Introduction
Olduvai Gorge is a very important site located in Tanzania, east Africa. The place’s importance lies in
the fact that it has yielded uninterrupted history of evolution of biology and culture from the very
beginning of human kind.
Olduvai Gorge lies on Serengeti Plain within the boundary of Ngorongoro crater and its conservation
area. UNESCO designated it as a world heritage site. The steep gorge formed along the banks of the
upper reaches of Olduvai River exposed geological strata from Tertiary into Quaternary. From the
exposed beds biological and cultural remains of early men are found in a datable context.
Olduvai Gorge is made famous by Louis S. B. Leakey, a British Palaeoanthropologist who was born in
Kenya, Africa but was trained in Cambridge University, England in Anthropology and Archaeology.
He got his doctoral degree in African prehistory. The site Olduvai Gorge was intensively worked by
Louis Leakey from 1931 onwards. Both Louis Leakey and his wife Mary Leakey and later on their
sons Jonathan and Richard continued with exploration and excavation in east Africa. Olduvai Gorge
yielded more than 60 hominid fossils and countless stone tools made by early men.
Unique Geographical Location of Olduvai Gorge
Olduvai Gorge is located on the Great Rift Valley. It is a wide flat plain in East Africa formed
approximately 20 to 25 million years ago. Due to plate movement along the faults in East Africa land
went down and volcanoes were formed, which erupted. The great Serengeti Plain and Ngorongoro
crater is a part of the formation within which lies Olduvai Gorge. The valley floor is nearly 100 kms
wide. At present the land is made up of mountains, valleys and lakes. The lines of faulting pass through
the great lake region. Out of the two faulting lines, the Western line is marked by Lake Albert, Edward,
Kivu and Tangnyika. The eastern line of faults is marked by volcanoes, such as Kenya and
Kilimanjaro and a number of small lakes such as, Nakuru, Navaisha, Magadi and Eyasi(see map).
At the early phase of Quaternary prehistoric men witnessed widespread tectonic movement because of
which not only volcanoes erupted but land surface and even courses of water bodies were changed.
However, abundant fossil and cultural remains suggest that the area was inhabited by early man.
Quaternary climatic sequences of East Africa
According to G. Mortelmans, a famous geologist, the water bodies of the lakes of the rift valley served
as a “pluviometer “of gigantic scale (Aliman, 1957: 197). ‘Pluviometer’ means measuring unit for
understanding climatic conditions during Pleistocene period. Africa had undergone alternating wet and
dry phases during Pleistocene. The wet phases are known as pluvial and the dry phases lying in
between two pluvial phases are known as inter pluvial phases. A number of scientists, including L. S.
B. Leakey had worked on the Quaternary climatic sequence and it was resolved in the third Pan
African Congress, held in Livingston in 1955 that Kageran, Kamasian, Kanjeran, Gamblian, Makalian
and Nakuran should be recognized as stratigraphic climatic divisions in East Africa (Clark, 1957:
xxxi). Kageran was the earliest and Gamblian the last one during Pleistocene period. Major beds (Bed I
– IV) at Olduvai Gorge yielded evidences of Kamasian and Kanjeran pluvials.
Stratigraphic sequence at Olduvai Gorge
Olduvai Gorge presents an excellent cross section of Kamasian pluvial deposit belonging to Middle
Pleistocene time period. Wall of the gorge is over three hundred feet high. It has cut through the
Serengeti Plain and has exposed the deposits of Kamasian lake of earlier times. Fossils and artifacts
were found from all the layers (picture 2).
Basaltic rocks lie at the base of the Gorge. On the basaltic base of the Gorge several superposed beds
were found by Leakey (1974). Olduvai Gorge is divided into seven successive formations (Hay, 1976).
From oldest to Youngest, they are as follows: Bed I, Bed II, Bed III, Bed IV, the Masek beds, Ndutu
beds and Naisiusiu beds. These beds provide relatively complete record of Pleistocene period from
about 2.1 million years ago to 15,000years B.P. Sediments of Holocene, less than 10,000 years B. P.
are present in and near the Olduvai Gorge. Following is description of the beds after Leakey mostly.
