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Introduction

Global Change I devoted most of its time to an examination of the physical, geological and chemical processes that causes changes to the earth’s atmosphere and composition in the past and at present.  Global Change 2 will add another dimension to this equation – the role of human culture.  Human’s are a driving force in the world today and actually control many of the processes that cause global change.  Our goal is to understand that these are actually the products of human and cultural evolution and the role of humans has increased relatively recently. 

We want to briefly examine the evolution of hominids, the development of dependency on tools, the beginning and importance of fire, and the origin of language and its role in human society.

 Hominid Evolution

Human primate ancestors were forest dwelling only 6-7 million years ago in Africa.  This was a geological time period known as the Pliocene.  During this time there were continental changes that resulted in changes in the extent of the sub-tropical forest, isolation of some patches of forest, and the appearance of some primates who lived part of the time on the ground and not exclusively in the trees.

This fossil primate is known only from Africa and is called Ardipithecus ramidus.  It has been found in East Africa from contexts dating to 5 million years ago.  Its diet appears to have been vegetation and as a non-tool using primate it was small relative to the megafauna the inhabited Africa at that time.  These large animals were ancestral to elephants, hippos, antelopes, and other animals we know today but they were considerably larger.  We know about them from fossils found at sites in East Africa such as the Tanzanian site of Olduvai Gorge.

Geological and climatic forces were not constant or like those today during this period in hominid prehistory.  Volcanoes were a fact of life and a cooler climate impacted the distribution of edible plants and the composition and distribution of the forest.

Click here to see a hominid family tree.

Following Ardipithecus ramidus, our reputed primate fossil ancestor,  the Australopithicines evolved, radiated throughout east and South Africa, and evolved locally into several species.

Australopithecus anamensis is the earliest fossil form that has been identified and dated to ca.  4.5 million years ago.  It was not a tall animal and shows evidence that it was ground dwelling.  It did have pronounced sexual dimorphism with adult males larger than females and males having larger canine teeth.  It depended upon its physical strength for protection and for subsistence pursuits.  It lacked tools, fire, and speech as we known it.

Australopithecus afarensis is the well-known “Lucy” excavated in Ethiopia and dated to ca. 3.2 million years ago.  It was small in stature and lightweight as well.

Australopithecus africanus is important because it has been found in East and South Africa about 2.6 million years ago.  It was bipedal most of the time although it is possible that it spend some time in trees if for no other reason than to escape predators.  Skulls of Australopthecines have been found at the base of leopard lairs with tooth makes in the skull indicating that they were a component of the leopards diet.  

Bipedalism is an important hominid trait.  Walking on two legs allows the hands and arms to be free to carry food, to carry infants, and to bear sticks, bones, or stones for protection.  This physical development was significant for the development of family life and eventual dependency upon tools.  Evidence of bipedal comes from  reconstruction of leg anatomy and actually footprints from Laetoli in Tanzania indicating that the heel supported the weight of the stride. The creature that made them was A. afarensis and all subsequent hominids were walking on two legs.

The diet of the Australopithecines consisted of plants, most likely fruits, leaves, and grass.  The examination of use marks on the teeth of A. africanus suggests a pattern from a predominantly vegetable diet.  However, they may have engaged in scavenging food from kill sites of other predators.

Their technological base was minimal.  There are no tools made by these creatures but they may have used bones and stones for protection and sticks to dig roots.  Use of these natural products was mostly expedient with little if any modification.  They lacked fire.

Social life is not known.  The physical characteristic of infant skeletons suggest that they were born prematurely relative to other primates and therefore depended upon the mother at least to nurture and to protect them for several years before they could survive alone.  The large male canines could provide protection but also serve a role to preserve a dominance hierarchy in the group.  Their social life may have been one of “group families” with multiple female adult participation in child rearing and male provisioning a came with food carried from elsewhere.

Symboling is the expression of abstract ideas through speech or material objects.  Body paint is a form of symbolic expression and the designs are symbols.  We have no evidence that they were physically able to produce sounds as we do or to communicate with more than yells, grunts, or hand gestures but not as a grammar or complete expression of an idea beyond an immediate warning or other problem facing them.

The impact on the environment by Australopithecines was minimal.  They did not hunt or  use fire.  They did make and occupy campsites for short periods of time that left small spatial signatures on the landscape but no major scars or transformation of the vegetation or extinction of animals.

