What is Archaeology?

Archaeology is a sub-discipline of anthropology, which is the study of people, particularly human biological and behavioral variation in the present, as well as the past. More specifically, archaeology is the reconstruction of ancient behavior from the things people left behind. When combined with the study of the biological changes that the human lineage has undergone over the last several million years, archaeology provides an important part of our understanding of the evolutionary success of modern humans, Homo sapiens.

The job of an archaeologist can be a difficult one. Archaeologists study peoples' material culture, the things that are made, modified, or used by humans or our ancestors (generally referred to as hominins). The study of material culture includes examining artifacts, portable items such as baskets or hammers, and features, which are non-portable things such as buildings or fireplaces. Equally important to the archaeologist are contextual clues that are often learned only through painstakingly careful excavation. These clues include the location of the found artifacts (inside a temple, a grave, or a trash pile?) and their association with other artifacts (are hammers always found with an anvil?) or environment (do the associated animals suggest humans were living in subarctic tundra or a heavily forested valley?). Imagine the difficulty encountered if someone were to reconstruct your life, likes, dislikes, and habits from the things that you own, and you begin to get a sense of what archaeology is about. Throw out half or more of those things made of perishable materials (cloth, wood, etc.), jumble them up with your neighbor's possessions and those of their great-great-great-great grandchildren and you begin to get a clearer sense of the task at hand.

How, then, do archaeologists know what they think they know? Like geology, archaeology is a historical science. As we cannot observe the past directly, archaeologists approach it by setting up analogous conditions through experimentation and observation. For example, what if you wanted to know how stone tools were made? To answer this question, some archaeologists have conducted a series of practical learning experiments in which they make the tools themselves, thereby understanding the process of manufacturing stone implements from beginning to end (Whittaker 1994). Likewise, how do archaeologists determine if the bones found at a site are the result of hominin dinners versus those left behind by other animals? Archaeologists have conducted controlled experiments in which bones are fed to hyenas and other animals in captivity and in the wild, carefully studying the remains for traces to distinguish the marks made by these and other animals from those made by humans (Lyman 1994).

Consider archaeologists interested in learning what early campsites looked like. To address this, scientists have studied from an archaeological perspective living groups of hunter–gatherers groups recently operating in Australia, southern Africa, and elsewhere, providing a comparative baseline of what to expect (Yellen 1977). Indeed, this spirit of comparison is in many ways at the root of prehistoric archaeology. It wasn't until contact with the stone tool-equipped populations in the New World that Renaissance Europeans (living in an agrarian society with metal tools) recognized that the strangely shaped stones they had attributed to lightning strikes or fairies were in fact stone tools from their own forgotten hunting and gathering past (Daniel 1962, 1967).

What is the Relevance of Archaeology to Human Evolution?

The archaeological record provides a unique, long-term view of the evolution of human behavior. The study of human evolution includes an examination of the physical, genetic, and behavioral variation of the hominin lineage since we diverged from other apes some seven million years ago or more. Although the shape of fossilized bones does record major changes in hominin behavior (such as habitually upright posture), it is not until about 2.5 million years ago with the first appearance of the archaeological record that we have abundant evidence for a more complete range of early human behaviors. Whereas morphological changes are the outcome of selective pressures acting on several generations, artifacts can record snapshots of the past, such as the time it took to make a stone tool, butcher an animal carcass, and transport meat back to friends and family.

In addition to providing a potentially different time perspective on the past, the relatively abundant archaeological traces from about 2.5 million years onward signal our increasing reliance on material culture as a key element of human survival and socialization (Table 1). Unlike most other animals, humans have long relied extensively on material items for basic survival needs (e.g., tools for hunting and cutting), as we lack, for example, the claws or sharp canine teeth of most carnivores. In addition to a complex knowledge of animal behavior and plant properties, human hunting and gathering involves bows, arrows, traps, digging sticks, and other items of material culture. Indeed, the earliest archaeological traces suggest hominins used tools to gain access to food and that natural selection may have favored those hominin groups with ready access to meat, marrow, and other food items more readily obtainable with tools.

