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 A105 Human Origins and Prehistory
Lecture 10

Early Homo and Cultural Beginnings in the Hominid Lineage

I. Early Homo

    We examined the earliest representatives of the genus Homo, examining their adaptation and the question of how many species are represented. 

     The following outline assumes that there are two species, which I think is the  most likely scenario; make sure to look at the activity. 

   A. Homo habilis ~2.0-1.6 Mya 
        1st member of our genus; could date as early as 2.4 mya (controversial). 
 Face beginning to look more humanlike, body is still australopithecine-like. 

         KNM-ER 1813 cranium; OH 62 for postcrania. (OH 24 another cranium.)
    Brain size averages 600cc (as in 1813); wide variation (recall, africanus:450cc)
    Brow ridge present, smaller than A. africanus 
    Rounder skull 
    Smaller face, less prognathic 
    Zygomatics recede backward 
    First appearance of bony nose 
    Molars are smaller, mandible lighter than in A. africanus
    Smallest body size of known hominids – height estimate 3’3” 
    Long arms, curved fingers 

  B. Homo rudolfensis 2.0 Mya 
       KNM-ER 1470 cranium; KNM-ER 1472 femur 
    Very large brain, 770cc 
    Face still australopithecine-like in many ways. 
    No brow ridge 
    Face tall, flat, no bony nose, prognathic. 
    Squared-off zygomatics, big molars (size of A. africanus molars) 
    Femur very humanlike; suggests end of partial arboreality. 

 Early Homo: One Species or Two?
    Some argue only one species: competitive exclusion (i.e., you can't have two very similar species in the same habitat simultaneously; one will be better adapted and make the other go extinct). 
    In this case, would have to assume great sexual dimorphism (1470 male, 1813 female). Must examine pattern, compare with usual patterns of dimorphism in primates. 

Sexually Dimorphic? 
   Facial height can be sexually dimorphic, as in this case. 
   Brain size: Difference (770 vs. 600 cc) is more extreme than even in gorillas. 
   Browridge, nose: Normally the male’s is bigger; here the “female’s” is. 
   Teeth: Usually males and females have similar tooth sizes, or at least similar tooth
 proportions.  Here, this is not the case.  Could imply a dietary difference, which
 would not be expected for males and females of a single species. 
   Facial flatness: Also should be similar in a single species, because it relates to the
 chewing muscles. 
   Postcrania: Females tend to have longer legs for body weight than males.  Here,  it is  the reverse. 

                   The above indicates that we most likely have two separate species. 
                   So, which gave rise to later hominids, and which is a side branch? 
                   Answer depends: Is big brain more important, or are face and teeth? 
                   Many scientists would go with H. rudolfensis (1470), but the issue is far from settled.

II. Cultural Beginnings in the Hominid Lineage
Beginning 2.6-2.5 mya, cultural evolution becomes visible in the archaeological record alongside biological evolution. 

  • Early prehistoric archaeology began as antiquarians (interested primarily in artifacts of more recent periods as art objects) dug past the historical levels of their sites.  They began to uncover stone tools.  Later, these artifacts began to be found in many locations.
  • At first, stone tools were thought to be bizarre natural phenomena, not readily accepted as the work of ancient humans.
  • Then, Europeans encountered New World peoples, some of whom still used stone tools. They concluded that stone tools must be the artifacts of "primitive" people, and concluded that these New World peoples must be primitive as well.  (Today we know that their cultures were not primitive at all, but quite sophisticated.)
  • It took time before stone tools could be accepted as ancient.
  • Mid to late 1800s -- Boucher de Perthes, working in the gravels of the Somme River (France), found stone tools along with extinct animal bones.  He was greeted with skepticism, but his site convinced two visiting archaeologists, and eventually stone tools came to be accepted as the artifacts of ancient people.
  • Three-Age system: Stone Age, Bronze Age, Iron Age; later, the Stone Age was split into three phases: Palaeolithic, Mesolithic, Neolithic.
  • de Mortillet, Lartet and Christy added phases of Palaeolithic, technological assemblage classifications, type sites for industries.
The Palaeolithic is the time period we will be most concerned with for the rest of the semester. (It ends less than 12,000 years ago; the Neolithic coincides with the beginning of agriculture; and the Mesolithic characterizes the period between the waning of the glaciers and the beginning of agriculture.)

