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This text was drafted by award-winning MMW TAs Tara Carter and Beth Peterson, (Anthropology) in the summer of 2008, supported by the MMW-based research funds left in his account on the death of Prof. Donald F. Tuzin, long an instructor and supporter of MMW. The text was substantially modified by Professor David K. Jordan in summer, 2011 to fit it to the needs of MMW-11.
This text may be freely reproduced for non-commercial educational purposes.
Our model of early hominid evolution is made more complicated because of what paleontologists describe as the “mosaic” nature of evolution. Mosaic evolution is a pattern of evolutionary change where the rate of change in different systems is not the same. That is, changes in one system, say locomotion, occur at a different rate from changes in another system, say diet. While we cannot parse out the direct effects of these fluctuations on the evolution of various systems in early hominids, the overall effects can be seen in the suite of characteristics we see in the early hominids that differentiate them from hominoids.
What does it mean to be human? What are the distinctive traits or markers that make us us? There are four broad traits that readily come to mind when trying to distinguish us from other animals: (1) Bipedalism, (2) large, complex brains, (3) complex language abilities, (4) a significant role for culture (shared, transmitted, morally forceful understandings) and cultural traditions.
The Essential Fossils web folio contains descriptions of some of the most important fossil hominids we know about. (Open in separate window..) In this essay we merely broadly summarize what these specimens suggest about the four Hallmark Traits.
Conclusions: Which form is the earliest bipedal specimen depends upon how fussy we are about what exactly constitutes bipedalism. Must it be identical with our own? Pretty clearly even the earliest hominids walked on two feet, sometimes in addition to moving other ways. And we see in Australopithecus and earlier forms —we have the best evidence from Lucy, the famous A. afarensis specimen— a “mosaic” of traits that leads to ambiguity about where to draw the “first bipedal” line. We can safely say that Homo habilis, Homo erectus, and Homo ergaster were bipedal, and that Homo erectus and Homo ergaster were even highly efficient bipedal walkers. In fact, their lower skeletal anatomy is nearly identical to our own. The “mosaic of traits” that described Lucy’s complex bipedalism are not present in early Homo.
Conclusions: Despite the Hollywood stereotype of grunting cavemen, it is highly unlikely that Neanderthals had no formal speech. It is unclear if earlier hominids likewise had the physiological ability for speech since DNA cannot be extracted to test for the FOXP2 gene, a gene associated with modern speech and recently discovered to be present in Neanderthal DNA. It seems likely that some forms of simple language (whatever that means) pre-date Neanderthals. Researchers have been impressed to discover that among modern apes a variety of specific calls are not innate, but are shared, learned behavior. In other words, they are technically a cultural adaptation. But they are not patterned the way speech is patterned and probably represent a different adaptation.
With Cro-Magnon, all the necessary “equipment” is present, including the hyoid bone for controlled speech, and a complex brain for conceptualizing the world with abstract symbols. The complexity of Upper Paleolithic cultural artifacts and behaviors associated with them makes it inconceivable to most scholars that Cro-Magnon populations would not have fully developed languages.
Anthropologists define “culture” as the sum of the shared, learned, morally forceful, understandings of a group of people. (Fuller Definition)
Obviously, Not all aspects of culture leave a material trace, especially when we are looking as far back as 7 million years ago. We will focus our attention on some crucial hints that are evident in the record of earlier hominids.
Many animals can be said to use “tools,” from chimpanzees to sea otters. But hominids took tool-making to new levels and humans ultimately became totally dependent on those tools, from sickles to airplanes, from hammers to cell phones. But the beginning of our dependency was quite simple, and the surviving evidence of it simpler yet: stone tools. (For a web site showing most of the types of stone tools discussed here, in a separate window , click here.)
The evidence for tools 7 million years ago, in the early days of the hominid line, is sparse. The few possibly modified stones associated with the earliest hominids we know about —Sahelanthropus, Orrorin, Ardipthicus— have been interpreted as possibly intentionally created cutting edges. That’s not much to go on.
