Jebel Irhoud: The Oldest Known Homo sapiens Fossils in Morocco

Jebel Irhoud is a hill in western Morocco whose ancient cave deposits contain the oldest known fossils of Homo sapiens, our own species. First uncovered by miners in 1961, the fossils were long thought to be around 40,000 to 160,000 years old. In 2017 new excavations and dating showed they were about 315,000 years old, pushing back the known origin of our species by some 100,000 years and changing ideas about where and how modern humans evolved.

Background: a mine and a mystery skull

Jebel Irhoud lies in a dry, hilly region about 100 kilometres west of Marrakesh, between the city and the Atlantic coast. In the 1950s and 1960s the hill was mined for barite, a mineral used in industry. In 1961 miners blasting into the limestone exposed a cave entirely filled with sediment, and among the debris was an almost complete human skull, now known as Irhoud 1.

The skull reached the palaeontologist Émile Ennouchi, who described it in 1962. A second, partial braincase, Irhoud 2, was found soon afterwards, and in 1968 the lower jaw of a child, Irhoud 3. The French archaeologist Jacques Tixier also excavated at the site in the late 1960s, recovering stone tools and animal bones.

The “African Neanderthal”

Because the stone tools resembled the Mousterian industry made by Neanderthals in Europe, and because the skulls had heavy brow ridges, the Jebel Irhoud people were at first described as a North African form of Neanderthal. Early estimates of their age were around 40,000 years, based on assumptions about the animal bones and tools.

In the following decades anatomists increasingly recognised that the faces looked modern and that the fossils were not Neanderthals at all. By the 1980s and 1990s they were usually described as “archaic Homo sapiens”, although their age remained uncertain. In 2007 a study of the child’s jaw by Tanya Smith and colleagues used electron spin resonance dating to estimate an age of about 160,000 years, and found that the child’s teeth had grown at a slow, modern human pace.

New excavations from 2004

In 2004 a team led by Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig and Abdelouahed Ben-Ncer of Morocco’s National Institute of Archaeology and Heritage Sciences (INSAP) reopened excavations. Mining had removed much of the cave, but a remnant of the original deposits survived and could be studied with modern methods.

Over several seasons the team recovered new human fossils, including a partial skull, a nearly complete adult lower jaw and several teeth. Together with the earlier finds, the site has yielded around two dozen human fossils belonging to at least five individuals: three adults, an adolescent and a child of about eight years. Crucially, the new fossils were found in layers that could be directly linked to datable material.

Redating the fossils in 2017

On 8 June 2017 the team published two papers in the journal Nature. The first, led by Daniel Richter, reported thermoluminescence dates from flint tools that had been heated in fires. When flint is strongly heated its “luminescence clock” is reset, so measuring the light it releases in the laboratory reveals how long ago it was burnt. The flints gave an average age of about 315,000 years, with an uncertainty of around 34,000 years.

The team also recalculated the electron spin resonance date of the Irhoud 3 tooth using new measurements of the surrounding radiation, obtaining about 286,000 years, with an uncertainty of around 32,000 years. Electron spin resonance dates depend heavily on estimates of the natural radiation a tooth has absorbed from the sediment around it, and the new excavations made it possible to measure that environment directly rather than estimating it. The two results were consistent with each other and doubled the previous estimate for the site. Before this, the oldest securely dated Homo sapiens fossils had been those from Omo Kibish in Ethiopia, then thought to be about 195,000 years old.

What the fossils look like

The second paper, led by Hublin, analysed the anatomy using computed tomography and 3D shape analysis. The face of the Jebel Irhoud people was short, flat and tucked under the braincase, falling within the range of living humans. Their lower jaws and teeth were also largely modern in form, though the teeth were relatively large.

The combination is telling. Neanderthals, living in Europe at about the same time, had large projecting faces and long braincases, while earlier African humans such as the one from Kabwe had massive brow ridges and broad faces. The Jebel Irhoud people already shared the small, retracted face of later Homo sapiens, which is why most researchers place them on our own lineage despite their archaic skull shape.

