Determining the age of the oldest human remains is a challenging endeavor that has captivated archaeologists and anthropologists for over a century. Through meticulous excavations, radiometric dating methods, and advancements in technology, scientists have been able to push back the dates of the earliest human fossils and artifacts further and further into the past.
Earliest Hominin Fossils
The earliest potential hominin fossils date back over 6 million years ago to the Late Miocene epoch. In 2000, researchers uncovered a jawbone in Chad, central Africa, dating to between 6 and 7 million years old. Named Toumai (“hope of life” in a local language), the fossil likely belonged to a human ancestor species called Sahelanthropus tchadensis. While Toumai displays some human-like features, there is debate over whether it belongs in the human family tree or not.
More conclusively hominin fossils date to between 4 and 6 million years ago. The species Australopithecus anamensis, discovered in Kenya, lived around 4.2 million years ago. Fossils of Ardipithecus ramidus have been dated to 4.4 million years old. Additional species within the Australopithecus genus, such as Australopithecus afarensis (famous for the 3.2 million year old skeleton “Lucy”), emerged around 3-4 million years ago. These early hominins walked upright and had brain sizes approaching modern chimpanzees.
Earliest Homo Species
The earliest members of the Homo genus, to which modern humans belong, originated around 2.8 to 2.5 million years ago. Species such as Homo habilis or Homo rudolfensis had brains about twice the size of the Australopithecus. This increased cranial capacity allowed for greater intelligence and tool use.
In 2013, fossil jaws dating to 2.8 million years ago were discovered in the Ledi-Geraru region of Ethiopia. The species Homo afarensis, also known as a candidate “Ledi” or “Nala” species, combines primitive and advanced physical traits. If confirmed as a distinct Homo species, these Ledi fossils would be the oldest known members of the Homo genus.
Homo erectus and Homo heidelbergensis
The human ancestor Homo erectus emerged around 2 million years ago. H. erectus had a modern human-like body proportions and size, was adept at making stone tools, and likely hunted cooperatively. Some of the oldest H. erectus remains come from sites in Africa, such as a nearly complete 1.8 million year old skeleton from Kenya.
Homo heidelbergensis appeared around 700,000 to 600,000 years ago in Africa. H. heidelbergensis had a larger braincase and more advanced tool technologies than H. erectus. Fossils indicate they lived in colder climates across Africa, Europe, and western Asia.
Homo neanderthalensis
Homo neanderthalensis, better known as the Neanderthals, emerged sometime after 430,000 years ago. Remains have been found across Europe, the Middle East, and Central Asia. This human relative had a stocky build, large nose, and angled cheekbones. Neanderthals used stone tools, controlled fire, lived in shelters, and ritually buried their dead.
The oldest Neanderthal fossil dates back 430,000 years ago. Discovered in Spain, this skull displays features typical of Neanderthals. Even older Neanderthal remains may exist but require further validation through dating methods and comparative studies.
Homo naledi
In 2013, excavations in South Africa’s Rising Star Cave system uncovered a previously unknown human relative – Homo naledi. These hominins had small brains, curved fingers, and other primitive features. What makes H. naledi so fascinating is the geological age of the remains.
Through advanced dating techniques, researchers determined the H. naledi fossils to be between 335,000 and 236,000 years old. This places H. naledi existing at the same time as the first Homo sapiens in Africa. The discovery reveals surprising diversity in our genus just on the eve of modern humans.
Homo sapiens
Anatomically modern humans, Homo sapiens, arose around 300,000 years ago in Africa. Early H. sapiens used stylistically advanced tools, wore jewelry, and had cultural rituals surrounding death. Populations began migrating out of Africa around 60,000 years ago.
In 2017, fossils recovered from Jebel Irhoud in Morocco were dated to around 315,000 years ago and attributed to an early form of H. sapiens. If correct, these 315,000 year old remains are evidence of the earliest known members of our species.
Omo Kibish and Herto Remains
Along with Jebel Irhoud, other fossils contend for the title of the oldest known H. sapiens. The Omo Kibish remains from Ethiopia have been dated to around 195,000 years old. skeletons from Herto, also in Ethiopia, date to 160,000 years ago.
Both the Omo and Herto fossils exhibit modern human morphology and behaviors. These include a high, rounded skull, small face, and evidence of burial rituals. However, since H. sapiens did not have all its anatomical traits right from the start, debate continues over what defines the earliest members of our species.
Skhul and Qafzeh Fossils
In Israel, Skhul Cave and Qafzeh Cave have yielded Homo sapiens fossils dated to between 120,000 and 90,000 years ago. Along with advanced tool technologies, the sites contain shells with residue suggesting they were used as jewelry or pigments. Burials were also found suggesting possible mortuary practices.
While the Skhul/Qafzeh people appear anatomically modern, they left Africa tens of thousands of years before the main H. sapiens migration. Their presence in the Middle East so early is still puzzling to anthropologists today.
Conclusion
After over a century of discoveries, the oldest remains conclusively belonging to the human lineage date back over 6 million years ago. The exact path of human evolution contains many side-branches, false starts, and extinct species. However, evidence increasingly connects the deepest roots of the Homo genus to fossil hominins over 2.5 million years old. H. sapiens evolved relatively recently, around 300,000 years ago, but our story stretches far back through time.