- Moroccan jawbones dated to 773,000 years ago sit near the evolutionary split of modern humans and Neandertals.
- Earth's last magnetic reversal locked the fossils' age to within 4,000 years — rare precision for this era.
- Tooth scans show a mosaic of archaic and transitional traits, distinct from both Homo erectus and Homo antecessor.
When carnivores dragged bodies into a Moroccan cave 773,000 years ago, they unknowingly preserved something extraordinary: hominin fossils alive at the precise moment Earth's magnetic field reversed direction.
An international team led by Jean-Jacques Hublin at the Max Planck Institute for Evolutionary Anthropology reports in Nature that jawbones and remains from Thomas Quarry I near Casablanca illuminate populations near the evolutionary split.
© Hamza Mehimdate, Programme Préhistoire de Casablanca
This branching eventually produced Homo sapiens, Neandertals, and Denisovans. The team has been excavating Morocco's coastal formations for three decades.
Magnetic Timing Locks Down Age
Dating hominin fossils from this era typically involves guesswork spanning tens of thousands of years.
The Grotte a Hominides cave system solved that problem by capturing something geologists dream about: the Matuyama-Brunhes transition, when Earth's magnetic poles last flipped.
What is the Matuyama-Brunhes transition?
The Matuyama-Brunhes transition is the most recent reversal of Earth's magnetic poles, when north and south switched positions about 773,000 years ago. The flip took between 8,000 and 11,000 years to complete, and magnetic minerals in sediment recorded its exact moment as they solidified – giving geologists a precise timestamp baked into rock layers worldwide.
Giovanni Muttoni from the Universita degli Studi di Milano and colleague Serena Perini collected 180 sediment samples from the cave deposits. The magnetic minerals inside recorded the exact moment of reversal with stunning clarity.
Key figure
773,000 ± 4000
Age of hominin fossil found in Morocco
That transition happened 773,000 years ago, give or take 4,000 years. The hominin fossils sat in layers deposited during the flip itself, which took between 8,000 and 11,000 years to complete.
For African Pleistocene sites, this precision is almost unheard of.
Carnivore Dens Preserve Human Relatives
The fossils tell a grim story. A nearly complete adult mandible, a second partial jaw, a child's jawbone, vertebrae, and isolated teeth all bear predator marks. One femur shows clear gnawing damage.
Matthew Skinner used microCT imaging to study internal tooth structures hidden beneath worn enamel surfaces. These enamel-dentine junctions carry taxonomic signatures.
The scans revealed something unexpected: these hominins differed from both Homo erectus and Homo antecessor, the roughly contemporary population from Spain's Gran Dolina site.
These hominins differed from both Homo erectus and Homo antecessor.
The teeth retained primitive features but lacked traits that later defined Neandertals. Shara Bailey notes the dental morphology suggests regional population differences already existed by the end of the Early Pleistocene.
The Sahara periodically opened corridors allowing fauna to move between Northwest Africa and eastern savannas.
African Roots Meet European Cousins
The Grotte a Hominides hominins display what paleoanthropologists call a mosaic: some archaic African characteristics mixed with features approaching later Middle Pleistocene forms from both Africa and Eurasia.
Certain traits recall Homo antecessor from Atapuerca. This hints that ancient population exchanges between Northwest Africa and southern Europe might have occurred before 773,000 years ago. But by the time of the magnetic reversal, these groups had clearly separated.
The palaeontological evidence shows repeated connections between Northwest Africa and the savannas of the East and South.
Denis Geraads, Senior Researcher at Muséum National d'Histoire Naturelle, France
Genetic evidence suggests the last common ancestor of Homo sapiens, Neandertals, and Denisovans lived between 765,000 and 550,000 years ago. The Moroccan fossils align with the older end of that window.
Morocco's Coastal Time Capsule
Morocco's Atlantic coast preserves a remarkable succession of Pleistocene cave systems, coastal dunes, and fossil-rich formations shaped by repeated sea level changes. David Lefevre from the Universite de Montpellier Paul Valery explains that rapid cementation of coastal sands created ideal preservation conditions.
The Thomas Quarry I site alone spans deposits from 1.3 million years ago through multiple occupation phases.
What makes these fossils significant extends beyond their age. They may represent the closest we can get to populations standing at the base of our evolutionary branch. This was before the split that sent Neandertals and Denisovans into Eurasia while other groups remained in Africa.
Northwest Africa wasn't peripheral to human evolution. It was central to the story unfolding as our lineage began its divergence from extinct human relatives.
Fact Check: Claim-by-Claim Verification Verified
The recap accurately represents the Max Planck Institute press release and aligns with the described Nature paper findings on 773,000-year-old Moroccan hominin fossils dated via Matuyama-Brunhes reversal.
Commentary
- Article's phrasing "humanity's last shared ancestor" is a dramatic popular science summary; source describes fossils as "near the root" of the lineage or "best candidates" for populations near the shared ancestry base, with appropriate hedging.
- Genetic divergence estimates vary slightly across studies (e.g., 765-550 ka from nuclear DNA); fossils align with older end, representing a pre-split African population rather than the exact LCA.
- Matuyama-Brunhes age generally ~780 ka in literature, but study refines site-specific date to 773 ka with high precision.
Sources used for verification
Academic/Peer-reviewed:
Other reliable sources:
Fact-checked by Perplexity Sonar Pro on 2026-01-07
