# Introduction to Paleoanthropology/Origin

## Beginning of the 20th Century

In 1891, Eugene Dubois discovers remains of hominid fossils (which he
will call *Pithecanthropus*) on the island of Java, in southeast Asia.
The two main consequences of this discovery:

-   stimulated research for a \"missing link\" in our origins
-   oriented research interest toward southeast Asia as possible cradle
    of humanity

Yet, in South Africa, 1924, Raymond Dart accidentally discovered the
remains of child (at Taung) during exploitation of a quarry and
publishes them in 1925 as a new species - *Australopithecus africanus*
(which means \"African southern ape\"). Dart, a British-trained
anatomist, was appointed in 1922 professor of anatomy at the University
of the Witwatersrand in Johannesburg, South Africa. Through this
discovery, Dart:

-   documented the ancient age of hominids in Africa and
-   questioned the SE Asian origin of hominids, arguing for a possible
    African origin.

Nevertheless, Raymond Dart\'s ideas were not accepted by the scientific
community at the time because:

-   major discoveries carried out in Europe (such as Gibraltar, and the
    Neander Valley in Germany) and Asia (Java) and
-   remains of this species were the only ones found and did not seem to
    fit in phylogenetic tree of our origins and
-   ultimately considered simply as a fossil ape.

It took almost 20 years before Dart\'s ideas could be accepted, due to
notable new discoveries:

-   in 1938, identification of a second species of Australopithecine,
    also in South Africa: *Paranthropus (Australopithecus) robustus*.
    Robert Broom collected at Kromdraai Cave the remains of a skull and
    teeth,
-   in 1947, other remains of *Australopithecus africanus* found at
    Sterkfontein and Makapansgat, and
-   in 1948, other remains of *Paranthropus robustus* found at
    Swartkrans, also by R. Broom.

## 1950s - 1970s

During the first half of the 20th century, most discoveries essential
for paleoanthropology and human evolution were done in South Africa.

After World War II, research centered in East Africa. The couple Mary
and Louis Leakey discovered a major site at Olduvai Gorge, in Tanzania:

-   many seasons of excavations at this site - discovery of many layers
    (called beds), with essential collection of faunal remains and stone
    tools, and several hominid species identified for the first time
    there;
-   In 1959, discovery in Bed I of hominid remains (OH5), named
    *Zinjanthropus (Australopithecus) boisei*;
-   L. Leakey first considered this hominid as the author of stone
    tools, until he found (in 1964) other hominid fossils in the same
    Bed I, which he attributed to different species - *Homo habilis*
    (OH7).

Another major discovery of paleoanthropological interest comes from the
Omo Valley in Ethiopia:

-   from 1967 to 1976, nine field seasons were carried out;
-   In 1967, discovery of hominid fossils attributed to new species -
    *Australopithecus aethiopicus*
-   217 specimens of hominid fossils attributed to five hominid species:
    *A. afarensis*, *A. aethiopicus*, *A. boisei*, *H. rudolfensis*, *H.
    erectus*, dated to between 3.3 and 1 Million years ago.

Also in 1967, Richard Leakey starts survey and excavation on the east
shore of Lake Turkana (Kenya), at a location called Koobi Fora:

-   research carried out between 1967 and 1975
-   very rich collection of fossils identified, attributed to *A.
    afarensis* and *A. boisei*

In 1972, a French-American expedition led by Donald Johanson and Yves
Coppens focuses on a new locality (Hadar region) in the Awash Valley
(Ethiopia):

-   research carried out between 1972-1976
-   in 1973, discovery of most complete skeleton to date, named Lucy,
    attributed (in 1978 only) to *A. afarensis*
-   more than 300 hominid individuals were recovered
-   discoveries allow for a detailed analysis of locomotion and
    bipedalism among early hominids

From 1976 to 1979, Mary Leakey carries out research at site of Laetoli,
in Tanzania:

-   In 1976, she discovers animal footprints preserved in tuff (volcanic
    ash), dated to 3.7 million years ago (MYA).
-   In 1978-1979, discovery of site with three series of hominid
    (australopithecine) footprints, confirming evidence of bipedalism.

## 1980 - The Present

### South Africa

Four australopithecine foot bones dated at around 3.5 million years were
found at Sterkfontein in 1994 by Ronald Clarke:

-   oldest hominid fossils yet found in South Africa
-   They seem to be adapted to bipedalism, but have an intriguing
    mixture of ape and human features

Since then, eight more foot and leg bones have been found from the same
individual, who has been nicknamed \"Little Foot\".

### Eastern Africa

Recent discovery of new *A. boisei* skull is:

-   one of the most complete known, and the first known with an
    associated cranium and lower jaw;
-   It also has a surprising amount of variability from other *A.
    boisei* skulls, which may have implications for how hominid fossils
    are classified.

Recent research suggests that the some australopithecines were capable
of a precision grip, like that of humans but unlike apes, which would
have meant they were capable of making stone tools.

The oldest known stone tools have been found in Ethiopia in sediments
dated at between 2.5 million and 2.6 million years old. The makers are
unknown, but may be either early *Homo* or *A. garhi*

A main question is, how have these species come to exist in the
geographical areas so far apart from one another?

### Chad

A partial jaw found in Chad (Central Africa) greatly extends the
geographical range in which australopithecines are known to have lived.
The specimen (nicknamed Abel) has been attributed to a new species -
*Australopithecus bahrelghazali*.

In June 2002, publication of major discovery of earliest hominid known:
*Sahelanthropus tchadensis* (nickname: \"Toumai\").


# Introduction to Paleoanthropology/Bones

## Bone Identification and Terminology

### Skull

**Cranium**: The skull minus the lower jaw bone.

**Brow, Supraorbital Ridges**: Bony protrusions above eye sockets.

**Endocranial Volume**: The volume of a skull\'s brain cavity.

**Foramen Magnum**: The hole in the skull through which the spinal cord
passes.

-   In apes, it is towards the back of the skull, because of their
    quadrupedal posture
-   In humans it is at the bottom of the skull, because the head of
    bipeds is balanced on top of a vertical column.

**Sagittal Crest**: A bony ridge that runs along the upper, outer center
line of the skull to which chewing muscles attach.

**Subnasal Prognathism**: Occurs when front of the face below the nose
is pushed out.

**Temporalis Muscles**: The muscles that close the jaw.

### Teeth

**Canines**, **Molars**: Teeth size can help define species.

-   Gorillas eat lots of foliage; therefore they need very large molars,
    they also have pronounced canines.
-   Humans are omnivorous and have smaller more generalized molars, and
    reduced canines.

**Dental Arcade**: The rows of teeth in the upper and lower jaws.

-   Chimpanzees have a narrow, U-shaped dental arcade
-   Modern humans have a wider, parabolic dental arcade
-   The dental arcade of Australopithecus afarensis has an intermediate
    V shape

**Diastema**: Functional gaps between teeth.

-   In the chimpanzee\'s jaw, the gap between the canine and the
    neighboring incisor, which provides a space for the opposing canine
    when the animal\'s mouth is closed
-   Modern humans have small canines and no diastema.

## Using Bones to Define Humans

### Bipedalism

Fossil pelvic and leg bones, body proportions, and footprints all read
\"bipeds.\" The fossil bones are not identical to modern humans, but
were likely functionally equivalent and a marked departure from those of
quadrupedal chimpanzees.

Australopithecine fossils possess various components of the bipedal
complex which can be compared to those of chimpanzees and humans:

-   A diagnostic feature of bipedal locomotion is a shortened and
    broadened ilium (or large pelvic bone); the australopithecine ilium
    is shorter than that of apes, and it is slightly curved; this shape
    suggests that the gluteal muscles were in a position to rotate and
    support the body during bipedal walking
-   In modern humans, the head of the femur (or thigh bone) is robust,
    indicating increased stability at this joint for greater load
    bearing
-   In humans, the femur angles inward from the hip to the knee joint,
    so that the lower limbs stand close to the body\'s midline. The line
    of gravity and weight are carried on the outside of the knee joint;
    in contrast, the chimpanzee femur articulates at the hip, then
    continues in a straight line downward to the knee joint
-   The morphology of the australopithecine femur is distinct and
    suggests a slightly different function for the hip and knee joints.
    The femoral shaft is angled more than that of a chimpanzee and
    indicates that the knees and feet were well planted under the body
-   In modern humans, the lower limbs bear all the body weight and
    perform all locomotor functions. Consequently, the hip, knee and
    ankle joint are all large with less mobility than their counterparts
    in chimpanzees. In australopithecines, the joints remain relatively
    small. In part, this might be due to smaller body size. It may also
    be due to a unique early hominid form of bipedal locomotion that
    differed somewhat from that of later hominids.

Thus human bodies were redesigned by natural selection for walking in an
upright position for longer distances over uneven terrain. This is
potentially in response to a changing African landscape with fewer trees
and more open savannas.

### Brain Size

Bipedal locomotion became established in the earliest stages of the
hominid lineage, about 7 million years ago, whereas brain expansion came
later. Early hominids had brains slightly larger than those of apes, but
fossil hominids with significantly increased cranial capacities did not
appear until about 2 million years ago.

Brain size remains near 450 cubic centimetres (cc) for robust
australopithecines until almost 1.5 million years ago. At the same time,
fossils assigned to Homo exceed 500 cc and reach almost 900 cc.

