What does the Archaeology record tell us about the lifestyles of the early hominids?
In truth it is difficult to say anything definite about events that happened between one and five million years ago. Very few samples are actually left and they are primarily composed of bones and stones. Indeed as Pilbeam and Gould somewhat caustically note " this topic contains more practioneers than objects for study" (1). As a consequence of this lack of evidence and the surfeit of opinion things change. The order of species can change over time, the importance of artefacts alters and species play musical chairs around the evolutionary bush. This makes the story of evolution patchy, the issues around hominid order and capability uncertain and any comment upon consequent lifestyle full of conjecture.
Lack of evidence leads to conjecture, and conjecture to debate. As Renfrew and Bahn put it "paleoanthropologists have strongly differing views on how fossil remains for human evolution should be interpreted" (2). Therefore, anything that is said about early hominid lifestyle, tends, by many, to be couched in the language of uncertainty. Witness, for example, Tattersall's use of language in his book Becoming Human; "it's a good bet", "probably", "tend to the view", and "the evidence suggests" (3).
The essay begins by definig and exploring issues within the archaeological record. We then describe how the record can contribute to lifestyle analysis by reviewing fossil, artefact and environmental record. We then review briefly the currently understood chronology and most important physical and implied lifestyle developments.
What is the archaeological record and how do we use it?
Archaeology is a broad church. It is composed of a wide range of scientific schools and operates best in an interdisciplinary basis. For example, we will find the need for geologists to comment on rock stratification and ageing, we will need palaeontologists to review fossil and bones and we will need biologists to comment on bone structure and skeletal implications. Climatologists can assist by commenting on weather cycles and plant specialists can offer advice on the existence and nature of prehistoric flora. Dental experts are needed to comment upon the capability of different teeth. Animal specialists can comment on the structure and behaviour of other 'competing' species. Co-operation and an interdisciplinary approach are key if meaningful comment is to made about homind lifestyle.
But more problems arise. Improved evidence in one area can create more controversy in another.. And there are still many huge unknowns. How many hominid species for example co-existed? Did their lifestyles involve conflict with one another? Is evolution linear or does it as Stephen Jay Gould, Tattersall and Eldredge imply move as a result of "punctuated equilibria"(4). If "change is difficult and rare rather than inevitable and continual" the environment and lifestyles change rapidly and dramatically (5)? Questions such as these intrigue and drive current hominid lifestyle research.
Moreover, we can often confuse ourselves. We may, for example, believe without question all the previous evidence and we may only ever see what we wish to see. We may impose upon a two million year old hominid modern behavioural traits which seem eminently sensible, but which are totally unproven. And we may, as Durent points out, change our views "as a direct response to contemporary social experience" (6).
Yet armed with this interdisciplinary team of archaeologists and as much objectivity as we can muster we can often tell a great deal from the very little evidence we have. Isaac in The Archaeology of Human Remains sets out a framework for analysis or "structure for modern inquiry" as he calls it (7) . There are, he says, three main factors to consider. These are traces of material artefacts, the palaeontology and fossils and the impact of adaptation caused by the influence of the environmental context. Material artefacts indicate craft practices, are markers of food refuse sites, and foci of activity. They are therefore indicators of hominid activity over the landscape and a commentary upon lifestyle. From this evidence we can make inferences of levels of technology, utility of equipment, aspects of diet, group organisation and land use patterns.
How does the fossil record help?
The skeletal remains of hominid provide evidence in a number of ways that impacts upon lifestyle. For example, by commenting upon the size of the creature we can form a view as to its relative position with a physical hierarchy of other animals. If it was small, as most early hominids, such as Lucy, were, at 1.3 metres and light at 30 kg, then it may be easily attacked. There is evidence that early hominids were preyed upon particularly by leopards, and therefore may have behaved in a defensive and highly cautious manner. If it was larger, say, Australophithecus boisei we might assume a slightly different , or ore confident set of behaviours.