The technique for producing these edges is simple: drop a stone or bang it on another stone to break off a piece, exposing a sharp edge. Stones break through natural forces, such as stones rolling down hill slopes or along riverbanks, and it is difficult to tell if a simple broken stone was made (or used) as a tool or not. However, comparisons with modern primatology suggest a very strong likelihood that digging sticks or other perishable objects would have been used as tools for various purposes. Fingernails are good, but to this day there are jobs better done with sticks. Of sticks and stones, all we have, of course, are the stones.
Australopithecines may have made sharp edges on stones by smashing stones together to break them, creating what have been called cobbles. Typically these are simply broken stones, with a modestly sharp edge along the line where they are broken, and they can be identified only if enough pieces have been removed to preclude the possibility of their being mere results of non-human natural forces. Unfortunately, a stone can turn into a cobble with very modest modification, and the line between tools and accidents is often unclear.
(In the late 1800s, when one exciting 2-million-year-old European “artifact” turned out to be simply the accidental product of natural forces, it was derisively called an eolith, a “wind stone.” The term remains available to be used with erudite and condescending dismissiveness whenever archaeologists extend their claims beyond their evidence.)
More cobbles have been found associated with Australopithecus sites than with earlier hominid contenders. The oldest of these sites date to 2.6 million years ago in Ethiopia and are associated specifically with an Australopithecus form called A. garhi. Some researchers have suggested similar tools to have been found at A. anamensis, A. afarensis, and A. africanus sites. Other researchers remain skeptical that these cobbles are in fact tools, rather than just naturally occurring broken stones —eoliths. The close association with Australopithecine fossils and cobbles suggests that, if they were not creating sharp-edged broken stones, Australopithecine hominids may have been opportunistically using them.
The name H. habilis means “handy man.” (Our word “able” comes from the same Latin word: habilis.) H. habilis created choppers (also called pebble tools or chopper tools), using a technique called Oldowan, named after Olduvai Gorge, Tanzania, where many Oldowan tools have been discovered. Unlike cobbles, Oldowan pebbles or choppers are made from carefully selected stones, usually with water-smoothed river pebbles from which several chunks have been detached on one end, producing a rounded end and a pointed one. The rounded end is easier to hold while in use. More than with simple cobbles, the maker, much like a sculptor, had to imagine the tool within the stone and devise a method for producing the desired shape. Some argue that this represents a giant leap of imagination. That imagination and the associated technological skill are what make this first evidence of serious tool-making so important in our understanding of hominid evolution.
H. erectus and H. ergaster: Oldowan style tools were also made by erectus and ergaster, but these hominids also produced hand axes, in a style that has been named Acheulean (ash-you-LEE-uhn), named after the town Saint Acheul in France where they were first discovered. These hand axes were made by flaking or chipping off bits of stone around all the edges, creating a tool shaped like a teardrop or football. These hand axes were not hafted onto handles, as far as we know. Apparently they were, as their name implies, simply held in the hand while in use. They would have been used to complete a wide variety of tasks, from cutting wood to scraping and cutting animal hides. Acheulean hand axes are more efficient than Oldowan tools, so efficient in fact they remain the dominant tool technology for almost 2 million years!
Some researchers have argued that these tools help to explain how and why Homo erectus was able to travel, eventually leaving Africa. With these tools in hand, erectus could rely on a mixed diet from both hunting (or at least efficient scavenging) and gathering plant foodstuffs, following their food on the hoof, that is, migratory animals.
H. heidelbergensis continued to make the Acheulean hand axes, but a 400,000 year old wooden spear surviving at a site in Germany reminds us to think of stone tools as only one part of a larger “kit” of equipment, most of which would have been made of perishable materials.
