WHY WE STUDY HUMAN ORIGINS

To understand human origins and the evolution of any specific species,
scientists study the behavior and anatomy of animals that have similar
characteristics.

There is a universal curiosity about our past that is shared by all people. The
idea that there were animals and plants in ancient times that are different from
those we see today arouses our interest. This wonder about human origins
typically involves questions about why humans evolved, and why hominids seem to
have crossed the ape-human threshold only once. This curiosity also makes us
ask: From what group of primates did our earliest hominid ancestors diverge
(branch off) and when? Where did the human career begin? And, why did some early
hominids disappear while others evolved into later species? Most of these issues
can be addressed through study of the fossil record.

The fossil record allows us to glimpse the stages in human evolution. Fossils
provide direct evidence of our ancestors and of the changes in behavior that
occurred at various stages in the human career. Through studies of the anatomy
and behavior in living animals, scientists can draw conclusions about the
behavior of extinct species when enough fossil remains have been found.

The study of fossils is important for another reason. For centuries, the most
widely accepted explanations of human origins were based on religious teachings
or on creation myths of tribal societies. Then in the mid-1800s an Englishman
named Charles Darwin proposed the idea that plants and animals change slowly
through geological time as they naturally adapt to changes in the environment.
As his idea gained acceptance, scientists sought to understand human evolution
as part of the natural world. The earliest scientific thinking about human
evolution was based on studies led by Thomas Henry Huxley and others in Europe
who compared humans and apes. Huxley believed that anatomically, African apes
and humans were similar, more similar in fact than apes were to monkeys.

At the time when Darwin and Huxley were working on their theories, no early
hominid fossils were known. It was not until 1925 that Raymond Dart, working in
South Africa, found the first hominid fossil. This find began to make clear the
events in early hominid evolution. As Huxley predicted, the South African
fossils shared similarities with the African apes.

Since the recovery of the first South African fossils, exploration in other
parts of Africa have uncovered not only a wealth of fossils, but also
archaeological remains of stone tools and other traces of hominid activity. The
evidence has led some to believe that early hominids were hunting, predatory
ape-men and -women. Others have suggested that our earliest ancestors were
tree-dwelling apes, or four-legged knuckle-walkers, or even bipeds that lived in
water. In some cases, the differences of opinion are the result of the
incompleteness of the fossil record. In other instances, the different ideas
come from different views about what evidence is important in reconstructing the
past. In all cases, the discovery of fossils and their careful study provide the
only scientific way to test various unproved theories.

Today we recognize that elements of almost every aspect of our anatomy and
behavior are rooted in our evolutionary past. By studying the record of that
history, we will gain a better understanding of ourselves.

The adjective predatory describes animals that live by capturing and feeding on
other animals.

The adverb "anatomically" comes from the noun "anatomy," which refers to the
study of the structure of animals or plants. Appropriately it traces its roots
to two Greeks words: ana, meaning "up," and temnein, meaning "to cut."

The noun "fossil" traces its roots to ancient Latin. Since a ditch is something
that is dug out of the earth, the ancient Romans used their participle fossum
("having been dug") to form the noun fossa ("ditch"). When speakers of English
sought a word to represent "hardened remains of plant life or animal life" that
were found within the earth's crust, they appropriately borrowed the Latin fossa
and formed "fossil."

The word "skeleton" clearly reflects its roots, the Greek participle skeletos,
meaning "dried up."




WHO'S WHO AMONG THE EARLY HOMINIDS?

The early hominids are often called "ape-men" because of the features they share
with apes and with humans. Their skulls, teeth, and limbs recall those of apes,
while the fact that they walked bipedally (on their two lower limbs) makes them
similar to humans. The fossil record of early hominid evolution shows both
primitive (ape-like) and advanced (human-like) features. This supports DNA
evidence of our close relationship to the African apes. The earliest hominids
are divided into three genera or groups.

ARDIPITHECUS ("ground ape")

The earliest group is the Ardipithecus. The species known as Ardipithecus
ramidus is the oldest hominid known and dates back 4.4 m.y.a. It was recovered
from the site of Aramis in the Awash River Valley of Ethiopia in 1994. (The
species name, ramidus, means "root" in the language of the Afar people who live
in this area in northern Ethiopia.) Little has been published on the
Ardipithecus fossils but the group appears to have primitive, ape-like, skeletal
anatomy with small molar teeth and large front teeth.

AUSTRALOPITHECUS ("southern ape")

The second group is Australopithecus, a widespread group of early hominids found
in East and South Africa. Uncovered fossils date from more than 4 m.y.a, to
around 2 m.y.a. Two species of this group, A. anamensis and A. afarensis, are
the most ancient of the australopithecines. A third species, A. africanus, is
more recent. Found principally in southern Africa, A. africanus dates to between
3 and 2 m.y.a. Compared to later hominids, including modern humans,
australopithecines have relatively small brains, large molars and pre-molars,
small front teeth, long upper limbs, short lower limbs, and large differences in
size between males and females. Yet, in spite of these differences, the
australopithecines were more like humans than apes because they walked on their
two lower limbs.

In 1995 a new species of Australopithecus, known as A. bahrelghazali, was
discovered in Chad, near the Bahr el-Ghazal River, on what is now the southern
margin of the Sahara Desert. The fossils that were uncovered were a lower jaw
and part of an upper jaw and tooth. They date to between 3.5 and 3 m.y.a. Animal
remains found with these hominid fossils indicate that this area had rivers,
lakes, and forests in Pliocene and Pleistocene times.

PARANTHROPUS ("similar to man")

The species of the genus known as Paranthropus existed at approximately the same
time as A. africanus and early Homo. The size of the skull, with its robust jaws
and teeth, indicates that this large-toothed, small-brained hominid had massive
chewing muscles. Scientists refer to these hominids as the "robust"
australopithecines. Like the Australopithecus species, Paranthropus was also
bipedal and probably spent more time on the ground than did A. afarensis and A.
africanus. This conclusion comes from analyzing the very human-like hand and
foot bones of Paranthropus. Studies seem to indicate that Paranthropus ate
mainly grasses and other plants, while Australopithecus ate all types of food,
both plant and animal.

The earliest specimen of Paranthropus was found in northern Kenya and dates to
around 2.5 m.y.a. It is known as the "black skull" because of its dark staining.
The black skull has a small brain case with large crests for the attachment of
huge chewing muscles, a longish snout, and a very primitive (ape-like) skull
base, similar to that of A. afarensis.

Fossils of the species known as Paranthropus robustus come from a series of
limestone caves in South Africa. P. robustus had massive molars and premolars
with relatively small front teeth. By studying the wear patterns of their teeth,
scientists have learned that P. robustus ate hard plant foods and took in sand
and grit with their principally vegetarian diet. Although roughly similar in
size and weight to A. africanus, P. robustus had larger jaws and teeth. (The
name robustus means "strong and hardy.") The structure of Paranthropus' hand
bones indicates that this hominid used (and perhaps made} simple stone and bone
tools.