What might account for this later and rapid expansion of hominid brain
size? One explanation is called the \"radiator theory\": a new means for
cooling this vital heat-generating organ, namely a new pattern of
cerebral blood circulation, would be responsible for brain expansion in
hominids. Gravitational forces on blood draining from the brain differ
in quadrupedal animals versus bipedal animals: when humans stand
bipedally, most blood drains into veins at the back of the neck, a
network of small veins that form a complex system around the spinal
column.

The two different drainage patterns might reflect two systems of cooling
brains in early hominids. Active brains and bodies generate a lot of
metabolic heat. The brain is a hot organ, but must maintain a fairly
rigid temperature range to keep it functioning properly and to prevent
permanent damage.

Savanna-dwelling hominids with this network of veins had a way to cool a
bigger brain, allowing the \"engine\" to expand, contributing to hominid
flexibility in moving into new habitats and in being active under a wide
range of climatic conditions.

### Free Hands

Unlike other primates, hominids no longer use their hands in locomotion
or bearing weight or swinging through the trees. The chimpanzee\'s hand
and foot are similar in size and length, reflecting the hand\'s use for
bearing weight in knuckle walking. The human hand is shorter than the
foot, with straighter phalanges. Fossil hand bones two million to three
million years old reveal this shift in specialization of the hand from
locomotion to manipulation.

Chimpanzee hands are a compromise. They must be relatively immobile in
bearing weight during knuckle walking, but dexterous for using tools.
Human hands are capable of power and precision grips but more
importantly are uniquely suited for fine manipulation and coordination.

### Tool Use

Fossil hand bones show greater potential for evidence of tool use.
Although no stone tools are recognizable in an archaeological context
until 2.5 million years ago, we can infer nevertheless their existence
for the earliest stage of human evolution. The tradition of making and
using tools almost certainly goes back much earlier to a period of
utilizing unmodified stones and tools mainly of organic, perishable
materials (wood or leaves) that would not be preserved in the fossil
record.

How can we tell a hominid-made artifact from a stone generated by
natural processes? First, the manufacturing process of hitting one stone
with another to form a sharp cutting edge leaves a characteristic mark
where the flake has been removed. Second, the raw material for the tools
often comes from some distance away and indicates transport to the site
by hominids.

Modification of rocks into predetermined shapes was a technological
breakthrough. Possession of such tools opened up new possibilities in
foraging: for example, the ability to crack open long bones and get at
the marrow, to dig, and to sharpen or shape wooden implements.

Even before the fossil record of tools around 2.5 Myrs,
australopithecine brains were larger than chimpanzee brains, suggesting
increased motor skills and problem solving. All lines of evidence point
to the importance of skilled making and using of tools in human
evolution.

## Summary

In this chapter, we learned the following:

1\. Humans clearly depart from apes in several significant areas of
anatomy, which stem from adaptation:

-   bipedalism
-   dentition (tooth size and shape)
-   free hands
-   brain size

2\. For most of human evolution, cultural evolution played a fairly
minor role. If we look back at the time of most australopithecines, it
is obvious that culture had little or no influence on the lives of these
creatures, who were constrained and directed by the same evolutionary
pressures as the other organisms with which they shared their ecosystem.
So, for most of the time during which hominids have existed, human
evolution was no different from that of other organisms.

3\. Nevertheless once our ancestors began to develop a dependence on
culture for survival, then a new layer was added to human evolution.
Sherwood Washburn suggested that the unique interplay of cultural change
and biological change could account for why humans have become so
different. According to him, as culture became more advantageous for the
survival of our ancestors, natural selection favoured the genes
responsible for such behaviour. These genes that improved our capacity
for culture would have had an adaptive advantage. We can add that not
only the genes but also anatomical changes made the transformations more
advantageous. The ultimate result of the interplay between genes and
culture was a significant acceleration of human evolution around 2.6
million to 2.5 million years ago.


# Introduction to Paleoanthropology/Hominids Early

## Overview of Human Evolutionary Origin

The fossil record provides little information about the evolution of the
human lineage during the Late Miocene, from 10 million to 5 million
years ago. Around 10 million years ago, several species of large-bodied
hominids that bore some resemblance to modern orangutans lived in Africa
and Asia. About this time, the world began to cool; grassland and
savanna habitats spread; and forests began to shrink in much of the
tropics.

The creatures that occupied tropical forests declined in variety and
abundance, while those that lived in the open grasslands thrived. We
know that at least one ape species survived the environmental changes
that occurred during the Late Miocene, because molecular genetics tells
us that humans, gorillas, bonobos and chimpanzees are all descended from
a common ancestor that lived sometime between 7 million and 5 million
years ago. Unfortunately, the fossil record for the Late Miocene tells
us little about the creature that linked the forest apes to modern
hominids.

Beginning about 5 million years ago, hominids begin to appear in the
fossil record. These early hominids were different from any of the
Miocene apes in one important way: they walked upright (as we do).
Otherwise, the earliest hominids were probably not much different from
modern apes in their behavior or appearance.

Between 4 million and 2 million years ago, the hominid lineage
diversified, creating a community of several hominid species that ranged
through eastern and southern Africa. Among the members of this
community, two distinct patterns of adaptation emerged:

-   One group of creatures (Australopithecus, Ardipithecus,
    Paranthropus) evolved large molars that enhanced their ability to
    process coarse plant foods;
-   The second group, constituted of members of our own genus Homo (as
    well as Australopithecus garhi) evolved larger brains, manufactured
    and used stone tools, and relied more on meat than the
    Australopithecines did.

## Hominid Species

!Map of hominid fossil sites in East
Africa.svg "Map of hominid fossil sites in East Africa")

  ------------------ ----------------------- ----------------- --------------------------
  **Species**        **Type**                **Specimen**      **Named by**
  Sahelanthropus     tchadensis \"Toumai\"   TM 266-01-060-1   Brunet et al. 2002
  Orrorin            tugenensis              BAR 1000\'00      Senut et al. 2001
  Ardipithecus       ramidus                 ARA-VP 6/1        White et al. 1994
  Australopithecus   anamensis               KP 29281          M. Leakey et al. 1995
  Australopithecus   afarensis               LH 4              Johanson et al. 1978
  Australopithecus   bahrelghazali           KT 12/H1          Brunet et al. 1996
  Kenyanthropus      platyops                KNM-WT 40000      M. Leakey et al. 2001
  Australopithecus   garhi                   BOU-VP-12/130     Asfaw et al. 1999
  Australopithecus   africanus               Taung             Dart 1925
  Australopithecus   aethiopicus             Omo 18            Arambourg & Coppens 1968
  Paranthropus       robustus                TM 1517           Broom 1938
  Paranthropus       boisei                  OH 5              L. Leakey 1959
  Homo               habilis                 OH 7              L. Leakey et al. 1964
  ------------------ ----------------------- ----------------- --------------------------

### *Sahelanthropus tchadensis* (\"Toumai\")

!Sahelanthropus tchadensis - commonly called \"Toumai\". A hominid
skulll from 6-7 million years
ago

-   Named in July 2002 from fossils discovered in Chad.
-   Oldest known hominid or near-hominid species (6-7 million years
    ago).
-   Discovery of nearly complete cranium and number of fragmentary lower
    jaws and teeth:
    -   Skull has very small brain size (ca. 350 cc), considered as
        primitive apelike feature;
    -   Yet, other features are characteristic of later hominids: short
        and relatively flat face; canines are smaller and shorter; tooth
        enamel is slightly thicker (suggesting a diet with less fruit).
-   This mixture of features, along with fact that it comes from around
    the time when hominids are thought to have diverged from
    chimpanzees, suggests it is close to the common ancestor of humans
    and chimpanzees.
-   Foramen magnum is oval (not rounded as in chimps) suggesting upright
    walking position.

### *Orrorin tugenensis*

-   Named in July 2001; fossils discovered in western Kenya.
-   Deposits dated to about 6 million years ago.
-   Fossils include fragmentary arm and thigh bones, lower jaws, and
    teeth:
    -   Limb bones are about 1.5 times larger than those of Lucy, and
        suggest that it was about the size of a female chimpanzee.
-   Its finders claimed that Orrorin was a human ancestor adapted to
    both bipedality and tree climbing, and that the australopithecines
    are an extinct offshoot.

### *Ardipithecus ramidus*

!Skeleton of *Ardipithecus
ramidus*

-   Recent discovery announced in Sept. 1994.
-   Dated 4.4 million years ago.
-   Most remains are skull fragments.
    -   Indirect evidence suggests that it was possibly bipedal, and
        that some individuals were about 122 cm (4\'0\") tall;
    -   Teeth are intermediate between those of earlier apes and
        Austalopithecus afarensis.

### *Australopithecus anamensis*

-   Named in August 1995 from fossils from Kanapoi and Allia Bay in
    Kenya.
-   Dated between 4.2 and 3.9 million years ago.
-   Fossils show mixture of primitive features in the skull, and
    advanced features in the body:
    -   Teeth and jaws are very similar to those of older fossil apes;
    -   Partial tibia (inner calf bone) is strong evidence of
        bipedality, and lower humerus (the upper arm bone) is extremely
        humanlike.

