete skull and jawbone.
Gif: Image by Matt Crow, courtesy of the Cleveland Museum of Natural History. Facial reconstruction by John Gurche made possible through generous contribution by Susan and George Klein. (Gif source: YouTube)
Decade's EndDecade's EndGizmodo, io9, and Earther look back at our passing decade and look ahead at what kind of future awaits us in the next ten years.

Unlike humans living today, our distant ancestors exerted a very small footprint on the planet, leaving barely anything behind to chronicle their time on Earth. With the discovery of each new skull fragment, femur, and stone tool, however, archaeologists are methodically piecing together the fractured history of our species and other hominins closely related to us.

Discoveries made over the past 10 years have added appreciably to this unfolding story, as traditional archaeological techniques have been bolstered by incredible new advances in genetics, dating technologies, artificial intelligence, and other transformative analytical tools.

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Here’s a look back at some of the most significant archaeological and anthropological discoveries of the past decade that fundamentally changed our understanding of human origins.

Putting a face on a pivotal ancient species

A nearly intact skull found three years ago in Ethiopia provided a much-needed glimpse into the facial characteristics of Australopithecus anamensis—an early hominin linked to human evolution. Before this, the species was only known from bits of teeth and jaw. Analysis of the skull by paleoanthropologist Yohannes Haile-Selassie from the Cleveland Museum of Natural History and his colleagues revealed a mix of old and modern features, including a long, robust, and protruding face, small teeth, and a large cranium compared to similar species.

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Dated to 3.8 million years old, the discovery suggests A. anamensis lived alongside A. afarensis for around 100,000 years—a period of overlap that further complicates our understanding of this genus.

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On a related note, important research from earlier this year showed that Australopithecus sediba is unlikely to be a direct ancestor of our species, Homo sapiens. We still don’t know which Australopithecine spawned humanity, but A. afarensis appears to be the best candidate.

The earliest fossil evidence of modern humans in Africa

A stunning discovery from the Jebel Irhoud archaeology site in Morocco reset the origin date of Homo sapiens to 300,000 years ago, which was 100,000 years older than the previous oldest record. The evidence, presented in 2017 and analyzed by researchers from the Max Planck Institute for Evolutionary Anthropology and the National Institute for Archaeology and Heritage in Morocco, consisted of fossils belonging to five early modern humans, along with stone tools, animal bones, and signs of fire use.

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For perspective, the very first humans—that is, species slotted into the Homo genus—emerged long before that, including Homo habilis (~2.1 million to 1.5 million years ago), Homo rudolfensis (~1.9 million years ago), and Homo erectus (~1.9 million to 600,000 years ago).

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In addition to pushing back the inception date of our species, the discovery bolstered an emerging perspective that human evolution wasn’t confined to a single geographical location, nor did anatomically modern humans evolve from a single ancestral population. As study co-author Jean-Jacques Hublin put it, “There is no Garden of Eden in Africa, because the Garden of Eden is Africa.” The discovery of 2.4-million-year-old tools in Algeria the following year provided even more evidence in support of this claim.

The discovery of a new human species—Homo naledi

In 2013, scientists stumbled upon one of the most significant archaeological discoveries of the decade: a previously unknown extinct human species, which they named Homo naledi.

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The remains of 15 individuals were excavated from South Africa’s Rising Star Cave by an all-female team of archaeologists. The resulting analysis, which involved researchers from the University of the Witwatersrand in South Africa and other institutions, showed that these ancient hominins featured very human-like teeth, wrists, legs, and feet, but with a small brain case, shrugged shoulders, curved fingers, and hips reminiscent of Australopithecus. In an email to Gizmodo, Jeremy DeSilva, an associate professor of anthropology at Dartmouth College, explained the significance of the find:

Surprisingly, Homo naledi shared the landscape with our own Homo sapiens ancestors only 250,000 years-ago, further complicating a Pleistocene world already occupied with Neanderthals, Denisovans, and island-dwelling hobbits. Not only were the fossils transformative, but Lee Berger and his team used these fossils to change the way our science is done. The recovery of the fossils was live-tweeted, connecting the world with science as it was happening in real-time. A large international team, consisting of many recent Ph.D. recipients, was assembled to work on the fossils. The results of the team’s work were published in open-access scientific journals. And 3D surface scans of the fossils themselves are available at no cost. The days of paleoanthropologists hoarding their fossils like gollums, in possession of the one ring to rule them all, are nearing an end. Meanwhile, these fossils are a startling awakening that there is a lot more out there just waiting to be discovered.

