Homo erectus (and Homo ergaster?)
- supraorbital torus (extremely heavy brow ridge)
- occipital torus
- receding forehead (in comparison to modern humans)
- high degree of postorbital constriction
- less prognathic face
- teeth smaller in proportion to the rest of the skull
- very thick cranial vault bones
- sagittal keel
- large brain (approximately 900-1100 cc)
The increase in brain size
from a H. habilis range (600-750 cc) marks a trend in human
evolution which selected for increased cognitive abilities. Just as
behavioral differences between H. habilis and the
Australopithecines existed, so indeed do behavioral differences
distinguish H. erectus from earlier species. The introduction of a
new stone tool technology loosely coincides with the emergence of the
first H. erectus fossils. This tool industry has been called the
Acheulean tool industry.
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The Acheulean handaxe
suggests a higher degree of behavioral sophistication in its makers due to
its standardization and bilateral symmetry. The consistency with which the
same teardrop-shaped axe is found in Acheulean
sites provides evidence for a mental image in the design and
manufacture of these tools. Additionally, the degree of symmetry and
spatial organization suggests that H. erectus was cognitively
capable of adopting different perspectives as well as holding these
different perceptions in memory during the tool's manufacture.
The Acheulean industry is found wherever H. erectus migrated, except for the Far East. It is unclear why Acheulean tools were not utilized there; perhaps it was not of necessity, or maybe a different material was used in lieu of stone tools. Or, perhaps these populations just never learned how to make Acheulean tools before migrating out of Africa. Also, while the general skeletal characteristics listed above describe Homo erectus in relation to other hominids, there is a good deal of morphological variability within this taxon, from west to east (see below for further examination of this topic).
The functional significance of the Acheulean tool industry has been debated, and several possibilities have been proposed:
- butchering large animals
- digging up resources found in the ground
- use as missiles against prey and/or predators
- stripping bark to get at edible layers
- use as "flake-dispensers" rather than tools
Again, while the functional
use for many of these tools is uncertain, the industry remained constant
for about 1 million years.
The First Migration
H. erectus was the first hominid to successfully migrate out of Africa to neighboring regions (click here to see a map of H. erectus sites). Fossil specimens attributed to this species have been found as early as 1.8 mya at various sites, including Dmanisi (Republic of Georgia), Modjokerto (Java), and Longgupo Cave (central China). These indicate that H. erectus was able to migrate and successfully colonize other regions, including some in temperate environments. Evidence for the controlled use of fire may have allowed them to exploit these colder, increasingly seasonal environments.At 1.5 - 1.6 mya, the sites
of Swartkrans (S. Africa) and Koobi Fora (E. Africa) provide evidence for
fire, although difficulties arise in determining whether or not the fires
were deliberately manipulated by H. erectus. A site in China (Zhoukoudian)
provides the earliest undisputed evidence, although that site dates to
approximately 500,000 years ago.
Archaic H. sapiens
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From approximately 400 - 200 kyr ago, another group of hominids emerged in Africa and Europe. Lumped into a group known as archaic H. sapiens, these specimens exhibited a further increase in cranial capacity (pictured at left is an archaic H. sapiens from Kabwe, Zambia). A higher forehead and reduction of some of the heavier morphological features (e.g., browridge, occipital torus) distinguish them from earlier H. erectus groups. |
Neandertals
| The Neandertals represent a highly specialized, highly derived European offshoot that coexisted with populations of anatomically modern H. sapiens. Recent genetic evidence suggests that gene flow between populations of modern humans and Neandertals was minimal. This may shed some light on the issue of the rather sudden disappearance of Neandertals in Europe, an occurence which has traditionally attributed to the arrival and colonization of H. sapiens sapiens. |  |
Characteristics of
Neandertal skeletons include:
- very large brains (larger than modern humans)
- rounded, elongated braincase
- very robust musculature
- protruding facial skeleton; large noses
Additionally, Neandertals shared a specialized tool kit known as the Mousterian industry, a Middle Paleolithic industry.
Mousterian tools exhibit a
technological advance over Early Stone Age/Lower Paleolithic technologies
in the efficient use of raw materials. Tool kits included up to 40
different types, many of which appear to have had specialized functions.
Additionally, tool manufacture was based on the Levallois flaking
technique:
The Levallois flaking technique is performed in three steps, shown in the above diagrams:
- preparation of the core circumference
- radial flaking, preparing the surface of the core
- detaching a flake from the prepared surface
Production of tools in this
fashion is very difficult in comparison to Acheulean industries, requiring
a much higher degree of preparation and planning. While flakes produced in
this manner were used in sophisticated ways (e.g., composite tools), the
technique itself produces a relatively high amount of waste.
Neandertal Behavior and Culture
Some points concerning the behavior of Neandertals include:
- very few established campsites
- buried their dead (e.g., Shanidar, La Ferrassie, La Chapelle-aux-saints, Le Moustier)
- many appeared to have lived short, traumatic lives
- cared for the old and sick (e.g., La Chapelle-aux-saints, Shanidar)
Intentional burial and care
for the seemingly more "weak" of their groups suggest that
Neandertal culture was more developed and sophisticated than hominid
species to precede them. Although their lifestyle was marked with both
climatic and behavioral hardships, they also were the first hominids to
care for the sick and infirm (at least from what evidence anthropologists
have now).
Paleolithic Controversies
The preceding descriptions seem clear enough, but underneath the basic classifications lies a major anthropological controversy.Some scholars believe that the variability seen between African and Asian Homo erectus means that these were completely different species, while others maintain the observed variability merely represents regional diversity. The view that there was more than one species of Homo erectus rests on the notion that the large distance between Asia and Africa reduced gene flow to such an extent that these hominids diverged and formed new species. Alternatively, those who believe there was but a single species of Homo erectus maintain that, while the distances between populations was certainly great, there was not enough time for species-level differentiation to evolve.
The implications this debate has for the emergence of modern Homo sapiens are profound. If there were actually two Homo erectus species, then we only emerged from one of them.
Therefore, some anthropologists are convinced that the African fossils should be assigned a new taxonomic classification, Homo ergaster, a label first applied to the 1.6 million year old skeleton of a male juvenile found at East Turkana in Eastern Africa. More controversies along these lines will be addressed in the next chapter.
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