Early HOMO (early "man")

Early Homo refers to the first members of our own group. The earliest fossils
date to around 2 m.y.a, and were found in East and South Africa. These hominids
had somewhat larger brains, smaller teeth, shorter, smaller faces, smaller
crests on their skulls, and more human-like hands and especially feet. They used
simple stone tools. There are only a few questionable scraps of evidence of Homo
earlier than 2 million years ago.

All of the early Homo fossils that date from around 2 to 1.6 m.y.a, were once
thought to belong to the species Homo habilis. In the last few years, however,
further study of fossil evidence has shown a great diversity in the Homo habilis
fossils from East Africa. As a result, many scientists now believe that Homo
habilis can be divided into two main species -- Homo habilis and Homo
rudolfensis.

HOMO HABILIS ("handy man")

Homo habilis is best known from the fossils found at Olduvai Gorge in Tanzania.
Fossils also have been recovered in Kenya and Ethiopia. Homo habilis has a
larger brain, and smaller, narrower premolar teeth than Australopithecus or
Paranthropus. Because of its larger brain, its teeth, and certain human-like
features seen in the hand and foot, Homo habilis is thought to be more
human-like than the australopithecines. Additional features of the hand and the
foot, as well as the proportions of the upper and lower limbs, indicate that H.
habilis was bipedal and worked with tools. These body features also suggest that
H. habilis was an adept tree climber (perhaps to escape danger, sleep, or forage
for plant foods). Homo habilis is most often considered to be the maker of
simple stone tools found in Olduvai Gorge and elsewhere in Africa at early
hominid sites. However, sites that yield early Homo fossils often also yield
fossils of Paranthropus. Such finds raise the question about whether one or both
species were tool-users. Numerous animal remains are also found at Homo habilis
sites. Archaeologists, however, disagree on whether early Homo actually hunted
and killed small animals or merely gathered and ate animals killed by others.

HOMO RUDOLFENSIS (no nickname)

Homo rudolfensis dates to the same time period as H. habilis. Yet,
geographically, it is limited more to northern Kenya. The famous skull (labeled
KNM-ER 1470), discovered by Richard Leakey, is representative of this species.
Its characteristic traits are a large brain and a broad, fiat face and
cheekbones. In addition, the molar and premolar teeth are broader than those of
H. habilis.

HOMO ERECTUS ("upright man")

Homo erectus is another, more "advanced" species of Homo. It dates back to the
Pliocene-Pleistocene epochs, beginning around 1.8 m.y.a. Homo erectus, unlike
other early hominids, is found not only in Africa, but also in Asia and Europe.

Homo erectus has smaller molars and premolars and smaller jaws than the
australopithecines and H. habilis. Homo erectus also has a larger brain with
thick skull bones and prominent brow ridges. The crests on the skull for the
attachment of chewing muscles are smaller in comparison with those of other
early hominids and the opening in the skull for the nose is broad. Homo erectus
appears to have been taller and heavier than other early hominids.

The best known specimen of Homo erectus is the "boy" skeleton from northern
Kenya. Dated to 1.6 m.y.a., the skeleton is thought to be that of a 12-year-old
boy who was about six feet in height. The limbs are robust and their proportions
are like those of modem humans with long lower limbs and shorter upper limbs.
Some anatomical features, such as the long neck of the thigh bone, resemble
those of earlier australopithecines. Other features, such as the size of the
head of the thigh bone, are more like those of modem humans. Some people believe
that the bones show evidence of a crippling disease. If true, this would call
for a re-interpretation of the height, weight, and other aspects of this
individual.

In Africa and Asia, Homo erectus is found at sites where the tools are more
advanced than those found at Paranthropus and H. habilis sites. "More advanced"
refers to their manufacture and the choice of raw materials used. Homo erectus
sites contain remains of large mammals such as elephants, horses, and hippos.
Archaeological sites where Homo erectus fossils have been found are widespread
over the globe and show signs of hunting, the use of fire, and primitive
dwellings.

DNA (deoxyribonucleic acid) is the master molecule that determines what a cell
is and does. DNA passes along the hereditary pattern.

Anamensis means "of the lake" and is a reference to the fact that the first
fossil of this species was found near Lake Turkana.

Afarensis refers to the Afar Triangle of Ethiopia where the fossils were found.

Homo rudolfensis was named for the lake near where it was found -- Lake Rudolf
(renamed Lake Turkana in 1979)

Note: To name the various groups of hominids, scientists traditionally use
Latin, Greek, and Arabic words, as well as place names and words from the
language spoken where a fossil is found.

NOTE: Australopithecus is often abbreviated to A., as in A. anamensis.
Paranthropus is often abbreviated to P., as in P. robustus.



GEOLOGIC TIME SCALE

Geologists have divided the history of the earth into time periods based on rock
deposits. The earliest time period dates back more than four and a half billion
years to when the earth's crust was forming. The appearance of human-like apes
seems to date to the Pliocene epoch. The present time period or epoch is known
as the Holocene, and it is relatively short. It includes only the last 10,000
years or so. The Pleistocene preceded the Holocene and began 1.64 million years
ago (m.y.a.). During this period, a number of glacier-like sheets of ice
advanced and retreated across the earth and many large mammals became extinct.
The Pliocene epoch lasted from 5.2 to 1.64 m.y.a, and many hominid fossils have
been found that date to this period. The Pliocene is characterized by major
climate and geographical changes throughout the world, especially in Africa. The
branching off of hominids from apes took place in the early Pliocene, around 5
m.y.a. Around 4.4 m.y.a., the earliest hominid, called Ardipithecus ramidus,
lived in Ethiopia.



COMPARE THE FOSSIL EVIDENCE

Australopithecus afarensis

*
Discovered in 1975 at Hadar, Ethiopia, this skull belonged to an adult male. The
jaw juts forward to support large front teeth. The bones below the eyes indicate
large, powerful chewing muscles. THe face at the cheek bones is wide and the
brain case is small.

Paranthropus robustus

*
Discovered in 1950 at Swartkrans, South Africa, this skull belonged to an adult
female. The jaw does not just forward as much. The front teeth are smaller, but
the molars are larger. The chewing muscles extend forward and helped to produce
a flat face. Like that of afarensis, the face is wide and the brain area small.

Homo rudolfensis

*
Discovered in 1972 at Koobi Fora, Kenya, this skull belonged to an adult male.
The jaw is far less pronounced. The teeth, especially the molars, are smaller.
So, too, are the chewing muscles. The brain case is much larger, and the skull
has expanded above the face.

Homo erectus

*
This skull was discovered in 1975 at Koobi Fora, Kenya, but scientists have not
yet determined whether it belonged to a male or female. The jaw is even less
pronounced, and the teeth and chewing muscles are smaller. The skull is thicker
and protects a larger brain.




