Early Homo has an increased brain capacity over the Australopithecines. The range is generally between 650 and 775 cc. This stage in hominid evolution has traditionally been called Homo habilis. It is probably more appropriate to simply think of it as early homo since labelling individual hominids becomes problematic based on the evidence that has accumulated. This does not mean there is little evidence to go on. Quite the contrary, as paleoanthropologists build an understanding of the fossil record between 3.0 and 2.0 million years ago, the problems of sorting out individual variations between fossils has been a major issue. Yet there are clear indications that during this critical period, early homo forms arose and different groups emerged perhaps as a result of slightly different adaptations. One of those forms is called Homo rudolfensis. H. rudolfensis is now the focus of inquiry as an early form of Homo that may give rise to other versions of Homo. (Reading on H. rudolfensis)

The specimen to the right is a cranium from Koobi Fora (KNM-ER 1813.) Note that the forehead rises more steeply than in the A. africanus specimens. The teeth are also smaller than those of A. africanus. It has a cranial capacity on the low end of the early Homo, less than the average of 646 cc. for Homo habilis. This skull is globular in shape. This is a characteristic shape that differs from the later Homo erectus. There is only moderate postorbital constriction in KNM-ER 1813 (remember this is constriction of the braincase immediately behind the face.)

The brain capacity for KNM-ER 1470 is large at 775 cc.. This is nearly within the size range of the later Homo erectus. Again there is moderate postorbital constriction and in more or less globular shape to the skull. A side view of KNM-ER 1470 is the next view in this sequence. If you have not done so already, read the section in your text about "Putting it all together". This will help you begin to envision where Homo habilis fits. Remember that brain size increase does not actually begin to take place until right around 2.0 million years ago. With an enlarged brain capacity, paleoanthropologists mark the emergence of "Homo". There is an article that will be passed out in class that focuses on brain size increase. Relate this to the emergence of Homo as a group and to trends that parallel the larger brain capacity.

These are both forms of early Homo. The specimen on the right is the larger brained KNM-ER 1470. As you can see, however, there is a generally globular shape to both crania. This shape along with a greater brain size are distinguishing characteristics of early Homo from the australopithecines.

Here is a view of an early Homo to contrast with that:

As a further contrast, look at this cranium from Olduvai Gorge:

This latter cranium represents the shift to an even larger brained hominid known as Homo erectus. Larger brain size can be tied to a number of different issues. Commonly we think that larger brain size automatically means more intelligence. This may not be necessarily true as we will explore later.

Remember there is a matter of overcoming the heat of the African savanna environment. As these hominids began to travel more and adapted to a more active lifestyle, this would have meant they required new means of physically adapting. Heat loss would have been an important factor enabling these hominids to move rapidly to where food was available. The larger brain comes with changes in stature that may provide us with a clue as to how these hominids were adapting to the African savanna. An interesting reading is an article by Elizabeth Vrba that relates to environmental changes that were occurring as these hominids we call "early Homo" were arising. Read this article to gain a better understanding:

The Pulse That Produced Us by Elizabeth S. Vrba (Natural History, 5/93, pages 47 - 51)

Postcranial Evidence

Postcranial remains of early Homo from Olduvai Gorge have been found. Don Johanson has suggested that Homo habilis had relatively short legs in comparison to the rest of the skeleton. Tim White has suggested that H. habilis was of a similar stature to A. afarensis in this regards. There is evidence that H. habilis also had somewhat curved toes and fingers along with the long arms and short legs. This would indicate a life in which tree-climbing continued to play some kind of role. Except for the bigger brain and its association with stone tools, H. habilis is vitually indistinguishable from the earlier australopithecines. This raises doubts about whether H. habilis should be regarded as a member of the genus Homo. Only a scant 200,000 years apparently separate Homo habilis from a markedly different H. Erectus, whose height ranged to over six feet in males and to well over five feet in females. It also appears that the gracile australopithecines were contemporary with H. habilis. Some paleoanthropologists give H. habilis a primary place in human evolution based on the association with simple stone tools. Simple stone choppers and flakes from the Omo Valley and Hadar regions of Ethiopia have been dated to 2.5 using potassium-argon techniques. These actually predate any finds of H. habilis. The only hominids alive at that point were australopithecines. So one key change that was occurring at some time around 2.0 million years ago was a shift in statute toward longer legs. Presumably this was an adaptation toward greater mobility. Here is further reading.

This is a specimen (StW53) from Sterkfontein in southern Africa. It has a brain size intermediate between A. africanus and H. erectus and therefore has been assigned as a transitional Homo (Homo habilis in east Africa). Note the similarities between this and the east African specimens you have just viewed.

This is an example of Homo erectus from Koobi Fora (KNM-ER 3733). This specimen dates to around 1.6 million years ago. This is one of the oldest dated specimens of H. erectus. It was found in association with another specimen (KNM-ER 406), an A. boisei individual. This laid to rest any argument that there was a single lineage model for human evolution.

Homo erectus is distinguished from the earlier Homo habilis on the basis of a brain capacity of 800 cc. or larger.

In looking at these two specimens, make some notes regarding your comparisons to these views. How do you compare A. africanus on the left with early Homo on the right in these views? Then look at the picture below of a Homo erectus and compare all three views.

This is the top view of a Homo erectus specimen. Note the postorbital constriction and the wide read portion of the skull. Homo erectus had the greatest width of their skulls well back. The braincase was long and low, and wide in the rear.

Homo erectus as a classic form in Africa can be seen in the following pictures:

Technically these pictures represent a fossil group known as Homo ergaster - one of several forms that make up a group we can refer to as Homo erectus.

The story of H. erectus can be placed in perspective if we explore one particular fossil find. This find was of a young boy around the age of 12 when he died. He died nearly 1.6 million years ago along a lake shore in east Africa. This find tells us a lot about him and Homo erectus. To learn more on this find read the following: The Story of the Turkana Boy

H. erectus is the first hominid to be found outside of Africa. Recent dating of fossils from Java raise questions about when hominids may have moved out of Africa. The dating of Javan finds suggests a much earlier exodus that may go back as early as 1.6 to 1.8 million years ago. You can see the basic similarity of Homo erectus (the ergaster form of Homo Erectus) from China and those you have already seen from African contexts. After 1.0 million years ago, Homo erectus began to spread out from Africa. Why hominid first left Africa is a question we can briefly address. It probably relates to two factors: (1) the success of Homo erectus as a hominid leading to a spread into new areas first in Africa and then outside of Africa, and (2) climatic changes that may have literally pushed hominids into new regions of the world. We will explore this further in another chapter of the Hominid Journey. A good place to do some reading is Brian Fagan's Journey from Eden. Fagan discusses the "Sahara Pump Effect" in the book. Climatic shifts may have forced HomoErectus populations out of north Africa into portions Asia and subsequently into Europe. Europe is not populated by hominids until around 800,000 years ago. We will explore the peopling of Europe as a cul-de-sac effect. It was not the primary place to migrate into probably due to the colder climatic conditions as the Ice Age progressed.

Views of African and Chinese Homo erectus Crania.

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