Table 1 Key Paleolithic industries, shown in stratigraphic order
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To date, the earliest archaeological traces are stone tools from sediments that are approximately 2.5 million years old and are found at Gona, Ethiopia (Semaw 2000; Stout et al. 2005). All human groups as well as many other primate populations, such as chimpanzees, use tools composed of organic materials such as wood that rarely preserve more than a few years (McGrew 1992), unlike stone, which is a very durable material. But some chimpanzee groups use stone to make and use crude tools for nut-cracking (Mercader et al. 2007), and bone tools presumably made by Paranthropus robustus show signs of being used for digging into termite mounds (Backwell and d'Errico 2001). As these examples show, the earliest stone artifacts likely underestimate the true age of tool use and perhaps reliance upon tools by hominins, as there may have been a time lag between when stone tools were being made and when we can detect them in the record. The Gona artifacts show that by 2.5 million years ago, some hominins had learned to consistently select high quality rocks from local streambeds, fracture these stones using cobbles as hammerstones in order to produce sharp-edged splinters called “flakes,” and to use these flakes as knives for removing skin or meat from animal carcasses (Fig. 1). Much like the marks on a kitchen cutting board, the direct evidence for this occurs on the bones themselves in the form of distinct cutmarks, as well as unique patterning of bone breakage distinctive of hominins determined through experimentation (Lyman 1994; Fig. 2).

Fig. 1
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Schematic illustration of how the earliest stone tools were made, striking sharp-edged flakes from a lava cobble by direct freehand percussion using a hammerstone. Shown is a sequence of three flake removals; note that the core from which the flakes are struck is rotated each time a flake is removed. Flaking is a controlled action requiring the correct combination of angles on the core, hand–eye coordination to strike a small spot, and use of the required force to remove the flake. Figure redrawn by Christopher Coleman from Schick and Toth (1993)

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Fig. 2
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Cutmarked antelope lower leg bone from site FwJj14A, Kenya, approximately 1.5 million years old. Photograph by B. Pobiner

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The advent and routine use of stone tools likely had a profound effect in broadening the range of food types available to our omnivorous primate ancestors. The identity of the crafters of the earliest stone tools is unknown (thus earliest tools are termed “Oldowan” after Olduvai Gorge, Tanzania; see Table 1). Anatomical evidence suggests that a number of species on the landscape around 2.5 million years ago, including Homo habilis, Australopithecus garhi, Paranthropus aethiopicus, and Paranthropus boisei, could have made them (Tocheri et al. 2008). Later members of the genus Homo (such as Homo erectus by 1.6 million years ago) show anatomical changes that suggest a meat-rich diet and resulting larger brain, reduced gut size, and changes in tooth morphology, whereas P. boisei became extinct (Aiello and Wheeler 1995), suggesting perhaps that more regular access to meat was a trait that characterized our genus. Whatever the long-term consequences, the changes in early hominin diet brought about by tool use was probably at first incremental. Early hominins were likely often in stiff competition with carnivores, and a major debate concerns the extent to which early hominins were passive scavengers or active hunters. In rare instances, as at approximately 1.8-million-year-old sites at places such as Olduvai Gorge, Tanzania, cutmarks are overlain by carnivore toothmarks, which by their placement must have been produced after the cutmarks. This demonstrates that in some instances, hominins had first access (Potts 1988).

Fossils found at early archaeological sites also show changes in the types of food hominins acquired and the distances they were transported. Early hominins such as H. habilis were probably often out-competed by carnivores, rarely acquired meat, and when they did, likely consumed it a short distance from the kill site (Faith et al. 2009). But by 50,000 years ago and probably much earlier, hominins were acquiring a diverse range of animals and transporting selected pieces with the most meat or nutritional value to home bases (Assefa 2006). Increasingly diverse wild game and careful selection of nutritionally rich elements may signal better hunting and has at least two more important implications. First, greater hunting skill combined with increased human population size had the consequence of putting substantial stress on local animal species, many of which underwent local population depletions or extinctions, at which point human hunters switched to different species, often with similar disastrous results on these other animal populations (Kuhn and Stiner 2001). Evidenced by this example, human impact on the environment is a very ancient story. A second important feature of food selection (particularly large game) and its transport to a home base or camp is that the transportation of the food, and its delayed consumption, provides the context for sharing amongst a larger group and thus the formation of the complex social obligations. It may also contribute to the sexual division of labor and changes in life history patterns that include extended periods of learning and paternal provisioning of young that are among the foundations of human society (Bird and O'Connell 2006; Hawkes et al. 1991, 1998; Isaac 1978).