The shape of thigh bones and joints indicate the ability to walk upright. This clearly influences lifestyle. Upright walking is a more efficient means of locomotion and therefore offers the prospect of greater activity in searching for food. The structure or proportion of the arm and leg bones can indicate a preference for tree dwelling or more open terrain. The shape of the feet can indicate ability to walk. The shape of the hands show the ability to grasp and hold objects. Early hominids stood upright, could move in the trees or on the ground and could hold items and perhaps used artefacts such as sticks to in their defence or to gather food.
Heads, jaws and teeth
The development of bipedalism and its importance is supported by other evidence. The position of the brain and how it is held to the vertebrae by the foramen magnum indicates a vertical posture and a horizontally held head. Much is made of brain size development. All species are measured in terms of their brain's cubic capacity with larger brains implying greater intelligence. This appears logical but may be flawed. Brain size has in some cases diminished during the course of evolution. And moreover, a great deal of evolutionary activity has taken place without significant increases in brain size. As Lewin puts it " the Darwinian structure began to come apart". (8) "Intelligence he continues could not have been an important engine in evolution as most of the physical changes occurred with virtually no expansion of apparent mental capacity". Posture and diet would appear to tell use more than brain size.
The shape of the jaw, the extent of certain muscle structure, and the extent and detail of teeth can give very strong indications of the diet employed. The teeth here are mainly designed to crush and grind berries and nuts. Thankfully teeth tend to survive because of their strong enamel content and can help us comment upon diet which can itself help describe lifestyle.
For example, the calorific content of such vegetarian food is typically low. Therefore the quantity need be eaten in order to survive is high. Accordingly, the amount of activity spent obtaining food and eating, or resting to conserve energy must have been substantial. Foraging for vegetarian food therefore becomes the main preoccupation and one of the dominant lifestyle factors. Early hominids will therefore remain close to such food sources, which implies at least reasonable access to trees or roots and water.
Arms and hands and feet
Over time the arms of hominids have reduced in length and changed in capability. We have seen a gradual shortening as their role changed from supporting a tree climbing lifestyle to a more carrying role. And hands have become more flexible, the development of the opposable thumb has facilitated better handling and feet have evolved from clasping to walking. All of these have implications for lifestyle. As these physical features developed we can see changes away from an ape like creature.
The structure of the pelvis has been shown to be important. As Lambert points out the pelvis in hominids is broader, shorter, flared and tilted when compared to say chimpanzees (9). There are at least two implications. One, that it facilitated upright walking and secondly that it implied a slightly more complex birthing procedure. This has led to suggestions that midwifery and group responsibilities may have been apparent within early hominids. These have clear lifestyle implications. As ever issues are debatable. An alternative diagnosis based upon teeth structure and their apparent closeness to apes and matching that with their behaviour suggest little social structure, sharing of food and little bonding. So even here we are unable to over little other than opinion.
Physical and lifestyle changes over time
As the hominids evolved their physical characteristics changed and elements of their lifestyle altered as well. Briefly, the chronological evidence support is as follows. We have scanty evidence of early hominids but can place Ardipithicus ramidus at 4.4 - 3.9.million years ago (myr). The jaw bone indicates that Ramidus was probably small bodied, small brained and predominantly ape like.
Ramidus was followed by Australopithicus anamensis who lived from 4.2 - 3.9 myr who was followed by Afarensis or most famously Lucy. Lucy has been described as bipedal, small bodied, long armed, slim hipped, with an ape like face, a heavy brow ridge, no chin and big molar teeth. Lucy was a bipedal ape but walked in a slightly bow legged manner. From a lifestyle perspective she had "features that would have made it relatively easy to move in the trees in search of food and protected sleeping sites" (10). Lambert agrees, believing "Afarensis spent much time in trees, perhaps sleeping high among the branches and lived in family groups which foraged for plant food" (11) .
Australopithicus africanus was a hominid found in Africa between 3 -1 myr. Africanus was small and light. Africanus walked upright, had strong neck muscles and a small brain that was differently structured to that of an Ape. The jaw muscles and teeth suggests he chewed plants leaves. According to Lambert there is dispute over their mode of life particularly around their ability to manufacture and use crude stone tools (12) .