### *Australopithecus afarensis*

!\"Lucy\", an *Australopithecus afarensis*
skeleton

-   Existed between 3.9 and 3.0 million years ago.
-   *A. afarensis* had an apelike face with a low forehead, a bony ridge
    over the eyes, a flat nose, and no chin. They had protruding jaws
    with large back teeth.
-   Cranial capacity: 375 to 550 cc. Skull is similar to chimpanzee,
    except for more human-like teeth. Canine teeth are much smaller than
    modern apes, but larger and more pointed than humans, and shape of
    the jaw is between rectangular shape of apes and parabolic shape of
    humans.
-   Pelvis and leg bones far more closely resemble those of modern
    humans, and leave no doubt that they were bipedal.
-   Bones show that they were physically very strong.
-   Females were substantially smaller than males, a condition known as
    sexual dimorphism. Height varied between about 107 cm (3\'6\") and
    152 cm (5\'0\").
-   Finger and toe bones are curved and proportionally longer than in
    humans, but hands are similar to humans in most other details.

### *Kenyanthropus platyops* (\"flat-faced man of Kenya\")

!Skull of *Kenyanthropus
platyops*.JPG "Skull of Kenyanthropus platyops")

-   Named in 2001 from partial skull found in Kenya.
-   Dated to about 3.5 million years ago.
-   Fossils show unusual mixture of features: size of skull is similar
    to *A. afarensis* and *A. africanus*, and has a large, flat face and
    small teeth.

### *Australopithecus garhi*

-   *A. garhi* existed around 2.5 Myrs.
-   It has an apelike face in the lower part, with a protruding jaw
    resembling that of *A. afarensis*. The large size of the palate and
    teeth suggests that it is a male, with a small braincase of about
    450 cc.
-   It is like no other hominid species and is clearly not a robust
    form. In a few dental traits, such as the shape of the premolar and
    the size ratio of the canine teeth to the molars, *A. garhi*
    resembles specimens of early Homo. But its molars are huge, even
    larger than the *A. robustus* average.
-   Among skeletal finds recovered, femur (upper leg bone) is relatively
    long, like that of modern humans. But forearm is long too, a
    condition found in apes and other australopithecines but not in
    humans.

### *Australopithecus africanus*

-   First identified in 1924 by Raymond Dart, an Australian anatomist
    living in South Africa.
-   *A. africanus* existed between 3 and 2 million years ago.
-   Similar to *A. afarensis*, and was also bipedal, but body size was
    slightly greater.
-   Brain size may also have been slightly larger, ranging between 420
    and 500 cc. This is a little larger than chimp brains (despite a
    similar body size).
-   Back teeth were a little bigger than in *A. afarensis*. Although the
    teeth and jaws of *A. africanus* are much larger than those of
    humans, they are far more similar to human teeth than to those of
    apes. The shape of the jaw is now fully parabolic, like that of
    humans, and the size of the canine teeth is further reduced compared
    to *A. afarensis*.

NOTE: *Australopithecus afarensis* and *A. africanus* are known as
gracile australopithecines, because of their relatively lighter build,
especially in the skull and teeth. (Gracile means \"slender\", and in
paleoanthropology is used as an antonym to \"robust\"). Despite the use
of the word \"gracile\", these creatures were still more far more robust
than modern humans.

### *Australopithecus aethiopicus*

-   *A. aethiopicus* existed between 2.6 and 2.3 million years ago.
-   Species known mainly from one major specimen: the Black Skull
    (KNM-WT 17000) discovered at Lake Turkana.
-   It may be ancestor of *P. robustus* and *P. boisei*, but it has a
    baffling mixture of primitive and advanced traits:
    -   Brain size is very small (410 cc) and parts of the skull
        (particularly the hind portions) are very primitive, most
        resembling *A. afarensis*;
    -   Other characteristics, like massiveness of face, jaws and
        largest sagittal crest in any known hominid, are more
        reminiscent of *P. boisei*.

### *Paranthropus boisei*

!Skull of *Paranthropus
boisei*

-   *P. boisei* existed between 2.2 and 1.3 million years ago.
-   Similar to *P. robustus*, but face and cheek teeth were even more
    massive, some molars being up to 2 cm across. Brain size is very
    similar to P. robustus, about 530 cc.
-   A few experts consider *P. boisei* and *P. robustus* to be variants
    of the same species.

### *Paranthropus robustus*

-   *P. robustus* had a body similar to that of *A. africanus*, but a
    larger and more robust skull and teeth.
-   It existed between 2 and 1.5 million years ago.
-   The massive face is flat, with large brow ridges and no forehead. It
    has relatively small front teeth, but massive grinding teeth in a
    large lower jaw. Most specimens have sagittal crests.
-   Its diet would have been mostly coarse, tough food that needed a lot
    of chewing.
-   The average brain size is about 530 cc. Bones excavated with *P.
    robustus* skeletons indicate that they may have been used as digging
    tools.

*Australopithecus aethiopicus*, *Paranthropus robustus* and *P. boisei*
are known as robust australopithecines, because their skulls in
particular are more heavily built.

### *Homo habilis*

!Skull of *Homo
habilis*

-   *H. habilis* (\"handy man\")
-   *H. habilis* existed between 2.4 and 1.5 million years ago.
-   It is very similar to australopithecines in many ways. The face is
    still primitive, but it projects less than in A. africanus. The back
    teeth are smaller, but still considerably larger than in modern
    humans.
-   The average brain size, at 650 cc, larger than in
    australopithecines. Brain size varies between 500 and 800 cc,
    overlapping the australopithecines at the low end and *H. erectus*
    at the high end. The brain shape is also more humanlike.
-   *H. habilis* is thought to have been about 127 cm (5\'0\") tall, and
    about 45 kg (100 lb) in weight, although females may have been
    smaller.
-   Because of important morphological variation among the fossils, *H.
    habilis* has been a controversial species. Some scientists have not
    accepted it, believing that all *H. habilis* specimens should be
    assigned to either the australopithecines or Homo erectus. Many now
    believe that *H. habilis* combines specimens from at least two
    different *Homo* species: small-brained less-robust individuals (*H.
    habilis*) and large-brained, more robust ones (*H. rudolfensis*).
    Presently, not enough is known about these creatures to resolve this
    debate.


# Introduction to Paleoanthropology/Hominids Early Chronology

## Phylogeny and Chronology

### Between 8 million and 4 million years ago

Fossils of *Sahelanthropus tchadensis* (6-7 million years) and *Orrorin
tugenensis* (6 million years), discovered in 2001 and 2000 respectively,
are still a matter of debate.

The discoverers of *Orrorin tugenensis* claim the fossils represent the
real ancestor of modern humans and that the other early hominids (e.g.,
Australopithecus and Paranthropus) are side branches. They base their
claim on their assessment that this hominid was bipedal (2 million years
earlier than previously thought) and exhibited expressions of certain
traits that were more modern than those of other early hominids. Other
authorities disagree with this analysis and some question whether this
form is even a hominid. At this point, there is too little information
to do more than mention these two new finds of hominids. As new data
come in, however, a major part of our story could change.

Fossils of *Ardipithecus ramidus* (4.4 million years ago) were different
enough from any found previously to warrant creating a new hominid
genus. Although the evidence from the foramen magnum indicates that they
were bipedal, conclusive evidence from legs, pelvis and feet remain
somewhat enigmatic. There might be some consensus that *A. ramidus*
represent a side branch of the hominid family.

### Between 4 million and 2 million years ago

*Australopithecus anamensis* (4.2-3.8 million years ago) exhibit mixture
of primitive (large canine teeth, parallel tooth rows) and derived
(vertical root of canine, thicker tooth enamel) features, with evidence
of bipedalism. There appears to be some consensus that this may
represent the ancestor of all later hominids.

The next species is well established and its nature is generally agreed
upon: *Australopithecus afarensis* (4-3 million years ago). There is no
doubt that *A. afarensis* were bipeds. This form seems to still remain
our best candidate for the species that gave rise to subsequent
hominids.

At the same time lived a second species of hominid in Chad:
*Australopithecus bahrelghazali* (3.5-3 million years ago). It suggests
that early hominids were more widely spread on the African continent
than previously thought. Yet full acceptance of this classification and
the implications of the fossil await further study.

Another fossil species contemporaneous with A. afarensis existed in East
Africa: *Kenyanthropus platyops* (3.5 million years ago). The fossils
show a combination of features unlike that of any other forms: brain
size, dentition, details of nasal region resemble genus
Australopithecus; flat face, cheek area, brow ridges resemble later
hominids. This set of traits led its discoverers to give it not only a
new species name but a new genus name as well. Some authorities have
suggested that this new form may be a better common ancestor for Homo
than *A. afarensis*. More evidence and more examples with the same set
of features, however, are needed to even establish that these fossils do
represent a whole new taxonomy.

Little changed from A. afarensis to the next species: *A. africanus*:
same body size and shape, and same brain size. There are a few
differences, however: canine teeth are smaller, no gap in tooth row,
tooth row more rounded (more human-like).

We may consider A. africanus as a continuation of *A. afarensis*, more
widely distributed in southern and possibly eastern Africa and showing
some evolutionary changes. It should be noted that this interpretation
is not agreed upon by all investigators and remains hypothetical.

Fossils found at Bouri in Ethiopia led investigators to designate a new
species: *A. garhi* (2.5 million years ago). Intriguing mixture of
features: several features of teeth resemble early *Homo*; whereas
molars are unusually larger, even larger than the southern African
robust australopithecines.