Archaeologists who study hominin diets often focus on bones, meat, and hunting not because this is an accurate reflection of what hominins ate or how they spent their time as perhaps perpetuated by Ardey (1976) but rather because bones preserve well compared to other elements of the diet. This preservational bias is important to recognize, as plants for example comprise from 20 to 70 percent of the diet of recent human foraging groups except for those living in arctic or subarctic conditions (Kelly 1995; Marlowe 2005). Our understanding of the non-meat components of the diet largely hinges on newly developed methods for their recovery and the chance discovery of sites with conditions of exceptional preservation. One exciting new technique focuses on dental calculus (what dentists refer to as plaque) on fossil teeth, whose incremental accumulation serves as a hard, protective coating for starch grains and other microscopic plant components that can be recovered with careful sampling (Henry and Piperno 2008). Organic materials are also preserved under circumstances whereby the artifacts are burned or buried under waterlogged conditions. For example, seeds and fruits have been recovered from the Neanderthal levels at Kebara Cave, Israel (Lev et al. 2005) about 55,000 years ago. At the open-air site of Gesher Benot Ya'aqov, also in Israel, nutshell fragments and the anvils and hammerstones used to crack them were recovered from lakeshore sediments dated to more than 780,000 years old (Goren-Inbar et al. 2002).

The use of stone tools to crack nuts at Gesher Benot Ya'aqov is an important reminder not only of the importance of tools used by hominins but also of their diversity in form, function, and material. As for bones, the focus on stones by those who study the archaeology of human evolution is largely due to their preservation. There are some important general patterns among the stone tool record of the last 2.5 million years (Table 1). First, in general, stone tool complexity increases through time. Even the earliest pieces recognized as stone tools demonstrate mastery of the necessary complex relations between hand–eye coordination, motor skills, and an understanding of the raw material properties involved in the production of sharp-edged splinters or flakes that were used with little subsequent modification. Later tool forms, such as the Clovis spear points used by hunters some 13,000 years ago in what is today the United States, show numerous technically demanding flake removals that essentially “sculpt” carefully shaped pieces (Fig. 3a). These points were in turn hafted through an equally complex process of applying resin or binding to join to the stone tip to a carefully shaped wooden pole, or shaft (Frison 2004).

Fig. 3
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Stone tools. a Clovis point, Dent Site, Colorado, approximately 13,000 years old (after Whittaker [1994]). b Front and side views of an Acheulian hand axe, Refuf Pass, Egypt, approximately 350,000 years old (after Coles and Higgs [1969]). Both artifacts redrawn by Christopher Coleman

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Necessity is the mother of all invention. Like the evidence for changes in diet, the increasingly complex stone tools suggest the need for hominins to acquire different sorts of food, or to acquire food more frequently, or in greater abundance, perhaps as a result of the effects of increased population pressure. This complexity in tool design may also be evidence of increased skill or intelligence, but is more likely a signal of the greater reliance of humans on technology for survival. As we are today dependent on the ability to control our food resources and buffer our risk of food shortages through large-scale food production, harvesting, storage, and distribution, along with the use of refrigeration and chemical preservatives, so too, albeit in a different way, did our hominin ancestors begin to gain increasing control over their food resources.