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Living between 335,000 and 236,000 years ago, these hominins stood around 4 foot 9 inches tall (1.44 meters) and weighed between 88 and 125 pounds (40 and 56 kilograms). Sadly, not much is known about Homo naledi, such as its relation to other Homo species, its diet, or how it moved through its Pleistocene landscape.

Updated migration dates for modern humans leaving Africa

Research in 2018 described the discovery of a partial human jawbone, along with several teeth still intact, in Israel’s Misliya Cave. Dated to between 175,000 and 200,000 years old, it’s the oldest evidence of Homo sapiens outside of Africa. The previous oldest modern human fossils were uncovered at the Levantine sites of Skhul and Qafzeh, which were dated at somewhere between 90,000 and 120,000 years old. The discovery, led by archaeologist Israel Hershkovitz from Tel Aviv University, showed that our species left Africa much earlier than previously thought.

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Earlier this year, a team led by paleoanthropologist Katerina Harvati from Eberhard Karls University of Tübingen presented new evidence showing that early modern humans were possibly present in Eurasia even earlier than the timeline suggested by the Misliya fossil. This evidence was in the form of a human skull fragment found more than four decades ago in Apidima Cave in southern Greece. Dubbed Apidema 1, the fragment was dated to approximately 210,000 years ago (the previous dating of the fossil placed it to around 170,000 years ago). Critics complained about the study, saying the skull fragment was badly distorted and that the dating was unreliable, among other issues.

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“The Apidima discovery puts early Homo sapiens in Europe in the Middle Pleistocene—a time and place previously considered the exclusive domain of Neanderthals,” Harvati told Gizmodo when asked about the significance of her team’s discovery. “It provides evidence from the fossil record that the two lineages—Neanderthals and modern humans—could have met and interbred much earlier than the Late Pleistocene.

What’s more, the discovery suggests that early modern humans were likely replaced by Neanderthals in this region by around 170,000 years ago, while highlighting the importance of southeast Europe and the eastern Mediterranean in human evolution, she said.

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The sequencing of Neanderthal and Denisovan genomes

In 2010, scientists managed to sequence the Neanderthal genome. According to archaeogeneticist Christiana Scheib from the University of Cambridge, this achievement not only answered a “hotly debated” question about whether modern humans mated with Neanderthals, it also kickstarted an entirely new field of study in which scientists could study archaic DNA.

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“When I was in college [in the late 2000s] I was taught that there was no way that humans and Neanderthals interbred,” Scheib told Gizmodo. “I can’t remember the exact argument, but I’m sure that at the time it was a good one based on fine and well-articulated points regarding skeletal structure and hybrid infertility. The technical feat of retrieving a full Neanderthal genome showed us that not only did our ancestors have children with Neanderthals, but that most humans on earth retain that legacy with some small percentage of Neanderthal DNA in our genomes.”

These genetic characteristics have since been tied to both positive and negative traits in humans, while raising “new and intriguing questions regarding the various populations of Neanderthals living in various regions when humans left Africa”and how “they interacted with our ancestors,” said Scheib. Scientists still aren’t sure if these inherited genes are beneficial or not, but as “more and more archaic genomes are sequenced and analyzed, we will gain a better picture of our own complex and compelling past,” she said.