Bed I is the lowest and the thickest deposit. Its average thickness is 60 meters. The bed consists of
Lava. Sedimentary layers lie over lava. Bed I is dated by Potassium-Argon method. Bed I at the
western part of the main Gorge is oldest and the dates range from 2.0 to 2.1 million years ago. Top of
Bed I is 1.7 million years old. It appears that the entire tool bearing areas and faunal remains came
from the upper part of Bed I and belongs to dates ranging between 1.85 to 1.7 million years of age. Bed
I is divided into five strata or layers. These are made up of clay stone and volcanic ash deposit of
Ngongoro volcano. Leakey termed the deposit as lacustrine marl. Bed I yielded tools belonging to
Oldowan industry. This industry is divided into four evolutionary stages. Louis Leakey’s wife Mary
Leakey discovered a hominid fossil from this bed. This was first named as Zinjanthropus boisie and
later classified as Paranthropus boisie. Palaecology of the time of formation of lower part of Bed I
showed that forested environment surrounding a lake prevailed at that time. By the time of deposition
of middle portion of Bed I the area had a mosaic environment with open woodland. Trees mingled with
grassland surrounded the lake. This indicated that climate was changing to drier condition. Early
hominines roamed the land at this time. Upper part of Bed I records a farther drying trend with open
landscape which announced the beginning of a dry period.
Bed II is found lying over Bed I. It is quite difficult to distinguish the contact zone between the two
beds. Thickness of Bed II varies between 20 to 30 meters. Bed II is spread over a wider area than Bed
I. There are two subdivisions of Bed II. Each of the subdivisions is distinct in their geological
characters and in sequence of deposit of tuff (volcanic ash). Bed II in its lower part had common
environmental element with Bed I, having more water in the lake and with the presence of swamps. In
later parts of the Bed II a gradual increase in grassland and shrinkage of lakes are evident. Savannah
type fauna prevailed at this stage. Bed II is dated to 1.7 to 1.15 million years ago. Onset of dry climate
in Bed II is detected around 1.6 million years back. Remains of Homo habilis are recovered from the
lower part of Bed II. Homo ergester, the African type of Homo erectus, remains came from the upper
part of Bed II. One interesting fact is to be noted that remains of Paranthropus boisie are found from
both lower and upper parts of Bed II. This Indicated that all the three types of hominines lived at
Olduvai simultaneously. A Group of artifacts designated as Chelles-Acheulian industry was recovered
from Bed II. Approximately around 1.15 million years back a wide spread faulting took place in
Olduvai basin, eroding Bed II and bringing about considerable change in palaeo-geography of the
region. This bed showed evidence of cultural change from Oldowan to Acheulian type of culture. Bed
III and Bed IV were subsequently deposited over the changed surface of the Olduvai basin.
Bed III varies in thickness from 10 to 15 metres (Alimen, 1957: 201).The deposit is reddish brown in
colour and is made up of volcanic detritus material (Hay, 1976:27). This bed was laid from 1.15
million years back to 0.80 million years ago. Shrinkage of lake and aridity suggest dry inter pluvial
climate. Acheulian industry is recovered from the site.
Bed IV is dated from 0.80 million years to 0.60 million years ago. Bed IV was formed with loads
deposited from the streams, when wet condition set in and river had more water. The bed was formed
during Kanjeran pluvial period. Increase of water in lake is indicated by rise of lake level. Rising water
level left its mark along the shore of the water body. This indicated onset of the wet pluvial period. Bed
IV yielded artifacts of Typical Acheulian industry.
Leakey discussed about Bed V, which is considered to have formed under a condition of severe earth
movement, resulting in faulting and eroding of Beds I to IV successively. This happened at a time of
inter pluvial period between Kanjeran and Gamblian pluvial. Hay (1976) distinguished three more
beds.
Masek bed is 400,000 to 600,000 years old. This bed was laid before the formation of the Gorge. One
Acheulian site is found in it.
On Masek bed lays Ndutu bed about 32,000 to 400,000 years old. Lower part of the bed dates to
40,000 to 60,000 years before present. Tools of Middle Stone Age are found from this bed.
Naisiusiu bed was formed when upper limit of Ndutu bed was eroded and the Gorge was formed and
reached to its present depth. This bed is made up of wind borne volcanic ash. The bed is dated by C14
method to 22,000 to 15,000 B.P. Homo sapiens remains and microliths are found from this bed.