Three main subdivisions of the Palaeolithic (more on this later):

  • Lower Palaeolithic, composed of the Oldowan and Acheulean industries
  • Middle Palaeolithic, composed of the Mousterian in Europe and the Near East and broadly similar industries elsewhere
  • Upper Palaeolithic, composed of first the Aurignacian (most of Europe) and later very diversified regional cultures.
  • In sub-Saharan Africa, we speak of the Early, Middle, and Later Stone Age insted of the periods just mentioned.  Though broadly contemporary with the Palaeolithic periods, there are some chronological and technological differences that lead us to distinguish these Stone Ages from the Palaeolithic subdivisions.
What might we expect the very earliest tools to look like?  It is probable that early hominids used natural materials as tools like chimps do, perhaps even to a greater extent.  (Keep in mind that chimps are not totally dependent on their tools in the way that humans depend on theirs.)  However, most of the materials chimps use for tools would not be preserved in the archaeological record for millions of years.  Stone tools are the first definite artifacts we have.

The Oldowan, 2.6-1.6 mya
The simplest stone tool technology, consisting mainly of cores and flakes.  Though the industry itself lasts until 1.6 mya, toolkits at a similar technological level continued to be made almost up until modern times. Named for Olduvai Gorge, where it was first discovered.
Oldowan Artifact Types

  • Manuports: stones brought to sites that do not occur naturally in the area.
  • Hammerstones: used to knock flakes off cores.  Identified by areas of heavy battering.
  • Polyhedrons, discoids, cores: Cobbles that have had flakes removed. Their specific names refer to their shapes; most were probably primarily used simply to produce flakes.
  • Spheroids: round stone balls.  Result of using relatively soft stone as a hammerstone.
  • Choppers: cobbles with several flake removals that looked like they could be used to chop.
  • Flakes: pieces removed from cores.
  • Scrapers, flakes and cores with many very small flakes removed from an edge (this is called retouch). 
Note that the artifact names do not necessarily imply anything about their function.  Artifacts in bold type are those that appear to have been more important.

When the Oldowan was discovered, it was assumed that the choppers and scrapers were the "true tools" and the object intended by the hominids.  However, researchers later performed experiments, reproducing Oldowan tools and looking at wear patterns on the artifacts themselves to determine their uses. The experiments show that the tools were used for: breaking bones, cutting wood, cutting grass, butchery, scraping hides.  And there was no definite association between any particular tool shape and a function -- scrapers were not used just to scrape hides, for instance.

It also appears that the point of Oldowan flaking was to get sharp edges.  The rocks that provided the flakes (choppers, cores) may have been used also, but were probably not the goal of flaking.

Important Oldowan Features

  • Simple technology, but shows clear understanding of flaking techniques and rock fracture properties.
  • Proportion of flake types suggests right-handedness.
  • Types are simple and not terribly numerous, but there is a good deal of variation.  This suggests that the hominids didn't have specific forms in mind when making their tools -- they didn't have what we would call a mental template. 
Important Oldowan Site: FLK "Zinj" level, Olduvai Gorge, Tanzania
The following is a more detailed outline of the material I presented in class concerning the FLK "Zinj" level, with clarifications.  Since this is one of the most important sites, I decided to give you a more complete "outline" than usual.  If I were to ask about this site on an exam (hint, hint, hint) you wouldn't need to know all the specifics (numbers, etc.) but should be able to explain the basic arguments.