The evolutionary relationship of A. garhi to other hominids is still a
matter of debate. Its discoverers feel it is descended from A. afarensis
and is a direct ancestor to Homo. Other disagree. Clearly, more evidence
is needed to interpret these specimens more precisely, but they do show
the extent of variation among hominids during this period.

Two distinctly different types of hominid appear between 2 and 3 million
years ago: robust australopithecines (*Paranthropus*) and early *Homo*
(*Homo habilis*).

The first type retains the chimpanzee-sized brains and small bodies of
Australopithecus, but has evolved a notable robusticity in the areas of
the skull involved with chewing: this is the group of robust
australopithecines (*A. boisei*, *A. robustus*, *A. aethiopicus*).

-   The Australopithecines diet seems to have consisted for the most
    part of plant foods, although *A. afarensis*, *A. africanus* and *A.
    garhi* may have consumed limited amounts of animal protein as well;
-   Later Australopithecines (*A. boisei* and robustus) evolved into
    more specialized \"grinding machines\" as their jaws became markedly
    larger, while their brain size did not.

The second new hominid genus that appeared about 2.5 million years ago
is the one to which modern humans belong, *Homo*.

-   A Consideration of brain size relative to body size clearly
    indicates that Homo habilis had undergone enlargement of the brain
    far in excess of values predicted on the basis of body size alone.
    This means that there was a marked advance in information-processing
    capacity over that of Australopithecines;
-   Although *H. habilis* had teeth that are large by modern standard,
    they are smaller in relation to the size of the skull than those of
    Australopithecines. Major brain-size increase and tooth-size
    reduction are important trends in the evolution of the genus Homo,
    but not of Australopithecines;
-   From the standpoint of anatomy alone, it has long been recognized
    that either A. afarensis or *A. africanus* constitute a good
    ancestor for the genus Homo, and it now seems clear that the body of
    *Homo habilis* had changed little from that of either species.
    Precisely which of the two species gave rise to *H. habilis* is
    vigorously debated. Whether *H. habilis* is descended from *A.
    afarensis*, *A. africanus*, both of them, or neither of them, is
    still a matter of debate. It is also possible that none of the known
    australopithecines is our ancestor. The discoveries of
    *Sahelanthropus tchadensis*, *Orrorin tugenensis*, and *A.
    anamensis* are so recent that it is hard to say what effect they
    will have on current theories.

What might have caused the branching that founded the new forms of
robust australopithecines (Paranthropus) and Homo? What caused the
extinction, around the same time (between 2-3 million years ago) of
genus Australopithecus? Finally, what might have caused the extinction
of Paranthropus about 1 million years ago?

No certainty in answering these questions. But the environmental
conditions at the time might hold some clues. Increased environmental
variability, starting about 6 million years ago and continuing through
time and resulting in a series of newly emerging and diverse habitats,
may have initially promoted different adaptations among hominid
populations, as seen in the branching that gave rise to the robust
hominids and to Homo.

And if the degree of the environmental fluctuations continued to
increase, this may have put such pressure on the hominid adaptive
responses that those groups less able to cope eventually became extinct.
Unable to survive well enough to perpetuate themselves in the face of
decreasing resources (e.g., Paranthropus, who were specialized
vegetarians) these now-extinct hominids were possibly out-competed for
space and resources by the better adapted hominids, a phenomenon known
as competitive exclusion.

In this case, only the adaptive response that included an increase in
brain size, with its concomitant increase in ability to understand and
manipulate the environment, proved successful in the long run.

## Hominoid, Hominid, Human

The traditional view has been to recognize three families of hominoid:
the *Hylobatidae* (Asian lesser apes: gibbons and siamangs), the
*Pongidae*, and the *Hominidae*.

-   The Pongidae include the African great apes, including gorillas,
    chimpanzees and the Asian orangutans;
-   The Hominidae include living humans and typically fossil apes that
    possess a suite of characteristics such as bipedalism, reduced
    canine size, and increasing brain size (e.g., australopithecines).

### The emergence of hominoids

Hominoids are Late Miocene (15-5 million years ago) primates that share
a small number of postcranial features with living apes and humans:

-   no tail;
-   pelvis lacks bony expansion;
-   elbow similar to that of modern apes;
-   somewhat larger brains in relationship to body size than similarly
    sized monkeys.

### When is a hominoid also a hominid?

When we say that *Sahelanthropus tchadensis* is the earliest hominid, we
mean that it is the oldest fossil that is classified with humans in the
family *Hominidae*. The rationale for including *Sahelanthropus
tchadensis* in the *Hominidae* is based on similarities in shared
derived characters that distinguish humans from other living primates.

There are three categories of traits that separate hominids from
contemporary apes:

-   bipedalism;
-   much larger brain in relation to body size;
-   dentition and musculature.

To be classified as a hominid, a Late Miocene primate (hominoid) must
display at least some of these characteristics. *Sahelanthropus
tchadensis* is bipedal, and shares many dental features with modern
humans. However, the brain of *Sahelanthropus tchadensis* was no bigger
than that of contemporary chimpanzees. As a consequence, this fossil is
included in the same family (Hominidae) as modern humans, but not in the
same genus.

### Traits defining early *Homo*

Early Homo (e.g., *Homo habilis*) is distinctly different from any of
the earliest hominids, including the australopithecines, and similar to
us in the following ways:

-   brain size is substantially bigger than that of any of the earliest
    hominids, including the australopithecines;
-   teeth are smaller, enamel thinner, and the dental arcade is more
    parabolic than is found in the earliest hominids, including the
    australopithecines;
-   skulls are more rounded; the face is smaller and protrudes less, and
    the jaw muscles are reduced compared with earliest hominids,
    including the australopithecines.


# Introduction to Paleoanthropology/Hominids Early Behavior

in human evolution is about the diet of our earliest ancestors. The
presence of primitive stone tools in the fossil record tells us that 2.5
million years ago, early hominids (*A. garhi*) were using stone
implements to cut the flesh off the bones of large animals that they had
either hunted or whose carcasses they had scavenged.

Earlier than 2.5 million years ago, however, we know very little about
the foods that the early hominids ate, and the role that meat played in
their diet. This is due to lack of direct evidence. Nevertheless,
paleoanthropologists and archaeologists have tried to answer these
questions indirectly using a number of techniques.

-   Primatology (studies on chimpanzee behavior)
-   Anatomical Features (tooth morphology and wear-patterns)
-   Isotopic Studies (analysis of chemical signatures in teeth and
    bones)

## What does chimpanzee food-consuming behavior suggest about early hominid behavior?

### Meat consuming strategy

Earliest ancestors and chimpanzees share a common ancestor (around 5-7
million years ago). Therefore, understanding chimpanzee hunting behavior
and ecology may tell us a great deal about the behavior and ecology of
those earliest hominids.

In the early 1960s, when Jane Goodall began her research on chimpanzees
in Gombe National Park (Tanzania), it was thought that chimpanzees were
herbivores. In fact, when Goodall first reported meat hunting by
chimpanzees, many people were extremely sceptical.

Today, hunting by chimpanzees at Gombe and other locations in Africa has
been well documented.

We now know that each year chimpanzees may kill and eat more than 150
small and medium-sized animals, such as monkeys (red colobus monkey,
their favorite prey), but also wild pigs and small antelopes.

Did early hominids hunt and eat small and medium-sized animals? It is
quite possible that they did. We know that colobus-like monkeys
inhabited the woodlands and riverside gallery forest in which early
hominids lived 3-5 Myrs ago. There were also small animals and the young
of larger animals to catch opportunistically on the ground.

Many researchers now believe that the carcasses of dead animals were an
important source of meat for early hominids once they had stone tools to
use (after 2.5 million years ago) for removing the flesh from the
carcass. Wild chimpanzees show little interest in dead animals as a food
source, so scavenging may have evolved as an important mode of getting
food when hominids began to make and use tools for getting at meat.

Before this time, it seems likely that earlier hominids were hunting
small mammals as chimpanzees do today and that the role that hunting
played in the early hominids\' social lives was probably as complex and
political as it is in the social lives of chimpanzees.

When we ask when meat became an important part of the human diet, we
therefore must look well before the evolutionary split between apes and
humans in our own family tree.

### Nut cracking

Nut cracking behavior is another chimpanzee activity that can partially
reflect early hominin behavior. From Jan. 2006 to May 2006, Susana
Carvalho and her colleagues conducted a series of observation on several
chimpanzee groups in Bossou and Diecké in Guinea, western Africa. Both
direct and indirect observation approach was applied to outdoor
laboratory and wild environment scenarios. [^1]

The results of this research show three resource-exploitation strategies
that chimpanzees apply to utilize lithic material as hammers and anvils
to crack nut: 1) Maximum optimization of time and energy (choose the
closest spot to process nut). 2) Transport of nuts to a different site
or transport of the raw materials for tools to the food. 3) Social
strategy such as the behavior of transport of tools and food to a more
distant spot. This behavior might relate to sharing of space and
resources when various individuals occupy the same area.

The results demonstrate that chimpanzees have similar food exploitation
strategies with early hominins which indicate the potential application
of primate archaeology to the understanding of early hominin behavior.