At around 2.5 million years ago a larger and stronger hominid emerged called Australophiecus robusticus. This homid grew to 1.6 metres tall and weighed about 50 kgs. Robusticus could have been 60% taller and 25% heavier than africanus. This simple fact must have had some influence on life style but precisely what is difficult to determine. Again powerful jaw muscles are evident and very large cheek teeth are present. As Lambert comments "all this suggests that robustus must have eaten hard tough foods perhaps including seeds".
In East Africa from 2.5 to 1 million years ago there lived a still larger hominid called Australophicus boisei. Bosei is nearly twice the height and weight of afarensis and in this regard was close to modern humans. With immense molar teeth he became nicknamed "nutcracker man", although Bosei appears to have been a leaf chewer. Leakey thought him to be fruit eating as the teeth are similar to chimpanzees. The omnivour diet would have composed of roots, seeds, eggs, fungi, insects and perhaps reptiles. There is no signs of bone crunching on any teeth. The use of stone tools to break bones and extract marrow is therefore disputed for Bosei.
Between 2.4 and 1.9 million years ago another species of homid existed known as Homo habilis. Homo habilis means handy man and this description is mainly a consequence of the hand bones which suggest "a strong but sensitive grip". Habilis bones are often associated with artefacts. Yet somewhat confusingly Habilis was smaller than both Robusticus and Bosei.
So, thus far, we have a predominantly upright walking ape like creatures who appears to have existed on a largely vegetarian diet and spent the majority of their time either finding food or eating it. Their teeth were largely incapable of cutting meat even if they acquired it through opportunist scavenging. They appear to have inhabited an environment that produced nuts, berries, seeds, leaves and small insects. This would suggest a habitat of thorn bush savanna, fruiting trees and bushes and close to streams and rivers with a rich diversity of bird life. We will look at the environment later. First of we need to address the issue of artefacts.
What do the tools tell us about lifestyle?
The evidence we have shows that hominids began using stone tools at about 2.5myr in the Olduvai Gorge and thus could have been used by Afarensis and Bosei. Any evidence of the use of wooded, bone or other tools has disappeared into dust but the first stone tools are believed to have been used for splitting bones. Other tools were used for chopping, scrapping and possible even as bolas to trap animals. Although this last item suggests a much more aggressive hunting activity than is currently generally supported.
Several conclusions may be drawn from the existence of tools. First of all tool making is considered indicative of improved intelligence and is one of the ways the presence of modern human characteristics may be acknowledged. And this intelligence may imply other lifestyle attributes such as specialisation, such as tool making and perhaps a crude social structure. Secondly, the use of tools implies a change in diet and in early hominids an increased interest in eating meat. It is also proven that early hominids carried raw flint around with them in order to make tools when they found the carcass. Again this shows intelligence in that they were prepared. And if they were prepared for carving up a carcass that what else did they prepare for?
As the evidence has broadened and become greater so the conclusions have changed. Dart, for example, suggested that if hominids lived in open grassland they could not have survived on a vegetarian diet and therefore had to hunt. Hence in the 1950's hominids were "blood splattered" and violent killer apes (13). By the mid 1970's the hunting thesis had fallen apart. There is of course debate as to how the meat was obtained. Be it as scavenge from dead creatures or stealing from other carnivorous. Work by Blumenschine has calculated that wild cats only eat say 15% of the body mass of their victims, hominid could take the next part with the remainder being left to hyenas and vultures.
Yet as Isaacs points out it is not just the existence of tools that is important for lifestyle analysis. It is their location and co-location with bone that can tells us a lot (14). Here he offers his "foci" framework. His analysis of site 50 and other sites enables him to pose four types of site. These sites are based on the relative mix of bones and are named A,B, C and M. and are show in Table One
Table One
· Site A is essentially a tool manufacturing site where core,
flake and debitage are evident.
· Site B is composed of tools and bones of a single animal. This
implies that the animal was butchered on site. The tools may have been
use to cut up meat or to crush bones in order to obtain the marrow.
· At site C we have evidence of many tools and many varieties of
bones. This implies that this was a regular butchering site and that the
kill was taken to this site to be worked on.
· Site M is thought to be a homebase, that is a site to which hominids
frequently returned after scavenging.