THE LEAKEYS AT OLDUVAI GORGE

For thousands of years the Maasai grazed their cattle in and around Olduvai
Gorge. Many of those proud people must have noticed the mysterious fossil bones
scattered across the floor of the gorge. It was not until 1911, however, when a
German professor named Kattwinkel stumbled upon the gorge, that Europeans became
aware of this wonderful archaeological site. Kattwinkel's initial observations
recorded the presence of rich mammal fossils and archaeological remains such as
stone tools.

Upon hearing about these discoveries, a German expedition directed by Hans Reck
traveled to Olduvai in 1913 to conduct the first scientific studies. This
expedition discovered a nearly complete human skeleton, which was first thought
to be very old. World War I ended German study of the gorge because Britain soon
gained control of most of East Africa.

Louis Leakey, a young scientist, later examined this Olduvai skeleton in Europe.
In 1931, he led an expedition to Africa to determine the skeleton's age. During
this visit, Leakey immediately found ancient stone tools and fossil bones. He
became convinced that Olduvai was an important fossil site. Leakey began to
organize the necessary support and materials for prolonged studies at Olduvai.
At the time, there were few roads in East Africa, and conducting a study at
Olduvai was extremely difficult. All food and water for the field season had to
be brought to the camps, and people typically camped under rough conditions for
two months or more. However, Olduvai is positioned within the short grass plains
of an area known as the Serengeti, and the beauty one encounters living among
the zebra, wildebeest, giraffe, and lions rids the mind of thoughts of
discomfort.

Leakey returned to Olduvai in 1932 and 1934. His wife Mary soon joined him, and
expeditions to Olduvai became a regular occurrence through the years. Louis and
Mary formed a great team. Louis specialized in the hominid fossils, while Mary
focused on the stone tools. Louis was an excitable scientist prone to
spectacular announcements, while Mary was a careful and diligent scientist who
worked slowly toward a solid conclusion.

Mary soon took over the main responsibilities for the excavation of
archaeological sites. She pioneered the careful excavation techniques that now
characterize stone-age archaeology. This included carefully plotting on graph
paper the position of every artifact and bone, even if they numbered in the
hundreds of thousands. In 1959, while excavating an important hominid site
called FLK1, Mary discovered perhaps the most famous Olduvai hominid. The skull
had extremely large molars and showed signs of powerful muscles for chewing
food. The Leakeys dubbed it "Nutcracker Man." The fossil's official name was
Zinjanthropus boisei. Olduvai's fame was sealed, and this find was followed by
many others. Today more are still being found.



"ZINJ"

The discovery of the "Zinj" skull (now called Paranthropus boisei) at Olduvai
Gorge made Louis and Mary Leakey famous. It was the first australopithecine
found outside of South Africa. The discovery of "Zinj" and its dating by the
potassium-argon (K/Ar) method extended interest in early hominids from South
Africa to East Africa. "Zinj" was the first early hominid fossil the Leakeys
found after 30 years of searching. Note that in this photo, the "Zinj" skull has
been fitted with a reconstructed lower jaw.

*
Geologists at the University of California, Berkeley, used their new method of
dating volcanic ashes, -- called the potassium-argon (K/Ar) method -- to date
the ashes above and below the skull and fixed the date at 1.76 m.y.a. This date
made "Zinj" the first hominid fossil to be reliably dated. At the time, most
people thought the Pleistocene went back only 200,000 years. After the discovery
of "Zinj," palaeontologists had to rethink their dating charts for hominids.

*
Zinj is the ancient Arabic word for "East Africa." Zinjanthropus means "East
African man."

*
"Boisei" refers to Charles Boise, and American businessman who supported the
Leakeys' projects with financial contributions.




LIFE IN OLDUVAI GORGE

Between 1.9 and 1.7 m.y.a., several different species of early hominids lived in
the region where Olduvai Gorge is today. We think that they moved around in
groups made up of a few males and females as well as children and older
relations. Much of the time was probably spent collecting wild plant foods,
berries, and underground stems or roots.

The location of several archaeological sites in the area suggests that these
early hominids took advantage of many different environments that surrounded a
salt lake in the high grasslands of East Africa. There were hills and mountains
with forests nearby, and around the lake there were mud fiats, swamps, and
grasslands. Famous archaeological sites such as FLK-Zinjanthropus (where the
"Zinj" skull was discovered) are found near the lakeshore in places where trees
probably followed streams that fed fresh water into the lake. Many
archaeologists think that the presence of shade and fresh water is part of what
made these favorite places.

Here early hominids made and used tools, prepared food, and left piles of
garbage. More than 2,000 fragments of stone tools were found at
FLK-Zinjanthropus. The raw materials that early hominids chose for making the
stone tools tell us something about their capabilities. They carried the stone
from rock outcrops a few miles away. They picked rocks that are especially hard
and that break in a predictable manner when "worked" to form a tool.
Archaeologists have been able to fit some of the stone fragments back together,
like a puzzle, to form the original rocks from which tools were made. From this
we know that our ancestors also knew the right angle to hit the cobble, or core,
in order to successfully produce sharp-edged flakes. Such flakes were used to
cut meat off animal carcasses. Shaped cobbles (called choppers) were probably
also used to extract the marrow from inside the bones, or to chop up plant
foods. Some of these activities left damage -- known as polish -- on the stone
tools that we can see to this day.

More than 60,000 fragments of bone were also found at FLK-Zinjanthropus,
including birds, amphibians, fish, and many large mammals. A few of these bones
have cut marks. Others have impact scars that were made accidentally by early
hominids using stone tools to strip meat off bones and to break bones open for
marrow. This shows us that early hominids were eating meat 1.8 m.y.a. There are
also some carnivore gnaw marks preserved on bones at hominid sites. These marks
indicate that animals such as hyena or extinct large wild cats ate off the
carcasses as well. As a result, some archaeologists suggest that the early
hominids scavenged meat from the kills of other carnivores like lions,
sabre-toothed cats, and leopards. Others think that the early hominids hunted
for food, and that the carnivores chewed on bones left at camps. Possibly both
occurred.

There is also discussion about whether the famous early sites at Olduvai were
places where hominids shared food, conducted many social activities, and camped
for days or weeks at a time, or whether they used such places repeatedly for
special tasks, a few hours at a time, leaving stone there for future use. Many
archaeologists think that the presence of meat and the danger from carnivores
would have prevented the use of these places for sleeping and as home-bases.
Others believe that the early hominids would have responded to competition from
other carnivores by co-operation and by tool use. They also believe that
hominids were able to defend resources such as plant foods, raw materials, and
meat from attacks by other hominids or large carnivores.

Yet, whether hominids used the sites for short or long periods, the kind of
activities that they undertook at these sites almost certainly made it
advantageous to be social, and led to the development of culture and large
brains.