H. neanderthalensis : Neanderthal tool-making represents advances in both technology and skill. Neanderthals created a highly sophisticated flaked-stone technology called Mousterian. A distinctive feature of the Mousterian toolkit are stone tools made by a technique called Levallois (leh-vall-WAH), named after the Levallois-Perret suburb of Paris where many of these tools were discovered. The Levallois technique starts by creating a slightly dome-shaped disk with the top flattened off. Next a series of flakes is struck off the sides of the dome, proceeding around and around. When each flake falls off, it is already formed into a distinctive and useful shape, requiring only touch-up to reach its final form. It is possible to continue around and around the perimeter of the ever-smaller core knocking off flake after flake until the “dome” is too small to be of further use because the chips have become too small. The Levallois method provides good control over the size and shape of the final flakes, which could then be used as scrapers or knives or to produce useful points.
The range of tools in the Mousterian assemblage is quite broad, although stone tools are often crude enough that they can be hard to classify usefully. But the most impressive thing about it is that Neanderthals were clearly producing different stone tools for specific activities, rather than using a hand ax for everything, indicating a degree of specialization and advanced thinking not seen before. Not very advanced, but much beyond what a Homo erectus could probably manage. And the ingenious Levallois technique in particular, requiring a great deal of foresight into the desired final product, suggests the ability to generate a far more complex “mental template” than evidenced in earlier fossil specimens.
In addition to the Levallois technique, hand-held spears (thrusting spears) have also been discovered at Neanderthal sites. These spears could be used to hunt big game animals at close range. After Neanderthals and Homo sapiens came into contact, Neanderthals in France and northern Spain seem to have developed an imitation of Homo sapiens technology, called Châtelperronian. Although the evidence is open to several interpretations, some scholars have argued this is an indication of cultural sharing and communication between the two groups, perhaps indicating that the two were more alike than we often think. It is argued today that the Châtelperronian industry indicates that Neanderthals were keen decision-makers, able to seize new opportunities and adapt them to their own needs —a skill we think of as distinctly human. (An earlier view was that H. sapiens was simply inheriting some techniques used by Neanderthals. That view still has thoughtful defenders.)
Cro-Magnon: The oldest known distinctively H. sapiens tool types are found in Africa and date to nearly 195,000 years ago, reaching Asia by 50,000 years ago, Europe by 41,000 years ago, and North America by 20,000 years ago.
As with all other aspects of culture, tool-making technology burgeons with new innovations in the hands of Homo sapiens. These technologies include fine blade technology, needles, rope, atlatls (spear-throwers), harpoons, fishhooks, and for the first time we know of, a proliferation of tools made from antler and bone not just stone. Indeed the main purpose of some of the stone tools was apparently the manufacture of other tools, the wood and bone ones.
From what we can tell from the fossil record and by models designed through modern primatology studies, early hominids all the way through Neanderthals lived in small groups. This may have been a way to combat resource scarcities and as a tool in resolving conflict.
Homo sapiens, in contrast, has lived in social groups of a variety of sizes, from as low as a dozen or two in foraging bands, to the vastly larger modern statues, including well over a billion in China today. One of the most important theoretical problems in the study of early societies is how they were able to get larger —from band to tribe to chiefdom to kingdom to archaic empire— a question that critically involves changes in the governance structures.
Early hominids like Sahelanthropus and Australopithecus probably had similar a group structure to that of modern non-human primates, characterized by a few pair bounding couples, other females and their offspring, older males, and a few female adolescents. This form of social organization seem to include very few young adult males. Why?
Sexual dimorphism, the difference in size between males and females, is a common trait among all hominids. Some researchers have argued that the presence of substantial sexual dimorphism indicates that there was competition for mates, with dimorphic traits playing a role in sexual selection. (Big burly males could whip little wimpy ones in competition for females, who did not need to be burly to be fought over.) If there was such competition, it would make sense for a few “winning” males to kick out any potential rivals, leaving genes for large male size in the resultant population. (The “kicked out” wimpy males presumably perished in ignominy, according to this model.)