Climatic condition at Olduvai Gorge fluctuated between wet pluvial and dry inter pluvial periods.
Olduvai Gorge is situated on the great rift valley of East Africa. Presence of faults caused several large
scale earth movements. However the area attracted a variety of mammals, especially medium sized
antelopes. Early men lived in the lake shores and along the fresh water streams.
Palaeoanthropology and Olduvai Gorge
Olduvai Gorge has given proper understanding of human evolution for the first time. L. S. B. Leakey,
Mary Leakey and their sons discovered hominine remains from Olduvai Gorge. Later on teams from
Tanzania and from America made important discoveries of fossils of early human beings.
First discovery was made in 1959 by Mary Leakey of the hominid labeled as OH5, which was
nicknamed as “Nutcracker Man” because of the large size of its molar teeth. It was 1.75 million years
old, had a flat face, huge teeth, a large crest on the top of his head and a small brain. Leakey named it
as Zinjanathropus boisie. It is known at present as Paranthropus boisie (fig. 1).
Mary Leakey and her son Jonathan Leakey discovered the remains of another hominid in 1960. It was
labeled as OH 7 (fig. 2). It was found 300 yards away from the place where nutcracker man’s remains
were found. The skull had a significantly larger brain (680 CC). Leakey also found some hand bones
and skull fragments from the same place as OH 7. Hand bones showed that the hominid was capable of
precision grip, which is considered as capacity for fine manipulation of objects with its hands. Leakey
named the hominid as Homo habilis meaning ‘handy’ man because he used to carry stones with his
hands to make tools and pave the floors of his habitation ground. Richard Leakey, another son
discovered another Homo habilis in 1972. Homo habilis was dated to 1.9 million years ago. In 1960 a
well preserved foot, labeled as specimen no. OH 8, was discovered at Olduvai Gorge. The foot
belonged to Homo habilis. It had modern looking foot arches, showing that it had a bipedal gait and
walked like modern man. Probably it was attacked by a crocodile. A full skull of Homo habilis was
found in 1968. It was nicknamed as “Twiggy” (OH 24).
Leakey discovered a skull cap labeled as OH 9. It is also known as Chellean Man. It was dated to be
1.9 million years old. Though it was discovered in the same year as the discovery of Homo habilis, it
was found that the specimen has a cranial capacity of 1,065 CC (cubic centimeter), much bigger in size
than Homo habilis. The skull had thick brow ridges and a low sloped forehead. Leakey placed it in the
group Homo erectus (Fig. 3).
Another incomplete skull cap labeled as OH 12, also known as “Pin head” Man was discovered at
Olduvai Gorge in 1962. It is similar OH 9 but had a smaller brain size 750cc and dates between
800,000 and 120,000 years old. Homo erectus of Africa is designated as Homo ergaster.
Fossil remains of Olduvai Gorge have placed the site as the Homeland of Mankind. Beginning from 2
million years Paranthropus, Homo habilis and Homo ergaster Species evolved and roamed the
grounds of Olduvai basin.
Archaeological remains from Olduvai Gorge
Stone Age sequence in Africa differed from those of Europe. The African sequence follows the order
as follows (Clark, 1957).
Early Stone Age
First Intermediate
Middle Stone Age
Second Intermediate
Late Stone Age
Olduvai Gorge had yielded cultural remains of Early Stone Age from the pluvial and interpluvial
sequences of Kamasian and Kanjeran (Fig. 4 –Oakley: 180). The Oldowan culture was first
recognized by Leakey in Bed I of Olduvai Gorge in Tanzania. The industry is placed to the upper part
of Lower Pleistocene. Around 2 million years ago the first species of Homo habilis started to make
tools. These are made by Mode 1 type technology and are classified as Oldowan tools and the culture
is known as Oldowan culture. Hominine group named as Paranthropus boisei was dated to 1.8 miilion
years ago. It appeared that at Olduvai Gorge both Homo sp, and Paranthropus were present
simultaneously. The latter disappeared about 1 million years back. Tool making was done by the Homo
species.