Hominin ingenuity can been seen in the broadly similar patterns of technological development across much of the globe, with comparable solutions independently developed to solve what were likely common problems of subsistence or survival. For example, by about 1.5 million years ago, hominins developed Acheulian handaxes (Table 1), thin teardrop-shaped implements that probably served as a tool for cutting and chopping and as a source for other sharp-edged flakes: a Swiss Army knife of the Paleolithic (Fig. 3b). Similar tools were used throughout Africa and Eurasia for well over a million years, and the available data suggest the possibility that this tool form was independently reinvented by multiple hominin species (Clark and Riel-Salvatore 2006). And from at least 100,000 years ago, similar methods of producing flakes and the use of flake tools as spear points characterize diverse hominin populations during the Middle Paleolithic and Middle Stone Age (Table 1), including both Neanderthals in Eurasia and early H. sapiens in Africa (Shea 2006).

Importantly, many items of material culture were probably invented in parallel not only by geographically distinct populations but probably also by different species. The archaeological record reveals in many instances strikingly similar behavioral patterns among physically distinct groups of hominins. To continue the comparison between Neanderthals and H. sapiens initiated above, there are no measurable differences in hunting ability or animal prey acquired by these two types of hominin among the well-preserved food remains found in caves across Eurasia, from Roc de Combe in France (Grayson and Delpech 2008) to Ortvale Klde in the Republic of Georgia (Adler et al. 2006).

This leads to the obvious question of what led to the evolutionary success of our species. Unlike the case for most of the last several million years, H. sapiens is the only extant hominin species and has been so for at least the last 10,000 years. Part of the answer to our evolutionary success may be biological, such as high birth rates or climate-specific adaptations (Finlayson 2004; Zubrow 1989). However, as archaeologists, we are particularly interested in social factors that may have led to our evolutionary success, such as differences in the division of labor (Kuhn and Stiner 2006) or communication, particularly in the sharing of information between individuals, among groups, and across generations.

Although language doesn't fossilize and the earliest writing dates to “only” about 5,500 years ago (and outside this review), there is good archaeological evidence to suggest that by at least 40,000 years ago, some populations of H. sapiens began using material culture to convey important information in ways not previously seen or used by other hominin species. Beads, a broad term used here to describe a non-utilitarian group of objects for personal adornment, provide one important example. Small seashells, some with naturally occurring holes, others with deliberate perforations, and many with wear traces suggesting being suspended on string, occur on Upper Paleolithic and Later Stone Age (Table 1) sites in the Mediterranean and in South Africa. They date from perhaps as far back as 80,000 years ago and are abundant by 30,000 years ago (Bouzouggar et al. 2007; White 2003). Artifacts from areas further from the coast such as parts of eastern Africa show beads were made from land snail shell fragments (Assefa et al. 2008). Ostrich eggshells were also used to make beads, whereby fragments were carefully broken and ground into disk-shaped beads by about 40,000 years ago (Ambrose 1998; Fig. 4).

Fig. 4
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Modified teeth from French Aurignacian sites (not to scale): (a) wolf canine, (b) deer vestigial canine, and (c) human molar. Images courtesy of Randall White

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Perhaps some of the most striking examples come from Upper Paleolithic Aurignacian sites in Europe (Table 1). Aurignacian sites are characterized by a distinct suite of artifacts (such as long flakes called blades and antler projectile points) and, at perhaps 35,000 years ago, are associated with the earliest populations of H. sapiens in Europe (Bailey et al. 2009). Aurignacian people used teeth, with holes carefully drilled or with grooves incised to aid their suspension, as parts of necklaces or perhaps sewn onto clothing. Importantly, although these teeth are from a variety of animals, they belong to completely different sorts of animals than those being hunted. For example, the beads from Castanet and Brassempouy in France were composed of the drilled teeth of fox, red deer, wolf, and even rarely, humans, whereas reindeer, horse, and various bovids dominate the food refuse at these Aurignacian sites (White 2007). These teeth clearly had significant meaning to their wearers, and the presence of similar pierced teeth at numerous Aurignacian sites suggests that knowledge of their significance was probably shared among a fairly wide audience of friends, relatives, and other members of the extended population.