(Counter-arguments from studies of modern primate behavior, however, suggest that smaller males can develop mating strategies that do not depend upon defeating larger animals in direct competition, and that choice by females may play a bigger role in such interactions than was previously realized. This makes it less convincing to draw conclusions about probable social structure based on differences in average size of male and female specimens.)
The evolution of bipedalism would have had a profound effect on hominid group organization. As a result of the skeletal changes necessary to accommodate bipedal locomotion, such as narrowing of the pelvic region, pregnancy and infant care dramatically changed. Hominid infants are far more dependent and less developed than are the young of most other animals. Just compare a newborn horse, which can walk within minutes of birth, and a human child who cannot walk for nearly a year after birth. This underdevelopment at birth is not seen just in walking, but in cognitive ability as well.
We can see this difference in modern populations of both humans and chimpanzees. A chimpanzee infant is born with 40% the brain size of an adult and by the time it is a year old, 80%. Human infants, in contrast, are born with a brain size 25% that of an adult. When that child reaches 5 years in age, its brain size will still only be 50% that of adult. It is not until age 10, that a child will have a brain size 95% that of an adult. Changes in group organization, and even perhaps a longer lifespan, may have been a response to this greater dependency.
The so-called “grandmother hypothesis” suggests that older females, beyond their reproductive years, helped out younger mothers by supplying food and looking after children. This assistance increased the chances for infants to reach childhood, and for children to reach adulthood. Having a couple of grandmas in every group would have been, as it often is today, viewed favorably, making older females highly valued in the group. This value insured that they in turn would be looked after, lengthening their lifespan. Human females live well past their reproductive years, a trait highly unusual when compared to other animals. It therefore may have been selectively advantageous for human females to have such a long life after the cessation of reproductive capacity (i.e., after menopause). The grandmother hypothesis offers one explanation for this, an explanation that begins with bipedalism.
Large-scale population concentrations were not possible in most areas of the world before the advent of agriculture. There is therefore a strong correlation between group size, group organization, and available food resources. As we have seen, state organized societies are only possible when large amounts of durable foodstuffs are available. Otherwise, staying small makes the most sense.
Today, we inhabit just about every location on the planet. But for most of our hominid history our ancestors could only be found in eastern and southern Africa. We have already seen how group size and the environmental setting go hand in hand. Before Homo erectus, the best way to ensure survival was to stay in small, mobile groups.
With Homo erectus we see a new alternative: a meatier diet. This was made possible with the development of the Acheulean hand ax, which enabled erectus to process and butcher meat, but not necessarily to hunt. Most scholars see a strong correlation between this new ability to rely more on a meat diet and erectus’ move out of Africa. Why? A shift to meat allowed hominids to travel since, unlike plants, which are regionally specific and sometimes harmful, animals are migratory. Perhaps erectus was simply following the herd and ended up in new areas.
Equally important to this argument is the likelihood that erectus could have at least controlled fire for cooking meat. Cooked meat is far easier for our stomachs to digest than raw meat, which, like some plants can be dangerous.
We can see the impact of this development if we examine the evolution of the size and structure of the hominid stomach. Today, we have relatively small guts, and in fact, the size of an Australopithecus stomach was much larger, proportionate to its size, than our own. Large, complex, stomachs are needed to digest most raw plants and nuts, but the same is not true for cooked meat.
A few scholars debate whether erectus had the technology to hunt and cook meat (although the evidence seems to favor the view that this was the case), but there is no doubt that Homo heidelbergensis and Homo neanderthalensis did. Many scholars have suggested that a diet high in cooked meat is linked to the development of larger brains with a highly developed neocortex. If this is true, those handy hand axes had a profound effect on hominid evolution!
In addition to changes in diet, there is archaeological evidence to suggest that Homo heidelbergensis and Homo neanderthalensis built shelters and made clothing. This would have been especially necessary under the Ice Age climatic conditions of the Middle Paleolithic. Clothing and rock shelters, however, would not have been enough to endure these conditions.