The braincase, however, was long and low rather than tall and rounded as in present-day people. Brain size was within the modern range, but its shape was different. This suggests that the modern human face evolved first, while the distinctive globular braincase of living people, perhaps reflecting changes in the organisation of the brain, developed gradually over the following 200,000 years or more.

Life at the site

The cave was used by people who made Middle Stone Age tools, the African tradition that followed the earlier hand-axe industries. Many tools were made with the Levallois technique, in which a stone core is prepared so that flakes of a planned shape can be struck off; they include points and scrapers, some perhaps used as spear tips. Flint for the tools appears to have been brought in from sources outside the immediate area.

Animal bones show that gazelles were the main prey, with zebras, wildebeest and other large mammals also present, in what was then a more open, grassy landscape than today. Burnt bones and flints show that the occupants regularly used fire. The site was probably a hunting camp, visited repeatedly rather than lived in permanently.

A pan-African origin

The Jebel Irhoud results changed the map of human origins as well as the timeline. For decades the textbook view had placed the birth of Homo sapiens in East Africa around 200,000 years ago. Finding the oldest fossils in the far north-west of the continent led Hublin’s team to propose a “pan-African” model, in which our species emerged across a large part of Africa through networks of populations exchanging genes and ideas.

Genetic evidence pointed in a similar direction. Also in 2017, a study of ancient genomes from southern Africa led by Carina Schlebusch estimated that the deepest splits among modern human populations occurred roughly 350,000 to 260,000 years ago, consistent with the idea that Homo sapiens was already present, in some form, by the time of the Jebel Irhoud fossils.

Other fossils support a complex picture. The skull from Florisbad in South Africa, about 260,000 years old, may belong to an early form of our lineage. In 2022 the Omo Kibish fossils were redated to at least about 230,000 years old. Meanwhile very different humans, such as Homo naledi and the large-browed individual from Kabwe, were living in Africa at broadly the same time as the Jebel Irhoud people.

Not every researcher agrees on the details. Some argue that the Jebel Irhoud fossils represent a population close to, but not yet fully part of, Homo sapiens, and that the word “oldest” depends on how our species is defined. Others caution that a few well-dated sites cannot pin down a single place or moment of origin. The dating itself, however, has been widely accepted.

Myths and facts

A common headline after 2017 suggested that “humans came from Morocco”. The researchers themselves argued the opposite: the site shows that early Homo sapiens lived across Africa, not that our species began at one spot. Another misconception is that the Jebel Irhoud people looked exactly like us; their elongated braincases would have made their heads look noticeably different, even though their faces would not have stood out in a modern crowd.

The site also says nothing directly about when modern humans left Africa. The main dispersal that led to the global spread of our species, described in Out of Africa, happened much later, mostly within the last 100,000 years.

Timeline

• c. 315,000 years ago: Early Homo sapiens use the Jebel Irhoud cave as a hunting camp.
• 1961: Barite miners expose the cave and find the Irhoud 1 skull.
• 1962: Émile Ennouchi describes the skull; the partial braincase Irhoud 2 is found.
• 1968: The child’s lower jaw, Irhoud 3, is discovered.
• 2004: Jean-Jacques Hublin and Abdelouahed Ben-Ncer begin new excavations.
• 2007: Electron spin resonance dating suggests an age of about 160,000 years.
• 2017, 8 June: Nature publishes the new fossils and an age of about 315,000 years.
• 2022: Omo Kibish fossils in Ethiopia are redated to at least about 230,000 years.

Why it matters

Jebel Irhoud showed that our species is considerably older than once believed and that its roots extend across the whole of Africa. The mix of a modern face and an older-style braincase reveals that Homo sapiens did not appear fully formed but took shape gradually. For anyone asking when and where humans like us first appeared, this Moroccan hillside is now an essential part of the answer.