The Evolution of Genus Homo

Fig. 7-8, p. 165

The Evolution of Genus Homo © 2010 The McGraw-Hill Companies, Inc. All Rights Reserved

Homo habilis “Handy man.” The first fossil members of the genus Homo appearing 2.5 million years ago, with larger brains and smaller faces than australopithecines.

Lower Paleolithic The first part of the Old Stone Age. Its beginning is marked by the appearance 2.6 million years ago of Oldowan tools.

Lower Paleolithic Tools The earliest stone tools have been found in the vicinity of Lake Turkana in northwestern Kenya, in southern Ethiopia, in Olduvai Gorge in Tanzania, and in Hadar in Ethiopia— often in the same geological strata as Homo habilis fossils. These tools consist of implements made using a system of manufacture called the percussion method. Sharp-edged flakes were obtained from a stone either by using another stone as a hammer or by striking the pebble against a large rock to remove the flakes.

Percussion Method By 2.5 million years ago, early Homo in Africa had invented the percussion method of stone tool manufacture. This technological breakthrough, which is associated with a significant increase in brain size, made possible the butchering of meat from scavenged carcasses.

Oldowan Core Tools Flake Tools A toolmaking tradition from Africa associated with early Homo. Core Tools Tools made by taking flakes off a stone nucleus. Flake Tools Tools made from the flakes removed from a stone core.

The Evolution of Genus Homo To New Lands What prompted H. erectus to leave the savannas to which they were apparently so well adapted? We can’t know the answer for sure, but a good guess is that the spread of H. erectus was simply the outcome of their reproductive success. Their big brains enabled them to exploit the savannas to a greater extent than had other hominins to date.

Cranial Capacity in Homo erectus

Homo erectus China 1.8 mya Ethiopia 1 mya Georgia 1.75 mya Italy 800,000 ya Java 1.8 mya Kenya 1.5mya Tanzania 1.4 mya Mean brain size 984 ml

Homo erectus Fossils These casts of the skull cap and thighbone of Homo erectus were made from the original bones found by Eugene Dubois at Trinil, Java.

The Evolution of Genus Homo © 2010 The McGraw-Hill Companies, Inc. All Rights Reserved

Fig. 7-5, p. 162

Alternate Designations For Homo erectus Fossils From Eurasia And Africa Name Explanation Homo ergaster Some paleoanthropologists feel the large-brained successors to H. habilis from Africa and Asia are too different to be placed in the same species. They use H. ergaster for the African specimens, saving H. erectus for the Asian fossils. Turkana boy Acheulean hand-axe Brain size 800ml-880ml

Acheulean Hand-axe To fabricate this Acheulean hand-axe from flint, the toolmaker imposed a standardized arbitrary form on the naturally occurring raw material.

p. 165

p. 158

Alternate Designations For Homo erectus Fossils From Eurasia And Africa Name Explanation Homo antecessor This name was coined by splitters for the earliest Homo fossils from western Europe discovered in Spain; antecessor is Latin for “explorer” or “pioneer.” 780.000 ya Brain size 1,000ml Homo heidelbergensis Named for the Mauer jaw, this name is now used as a designation for all European fossils from about 500,000 years ago until the appearance of the Neandertals. Brain size mean 1,247 ml

The Evolution of Genus Homo Big Brains, Archaic Skulls H. neanderthalensis, H. heidelbergensis, and H. antecessor are marked by brain sizes within the modern human range that, indeed, match or approximate the modern human average; nonetheless, they have other features, especially of the cranium, that retain primitive characteristics. Levallois Technique A tool technology involving striking uniform flakes form a prepared core

Levalloisian Technique Drawing A shows the preparatory flaking of the stone core; B, the same on the top surface; C, the final step of detaching a flake; and D, the final step of detaching a flake of a size and shape predetermined by the preceding steps.

p. 169

Kao Poh Nam Rock Shelter Archaeologists excavate a hearth at a rock shelter in Kao Poh Nam, Thailand. This hearth testifies to human use of controlled fire 700,000 years ago.

Use of Fire The use of fire is another sign of H. erectus’ developing culture and technology. The 700,000-year-old Kao Poh Nam rock shelter in Thailand provides compelling evidence for deliberate controlled use of fire. Homo erectus may have been using fire even earlier, based on evidence from Swartkrans in South Africa. In deposits estimated to date between 1 and1.3 million years ago, bones have been found that had been heated to temperatures far in excess of what one would expect as the result of natural fires.

Dmanisi skull 1.8 mya From Georgia a cranium excavated in 2005 and known simply as Skull 5, which scientists described as “the world’s first completely preserved adult hominid skull” of such antiquity. Unlike other Homo fossils, it had a number of primitive features: a long, apelike face, large teeth and a tiny braincase, about one-third the size of that of a modern human being. This confirmed that, contrary to some conjecture, early hominids did not need big brains to make their way out of Africa

In their report, the Dmanisi researchers said the Skull 5 individual “provides the first evidence that early Homo comprised adult individuals with small brains but body mass, stature and limb proportions reaching the lower range limit of modern variation.”

Skeletal bones associated with the five Dmanisi skulls show that these hominids were short in stature, but that their limbs enabled them to walk long distances as fully upright bipeds. The shape of the small braincase distinguished them from the more primitive Australopithecus genus, which preceded Homo and lived for many centuries with Homo in Africa.