Site Description 
      The site is about 315 square meters, and was located on the shore of ancient
      Lake Olduvai.  An overlying ash layer was dated to 1.75 million years ago.  The
      distribution of materials, both horizontally and vertically, indicates that water
      disturbance was probably not an important factor at the site.  The bones do not
      show a lot of weathering, and differences in weathering from bone to bone likely
      reflect their having been exposed for varying, but still similar, amounts of time
      before burial.  If the bones were in fact left over a period of time, they might
      have taken about 5-10 years to accumulate, which would be very strange for
      modern hunter-gatherers (they tend to use sites for a few months and then not
      again for years). This fact has led some to suggest that the Olduvai sites may
      have been used differently from the way modern hunter-gatherers use their sites,
      maybe as a place to keep (cache) stones to use in processing animals. 

Finds
       2500 Oldowan stone tools 
       60,000 fossil bones; 3500 from large mammals, 16,000 microfauna.  The rest
are too fragmentary to be identified. 
       One fossil hominid is known from this site, a robust australopithecine.  Generally, however, the hominid that is assumed to be responsible for this site is early             Homo, or perhaps H. erectus.

Interpretation: Bunn and Kroll 
   Studied 172 skeletal elements, the remains of 40-45 individual animals, looking
at which parts were present and at the stone tool cutmarks on the bones. They
noted that bulky, relatively non-nutritious parts (heads, vertebrae, ribs) were less
common than relatively nutritious parts (legs and mandibles).  Those less
frequent parts are also those most commonly left behind by carnivores and
modern hunters.  The cutmarks, relatively numerous, are found on both the
midshaft (two-thirds) and near the joints (one-third).  Experimentation shows
that cutmarks on the joints indicate disarticulation of the animal, while shaft
cutmarks were thought to indicate meat removal. 
      From the above, Bunn and Kroll inferred that hominids brought the animal
bones to the site (because the parts present were those commonly brought by
hunters), and that they were either hunters or the first scavengers to find the kills
(because the joint cutmarks showed disarticulation, and the shaft cutmarks
showed that hominids got to the kill while there was enough meat left to cut off). 
In fact, they suggested that hunting may even have been more important,
because they considered it unlikely that hominids would have been able to reach
carcasses before other predators. 

Problems and Alternatives 
     First, later investigators disagreed with Bunn and Kroll's identification of some of
the cutmarks; they found fewer than B & K had said there were. They also
raised the possibility that some cutmarks were caused by trampling of animals
(hooves and kicked stones could have made marks). Also, if hominids were
hunting, scientists like Binford said that there should have been many more
cutmarks on the joints, and that the midshaft cutmarks might instead indicate that
hominids got access to the carcass relatively late and therefore had to hack away
the little meat that remained after other carnivores had eaten.  Another problem
with the idea that hunting was responsible is that studies had begun to appear
suggesting that even Neandertals had not been as good at hunting as modern
people, making it unlikely that early Homo was a good hunter. 
     Even more important were the 13 specimens on which cutmarks and
carnivore tooth marks overlapped, some with the toolmarks on top (indicating
scavenging by hominids of carcasses already nibbled by other carnivores) and
some with the chew marks on top (indicating that carnivores visited the site after
hominids had left).  This finding showed that hominids were sometimes late
arrivals at the kill, and that carnivores also contributed in some way to the
Olduvai bone assemblages. 

What are we left with? 
  Despite the objections raised, it is fairly widely agreed that hominids were
making use of meat as a food resource at Zinj and other Olduvai sites; some of
the cutmarks are agreed upon.  They also seem to have been smashing limb
bones to get access to the marrow.  Though it is possible that some hunting
occurred, we only have convincing evidence for scavenging from sites like this.

Who made the stone tools?
   We have a number of candidates, but not yet enough evidence to choose among them.  Anatomical studies that have been carried out on robust australopithecines shows that they were capable of using stone tools, but this does not prove that they did use tools. A. garhi is found at the same time as the earliest stone tools, at a site that is relatively nearby, but has not been found with tools.  It is often assumed that early Homo was the toolmaker.  However, we need more evidence.