THE DISCOVERY OF 'LUCY'

November 30, 1974, started the same as many other days at Hadar, an
archaeological site in East Africa. Donald Johanson and a student decided to
visit an area where they had previously found fossils. Their intention was to
map the locations of their earlier finds. While surveying the surrounding area,
Johanson spotted a small, broken piece of an arm bone sticking out of the
ground. As he and a graduate student knelt to examine it, Johanson recognized
that, although small, the bone was anatomically like that of humans. Johanson
picked up the fossil and the two men continued to search the area. It soon was
clear that they had happened upon the bones of a small hominid. Their excitement
grew as Johanson recognized that they had found not only a relatively complete
skeleton, but also one that was spectacularly well preserved.

It took three weeks for an international team of geologists and palaeontologists
to collect and map the several hundred fragments of the skeleton. At first they
wondered if the fossils could possibly belong to a single individual -- a rare
occurrence in hominid palaeontology. After observing the close proximity of the
bones and the fact that no pieces were "duplicates," the team realized that they
had some 40 percent of a single individual.

Because of her small body size (she stood three feet six inches and weighed
around 60 pounds) and the anatomy of her pelvis (males and females have a
different pelvic shape), the skeleton was thought to be that of a female. The
fact that the bones were buried together and were in good condition indicated
that she died a non-violent death. There was no evidence that she fell prey to
any of the carnivores at Hadar or that scavengers later disturbed her remains.
Instead, it appeared that she died and was buried in mud or sand fairly quickly
so that her bones were not scattered by water or destroyed by weathering. Only
about one in every one million individual animals meet all the criteria for
becoming a fossil. Even fewer ever experience the rare sequence of events that
leads to the preservation of the bones of one individual. The skeleton was named
"Lucy" by team members after the Beatles' song "Lucy in the Sky with Diamonds,"
which they listened to during the celebrations following the discovery.

Detailed studies of Lucy, both in the field and later in the laboratory,
provided evidence of a new species called Australopithecus afarensis. Study of
her pelvis indicated not only that she was a female, but that when she was on
the ground, she walked bipedally, on her lower limbs. While Lucy was small by
hominid standards, bones of A. afarensis males from Hadar were considerably
larger. This indicated that there was a difference in size between males and
females. Such a difference is commonly found in primates that live on the ground
rather than in the trees.

While study of Lucy's fossil remains showed that she was bipedal, it also
suggested that she spent considerably more time in the trees than do modern
humans. The structure of her hip bone, thigh, knee, and foot suggested the early
stages of a bipedal walk. Yet, her relatively long upper limbs; long, curved
fingers and toes; ankle joint; shoulder blade; and other features indicate that
Lucy was still a part-time tree climber. Thus she appears to have been more
skilled in the trees than we are, but perhaps less agile than either chimpanzees
or gorillas.

The view that Lucy was a biped, but one that still relied on the trees, receives
support from studies of forest chimpanzees who are at home both in the trees and
on the ground. Chimpanzees spend considerable time in the trees, where they find
food, escape danger, rest during the day, and sleep every night. At the same
time, chimpanzees are at home on the ground, where they travel long distances
and where they are found during the heat of the day when the forest floor is
considerably cooler than the treetops. The great difference between Lucy and
apes lies in the fact that when she was on the ground, Lucy walked bipedally,
while chimpanzees, when on the ground, walk on all fours.

Lucy's bones indicated that she was fairly healthy. Her teeth and the joining of
growth plates in her limb bones prove that she had reached adulthood.
Examination of her remains showed changes in the back bones, but these were not
significant enough to have contributed to her death.

From rock samples collected at Hadar, geologists were able to fix the time
period in which Lucy lived at around 3 m.y.a. Other fossil plants and animals
found in the area also yielded clues about the environment in which Lucy died,
and presumably also lived. It is thought that Hadar was wetter and had more
plant life during Lucy's time, unlike its hot and dry climate today. Pollen
taken from soil at Hadar provided evidence of juniper and olive trees in Lucy's
time.

Earth samples suggest that water in the form of lakes and streams was close by.
Lucy and her kind probably occupied a variety of habitats including forests,
drier woodlands, grassy areas, and lakesides. Across these habitats, which are
similar to the ones used by chimpanzees and humans in Africa today, Lucy's
ability to walk bipedally and, at times, to climb, would have suited her well.

To see Lucy "in motion," flip the pages of this issue, keeping your eye on her
form in the lower right-hand corner of the page.

To see a reconstruction of Lucy and her friend by the English artist John
Holmes, turn to page 6. Remember that scientists believe Lucy was only 3 feet 6
inches tall.




FOOTSTEPS AT LAETOLI

On a day more than three million years ago, the Sadiman volcano in East Africa
erupted, spewing ash across a plain known today as Laetoli in present-day
northern Tanzania. Rain followed, leaving the ash damp and somewhat slippery.
Soon after, three hominids carefully made their way across the plain. Then came
a dry spell and the volcanic ash set like cement -- preserving the footprints of
the three who had walked across the area. Over the thousands of years during
which Sadiman remained active, the eruptions continued until the footprints were
buried beneath layers of hardened volcanic ash to a depth of approximately 90
feet.

Over the next three million years, the rain, wind, and streams that coursed
along the plain slowly ate away at the ash, now turned into stone called tuff.
Not until 1976 were the footprints discovered. Archaeologist Mary Leakey began
excavating at Laetoli in 1974. Two years later, the first animal prints were
found. Three visitors to Leakey's campsite were, as Leakey later wrote, amusing
themselves "by throwing lumps of dried elephant dung at each other ... Andrew [a
visitor] fell down in the process and noted that he was lying on a hard surface
which appeared to contain ancient animal footprints, including those of a
rhinoceros."

Two years later, Paul Abell, a geochemist on Leakey's team, discovered a hominid
footprint. Further excavations of the volcano deposits -- now known as the
Footprint Tuff -- revealed a trackway some 89 feet long with animal tracks,
various geological features, and two trails of hominid footprints. At first, it
was thought that only two hominids made the prints and that the prints that were
larger and less clear were the result of the hominid slipping in the wet ash.
Today, most anthropologists agree that three hominids passed this way together.
The larger one was about five feet tall. Behind him and in his footsteps walked
another hominid about four and a half feet tall. The third measured only about
four feet in height and walked slightly behind the first. All took short steps,
which is not surprising considering the conditions and the terrain.

The discovery of these footprints provided information about the anatomy and
behavior of hominids that fossil bones cannot provide. The prints clearly show
the big toe is in line with the rest of the foot. This means that these hominids
definitely walked on two feet exactly as we do. Whether they also climbed trees
is still a matter of debate.

The footprints also preserve an unmistakable arch to the foot. The arch occurs
only in humans and works as a type of natural "shock-absorber" for the forces
that result from all the weight being concentrated on a single supporting limb.

While the footprints answer many questions scientists had about hominids, there
are still many that remain unanswered. Yet, even as the research continues,
paleoanthropologists know that some questions will never be answered. Where were
the hominids going? Were they carrying anything? Were they a family? How did
they communicate?