The precise meaning of beads and other items of ancient material culture to those who made and used them are obscure to archaeologists today. Of course, we lack anyone to inform us of the sort of cultural context necessary to interpret these artifacts. Wedding rings provide a good example. Those of us living in the United States, Canada, and the United Kingdom (for example) recognize that a person wearing a ring on the fourth finger of the left hand is probably married. Rings are not universally exchanged at marriage, and when done so, the choice of hand or finger may vary cross-culturally. Although this tradition may derive from early beliefs about the presence of a vein in the fourth digit leading to the heart, the choice is arbitrary. From the perspective of the archaeologist, there is nothing about the physical characteristics of (most) wedding rings that would link them to marriage, rather it is the understanding of their meaning shared by members of a culture or community that lends them significance. The early beads found in the archaeological record could possibly be important objects that—like wedding rings—likely carried substantial cultural information, and may have been a key element of socialization and signifying to other humans within or outside of immediate groups. The difficulty of interpreting the meaning of things in the absence of social context is hilariously explored in the David Macaulay (1979) classic for all ages, Motel of the Mysteries, which provides an essential cautionary tale for anyone interested in the deep past.

Whatever their specific meaning, the appearance and abundance of beads and other uses of other forms of symbolism after about 40,000 years ago demonstrate the increasing use of material objects as expressions of group and/or individual identity. Since at least at one site in Russia, Kostenki, perforated shells (presumably made into jewelry) come from at least 500 km away (Anikovich et al. 2007), it's likely that by this time, trade within and between groups had become more prevalent. Sustaining these social networks would have necessitated increasing frequent and complex forms of communication—perhaps a precursor to today's cell phone and Blackberry-reliant cultures.

How Do You Teach the Archaeology of Human Evolution?

Archaeology is an integral part of paleoanthropology, the multidisciplinary approach to the study of human evolution. Archaeology provides the long-term perspective of human behavioral change and is the necessary complement to other approaches that emphasize biological change. The archaeological record is considerably richer than that of the human fossil record. Few sites preserve fossil hominins, but many contain archaeological “visiting cards” (Isaac 1981) that record their passage across the ancient landscape: stone tools, food, and living debris and other elements that open an important window into past human behavior.

The teaching of archaeology and human evolution can be achieved through a number of approaches. Establishing the key concepts can be done by first stressing the importance of thinking about “things” and the way that we use them. Archaeology is a fairly tactile thing, and there can be little replacement for actually seeing, or better yet, handling ancient artifacts or accurate facsimiles. These are available in many museums, online websites, or from commercially available firms, some of which are listed in the Appendix. A visit to a local museum, historical society, university or college, and/or an interaction with a professional archaeologist (every state has one, and you can find them here: http://www.rpanet.org/) can be a memorable, fun, inspiring, and educational experience (Eldredge 2009). Museums often have programs for school groups and educator guides to some exhibitions available to enhance a museum visit experience. Also consider working with your local school or public librarian to gather books, articles, and archival materials on archaeology and human evolution. Suggestions for creating your own on-site experience are listed in the Appendix.

Why Is Teaching Archaeology Useful, and How Does it Relate to Other Curriculum Topics?

Because archaeology is inherently multidisciplinary, you can use archaeological content to teach about chemistry, physics, biology, earth science, history, social studies, art, and other topics. Archaeology can be a good way to teach about more abstract principles: for instance, using radiocarbon dating to teach about isotopes in chemistry or physics. Also, climate change is a popular current topic; archaeologists often try to understand how human populations adapted to climate change in the past, giving us perspective on current human interactions with the planet. Archaeological inquiry is based on objects and evidence, so it can be used to teach about the process of science in general. It can also be used to teach critical thinking skills, problem solving, and citizenship; it enhances group and cooperative learning; and it is an excellent way to promote cultural awareness and sensitivity. For prehistoric cultures (those that lived before the advent of writing), examining archaeological material is often the only way we can begin to understand how people in the deep past lived. Capitalize on student interest in forensics TV shows and inherent desire to solve mysteries, and teach archaeology! In short, archaeology and human evolution can be gateways to broader training in critical thinking and a liberal arts and sciences education.