## What do tooth wear patterns suggest about early hominid behavior?

Bones and teeth in the living person are very plastic and respond to
mechanical stimuli over the course of an individual\'s lifetime. We
know, for example, that food consistency (hard vs. soft) has a strong
impact on the masticatory (chewing) system (muscles and teeth). Bones
and teeth in the living person are therefore tissues that are remarkably
sensitive to the environment.

As such, human remains from archaeological sites offer us a
retrospective biological picture of the past that is rarely available
from other lines of evidence.

Also, new technological advances developed in the past ten years or so
now make it possible to reconstruct and interpret in amazing detail the
physical activities and adaptations of hominids in diverse environmental
settings.

Some types of foods are more difficult to process than others, and
primates tend to specialize in different kinds of diets. Most living
primates show three basic dietary adaptations:

-   insectivores (insect eaters);
-   frugivores (fruit eaters);
-   folivores (leaf eaters).

Many primates, such as humans, show a combination of these patterns and
are called omnivores, which in a few primates includes eating meat.

The ingestion both of leaves and of insects requires that the leaves and
the insect skeletons be broken up and chopped into small pieces. The
molars of folivores and insectivores are characterized by the
development of shearing crests on the molars that function to cut food
into small pieces. Insectivores\' molars are further characterized by
high, pointed cusps that are capable of puncturing the outside skeleton
of insects. Frugivores, on the other hand, have molar teeth with low,
rounded cusps; their molars have few crests and are characterized by
broad, flat basins for crushing the food.

In the 1950s, John Robinson developed what came to be known as the
dietary hypothesis. According to this theory there were fundamentally
two kinds of hominids in the Plio-Pleistocene. One was the \"robust\"
australopithecine (called Paranthropus) that was specialized for
herbivory, and the other was the \"gracile\" australopithecine that was
an omnivore/carnivore. By this theory the former became extinct while
the latter evolved into *Homo*.

Like most generalizations about human evolution, Robinson\'s dietary
hypothesis was controversial, but it stood as a useful model for
decades.

Detailed analyses of the tooth surface under microscope appeared to
confirm that the diet of *A. robustus* consisted primarily of plants,
particularly small and hard objects like seeds, nuts and tubers. The
relative sizes and shapes of the teeth of both *A. afarensis* and *A.
africanus* indicated as well a mostly mixed vegetable diet of fruits and
leaves. By contrast, early *Homo* was more omnivorous.

But as new fossil hominid species were discovered in East Africa and new
analyses were done on the old fossils, the usefulness of the model
diminished.

For instance, there is a new understanding that the two South African
species (*A. africanus* and *A. robustus*) are very similar when
compared to other early hominid species. They share a suite of traits
that are absent in earlier species of Australopithecus, including
expanded cheek teeth and faces remodeled to withstand forces generated
from heavy chewing.

## What do isotopic studies suggest about early hominid behavior?

Omnivory can be suggested by studies of the stable carbon isotopes and
strontium(Sr)-calcium(Ca) ratios in early hominid teeth and bones.

For instance, a recent study of carbon isotope (13C) in the tooth enamel
of a sample of *A. africanus* indicated that members of this species ate
either tropical grasses or the flesh of animals that ate tropical
grasses or both. But because the dentition analyzed by these researchers
lacked the tooth wear patterns indicative of grass-eating, the carbon
may have come from grass-eating animals. This is therefore a possible
evidence that the australopithecines either hunted small animals or
scavenged the carcasses of larger ones.

There is new evidence also that *A. robustus* might not be a herbivore.
Isotopic studies reveal chemical signals associated with animals whose
diet is omnivorous and not specialized herbivory. The results from 13C
analysis indicate that *A. robustus* either ate grass and grass seeds or
ate animals that ate grasses. Since the Sr/Ca ratios suggest that *A.
robustus* did not eat grasses, these data indicate that *A. robustus*
was at least partially carnivorous.

## Summary

Much of the evidence for the earliest hominids (*Sahelanthropus
tchadensis*, *Orrorin tugenensis*, *Ardipithecus ramidus*) is not yet
available.

*Australopithecus anamensis* shows the first indications of thicker
molar enamel in a hominid. This suggests that *A. anamensis* might have
been the first hominid to be able to effectively withstand the
functional demands of hard and perhaps abrasive objects in its diet,
whether or not such items were frequently eaten or were only an
important occasional food source.

Australopithecus afarensis was similar to *A. anamensis* in relative
tooth sizes and probable enamel thickness, yet it did show a large
increase in mandibular robusticity. Hard and perhaps abrasive foods may
have become then even more important components of the diet of *A.
afarensis*.

*Australopithecus africanus* shows yet another increase in postcanine
tooth size, which in itself would suggest an increase in the sizes and
abrasiveness of foods. However, its molar microwear does not show the
degree of pitting one might expect from a classic hard-object feeder.
Thus, even *A. africanus* has evidently not begun to specialize in hard
objects, but rather has emphasized dietary breadth (omnivore), as
evidenced by isotopic studies.

Subsequent \"robust\" australopithecines do show hard-object microwear
and craniodental specializations, suggesting a substantial departude in
feeding adaptive strategies early in the Pleistocene. Yet, recent
chemical and anatomical studies on *A. robustus* suggest that this
species may have consumed some animal protein. In fact, they might have
specialized on tough plant material during the dry season but had a more
diverse diet during the rest of the year.

[^1]:


# Introduction to Paleoanthropology/Oldowan

Africa

## The Olduvai Gorge

2 million years ago, Olduvai Gorge (Tanzania) was a lake. Its shores
were inhabited not only by numerous wild animals but also by groups of
hominids, including Paranthropus boisei and Homo habilis, as well as the
later Homo erectus.

The gorge, therefore, is a great source of Palaeolithic remains as well
as a key site providing evidence of human evolutionary development. This
is one of the main reasons that drew Louis and Mary Leakey back year
after year at Olduvai Gorge.

Certain details of the lives of the creatures who lived at Olduvai have
been reconstructed from the hundreds of thousands of bits of material
that they left behind: various stones and bones. No one of these things,
alone, would mean much, but when all are analyzed and fitted together,
patterns begin to emerge.

Among the finds are assemblages of stone tools dated to between 2.2 Myrs
and 620,000 years ago. These were found little disturbed from when they
were left, together with the bones of now-extinct animals that provided
food.

Mary Leakey found that there were two stoneworking traditions at
Olduvai. One, the Acheulean industry, appears first in Bed II and lasts
until Bed IV. The other, the Oldowan, is older and more primitive, and
occurs throughout Bed I, as well as at other African sites in Ethiopia,
Kenya and Tanzania.

## Subsistence patterns

### Meat-eating

Until about 2.5 million years ago, early hominids lived on foods that
could be picked or gathered: plants, fruits, invertebrate animals such
as ants and termites, and even occasional pieces of meat (perhaps hunted
in the same manner as chimpanzees do today).

After 2.5 million years ago, meat seems to become more important in
early hominids\' diet. Evolving hominids\' new interest in meat is of
major importance in paleoanthropology.

Out on the savanna, it is hard for a primate with a digestive system
like that of humans to satisfy its amino-acid requirements from
available plant resources. Moreover, failure to do so has serious
consequences: growth depression, malnutrition, and ultimately death. The
most readily accessible plant resources would have been the proteins
accessible in leaves and legumes, but these are hard for primates like
us to digest unless they are cooked. In contrast, animal foods (ants,
termites, eggs) not only are easily digestible, but they provide
high-quantity proteins that contain all the essential amino acids. All
things considered, we should not be surprised if our own ancestors
solved their \"protein problem\" in somewhat the same way that chimps on
the savanna do today.

!Excavations at an Olduvai Gorge
site
Increased meat consumption on the part of early hominids did more than
merely ensure an adequate intake of essential amino acids. Animals that
live on plant foods must eat large quantities of vegetation, and
obtaining such foods consumes much of their time. Meat eaters, by
contrast, have no need to eat so much or so often. Consequently,
meat-eating hominids may have had more leisure time available to explore
and manipulate their environment, and to lie around and play. Such
activities probably were a stimulus to hominid brain development.

The importance of meat eating for early hominid brain development is
suggested by the size of their brains:

-   cranial capacity of largely plant-eating Australopithecus ranged
    from 310 to 530 cc;
-   cranial capacity of primitive known meat eater, Homo habilis: 580 to
    752 cc;
-   *Homo erectus* possessed a cranial capacity of 775 to 1,225 cc.

### Hunters or scavengers?

The archaeological evidence indicates that Oldowan hominids ate meat.
They processed the carcasses of large animals, and we assume that they
ate the meat they cut from the bones. Meat-eating animals can acquire
meat in several different ways:

-   stealing kills made by other animals;
-   by opportunistically exploiting the carcasses of animals that die
    naturally;
-   by hunting or capturing prey themselves.

There has been considerable dispute among anthropologists about how
early hominids acquired meat. Some have argued that hunting, division of
labor, use of home bases and food sharing emerged very early in hominid
history. Others think the Oldowan hominids would have been unable to
capture large mammals because they were too small and too poorly armed.

Recent zooarchaeological evidence suggests that early hominids (after
2.5 million years ago) may have acquired meat mainly by scavenging, and
maybe occasionally by hunting.