Shortly before Leakey and her team finished work at the site in 1979, they made
a replica of the best-preserved section. Then to preserve the site they covered
it with local river sand and volcanic boulders. They were unaware that mixed in
with the sand were acacia tree seeds and other seeds. In time, these seeds began
to germinate and grow. Concerned that the spreading tree roots would eventually
destroy the footprints, the Getty Conservation Institute and members of the
Tanzanian government met to discuss the situation in 1992. They agreed to remove
trees, tree roots, and other similar threats to the site; to re-excavate,
document, record, and conserve the trackway; and to rebury the trackway in a
manner that would ensure its long-term survival. Work began in 1993 and was
completed in 1997.

Aware that preservation of sites in remote areas such as Laetoli requires the
cooperation of the local Maasai people, the project members spoke with community
leaders. Two special ceremonies were held during which the trackway was given a
ritual Maasai blessing and included among the places honored by the Maasai
people.

For the long-term protection of this fragile site, the hominid trackway is
closed to the public. The Tanzanian Department of Antiquities has appointed two
Maasai men as full-time guards. The department also has instituted a maintenance
plan that calls for removal of new tree growth where necessary and repair of the
drainage system around the trackway.

An exhibition on Laetoli was created at the nearby Olduvai Museum so that people
can understand the importance of the hominid trackway and see a replica of it.




WHAT THE FOSSIL RECORD TELLS US

As the ancient hominids walked across the volcanic ash at Laetoli, they left
footprints, but no handprints. These hominids belonged to the species
Australopithecus afarensis, the same species as Lucy, a small-brained early
hominid. They were not, however, the only beings to walk across the slushy
surface. Animals of all types left their footprints or, in the case of worms and
snakes, trails of their bodies. The African sun at midday is like a clothes-iron
pressing down on the land. It was this heat that baked the ash hard. When Mary
Leakey discovered the footprints in 1976, they were a spectacular type of
fossil. They proved without a doubt that these early humans walked upright like
we do.

The term "fossils" refers to any trace of ancient activity, such as the
footprints described above, or any remains of a part of the body. The most
common body parts to become fossils are bones or teeth. Scientists generally
consider something fossilized if much of the organic material has been replaced
by minerals.

The source of these minerals is the sediment in which the fossil was deposited.
For example, mammal bone is about 40 percent organic (this provides flexibility)
and 60 percent inorganic (this provides strength and rigidity). During burial,
the organic part often degrades. If the conditions are right, the organic part
can be replaced by minerals in the sediment that give the stone-like character
to the fossil. If the sediment conditions are not right, this replacement does
not occur. The bone then disintegrates before becoming a fossil and is forever
lost. This means that fossils are only found in special contexts.

What are these special contexts? To become a fossil, a skeletal element must be
protected from natural forces of destruction. These include such animal
activities as being eaten by bone-crunching, flesh-eating hyenas. They also
include environmental factors, such as sun and rain. Rapid burial generally
increases the likelihood of an element becoming a fossil. Rapid burial often
occurs nears the shores of lakes, as at Olduvai Gorge, or from volcanic ash, as
with the Laetoli footprints. Other important preservation contexts include lack
of oxygen and very dry conditions. Both slow the loss of the organic part. If
conditions are right, and this is rarely true, fossils will form.

Fossils can be studied in various ways. Scientists often reconstruct the origin
of a fossil. They do this by analyzing how, when, where, and why it was buried.
Scientists then spend time carefully studying the position and the
characteristics of a fossil. Has the bone been gnawed by flesh-eating animals?
Are there cut marks from stone tools? Is the skeleton in the proper anatomical
position or has it been moved?

Scientists also spend time studying modern processes of fossil formation. In
fact, today's scientists spend as much time studying modern processes, such as
the manner in which hyenas destroy a carcass, as they do the ancient bones.
However, they cannot do their job if the fossil has been removed. This is why
you must not make collections of fossils when you find them. Photograph what you
see, and bring the photograph to the attention of a local archaeologist,
palaeontologist, or park authority. Leave the fossils untouched where you found
them.

Careful study of the characteristics of a fossil can help us assign the fossil
to a species, and this helps us understand evolutionary history. Further study
can be used to reconstruct the way an ancient animal moved, and what it ate. For
example, Lucy's pelvis is shaped like a bowl as with modern humans. We know from
studies of modern people and apes (such as chimps and orangutans) that this
bowl-shape is a design characteristic of walking on the two lower limbs.
Scientists can study the surfaces of bones to help them understand the muscles.
By analyzing the patterns of broken bones, they can learn more about the
lifestyle.

Today's technology has greatly expanded the amount of information we can gain
from studying a fossil. By analyzing scratch patterns on teeth we can
reconstruct the diet of early hominids. Analyses of bone chemistry have allowed
us to reconstruct the amount of meat in the diet. We can also reconstruct
hominid DNA from the fossil bones.

Every year, new techniques are developed. The pace of new research and
scientific advance in archaeology and palaeontology has never been as fast as it
is now. The future promises even more impressive results that will inform us
about the past, and you could be part of this process.




THE LEAKEY LEGACY

Louis and Mary Leakey's pioneering work and many significant discoveries began a
family legacy of exciting and innovative field studies in East Africa.

After Louis' death, Mary continued her work in Tanzania at Olduvai Gorge and
later at Laetoli, where she exposed the famous 89-foot long, 3.6 m.y.a. trail of
early human footprints. At this time, their son Richard, who is my husband, was
director of the Kenya National Museum, and was working the sediments east of
Lake Turkana. Field expeditions have made many significant discoveries in this
area that is both large and rich in fossils. In addition to early stone tools
that date to 1.9 m.y.a., members of the expedition found early evidence of Homo,
including skulls of Homo habilis, Homo rudolfensis, and Homo erectus. In the
1980s, following a move to the west side of the lake, Kamoya Kimeu made his
extraordinary discovery of the skull and skeleton of the Nariokotome Boy, a Homo
erectus youth.

In 1989, Richard was appointed director of the Kenya Wildlife Services (KWS).
During the next four years, he built the organization into an active body
committed to the conservation of wildlife. In 1994, shortly after a tragic
airplane accident in which he lost both his legs, he reluctantly resigned
because political interference was preventing him from doing his job
effectively. During the following four years, he was active in opposition
politics and, together with others, he founded an opposition party. Late in
1998, Richard was again appointed director of KWS, where he is once more
striving to protect the conflicting needs of the rising Kenyan population and
the diminishing wildlife.

When Richard took over KWS, he was no longer able to continue leading the field
operations at Turkana. I took over co-ordination of the field work and initially
surveyed a west Turkana site dated between 8 and 4 m.y.a. where I hoped to find
evidence of the earliest hominids or the latest common ancestor of African apes
and humans. In spite of the exceptional fossil animal record, after five field
seasons, the only new evidence of apes and humans was two isolated teeth. In
1994, my field expedition team and I moved south to search the slightly younger
deposits at Kanapoi. Here we found evidence of a new species of
australopithecine, Australopithecus anamensis. This 4.1 m.y.a. species
represents the earliest known australopithecine. Furthermore, it takes the
evidence for bipedal locomotion back almost half a million years earlier than
that at Laetoli.

