The Acheulean Period
In 1866, German biologist Ernst Haeckel had proposed the generic name "Pithecanthropus" for a hypothetical missing link between apes and humans.
In late 19th century, Dutch anatomist Eugene Dubois was in Indonesia, precisely on the Island of Java, in search for human fossils. In the fall of 1891, he encountered the now famous Trinil skull cap. The following year his crew uncovered a femur, a left thigh bone, very similar to modern human condition. He was convinced he had discovered an erect, apelike transitional form between apes and humans. In 1894, he decided to call his fossil species Pithecanthropus erectus. Dubois found no additional human fossils and he returned to the Netherlands in 1895.
Others explored the same deposits on the Island of Java, but new human remains appeared only between 1931 and 1933.
Dubois's claim for a primitive human species was further reinforced by nearly simultaneous discoveries from near Beijing, China (at the site of Zhoukoudian). Between 1921 and 1937, various scholars undertook fieldwork in one collapsed cave (Locality 1) recovered many fragments of mandibles and skulls. One of them, Davidson Black, a Canadian anatomist, created a new genus and species for these fossils: Sinanthropus pekinensis ("Peking Chinese man").
In 1939, after comparison of the fossils in China and Java, some scholars concluded that they were extremely similar. They even proposed that Pithecanthropus and Sinanthropus were only subspecies of a single species, Homo erectus, though they continued to use the original generic names as labels.
From 1950 to 1964, various influential authorities in paleoanthropology agreed that Pithecanthropus and Sinanthropus were too similar to be placed in two different genera; and, by the late 1960s, the concept of Homo erectus was widely accepted.
To the East Asian inventory of H. erectus, many authorities would add European and especially African specimens that resembled the Asian fossil forms. In 1976, a team led by Richard Leakey discovered around Lake Turkana (Kenya) an amazingly well preserved and complete skeleton of a H. erectus boy, called the Turkana Boy (WT-15000).
In 1980s and 1990s:
- new discoveries in Asia (Longgupo, Dmanisi, etc.); in Europe (Atapuerca, Orce, Ceprano);
- precision in chronology and evolution of H. erectus;
- understanding and definition of variability of this species and relationship with other contemporary species.
Unlike Australopithecines and even Homo habilis, Homo ergaster/erectus was distributed throughout Africa:
- about 1.5 million years ago, shortly after the emergence of H. ergaster, people more intensively occupied the Eastern Rift Valley;
- by 1 million years ago, they had extended their range to the far northern and southern margins of Africa.
Traditionally, Homo erectus has been credited as being the prehistoric pioneer, a species that left Africa about 1 million years ago and began to disperse throughout Eurasia. But several important discoveries in the 1990s have reopened the question of when our ancestors first journeyed from Africa to other parts of the globe. Recent evidence now indicates that emigrant erectus made a much earlier departure from Africa.
- Deposits accumulated between 1.4-1.0 million years ago;
- Stone tools of both an early chopper-core (or Developed Oldowan) industry and crude Acheulean-like handaxes. The artifacts closely resemble contemporaneous pieces from Upper Bed II at Olduvai Gorge;
- Rare hominid remains attributed to Homo erectus;
- Ubeidiya might reflect a slight ecological enlargement of Africa more than a true human dispersal.
Gesher Benot Yaaqov
- 800,000 years ago;
- No hominid remains;
- Stone tools are of Acheulean tradition and strongly resemble East African industries.
Republic of Georgia
In 1991, archaeologists excavating a grain-storage pit in the medieval town of Dmanisi uncovered the lower jaw of an adult erectus, along with animal bones and Oldowan stone tools.
Different dating techniques (paleomagnetism, potassium-argon) gave a date of 1.8 million years ago, that clearly antedate that of Ubeidiya. Also the evidence from Dmanisi suggests now a true migration from Africa.
- Dated to 1.8 million years ago
- Fragments of a lower jaw belonging either to Homo erectus or an unspecified early Homo.
- Fossils recovered with Oldowan tools.
- Dated between 500,000 and 250,000 years ago.
- Remarkable site for providing large numbers of fossils, tools and other artifacts.
- Fossils of Homo erectus discovered in 1920s and 1930s.
In 1994, report of new dates from sites of Modjokerto and Sangiran where H. erectus had been found in 1891.
Geological age for these hominid remains had been estimated at about 1 million years old. Recent redating of these materials gave dates of 1.8 million years ago for the Modjokerto site and 1.6 million years ago for the Sangiran site.
These dates remained striking due to the absence of any other firm evidence for early humans in East Asia prior to 1 Myrs ago. Yet the individuals from Modjokerto and Sangiran would have certainly traveled through this part of Asia to reach Java.
Did Homo ergaster/erectus only head east into Asia, altogether bypassing Europe?
Many paleoanthropologists believed until recently that no early humans entered Europe until 500,000 years ago. But the discovery of new fossils from Spain (Atapuerca, Orce) and Italy (Ceprano) secured a more ancient arrival for early humans in Europe.
At Atapuerca, hundreds of flaked stones and roughly eighty human bone fragments were collected from sediments that antedate 780,000 years ago, and an age of about 800,000 years ago is the current best estimate. The artifacts comprise crudely flaked pebbles and simple flakes. The hominid fossils - teeth, jaws, skull fragments - come from several individuals of a new species named Homo antecessor. These craniofacial fragments are striking for derived features that differentiate them from Homo ergaster/erectus, but do not ally them specially with either H. neanderthalensis or H. sapiens.