It is likely that hominids, perhaps even as far back as Australopithecus, used a system of reciprocity as a kind of insurance policy against uncontrollable natural forces. Reciprocity is really just a fancy term for sharing, but it is also sharing with a debt: delayed sharing if you will. Reciprocity is an exchange system, where individuals share amongst their group without thought of immediate return; individuals are expected to contribute when they can and receive when they do not have anything. This builds and maintains dependent relationships within the group. But, the individual who is too greedy and does not share runs the risk of punishment or even exile. When the system works, it ensures that everyone has enough food to eat and, when needed, additional hands to help carry out various tasks. This cultural system has been, and still is key to our survival, and proved to be particularly conspicuous in foraging studies studied ethnographically in the XXth century. (In the XXIst centuries all foraging societies have been destroyed or substantially modified, so further ethnographic study of foraging is effectively impossible.)
In addition to reciprocity there is archaeological evidence that Homo sapiens participated in trade networks. This form of exchange would likewise ensure a steady flow of necessary goods and services in a community.
Taken as a whole, tool technology, clothing and shelter craftwork, reciprocity, and trade all contributed to our survival. Biologically, we are hardly the most robust of creatures. We lack powerful claws and jaws for self-defense, we are fairly small —on the whole we are rather fragile beings. But the combination of our biological traits with cultural developments has made us a powerful force on the planet. Our creativity and resourcefulness have paved the way for successful human colonization in a variety of environments. From the extreme heat of Africa, to the chill of Siberia, we as a species can be found just about everywhere. Different cultural strategies are employed in different kinds of physical and social environments, which also makes us culturally a highly diverse species.
However, our successes are not without limitation. Evidence for how climatic change has shaped human societies is ample. In an age where terms such as “global warming” and “greenhouse gasses” have become popular watchwords in a society plagued with anxiety over the fate of the planet, it has become increasingly clear not only that the environment can impact human societies, but that we in turn possess the ability to alter our physical landscapes dramatically for the better and the worse.
A significant trait used to define “humanness” is our ability to define and make sense of the world through symbols. A symbol is an object, picture, or written word, that stands for something else by association, resemblance, or convention. Symbols represent ideas, concepts, or other abstractions. Thinking in abstractions, that is in symbols, is something perhaps distinctively human. It is a trait that has had a long, slow development and arguably began millions of years ago with the creation of the first stone tools, when an unmodified stone presented itself to a creative mind as a potential tool trying to get out.
Studies of non-human primate cognition show some ability for abstract thinking, but not at the level of modern humans. (We hinted at this in referring to the “mental template” involved in being able to foresee a stone tool in a mere stone.) Two areas to explore in the prehistoric development of abstract are ritual behavior, which takes events from everyday life and gives them some sort of symbolic meaning, and artistic expression. Both require a high degree of abstract thinking and can give us clues about this distinct human trait. Most importantly, both leave physical traces that an archaeologist can use as evidence to confirm or deny various hypotheses.
Our best archaeological evidence for ritualistic behavior comes from burials. Burial of the dead is a traditional practice found in most contemporary human cultures, sometimes in competition with cremation or other forms of disposal of dead bodies. Burial treatment comes in many different forms and can be done for a variety of different reasons, and is almost always steeped in ritual significance. There is no evidence of deliberate burial treatment for most of our hominid history. It seems probable for the first time with Neanderthals and it is certain with Upper Paleolithic humans.
The idea that Neanderthals may have buried their dead goes back to the discovery of skeletons at the site of Spy in Belgium in the late 19th century. The discovery consisted of two complete adult skeletons buried in a cave. More recently, a number of additional cave burials have been discovered, often with the bodies placed in a flexed position, suggesting deliberate burial. These individuals did not die in the spot they were found; they were moved there and placed in a pit with some care.