The field work at Turkana continues. The expeditions are now co-led by me and my
eldest daughter, Louise, who is currently studying for her Ph.D. at the
University College of London. Louise plans to continue the Turkana Basin
research and to develop projects that will shed yet more light on the early
evolution of our ancestors.

For several members of the Leakey family, searching for hominid fossils is a way
of life. African in mind and spirit, these Leakeys all have a personal
commitment to seeking answers to the question of human origins. Both Louis and
Mary Leakey worked in the field until their death --Louis in 1972 and Mary in
1996. Their son, Richard, found his first important fossil at age six. Meave,
Richard's wife, has been in the field since 1969. Today, Louise continues the
family tradition. She and her mother, Meave, are co-leaders of an expedition to
the west side of Lake Turkana.




PRESERVE YOUR PRINTS

YOU NEED:

• mud or wet sand (in the yard, at the beach, or mix some up in an old
dishpan)

• plaster of Paris (from a crafts or hardware store)

• disposable mixing container and stirrer (like a margarine tub and wooden
paint stirrer)

• water

• long strip of sturdy cardboard

• paper clips

When the hominids walked along the wet ash at Laetoli some 3.6 m.y.a., their
feet left prints that are still visible today. In 1969, when astronaut Neil
Armstrong became the first human to walk on the moon, his footprints remained
behind forever. If you want yours to last almost as long, then "step" this way!

DIRECTIONS

1 Place one foot -- with or without a shoe -- firmly into the mud or sand to
make a clear print. Then make a "collar" out of the cardboard in a size to fit
around the print. Fasten the ends of the strip together with the paper clips,
then push it into the mud or sand.

2 Mix the plaster of Paris following the package directions. The mixture should
be smooth and just thin enough to be pourable. Do not stir too much, as this
will make the plaster set too fast.

3 Pour about one inch of plaster into the cardboard collar. If necessary, use
the stirrer to spread the plaster out quickly. Cover the print evenly. If you
want to hang the finished cast, push one or two paper clips halfway into the wet
plaster to act as hangers.

4 Wait at least one hour for the plaster to set and harden. Carefully remove the
cast.

Note: You can make plaster handprints in the same way. Or, look for animal
tracks by a pond or stream, and turn their prints into works of art. You can
also press objects like seashells into the mud or sand and make prints of them.

WARNING: Never pour plaster of Paris down a drain, even if it's still wet! The
plaster will harden and could ruin your plumbing. Throw any leftovers in the
trash instead.




A HOMINID GLOSSARY

1 This term describes early hominids from Africa that lived from 4.5 m.y.a.
(million years ago) to 1 m.y.a. It includes species of the groups
Australopithecus and Paranthropus. Australopithecines differ from early Homo in
having larger teeth, smaller brains, and little dependence on stone tool
technology.

2 This word means standing and walking on two lower limbs ("legs"). Many
primates, especially apes, can occasionally stand and walk on two legs. Hominids
are bipedal, although the early australopithecines also climbed trees. Humans
are full-time bipeds.

3 This adjective describes flesh-eating animals.

4 The term "fossil" refers to any trace of ancient activity, such as footprints,
or any remains of a part of the body.

5 This term refers to the group of primates, both living and extinct, that
includes humans and their fossil ancestors. The first and most important
adaptation of the earliest hominids is the ability to move from one place to
another while standing and walking on their two lower limbs. Larger brains and
the ability to hold and work with "tools" are observed in later fossil hominids.

6 "Human" is sometimes used to describe both modern humans and our fossil
ancestors. Otherwise, it is used to describe modern humans who belong to the
species known as Homo sapiens ("knowing man").

7 This manner of moving from one place to another is shared by the three African
apes (chimpanzee, pygmy chimpanzee [or bonobo], and gorilla) that place the
backs of the middle sections of their fingers on the ground when they walk on
all fours.

8 This is one of a set of three teeth located on each side on the upper and
lower jaws in the back of the mouth. These teeth are used for crushing and
grinding food. Premolars refer to the two teeth that are positioned in front of
each set of molars.

9 This method of dating is used on volcanic rock. Geologists measure the ratio
of potassium to argon found in the volcanic rocks above and below where a fossil
is uncovered. When a volcano erupts, the potassium in the rock that has been
forced up is new. It then decays continuously at a set rate. The amount of argon
in the rock, on the other hand, increases with time. By comparing the ratio of
potassium to argon in the volcanic rock, geologists can date fossil finds at
specific sites.

10 When spelled with a capital "P," Primates refers to the order of mammals that
have flexible hands and feet, each with five digits. When not capitalized, the
word primates refers to a member of that group. These include humans, great
apes, lesser apes, monkeys, and prosimians.

Find the image that best describes each definition, and mark the appropriate
number in the box above the image. NOTE: One definition matches two images.
Answers are below.

Answers: Knuckle-walking, 7; Molar, 8; Potassium-argon dating, 9; Hominid, 5;
Fossil, 4; Carnivorous, 3; Human, 6; primate, 10; Bipedal, 2; Primates, 10;
Australopithecine, 1.




WHERE WAS HOME?

There's no place like home!" That's what Dorothy thought when she returned home
to Kansas after visiting Oz. What did she mean? While a "home" can take many
shapes and sizes, the idea of "a home" seems to be the same to people
everywhere. For example, homes are still central places where family members
like to gather to share a meal or celebrate a special occasion.

Have humans always had homes? Did the early hominids have homes? This is one of
the many puzzles about our past for which we do not have an answer. Yet exciting
new clues to the origins of "home" are being discovered every day.

The early tool users (dating to about 2.7 m.y.a.) left us piles of "garbage,"
namely stone cutting tools and the bones left after meaty meals. But we find no
clues to bedding material or shelters because plant remains are not preserved.

Did these hominids visit sites more than once? This seems likely, for two
reasons. First, many sites contain hundreds of pounds of stone that have been
battered or flaked into tools. Since the stone does not occur naturally on the
sites, it must have been carried in from several different sources. Second, at
many sites, bones from different animals show marks left by tool-using hominids
(such as cutmarks from stone tools). Since it is unlikely that such a variety of
animals died on the same spot, their remains were probably carried to the site
by hominids.

Think now like a prehistoric detective! Imagine the many different ways such
piles of garbage could accumulate at a site:

• Perhaps there were central places, like our homes today, where early
hominids gathered to share food they had collected and to sleep.

• Or perhaps the early sites were just ancient picnic sites, and early
hominids were messy eaters! Shady trees might have been attractive spots where
early toolmakers stopped in the heat of the day to feed, and use and to discard
stone tools. Think about our popular picnic sites today. If we just littered the
area with our food trash, instead of putting it in garbage cans, it would
quickly pile up.