If hominids obtained most of their meat from scavenging, we would expect
to find cut marks mainly on bones left at kill sites by predators
(lions, hyenas). If hominids obtained most of their meat from their own
kills, we would expect to find cut marks mainly on large bones, like
limb bones. However, at Olduvai Gorge, cut marks appear on both kinds of
bones: those usually left by scavengers and those normally monopolized
by hunters. The evidence from tool marks on bones indicates that humans
sometimes acquired meaty bones before, and sometimes after, other
predators had gnawed on them.

## Settlement patterns

During decades of work at Olduvai Gorge, Mary and Louis Leakey and their
team laid bare numerous ancient hominid sites. Sometimes the sites were
simply spots where the bones of one or more hominid species were
discovered. Often, however, hominid remains were found in association
with concentrations of animal bones, stone tools, and debris.

At one spot, in Bed I, the bones of an elephant lay in close association
with more than 200 stone tools. Apparently, the animal was butchered
here; there are no indications of any other activity.

At another spot (DK-I Site), on an occupation surface 1.8 million years
old, basalt stones were found grouped in small heaps forming a circle.
The interior of the circle was practically empty, while numerous tools
and food debris littered the ground outside, right up to the edge of the
circle.

## Earliest stone industry

### Principles

!Chopper from Olduvai, 1-2 Myrs
old
Use of specially made stone tools appears to have arisen as result of
need for implements to butcher and prepare meat, because hominid teeth
were inadequate for the task. Transformation of lump of stone into a
\"chopper\", \"knife\" or \"scraper\" is a far cry from what a
chimpanzee does when it transforms a stick into a termite probe. The
stone tool is quite unlike the lump of stone. Thus, the toolmaker must
have in mind an abstract idea of the tool to be made, as well as a
specific set of steps that will accomplish the transformation from raw
material to finished product. Furthermore, only certain kinds of stone
have the flaking properties that will allow the transformation to take
place, and the toolmaker must know about these.

Therefore, two main components to remember:

-   Raw material properties
-   Flaking properties

### Evidence

The oldest Lower Palaeolithic tools (2.0-1.5 million years ago) found at
Olduvai Gorge (*Homo habilis*) are in the Oldowan tool tradition.
Nevertheless, older materials (2.6-2.5 million year ago) have recently
been recorded from sites located in Ethiopia (Hadar, Omo, Gona, Bouri -
*Australopithecus garhi*) and Kenya (Lokalalei).

Because of a lack of remarkable differences in the techniques and styles
of artifact manufacture for over 1 million years (2.6-1.5 million years
ago), a technological stasis was suggested for the Oldowan Industry.

The makers of the earliest stone artifacts travelled some distances to
acquire their raw materials, implying greater mobility, long-term
planning and foresight not recognized earlier.

Oldowan stone tools consist of all-purpose generalized chopping tools
and flakes. Although these artifacts are very crude, it is clear that
they have been deliberately modified. The technique of manufacture used
was the percussion.

The main intent of Oldowan tool makers was the production of cores and
flakes with sharp-edges. These simple but effective Oldowan choppers and
flakes made possible the addition of meat to the diet on a regular
basis, because people could now butcher meat, skin any animal, and split
bones for marrow.

Overall, the hominids responsible for making these stone tools
understood the flaking properties of the raw materials available; they
selected appropriate cobbles for making artifacts; and they were as
competent as later hominids in their knapping abilities.

Finally, the manufacture of stone tools must have played a major role in
the evolution of the human brain, first by putting a premium on manual
dexterity and fine manipulation over mere power in the use of the hands.
This in turn put a premium in the use of the hands.

## Early hominid behavior

During the 1970s and 1980s many workers, including Mary Leakey and Glynn
Isaac, used an analogy from modern hunter-gatherer cultures to interpret
early hominid behavior of the Oldowan period (e.g., the Bed I sites at
Olduvai Gorge). They concluded that many of the sites were probably
camps, often called \"home bases\", where group members gathered at the
end of the day to prepare and share food, to socialize, to make tools,
and to sleep.

The circular concentration of stones at the DK-I site was interpreted as
the remains of a shelter or windbreak similar to those still made by
some African foraging cultures. Other concentrations of bones and stones
were thought to be the remains of living sites originally ringed by
thorn hedges for defense against predators. Later, other humanlike
elements were added to the mix, and early Homo was described as showing
a sexual division of labor \[females gathering plant foods and males
hunting for meat\] and some of the Olduvai occupation levels were
interpreted as butchering sites.

Views on the lifestyle of early *Homo* began to change in the late
1980s, as many scholars became convinced that these hominids had been
overly humanized.

Researchers began to show that early *Homo* shared the Olduvai sites
with a variety of large carnivores, thus weakening the idea that these
were the safe, social home bases originally envisioned.

Studies of bone accumulations suggested that *H. habilis* was mainly a
scavenger and not a full-fledged hunter. The bed I sites were
interpreted as no more than \"scavenging stations\" where early *Homo*
brought portions of large animal carcasses for consumption.

Another recent suggestion is that the Olduvai Bed I sites mainly
represent places where rocks were cached for the handy processing of
animal foods obtained nearby. Oldowan toolmakers brought stones from
sources several kilometers away and cached them at a number of locations
within the group\'s territory. Stone tools could have been made at the
cache sites for use elsewhere, but more frequently portions of carcasses
were transported to the toolmaking site for processing.

## Summary

Current interpretations of the subsistence, settlement, and tool-use
patterns of early hominids of the Oldowan period are more conservative
than they have been in the past. Based upon these revised
interpretations, the Oldowan toolmakers have recently been dehumanized.

Although much more advanced than advanced apes, they still were probably
quite different from modern people with regard to their living
arrangements, methods and sexual division of food procurement and the
sharing of food.

The label human has to await the appearance of the next representative
of the hominid family: *Homo erectus*.


# Introduction to Paleoanthropology/Acheulean

proposed the generic name \"*Pithecanthropus*\" for a hypothetical
missing link between apes and humans.

In late 19th century, Dutch anatomist Eugene Dubois was on the
Indonesian island of Java, searching for human fossils. In the fall of
1891, he encountered the now famous Trinil skull cap. The following year
his crew uncovered a femur, a left thigh bone, very similar to that of
modern humans. He was convinced he had discovered an erect, apelike
transitional form between apes and humans. In 1894, he decided to call
his fossil species *Pithecanthropus erectus*. Dubois found no additional
human fossils and he returned to the Netherlands in 1895.

Others explored the same deposits on the island of Java, but new human
remains appeared only between 1931 and 1933.

Dubois\'s claim for a primitive human species was further reinforced by
nearly simultaneous discoveries from near Beijing, China (at the site of
Zhoukoudian). Between 1921 and 1937, various scholars undertook
fieldwork in one collapsed cave (Locality 1) recovered many fragments of
mandibles and skulls. One of them, Davidson Black, a Canadian anatomist,
created a new genus and species for these fossils: *Sinanthropus
pekinensis* (\"Peking Chinese man\").

In 1939, after comparison of the fossils in China and Java, some
scholars concluded that they were extremely similar. They even proposed
that Pithecanthropus and Sinanthropus were only subspecies of a single
species, *Homo erectus*, though they continued to use the original
generic names as labels.

From 1950 to 1964, various influential authorities in paleoanthropology
agreed that Pithecanthropus and Sinanthropus were too similar to be
placed in two different genera; and, by the late 1960s, the concept of
Homo erectus was widely accepted.

To the East Asian inventory of *H. erectus*, many authorities would add
European and especially African specimens that resembled the Asian
fossil forms. In 1976, a team led by Richard Leakey discovered around
Lake Turkana (Kenya) an amazingly well-preserved and complete skeleton
of a *H. erectus* boy, called the Turkana Boy (WT-15000).

In 1980s and 1990s:

-   new discoveries in Asia (Longgupo, Dmanisi, etc.); in Europe
    (Atapuerca, Orce, Ceprano);
-   precision in chronology and evolution of *H. erectus*;
-   understanding and definition of variability of this species and
    relationship with other contemporary species.

## Site distribution

### Africa

Unlike Australopithecines and even *Homo habilis*, *Homo
ergaster/erectus* was distributed throughout Africa:

-   about 1.5 million years ago, shortly after the emergence of *H.
    ergaster*, people more intensively occupied the Eastern Rift Valley;
-   by 1 million years ago, they had extended their range to the far
    northern and southern margins of Africa.

Traditionally, Homo erectus has been credited as being the prehistoric
pioneer, a species that left Africa about 1 million years ago and began
to disperse throughout Eurasia. But several important discoveries in the
1990s have reopened the question of when our ancestors first journeyed
from Africa to other parts of the globe. Recent evidence now indicates
that emigrant erectus made a much earlier departure from Africa.

### Israel

**Ubeidiyeh**

-   Deposits accumulated between 1.4-1.0 million years ago;
-   Stone tools of both an early chopper-core (or Developed Oldowan)
    industry and crude Acheulean-like handaxes. The artifacts closely
    resemble contemporaneous pieces from Upper Bed II at Olduvai Gorge;
-   Rare hominid remains attributed to Homo erectus;
-   Ubeidiya might reflect a slight ecological enlargement of Africa
    more than a true human dispersal.

**Gesher Benot Yaaqov**

-   800,000 years ago;
-   No hominid remains;
-   Stone tools are of Acheulean tradition and strongly resemble East
    African industries.