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In a similar breakthrough, the Denisovan genome was sequenced soon after. The Denisovans were a sister species to the Neanderthals, who likewise went extinct around 35,000 to 40,000 years ago. (In case you’re wondering why the discovery of the Denisovans isn’t on this list, the first Denisovan fossils were uncovered in 2008, so technically their discovery dates to the previous decade). These hominins interbred with both Neanderthals and modern humans, and their genes live on in the DNA of southeast Asians and Melanesians. Archaeologists have very little fossil evidence of Denisovans—just the tip of a pinky finger, some teeth, and a lower jaw—so to say this DNA is valuable would be an understatement. Earlier this year, this genetic evidence allowed scientists to reconstruct the face and body of an adolescent female Denisovan.

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The discovery of a Neanderthal-Denisovan hybrid

In 2018, a genetic analysis of a bone fragment found in Siberia’s Denisova Cave revealed the presence of an individual who had a Neanderthal mother and a Denisovan father. In addition to showing that the two species of archaic humans interbred (exchanging both valuable and potentially deleterious genes in the process), the research, led by geneticists Viviane Slon and Svante Pääbo of the Max Planck Institute for Evolutionary Anthropology, showed that Neanderthals had migrated to the region at least 90,000 years ago.

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The firm dating of 64,000-year-old Neanderthal cave art

A series of paintings found in three Spanish caves in 2012 remained ambiguous in terms of origin due to unreliable dating techniques. It was consequently unclear if Neanderthals or modern humans painted the red and black figures, which included depictions of animals, dots, geometric signs, and hand stencils.

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Using uranium-thorium dating, researchers from the University of Southampton, the Max Planck Institute for Evolutionary Anthropology, and other institutions managed to finally date the artwork, placing the origin of the paintings to no earlier than 64,000 years ago. The work showed that cave art preceded the arrival of modern humans to Europe, and that Neanderthals, perhaps unsurprisingly, had the capacity for symbolic thought.

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A genome sequence belonging to man who lived 45,000 years ago

In 2014, scientists managed to sequence the genome of a 45,000-year-old man from western Siberia, making it one of the oldest high-resolution sequences ever obtained from an anatomically modern human. Fascinatingly, this man had about as much Neanderthal DNA as people living today, but the European and Chinese researchers were able to determine that his ancestors interbred with Neanderthals some 7,000 to 13,000 years before his birth. So in addition to placing early modern humans in Siberia by 45,000 years ago, the research provided better estimates as to when modern humans mated with Neanderthals—some 52,000 to 58,000 years ago, at least according to the genetic evidence.

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Improved estimates for when the Neanderthals went extinct

Modern humans and Neanderthals diverged from a common ancestor around 800,000 years ago. As the immediate ancestors of our species continued to evolve in Africa, our Neanderthal cousins managed to spread throughout Europe and much of Asia, but they eventually went extinct for reasons that remain unclear. Research from 2014 provided updated estimates as to when the last Neanderthals died.

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Using improved dating techniques, researchers from the University of Oxford and other institutions dated specimens and tools, including nearly 200 Neanderthal bones, from Western Europe to Russia, finding that Neanderthals went extinct between 39,000 and 41,000 years ago. The data also showed that the disappearance of the Neanderthals happened in a kind of “mosaic” pattern, in which the hominins vanished “at different times in different regions,” according to the paper. Importantly, the results revealed a temporal overlap of 2,600 to 5,400 years between Neanderthals and modern humans, during which time the two species interbred and possibly exchanged culture and technology.

The world’s oldest drawing

Archaeologists from the University of the Witwatersrand uncovered the oldest known drawing after analyzing a rock, dubbed L13, found in a South Africa’s Blombos Cave in 2011.

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Bearing the appearance of a modern hashtag, the drawing was made with a red ochre crayon. Scientists dated the drawing to around 73,000 years ago, predating the previous record by 30,000 years—not counting the aforementioned Neanderthal cave paintings, which were dated to 64,000 years ago.

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An astounding decade of discovery, to be sure. What’s particularly amazing is how many of these finds either upturned previous notions or introduced entirely new possibilities altogether. Humbling to think what the next ten years will bring.

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About the author

George Dvorsky

George is a senior staff reporter at Gizmodo.