• Or perhaps these places were where hominids could get some risky "fast
food." They used their sharp stone tools to steal meat quickly from nearby lion
kills, and then left the heavy stones and bones behind them as they hid from the
lions.

• Can you think of other possibilities?

Sometimes clues can come from unlikely places. Consider what research on our
closest living relative, the chimpanzee, has taught us about interpreting
archaeological evidence for "home" sites.

Chimpanzees today are an endangered species. This is tragic because, in the
wild, they are fascinatingly smart social animals that can teach us much about
ourselves. They feed on fruits, leaves, insects, and small animals during the
day and then make personal sleeping nests at night by weaving together leaves
and branches high in the trees. Chimps have large territories, but they do not
have "homes." Every chimp builds a new nest in a new place every night. (Very
young chimps sleep in their mother's nest.) If a chimp is feeding alone in the
forest, she will make a convenient sleeping nest there at the end of the day. In
this way, many solitary nests get built and then abandoned. If several chimps
are feeding in the same fruit tree in the late afternoon, they will often
cluster their nests together in the evening. Chimps will continue to build new
nests near that tree, as long as it is bearing fruit. Sometimes these popular
nesting grounds are close to places where chimpanzees have made and used tools,
such as the stones they used to crack nuts.

Why is chimp nesting interesting to an archaeologist? Let's do a thought
experiment. Imagine that some of the tools, food remains, and nesting debris
left behind by chimpanzees could be preserved for millions of years. How would
these "sites" appear to an archaeologist? They would be piles of garbage.

Obviously they would look different from the early hominid sites, because the
tools and food remains would be different. But these chimpanzee sites
demonstrate that littering the landscape is not a uniquely human trait.
Therefore, there is more than one way we can imagine early hominids creating
their sites of tool and feeding debris. Add frequent nesting sites to the list
we started above.

What do we need to solve this riddle? Patience, skill, creativity, and luck will
help! But our quest for the earliest home may be as difficult as finding a real
land of Oz. Like good detectives, archaeologists must constantly search for new
data. Still, we may never find the evidence we need. However, as long as we take
care to preserve ancient sites and conserve endangered animals today, the
scientists of tomorrow will be able to look for new evidence to challenge our
best ideas and improve our understanding of the human past.




NEWS FLASH

On April 22, 1999, Ethiopian anthropologist Berhane Asfaw and colleagues from
the U.S. and Japan announced the discovery of a new species of hominid and the
earliest traces of animal butchery. The discoveries come from the Middle Awash
study area in the Afar Desert of Ethiopia, and date to 2.5 m.y.a.

In 1996, project co-leader Tim White of the University of California, Berkeley,
found the first of the key fossils -- arm and leg bones of a small hominid
eroding from a low hill. About 600 feet away, erosion of the same geological
layer had exposed the skullcap of another hominid individual that was found by
UC Berkeley graduate student Yohannes Haile-Selassie in 1997. When the
scientists removed the specimen and examined it, they were surprised. It showed
a combination of bony and dental features never seen before: The face projects
forward. The braincase is crested and small. The premolars and molars are
enormous. The scientists therefore gave it a new name, Australopithecus garhi.
The word garhi means "surprise" in the Afar language. Pieces of six additional
hominid individuals were later found among the thousands of animal fossils from
the 2.5-million-year-old sediments. The scientists still cannot tell whether A.
garhi used stone tools, but the nearness of cutmarked antelope bones provides
circumstantial support for this idea. Analysis of the finds and the area
continues.




FOSSILS IN THE NEWS

JOHANNESBURG, SOUTH AFRICA: On Wednesday, December 9, 1998, workers at the site
of Sterkfontein near Johannesburg reported finding a nearly complete skeleton of
an early complete skeleton of an early australopithecine. Field assistants
Nkewane molefe and Stephen Motsumi, working for the University of the
Witwatersrand, located the skeleton in the limestone wall of a cave. Molefe and
Motsumi were searching for human fossils in the area that yielded "little foot,"
a collection of four foot bones from an early hominid described in 1994.

The new skeleton contains additional bones of the left foot and leg, as well as
bones of the right leg and foot. ALso among the newly discovered material are
bones from the vertebral column (spine), ribs, a skull, and teeth. The skull and
teeth will be especially important in the diagnosis of which species of early
hominid the new skeleton represents. Given its great antiquity, 3.2 to 3.6
m.y.a., the skeleton might even represent a new species of Australopithecus.
What is clear from the foot bones thus far is that while "little foot" was a
biped and walked on its two lower limbs, it also was an able climber. Most of
the new fossils remain in the limestone block in which they were discovered. It
will take researchers a year or more to extract the bones from the rock. After
that, scientists will be able to study the bones and draw conclusions about the
species and behavior of this early "ape-man."

Watch your newspapers and history journals in the months ahead for updates on
this project and other new finds in South and East Africa.

Look at the diagrams of a human foot and a chimpanzee foot above. The four foot
bones of "little foot" have been reproduces as "white" images in each diagram.
The two bones that correspond to the "little foot" bones above left have been
circled. Do they fit the human or chimp foot best?




LESSONS FROM THE ABORIGINES

What was it really like to live completely on wild foods the way our hominid
ancestors did for millions of years? Can modern-day hunter-gatherers offer
useful clues about how ancient proto-humans (first humans) behaved and survived
in the distant past?

To find the answers to these questions, scholars called ethnoarchaeologists have
lived with and studied groups of modern-day hunter-gatherers in remote areas
such as the Kalahari Desert of southern Africa, the tropics of the northern
Philippine Islands, the Alaskan Arctic, and the Central and Western deserts of
Australia.

All recent hunter-gatherers are modem human beings (Homo sapiens) whose cultures
are the product of long histories. They possess languages, practical skills,
beliefs, arts, and values that are fully modern in every sense. Thus, they
cannot be viewed as survivors of earlier stages in human evolution. So the
lessons we learn from modern-day hunter-gatherers cannot be applied directly to
our hominid ancestors as if they were "just like us."

Ethnoarchaeology tells us that the lives of the ancient hominids were often
completely different from anything we are likely to encounter today. However, we
can appreciate exactly what those differences as well as similarities are, and
why they are important, if we are to learn how our ancient hominid ancestors
lived.

When my wife and I lived with and studied the Western Desert Aborigines of
Australia in 1966-1970, most were living at or near settlements like missions
and government reserves. There were a few small groups, however, that still
lived by themselves away from these settlements. These "desert people" knew
about Europeans, but there were some who had not seen them yet. They were
full-time hunter-gatherers. They used traditional skills to navigate across vast
areas of desert, to locate water and food sources, and to fashion the tools
needed to survive under conditions that were harsh and unpredictable.