Isaac developed his thoughts and claimed that his homebase and associated hunting activity was the foundation of humanness. It implied role specialisation, social structure and sexually different tasks. There were of course many objections. Binford in particular proposed a scavenging rather than hunting approach and therefore undermined the rest of the thesis (15).
Given the existence of these homebases did early hominid create structures for shelter? There is little evidence. But some stones in Olduvai Gorge suggest the existence of wind breaks and the outline of a circular structure. Such a structure could easily have been roofed with long vanished branches. Lambert claims that shelters in the Olduvai Gorge can be dated to 1.8m yrs (16). Others are less sure. Tattersal is dismissive of sheltered homebases claiming they did not occur until 350,000 years ago (17) .
What can the environment tell us?
The climatic evidence is also patchy. Clearly the climate was different and changed dramatically over the four million years at issue. The jury is still out on the exact correlation between climate change and evolution and therefore hominid lifestyle. And indeed no coherent approach appears possible at the moment. Isaac believes early hominids inhabited such a wide variety of environments that perhaps it didn't matter. But there are he says common features notably patchy forest, open grassland, water courses fringed with trees and swamp habitats. While we can measure climatic change in Africa through carbon isotopes in tooth enamel and show the movement of antelope from woodland to grassland we can not yet correlate this changes with changes in hominind lifestyle.
Yet other evidence is more helpful. In Laetoli we believe the immediate habitat was one of relatively open grassland with few trees. We have tracks dated at 3.8 myr which confirm bipedalism and this hominid track way was made by A.afarensis who used their bipedalism to move across grasslands to clumps of trees. It would seem that early habitats were probably not as open as has been anticipated.
Conclusion
Our earliest ancestors behaviour or lifestyle is the focus of tremendous attention But because behaviour does not fossilize, "teasing details out of the archaeological record has proved arduous" (18 ). For the moment then there is little that we can say for sure about the lives of our forerunners. We can detect a gradual change from Ape to Homo and the main factors of bones and stones appear to support this thesis. But whatever the lifestyle of the first hominids it was clearly a successful one. For if the lack of significant change in the fossil record means anything in this context, this lifestyle endured for a very long time. Yet the evidence is still flimsy. And finally, as Cartmill comments all scientists are odd in some way but paleoanthropology is one of the oddest. For this reason alone there will always be bones of contention (19).
Matthew Walker 2002
References
1) Quoted in the introduction to The Making of Mankind, Richard Leakey, Michael
Joseph, 1981
2) Archaeology. Theories Methods and Practice. Renfrew and Bahn Chapter 4 p
163
3) Becoming Human, Ian Tattersall, Oxford University Press 1998
4) From Lucy to Language., p90 D Johnson and B Edgar, Cassell, 1996
5) From Lucy to Language., p91 D Johnson and B Edgar, Cassell, 1996
6) Durent in Bones of Contention, p 318, Roger Lewin University of Chicago Press
2000
7) The Archaeology of Human Origins. Glynn Isaac Cambridge University Press.
Chapter Three, Early hominids in action.
8) Durent in Bones of Contention, p 318, Roger Lewin University of Chicago Press
2000
9) The Cambridge Guide to Prehistoric Man, p111, Lambert Cambridge University
Press,1987
10) Becoming Human, Ian Tattersall, Oxford University Press 1998
11) The Cambridge Guide to Prehistoric Man, p114, Lambert Cambridge University
Press,1987
12) The Cambridge Guide to Prehistoric Man, p113, Lambert Cambridge University
Press,1987
13) Bones of Contention, p 314, Roger Lewin University of Chicago Press 2000
14) The Archaeology of Human Origins. Glynn Isaac Cambridge University Press.
Chapter Three, Early hominids in action.
15) Binford quoted in From Lucy to Language., p90 D Johnson and B Edgar, Cassell,
1996
16) The Cambridge Guide to Prehistoric Man, p113, Lambert Cambridge University
Press,1987
17) Becoming Human, Ian Tattersall, Oxford University Press 1998
18) From Lucy to Language., p90 D Johnson and B Edgar, Cassell, 1996
19) Cartmill in Bones of Contention, p 319, Roger Lewin University of Chicago
Press 2000