Perhaps the most tantalizing piece of evidence comes from Shanidar Cave in Iraq. Among the burials found there is a male who lived to be about 30 or 40 years old, old age for a prehistoric human. This individual had suffered a number of serious injuries that had left him blind in one eye, and withered away his right arm. Despite these injuries, this Shanidar man survived for a number of years in this weakened condition. To do so, he must have had help. The find vividly demonstrated Neanderthal concern for their fellow men, changing forever the modern view of them. Suddenly Neanderthals were being described as capable of “compassion”! At the same site, there is another individual, placed in the flexed position, with a large quantity of wildflower pollen found in association of the body. The wildflower pollen seems to have come from flowers laid over the body at the time of the burial. (Skeptics have suggested the flower pollen could have blown into the cave, but the burial was far too deep inside the cave for such a proposal to be realistic rather than merely curmudgeonly.)
An important question to ask of this evidence is whether these burials were motivated by ritual, perhaps something like ancestor worship, or whether the motivation was somehow utilitarian? Some scholars have suggested the motive for burying the dead was to keep scavenging animals from eating the bodies, perhaps indicating a degree of concern for the body after death.
Other researchers have suggested the motive was simply to keep larger animals from being attracted to the smell of rotting meat and coming too close to the camp. In that case, the bodies were merely being disposed of, not ritually buried. These scholars also point to a lack of accompanying grave goods as further evidence of a non-ritualistic nature of these burials.
Even in the absence of grave goods, of course, these burials could still be ritually charged. Our own burials usually include little by way of grave goods, after all. In some sects of Islam today, for example, individuals are buried in nothing more than a plain white shroud. And today’s “green” burials are deliberately spare. But no one would argue these are not deliberate and symbolically significant burials.
The evidence currently available suggests at least some degree of ritual treatment of the dead for some Neanderthal communities.
In contrast to the controversy surrounding the meaning of Neanderthal burials, the symbolic capacity of Homo sapiens is unmistakable. It did not appear immediately. H. sapiens bodies date to nearly 200,000 years ago, and, based on archaeological evidence, their behavior could have passed for something Homo erectus would have thought normal. But by 40,000 years ago, communities in Australia began cremating their dead, and in Europe numerous quite elaborate artifacts or grave goods were placed with the body. For many researchers the symbolic component of these sites is obvious. Such burials are completely absent in the earlier archaeological records.
While it is always possible that early hominids did practice art forms that simply were not preserved in the archaeological record (like song or dance or face painting), we have no definitive evidence of art until Homo sapiens.
This might be related to the development of the neocortex, the area of the brain responsible for abstract thinking. Homo habilis, for example, had a brain capacity of averaging about 650 cubic cm and did not seem to produce either elaborate tools or art. Homo erectus averaged more like 900 cubic cm, but also did not exhibit archaeologically visible symbolic elaborations. Neanderthals, with an average brain size like ours or slightly larger, made reasonably carefully worked tools, but there is no evidence of artistic production. None of the art forms that flourish in the Upper Paleolithic with Homo sapiens —cave painting, jewelry, figurines sculptures— have been discovered at Neanderthal sites.
The earliest evidence of artistic expression for Homo sapiens is found in Qafzeh, in Israel, and dates from about 92,000 years ago. Seventy-one red ochre pieces were found there, with several stone artifacts stained red by the ochre. Ochre is a yellow or reddish-brown soil that was commonly used in paints or dyes, so it is likely that people at Qafzeh were using the ochre deliberately to color these stones. Why they were coloring these stones remains elusive, but that this behavior indicates a kind of abstract thinking is clear.
Perhaps a more important, albeit thornier, question to ask is why we have art and other hominids do not and did not? Since Neanderthals apparently possessed the physiological ability for art —a reasonably highly developed neocortex (abstract thinking) and the FOXP2 gene (language, symbolic thinking)— we should consider that perhaps for them, art was not something valued or necessary.
Perhaps symbolic behavior had a survival value for anatomically modern humans. There may be some benefit in ordering our world, and our relationship to others, through symbols. Whatever the reason, art has become an integral part of how we define what it means to be human, and the production of non-instrumental, artistic objects has come to be a critical sign of cognitive capacity for physical anthropologists thinking about earlier human forms.
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