About 2.5 million years ago there were several species of Australopithecines in Africa from Ethiopia to South Africa.  One was the hominid ancestor of the genus Homo.  Despite the appearance of an advanced form of hominid, some Australopithecines, such as Australopithecus robustus, continued simultaneously.  The new genus Homo is called H. habilis in recognition of its true tool making abilities.

H. habilis was bipedal, showed sexual dimorphism, but had a larger brain than did Australopithecines.  Brain development suggests that it relied more on reasoning and thought than on instinct.  It has been suggested that parts of the brain were evolving to permit speech.

The hallmark of habilis was its tools.  They are called Oldowan and are pebble choppers, an implement made from a stone pebble with several flakes deliberately removed from two sides to form a cutting edge.  In other words, these tools evidenced pre-planning and formed a tradition regarded as the Basal Paleolithic starting 2.5 million years ago.  They were baseball sized and could be held easily in their small hands.

Their diet continued to be dominated by vegetation but evidence exists for scavenging and breaking bones to recover the nutritional marrow inside.  Large stone called manuports were carried to campsites to serve as anvils for breaking bones.

Social life may have been developing toward families with male and female infant nurturing. The exact nature of this arrangement is unknown.

Although there is no marked environmental destruction, the potential for a hominid impact on the environment was increasing.

Homo habilis evolved into Homo erectus.  This happened sometime around 1.8 million years ago in Africa.  The earliest form of this hominid in Africa is called H. ergaster.  Homo erectus was more human-like.  The brain was larger and it showed the least sexual dimorphism other than size.  Homo erectus developed the means to spread out of Africa through the Old World tropics and into some temperate zones.  It developed more complex and efficient tools and most important it made fire.

The control of fire is one of the most important developments in human history.  By doing so erectus could cook food and thus make it more digestible through chemical transformation.  For example, starches in roots could be broken down and made easier for complete digestion.  Toxins in plants could be destroyed; bacteria and other harmful agents in putrefied meat could be destroyed with heat.  In addition, fire allowed expansion into new environments by providing light, warmth, and protection from predators.  The potential for environmental change was present by employing fire to hunt game and to burn plant communities to stimulate production.

The first fire is found 500,000 years ago at Zhoukoudien Cave, China.  Other evidence has been found across Eurasia as far west as Spain and northward to England at a younger date.

Other notable developments are in the realm of technology.  Erectus was a hunter and not afraid to kill megafauna.  Fire-hardened wooden spears have been found in England and Germany.  They further expanded their diet by fishing and gathering shellfish.  Their stone tools became more elaborate and efficient.  They now made bifacial hand axes called Acheulian or Lower Paleolithic.  These were all-purpose cutting and digging tools.  The flakes that were removed were also used for cutting or scraping.

The social life of erectus is reflected in the arrangements of the camps.  These suggest hearth groups that may have been occupied by monogamous family groups.  The division of labor is reflected in the activities conducted around the hearth that distinguish food preparation and cooking from tool making and hunting.  A recognizable settlement pattern for these groups of probably related family members include basecamps, seasonal camps, resource procurement sites, and kill and butchering sites.

Symboling is apparent in erectus times.  By 150,000 years ago the anatomy of the throat could make a variety of controlled sounds we would recognize as speech.  Whether or not the spoke is another unresolved story.  However, some archaeologists believe that the ability to lead an organized social life and to possess shared symbols indicates that language was present.  Erectus used red ochre (iron oxide) for paint and body art.

Homo erectus was the first hominid to have a noticeable impact on the environment.  It could hunt, control fire and leave evidence of camps still present today.

H. erectus lived from about 1.8 million to 100,000 years ago.  It is ancestral to modern man, H. sapien sapiens and H. sapiens neandertalensis.   

 OUT OF AFRICA I

 Homo erectus is the first human radiation out of Africa and into the tropical and temperate areas of the Old World based upon dependence on culture.  It occurred between 1.8my-800k years ago. It is our common ancestor.

It moved into the Middle East about 1.4 million years ago based upon evidence from ’Ubeidiya (Israel) in the Jordan rift valley. It is next witnessed in Indonesia and later in temperate China near Beijing Asia 1-m yr. Evidence of it appears in Europe 500,00 years ago.   Evidence for this common ancestry comes from mitochrondrial DNA and stone tools.

The Neanderthal problem.  The source of the Neanderthals continues to be debated.  Neanderthals were thick boned, sloping browed human who were adapted physically for the cold climate of glaciated Europe. They appear 200,000 years ago and continue until about 35,00 years ago.  Homo erectus evolved into archaic Homo sapiens in Europe and these became the source of Neanderthals.  Others see them as deriving from H. erectus directly.  The source is not as important as is the recognition that the common ancestor is erectus who came from Africa.