Oldowan culture
The Oldowan tools are mostly made on pebbles of lava and quartz. The pebbles were struck with the
intention for getting the sharp end along one edge. These are known as choppers (fig. 5). The raw
material for tool making was procured from a distance of 19 km. This indicated the cognitive capacity
of early Homo for the deliberate choice of suitable raw materials for making Oldowan tools, meaning
that they searched for the raw materials and carried them to their place of work. Oldowan culture
flourished from Bed I into lower part of Bed II. Oldowan people lived through a dry phase in a
savannah type environment. The tools probably were used as missiles as well as for chopping
purposes.
Chelles-Acheulian culture
At Olduvai tools were collected layer by layer from the exposed sections of the Gorge (Leakey, 1951).
It was found that a good percent of pebble tool in Bed II were advanced types. These were worked
more extensively by removing flake scars in more than two directions and then in other directions.
Finally giving rise to a biface or hand axe. These are called biface because they were worked on both
the faces. There is a clear cut evidence of advancement and evolution of Oldowan culture into biface
culture. Leakey preferred to call this stage as Chelles-Acheul culture. The Chellean culture is also
known as advanced Oldowan culture in Olduvai Gorge. Tools of Chelles –Acheul culture are pointed
in outline or pear shaped or oval in outline. These have wavy or zigzag margin formed by the
intersection of deep flake scars from both the surfaces. Leakey divided Chelles-Acheul culture into 11
evolutionary stages from Bed II into Bed III and subsequently into Bed IV (fig. 4. Oakley, 1964: 180).
The assemblage at each level yielded different types of finished artifacts as well as handaxes, pebble
tools, flakes and flake tools. Pebble tools were gradually decreasing in frequency of occurrence.
Technique of manufacture of tools of Chelles-Acheul culture was direct percussion method. Flaking
was done by hammer stone, stone anvil or block on block method. That means the tools were fashioned
by directly hitting the stone with another stone. Chellean handaxes are very coarsely made. The tools
are made on pebble and they grade into pebble tools showing their origin in Oldowan culture (fig. 6).
Acheulian stage is distinguished from the Chellean by means of a new flaking technique and with the
advent of new types of handaxes. In Olduvai Gorge transition from Chellean to Acheulian is marked in
stages 4 and 5. The transition is from advanced Oldowan into Acheulian stage. Acheulian handaxes
were mostly pointed or oval and symmetrical in shape (fig. 7). The lateral margins are formed by the
removal of small shallow flake scars. Acheulian handaxes were made or at least finished by cylinder
hammer technique. Although Acheulian men used a variety of raw materials but the finished products
remained symmetrical, efficient and showed beautiful craftsmanship. A new type appeared with an axe
like transverse end instead of a pointed end. These bifaces are known as cleavers. These cleavers have
been tested on meat, wood and other objects. The experiment showed that the cleavers were very
efficient tools for skinning and cutting meat off the carcasses. Cleavers appeared in Acheulian stage
(fig. 8).
Acheulian is the techno complex attached to Homo ergaster/ homo erectus that appeared in Eastern
Africa 1.7 miilion years ago, reflecting greater cognitive, economic, social, and territorial complexity.
Acheulian represents a substantial technological advancement over Oldowan. Stone workers now had
the ability to produce large flakes (over 10cm long) and could make large artifacts such as handaxes or
bifaces, the knapping of which demanded minute knapping of a large flake on both sides. This careful
working produced a cutting edge along most of the axe border. The large formats of Acheulian tools
served several purposes including the butchery of large animals such as elephants, and hippopotami
(which would have required a great deal of force) and woodworking. Acheulian technology was one of
the most remarkable of all the palaeolithic techniques. It lasted almost over 1.5 millions of human
evolution, extended across the old world and formed the basic technological equipment for many and
very different human species.
Palaeolithic Living sites in Olduvai Gorge
A number of living sites were discovered at Olduvai Gorge (fig. 9, Oakley 1968: 185). Early man in
Olduvai Gorge lived basically on gathering of nuts, tubers and other vegetable food. Meat formed a
small part of their diet. Fish, birds and large mammals’ bones are left by early men at the site known as
FLK -Zinj. There is a debate whether men in Olduvai Gorge were scavengers or hunters. They could
be either or both.