One of the first things we learned from these people was how important
plant-food collecting was to their diet. People hunted a lot, but they did not
catch much. Except for an occasional kangaroo or emu, most of the meat they got
consisted of a few mouthfuls each day from small game. These included lizards
and witchetty grubs, a variety of large moth larvae that, believe it or not,
makes a pretty yummy meal and met their nutritional needs. Mainly, they foraged
for plants they could bring back to camp and process in some way to make them
edible. And, as it turned out, most of the foraging for plants and small game
was done by women and children.

Many people still think that hunting and gathering is a hit-or-miss way to live.
They imagine people wandering aimlessly over the countryside hoping to find
their next meal. What we saw, however, were people whose knowledge of the
landscape and resources was so good that, for them, foraging was more like an
outing to the supermarket. They located wild foods in the bush the way we know a
specific aisle in a grocery store. After watching the Aborigines foraging across
the desert in both good years and bad, we learned how wrong our usual ideas
about "man the hunter" and hunter-gatherers as "aimless wanderers" could be.

Because these people were very mobile and could not carry many objects with
them, they developed multipurpose tools. The spearthrower was portable and could
be used for a variety of important tasks. Beside hunting, the spear was used for
lighting fires, for mixing pigments and native tobacco, for

woodworking (using a shaped stone flake attached to one end), for sweeping a
campsite clear of thorns and pebbles, and as a percussion instrument at dances.
In some cases, decorated spearthrowers served a map-like function in which the
designs showed landmarks that were related to stories about mythical ancestors
and their travels.

Then there were appliances -- that is, tools like stone seed-grinding slabs that
were too heavy to be carried easily from place to place. These were usually left
permanently at campsites. There were also instant tools. These were fashioned
from locally available materials as needed for some particular task, and
discarded nearby after the task was finished. For example, women on foraging
trips often fashioned impromptu rings of grass. They used them as pads to
cushion heavily loaded wooden bowls on their heads when carrying plant foods
back to camp. These grass rings were tossed aside as soon as the women arrived
in camp and put down their loads. Another example would be a naturally sharp
stone flake picked up after killing an animal during a hunt. The flake was used
to cut open the animal's belly to remove the intestines and then thrown away.
This kind of behavior was common in the lives of the Aborigines, and it is
common in our lives, too. Think about how often you have used some odd object
for a task that has to be done right away, such as stirring a can of paint with
a scrap of wood. Our hominid ancestors probably used a lot of instant tools in
this way, but there is nothing at all "primitive" about such behavior. We do it,
too -- all the time!

Some aboriginal stone artifacts, such as small, disk-shaped scrapers, were
actually tools for making other tools. In the case of the Aborigines, this meant
mainly wooden artifacts like digging sticks, wooden bowls, and spearthrowers.
The Aborigines attached the stone scraper to the end of a wooden handle (usually
on a spearthrower) for a better grip. They sharpened it by biting flakes off the
edge of the scraper with their teeth. Until we actually saw the desert people
doing this, most archaeologists did not realize that a stone toolmaking
technique like this even existed. How many of the stone artifacts from ancient
hominid sites could have been used to make other tools? And could any of these
have been sharpened by biting off small flakes?

The lesson here is that it is better to understand technology as the different
ways people use materials rather than simply as a collection of objects or
artifacts. While fire is not an object, it is one of the most important kinds of
technology we find among modern-day and historic hunter-gatherers. Fire is
important for cooking, warmth, and other, less obvious tasks like clearing weeds
and thorns off abandoned campsites. One of its most important uses seems to be
keeping big predators away from the campsite. Large hunting animals are often
active at night and would certainly be attracted to camp-sites where people are
living, especially when they discard uneaten bits of food around their living
areas. A fire will always frighten them away. Yet archaeology so far has failed
to show any evidence of fire used by Australopithecus in Africa, and even
evidence for fire with early Homo is controversial. In other words, an important
branch of our ancient hominid ancestors lived as hunter-gatherers apparently for
millions of years without the use of fire.

Ironically, Aborigines living in the Australian interior during about the last
10,000 to 20,000 years did not have to worry about large-bodied predators, since
these animals were already extinct there. Before that time, however, there were
many big, fierce, lion-like marsupials (mammals with a pouch to carry their
young, exactly the way kangaroos and wallabies do) with razor-sharp,
ribbon-shaped teeth. Thanks to archaeology, we know that the ancestors of the
modem Aborigines have lived in Australia at least 40,000 years, and during most
of that time they used fire to keep these predatory animals away.

The main lesson to be learned from the Aborigines is that we must try to imagine
how our ancient hominid ancestors lived under conditions and in ways that were
completely different from any known, modem example of hunter-gatherer behavior.
They were not exactly "like us," yet they survived for millions of years and
passed on what they learned in ways that we are just beginning to understand.




OFF THE SHELF

BOOKS

The Atlas of Archaeology by Mick Aston & Tim Taylor (DK Publishing, 1998)

Girls Who Rocked the World by Amelie Welden (Beyond Words Publishing, 1999)

The Leakey Family: Leaders in the Search for Human Origins by Delta Willis
(Facts On File, 1992)

Searching for Velociraptor by Lowell Dingus and Mark A. Norell (HarperCollins
Publishers, 1996)

Stones and Bones! How Archaeologists Trace Human Origins prepared by the
Geography Department (Runnestone Press, 1994)

COBBLESTONE RESOURCES

The following issues of FACES provide a good cross-reference for this issue on
African origins of hominids:

Becoming Human (January 1988)

Who Were the First Americans? (November 1996)

OTHER RESOURCES

World History on File: Early Civilizations (Prehistory to 300 C.E.) by The
Diagram Group, Victoria L. Chapman & David Lindroth (Facts On File, 1999)

MAGAZINES

Discovering Archaeology: July/August 1999

National Geographic: November 1985, September 1995, March 1996, February 1997,
and August 1998.

MEDIA

Human Origins 10,000,000-8,000 B.C. and Cradle of Mankind (Landmark Media)

"In Search of Human Origins" (WGBH Boston)

Microsoft Encarta Africana (Redmond, Washington: Microsoft Corporation, 1998)




A DIFFERENCE OF OPINIONS

Many people think of science as a search for the truth, and thus expect
scientific knowledge to be objective and never changing. Not so! Science simply
seeks to provide the most accurate description, at any given moment, of the
universe around us.

Think about this for a minute. Science is constantly advancing. Yet advance is
impossible unless we can demonstrate that what we believe today is inaccurate or
at least incomplete. What marks science off from other ways of knowing is the
following: Scientific statements are designed to be testable, at least in
principle, by reference to the real world.

So we should not be surprised that scientists often disagree. Today there is,
for example, active debate between those who believe that our species, Homo
sapiens, had a single origin in Africa maybe around 150,000 years ago, and those
who think that today's major geographical groups of humans, while close-knit, go
back very much further in time. This disagreement is based on different views
about the nature of the evolutionary process, and of the actual fossil and
molecular evidence. At this point, a single African origin looks much more
possible. But, even if agreement is reached on this question, the next
disagreement will not be far away.