The evolution into different forms of Homo sapiens, modern man, relates to a general but contentious theory of modern human origins.  It is the multi-regional theory of hominid evolution, which contends that no one place or continent was the source of modern humans but many were after the spread of erectus.

Neanderthals subsided by hunting and gathering.  The hafted stone points on spears and made the points by a special new technique that enabled them to remove many flakes from a single block of stone.  These are called Mousterian tools or Middle Paleolithic.  There social life was one of families organized into kinship-based bands.  Their symbolic structure was obvious.  They buried their dead, sometimes practiced cannibalism, and had a bear cult that venerated the giant cave bear by placing its skull and other parts on special alters.  Most significant they may have depended upon true speech or language.

This illustration, from Juan Luis Arsurga, et al's Atapuerca,
shows the difference between Modern man's and Neandertal's craniums. 

What happened to the Neanderthals is an open debate.  Some claim that they were killed off directly or indirectly (out competed) by recently arriving modern man from Africa.  Others believe that the mated with evolving modern man in Europe and never disappeared at all but were absorbed into the gene pool of Europe.  Archaeological evidence supports the latter view where we find Mousterian technology and tool forms evolving into the Upper Paleolithic.  Skeletal evidence from Spain and Croatia suggests interbreeding.

 OUT OF AFRICA II

Source: http://www.handprint.com/LS/ANC/disp.html

Another theory calls for a second major migration from Africa into the Near East and eventually Europe.  It maintains that  Homo sapiens evolved in southern Africa and migrated up the eastern side of Africa and into the Near East.  This occurred between  200,000-100,00 years ago (or 100,000-50,000 yr. according to other calculations) in Africa.  This is the basis of the African  “African Eve” hypothesis determined by mitochrondrial DNA collected from modern populations.

In Europe these modern men are called Cro-Magnon and for all purposes the men and women appeared as we do.

The Upper Paleolithic technology was based upon the most efficient stone tool techniques that we have examined to date.  The removed numerous blades from a block of stone and then formed them into a variety of tools.  Knives, scrapers, gouges, engravers, harpoon barbs were all made from blades or deliberately broken pieces of blade.  They had many kinds of finely made bone tools including needles that they used to make tailored clothing and hide tents.  They wove carrying bags from plant fibers, made leather straps for bearing burdens.  Boats were part of their technology.

Symboling was predominant in their life.  They depended upon language and had elaborate art as we know from cave paintings in France, Spain, and Russia. Religion became obvious from symbols and the abstract ways they assembled and carved natural objects.      

The greatest impact on the environment was modern humans after 30,000 years ago.  They now had the technology to enter and live in the Arctic.  No habitat on earth was inaccessible to Upper Paleolithic humans.  There numbers were not great because of their hunting and gathering economy but they had the tools to hunt animals to extinction and to transform whole biomes with fire.

Peopling the World

Australia was colonized from Southeast Asia 40,000-60,000 years ago. Boats were required to accomplish this difficult feat.  Those who went show no African ancestry.  They were modern humans who evolved from Homo erectus.  They brought a technology that evolved in the forests of Southeast Asia and not the cold of Eurasia.

Fire, tents, burden straps, and tailored clothing allowed Upper Paleolithic people in Siberia to cross the Bering Land Bridge into North America 15,000-18,000 years ago.  This is the topic for our next lecture.

Summary

Today we briefly reviewed the major trends in human physical and cultural evolution.  We discussed the importance of bipedal locomotion and the beginnings of stone tool production.  We examined the first spread of humans from Africa – Homo erectus and its movement into areas of the Old World beyond Africa.  We explored its ability to make and depend upon fire.  We looked at changes in social life and the beginnings of language for effective communication.

Important words are highlighted as bold in the text.

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Suggested Readings

·         Klein, R. 1999 The Human Career. 2nd ed. University of Chicago Press, Chicago

·         Lieberman, P. 1990 Uniquely Human: The evolution of speech, thought, and selfless behavior. Harvard

·         University Press, Cambridge

·         Mellars, P.A. 1996 The Neanderthal Legacy. Princeton University Press, Princeton

·         Pfeiffer, J. 1978 The Emergence of humankind. Harper & Row, New York

·         Tattersall, I. 1995 The Fossil Trail. Oxford University Press, Oxford

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