### Republic of Georgia

In 1991, archaeologists excavating a grain-storage pit in the medieval
town of Dmanisi uncovered the lower jaw of an adult erectus, along with
animal bones and Oldowan stone tools.

Different dating techniques (paleomagnetism, potassium-argon) gave a
date of 1.8 million years ago, that clearly antedate that of Ubeidiya.
Also the evidence from Dmanisi suggests now a true migration from
Africa.

### China

**Longgupo Cave**

-   Dated to 1.8 million years ago
-   Fragments of a lower jaw belonging either to Homo erectus or an
    unspecified early *Homo*.
-   Fossils recovered with Oldowan tools.

**Zhoukoudian**

-   Dated between 500,000 and 250,000 years ago.
-   Remarkable site for providing large numbers of fossils, tools and
    other artifacts.
-   Fossils of *Homo erectus* discovered in 1920s and 1930s.

### Java

In 1994, report of new dates from sites of Modjokerto and Sangiran where
*H. erectus* had been found in 1891.

Geological age for these hominid remains had been estimated at about 1
million years old. Recent redating of these materials gave dates of 1.8
million years ago for the Modjokerto site and 1.6 million years ago for
the Sangiran site.

These dates remained striking due to the absence of any other firm
evidence for early humans in East Asia prior to 1 Myrs ago. Yet the
individuals from Modjokerto and Sangiran would have certainly traveled
through this part of Asia to reach Java.

### Europe

**Did Homo ergaster/erectus only head east into Asia, altogether
bypassing Europe?**

Many paleoanthropologists believed until recently that no early humans
entered Europe until 500,000 years ago. But the discovery of new fossils
from Spain (Atapuerca, Orce) and Italy (Ceprano) secured a more ancient
arrival for early humans in Europe.

At Atapuerca, hundreds of flaked stones and roughly eighty human bone
fragments were collected from sediments that antedate 780,000 years ago,
and an age of about 800,000 years ago is the current best estimate. The
artifacts comprise crudely flaked pebbles and simple flakes. The hominid
fossils - teeth, jaws, skull fragments - come from several individuals
of a new species named Homo antecessor. These craniofacial fragments are
striking for derived features that differentiate them from Homo
ergaster/erectus, but do not ally them specially with either *H.
neanderthalensis* or *H. sapiens*.


# Introduction to Paleoanthropology/Hominids Acheulean

## The hominids

### African *Homo erectus*: *Homo ergaster*

*H. ergaster* existed between 1.8 million and 1.3 million years ago.

Like *H. habilis*, the face shows:

-   protruding jaws with large molars;
-   no chin;
-   thick brow ridges;
-   long low skull, with a brain size varying between 750 and 1225 cc.

!Facial reconstruction of Turkana
Boy{width="300"}
Early *H. ergaster* specimens average about 900 cc, while late ones have
an average of about 1100 cc. The skeleton is more robust than those of
modern humans, implying greater strength.

Body proportions vary:

:   Ex. Turkana Boy is tall and slender, like modern humans from the
    same area, while the few limb bones found of Peking Man indicate a
    shorter, sturdier build.

Study of the Turkana Boy skeleton indicates that H. ergaster may have
been more efficient at walking than modern humans, whose skeletons have
had to adapt to allow for the birth of larger-brained infants.

*Homo habilis* and all the australopithecines are found only in Africa,
but H. erectus/ergaster was wide-ranging, and has been found in Africa,
Asia, and Europe.

### Asian *Homo erectus*

!Replica skull of \"Peking Man\", an Asian *Homo
Erectus*_presented_at_Paleozoological_Museum_of_China.jpg "Replica skull of "Peking Man", an Asian Homo Erectus")
Specimens of *H. erectus* from Eastern Asia differ morphologically from
African specimens:

-   features are more exaggerated;
-   skull is thicker, brow ridges are more pronounced, sides of skull
    slope more steeply, the sagittal crest is more exaggerated;
-   Asian forms do not show the increase in cranial capacity.

As a consequence of these features, they are less like humans than the
African forms of *H. erectus*.

Paleoanthropologists who study extinct populations are forced to decide
whether there was one species or two based on morphological traits
alone. They must ask whether eastern and western forms are as different
from each other as typical species.

If systematics finally agree that eastern and western populations of *H.
erectus* are distinct species, then the eastern Asian form will keep the
name *H. erectus*. The western forms have been given a new name: *Homo
ergaster* (means \"work man\") and was first applied to a very old
specimen from East Turkana in East Africa.

### *Homo georgicus*

Specimens recovered recently exhibit characteristic *H. erectus*
features: sagittal crest, marked constriction of the skull behind the
eyes. But they are also extremely different in several ways, resembling
*H. habilis*:

-   small brain size (600 cc);
-   prominent browridge;
-   projection of the face;
-   rounded contour of the rear of skull;
-   huge canine teeth.

Some researchers propose that these fossils might represent a new
species of Homo: *H. georgicus*.

### *Homo antecessor*

Named in 1997 from fossils (juvenile specimen) found in Atapuerca
(Spain). Dated to at least 780,000 years ago, it makes these fossils the
oldest confirmed European hominids.

Mid-facial area of antecessor seems very modern, but other parts of
skull (e.g., teeth, forehead and browridges) are much more primitive.
Fossils assigned to new species on grounds that they exhibit unknown
combination of traits: they are less derived in the Neanderthal
direction than later mid-Quaternary European specimens assigned to Homo
heidelbergensis.

### *Homo heidelbergensis*

Archaic forms of Homo sapiens first appeared in Europe about 500,000
years ago (until about 200,000 years ago) and are called Homo
heidelbergensis.

Found in various places in Europe, Africa and maybe Asia.

This species covers a diverse group of skulls which have features of
both Homo erectus and modern humans. !Facial reconstruction of *Homo
Heidelbergensis*{width="300"}
Fossil features:

-   brain size is larger than erectus and smaller than most modern
    humans: averaging about 1200 cc;
-   skull is more rounded than in erectus;
-   still large brow ridges and receding foreheads;
-   skeleton and teeth are usually less robust than erectus, but more
    robust than modern humans;
-   mandible is human-like, but massive and chinless; shows expansion of
    molar cavities and very long cheek tooth row, which implies a long,
    forwardly projecting face.

Fossils could represent a population near the common ancestry of
Neanderthals and modern humans.

Footprints of H. heidelbergensis (earliest human footprints) have been
found in Italy in 2003.

## Phylogenic relationships

For almost three decades, paleoanthropologists have often divided the
genus Homo among three successive species:

-   *Homo habilis*, now dated between roughly 2.5 Myrs and 1.7 Myrs ago;
-   *Homo erectus*, now placed between roughly 1.7 Myrs and 500,000
    years ago;
-   *Homo sapiens*, after 500,000 years ago.

In this view, each species was distinguished from its predecessor
primarily by larger brain size and by details of cranio-facial
morphology:

:   Ex. Change in braincase shape from more rounded in *H. habilis* to
    more angular in H. erectus to more rounded again in *H. sapiens*.

!A hypothesised family tree for *Homo*, proposed in
2012
The accumulating evidence of fossils has increasingly undermined a
scenario based on three successive species or evolutionary stages. It
now strongly favors a scheme that more explicitly recognizes the
importance of branching in the evolution of Homo.

This new scheme continues to accept *H. habilis* as the ancestor for all
later Homo. Its descendants at 1.8-1.7 million mears ago may still be
called H. erectus, but H. ergaster is now more widely accepted. By
600,000-500,000 years ago, *H. ergaster* had produced several lines
leading to H. neanderthalensis in Europe and *H. sapiens* in Africa.
About 600,000 years ago, both of these species shared a common ancestor
to which the name H. heidelbergensis could be applied.

## \"Out-of-Africa 1\" model

Homo erectus in Asia would be as old as Homo ergaster in Africa. Do the
new dates from Dmanisi and Java falsify the hypothesis of an African
origin for *Homo erectus*? Not necessarily.

If the species evolved just slightly earlier than the oldest African
fossils (2.0-1.9 million years ago) and then immediately began its
geographic spread, it could have reached Europe and Asia fairly quickly.

But the \"Out-of-Africa 1\" migration is more complex. Conventional
paleoanthropological wisdom holds that the first human to leave Africa
were tall, large-brained hominids (*Homo ergaster/erectus*). New fossils
discovered in Georgia (Dmanisi) are forcing scholars to rethink that
scenario completely. These Georgian hominids are far smaller and more
primitive in both anatomy and technology than expected, leaving experts
wondering not only why early humans first ventured out of Africa, but
also how.

## Summary

*Homo ergaster* was the first hominid species whose anatomy fully
justify the label human:

-   Unlike australopithecines and *Homo habilis*, in which body form and
    proportions retained apelike features suggesting a continued
    reliance on trees for food or refuge, *H. ergaster* achieved
    essentially modern forms and proportions;
-   Members also differed from australopithecines and*H. habilis* in
    their increased, essentially modern stature and in their reduced
    degree of sexual dimorphism.


# Introduction to Paleoanthropology/Acheulean Technology

Acheulean industry, enjoyed impressive longevity as a species and great
geographic spread. We will review several cultural innovations and
behavioral changes that might have contributed to the success of *H.
ergaster/erectus*:

-   stone-knapping advances that resulted in Acheulean bifacial tools;
-   the beginnings of shelter construction;
-   the control and use of fire;
-   increased dependence on hunting.

## The Acheulean industrial complex

(1.7 million - 200,000 years ago)

### Stone tools

By the time *Homo ergaster/erectus* appeared, Oldowan choppers and flake
tools had been in use for 800,000 years. For another 100,000 to 400,000
years, Oldowan tools continued to be the top-of-the-line implements for
early *Homo ergaster/erectus*. Between 1.7 and 1.4 million years ago,
Africa witnessed a significant advance in stone tool technology: the
development of the Acheulean industry. !Acheulean biface discovered in
Haute-Garonne,
France
The Acheulean tool kit included:

-   picks;
-   cleavers;
-   an assortment of Oldowan-type choppers and flakes, suggesting that
    the more primitive implements continued to serve important
    functions;
-   mainly characterized by bifacially flaked tools, called bifaces.

A biface reveals a cutting edge that has been flaked carefully on both
sides to make it straighter and sharper than the primitive Oldowan
chopper. The purpose of the two-sided, or bifacial, method was to change
the shape of the core from essentially round to flattish, for only with
a flat stone can one get a decent cutting edge.

One technological improvement that permitted the more controlled working
required to shape an Acheulean handax was the gradual implementation,
during the Acheulean period, of different kinds of hammers. In earlier
times, the toolmaker knocked flakes from the core with another piece of
stone. The hard shock of rock on rock tended to leave deep, irregular
scars and wavy cutting edges.

But a wood or bone hammer, being softer, gave its user much greater
control over flaking. Such implements left shallower, cleaner scars and
produced sharper and straighter cutting edges.

:

    :   **With the Acheulean Industry, the use of stone (hard hammer)
        was pretty much restricted to the preliminary rough shaping of a
        handax, and all the fine work around the edges was done with
        wood and bone.**

Acheulean handaxes and cleavers are generally interpreted as being
implements for processing animal carcasses. Even though cleavers could
have been used to chop and shape wood, their wear patterns are more
suggestive of use on soft material, such as hides and meat. Acheulean
tools represent an adaptation for habitual and systematic butchery, and
especially the dismembering of large animal carcasses, as *Homo
ergaster/erectus* experienced a strong dietary shift toward more meat
consumption.

Acheulean tools originated in Africa between 1.7 and 1.4 million years
ago. They were then produced continuously throughout *Homo
ergaster/erectus\'* long African residency and beyond, finally
disappearing about 200,000 years ago.

Generally, Acheulean tools from sites clearly older than 400,000 to
500,000 years ago are attributed to Homo ergaster/erectus, even in the
absence of confirming fossils. At several important Late Acheulean
sites, however, the toolmakers\' species identity remains ambiguous
because the sites lack hominid fossils and they date to a period when
*Homo erectus* and archaic *Homo sapiens* (e.g., *Homo heidelbergensis*)
overlapped in time.

### Other raw materials

Stone artifacts dominate the Paleolithic record because of their
durability, but early people surely used other raw materials, including
bone and more perishable substances like wood, reeds, and skin.

A few sites, mainly European, have produced wooden artifacts, which date
usually between roughly 600,000 and 300,000 years ago:

:

    :   Ex. At the site of Schöningen, Germany, several wooden throwing
        spears, over 2 m long. They arguably present the oldest, most
        compelling case for early human hunting.

## Diffusion of Technology

Wide variability in stone tools present with *H. erectus*. In Eastern
Asia, H. erectus specimens are associated not with Acheulean tools, but
instead with Oldowan tools, which were retained until 200,000 to 300,000
years ago.

This pattern was first pointed out by Hallam Movius in 1948. The line
dividing the Old World into Acheulean and non-Acheulean regions became
known as the Movius line. Handax cultures flourished to the west and
south of the line, but in the east, only choppers and flake tools were
found.

Why were there no Acheulean handax cultures in the Eastern provinces of
Asia?

-   history of research;
-   other explanations:
    -   quality of raw materials (fine-grained rocks rare)
    -   different functional requirements (related to environment and
        food procurement)
    -   \"bamboo culture\": bamboo tools used in place of stone
        implements to perform tasks;
-   Early dates in Java and Dmanisi explain situation

:

    :   Acheulean developed in Africa from the preceding Oldowan
        Tradition only after 1.8 Myrs ago, but if people moved into
        eastern Asia at 1.8 million years ago or before, they would have
        arrived without Acheulean tools.

In sum, while the Acheulean tradition, with its handaxes and cleavers,
was an important lithic advance by Homo ergaster over older
technologies, it constituted only one of several adaptive patterns used
by the species. Clever and behaviorally flexible, H. ergaster was
capable of adjusting its material culture to local resources and
functional requirements.

## Subsistence patterns and diet

Early discoveries of Homo ergaster/erectus fossils in association with
stone tools and animal bones lent themselves to the interpretation of
hunting and gathering way of life. Nevertheless this interpretation is
not accepted by all scholars and various models have been offered to
make sense of the evidence.

### First Scenario: Scavenging

Recently, several of the original studies describing *Homo
ergaster/erectus* as a hunter-gatherer have come under intense
criticism. Re-examination of the material at some of the sites convinced
some scholars (L. Binford) that faunal assemblages were primarily the
result of animal activity rather than hunting and gathering.

Animal bones showed cut marks from stone tools that overlay gnaw marks
by carnivores, suggesting that *Homo ergaster/erectus* was not above
scavenging parts of a carnivore kill.

According to these scholars, at most sites, the evidence for scavenging
by hominids is much more convincing than is that for actual hunting.

### Which scenario to choose?

The key point here is not that *Homo ergaster/erectus* were the first
hominid hunters, but that they depended on meat for a much larger
portion of their diet than had any previous hominid species.

Occasional hunting is seen among nonhuman primates and cannot be denied
to australopithecines (see *A.
garhi*).
But apparently for *Homo ergaster/erectus* hunting took an unprecedented
importance, and in doing so it must have played a major role in shaping
both material culture and society.

## Shelter and fire

For years, scientists have searched for evidence that *Homo
ergaster/erectus* had gained additional control over its environment
through the construction of shelters, and the control and use of fire.
The evidence is sparse and difficult to interpret.

### Shelter

Seemingly patterned arrangements or concentrations of large rocks at
sites in Europe and Africa may mark the foundations of huts or
windbreaks, but in each case the responsible agent could equally well be
stream flow, or any other natural process.

Therefore there appears to be no convincing evidence that *Homo
ergaster/erectus* regularly constructed huts, windbreaks, or any other
sort of shelter during the bulk of its long period of existence. Shelter
construction apparently developed late in the species\' life span, if at
all, and therefore cannot be used as an explanation of *H. ergaster\'s*
capacity for geographic expansion.

### Fire

Proving the evidence of fire by *Homo ergaster/erectus* is almost
equally problematic. Some researchers have suggested that the oldest
evidence for fire use comes from some Kenyan sites dated about 1.4 to
1.6 million years ago. Other scholars are not sure. The problem is that
the baked earth found at these sites could have been produced as easily
by natural fires as by fires started - or at least controlled - by *H.
ergaster/erectus*.

Better evidence of fire use comes from sites that date near the end of
*Homo erectus\'* existence as a species. Unfortunately, the identity of
the responsible hominids (either Homo erectus or archaic Homo sapiens)
is unclear.

The evidence at present suggests that fire was not a key to either the
geographic spread or the longevity of these early humans.

## Out-of-Africa 1: Behavioral aspects

Researchers proposed originally that it was not until the advent of
handaxes and other symmetrically shaped, standardized stone tools that
*H. erectus* could penetrate the northern latitudes. Exactly what, if
anything, these implements could accomplish that the simple Oldowan
flakes, choppers and scrapers that preceded them could not is unknown,
although perhaps they conferred a better means of butchering.

But the Dmanisi finds of primitive hominids and Oldowan-like industries
raise once again the question of what prompted our ancestors to leave
their natal land.

Yet, there is one major problem with scenarios involving departure dates
earlier than about 1.7-1.4 million years ago, and that is simply that
they involve geographic spread before the cultural developments
(Acheulean industry, meat eating, fire, shelter) that are supposed to
have made it possible.

A shift toward meat eating might explain how humans managed to survive
outside of Africa, but what prompted them to push into new territories
remains unknown at this time.

Perhaps they were following herds of animal north. Or maybe it was as
simple and familiar as a need to know what lay beyond that hill or river
or tall savanna grass. Also an early migration could explain
technological differences between western and eastern Homo erectus
populations.

The link between butchering tools and moves into northern latitudes is
the skinning and preparation of hides and furs, for reworking 1. into
portable shelters, and 2. into clothing. more skilful skinning meant
that skins would be better preserved, while fire would lead to meat
preservation (smoking) by the simple need to hang cuts of butchered meat
high up out of reach of any scavenging animals within smoke filled caves
or other dwellings. Having smoked meat then allowed deeper incursions
into otherwise hostile terrain, or a long-term food supply available in
harsh winters. With readily available and storable energy resources, and
protective clothing, they could push out into harsh northern latitudes
with comparative ease.

## Summary

Overall, the evidence suggests that *Homo ergaster* was the first
hominid species to resemble historic hunter-gatherers not only in a
fully terrestrial lifestyle, but also in a social organization that
featured economic cooperation between males and females and perhaps
between semi-permanent male-female units.