The Origin and Evolution of Man

In this article we will discuss about:- 1. Introduction to Origin of Man 2. Features of Man 3. History 4. Miscellaneous Remains 5. Biological Trends 6. General Consideration.

Contents:

Introduction to Origin of Man
Features of Man
History of Mankind
Miscellaneous Remains of Man
Biological Trends in Human Evolution
General Consideration on Human Ancestry

1. Introduction to Origin of Man:

The origin and evolution of man, Homo sapiens, have been a topic of great biological interest since time immemorial. The idea that man is a creation of a supernatural power prevailed for long time in earlier days.

But the Biologists view the origin of man using knowledge on morphology, physiology, embryology and fossil records. Man evolved from some unknown mammalian ancestor and reached the pinnacle of evolutionary fabric.

Man is placed under the family Hominidae of the order Primate and differs from other anthropoid apes by having: Large size of brain with greater functional ability (Maximum in Gorilla = 650 c.c., Minimum in Man = 1000 c.c.) The brain case is larger than face region.

The face is flatter with less protruding lower jaw. Continuous growth of long hair on head which are spare and short on body. Generalized hands with better developed thumbs and long leg with non-opposable big toe. Man is terrestrial in habit and walks erect on two feet. They surpass all other animals by possessing the ‘human features’ which are exclusive for them.

2. Features of Man:

In contrast to that of the anthropoids, the human line showed a large number of progressive features.

The features are:

(a) The face becomes flattened and is devoid of a nuzzle (Fig. 1.27).

(b) The brow ridges gradually decline and disappear.

(d) The skull is rounded at the rear.

(e) The foramen magnum and occipital condyles are shifted ventrally to join with the upright vertebral column.

(f) A mastoid process arises in the ear region.

(g) The teeth become smaller in size and are arranged in a U-shaped arc. The canines are moderate in size.

(h) The arms with the fingers are proportionately shorter. The feet are nongrasping. The toes are placed in line. The heal bone is elongated to help insertion of muscles in upright posture and walking.

(i) The vertebral column shows slight curvature.

(j) The ilia are wider than length. Broader ilia help insertion of the big gluteal muscles which is involved in balance.

The great apes can make sounds which indicate some desires and emotions but fail to describe-objects. But man can develop sounds into words symbolising things or ideas. The ape-prehuman transition is associated with the descent from trees to the ground which is of great significance in human evolution. This transition freed the hands for making and use of tools to supplement the action of the hands.

3. History of Mankind:

Before the practice of burial of the dead, remains of early man were limited to member of skulls (often partial) and some other bony remains. Remains of complete skeleton became more numerous when the practice of burial of the dead was followed.

The work of prehistoric man gave ample materials to draw an inference regarding the activities and manner of life. Limitations in material of early man make the direct line of descent more confusing.

The time and place when modern man first originated are controversial. The earliest anthropoids, Parapithecus, Propliopithecus, etc., (represented by the remains of jaws) were discovered from the Oligocene bed of Egypt.

During Miocene period the fossils of anthropoids showed considerable diversity, some possessing prehuman features may have evolved into human line and others leading toward the great apes. An anthropoid fossil, Dryopithecus is regarded to stand close to the point of divergence.

Primitive Hominids:

Discoveries of remains of prehistoric species and races will give an idea of human evolution. The major forms, as recorded uptil date, are as follows (Fig. 1.28).

Australopithecus, Zinjanthropus, etc., represent the primitive Hominids:

The remains of these hominids (Australopithecus, Zinjanthropus, etc.) were discovered in Mid-Pleistocene or earlier in Transvaal, South Africa in 1925 and in Olduvai Gorge Tanganyika in 1959. Many skulls and some skeletal parts have been discovered.

The characteristics are:

(a) The skull was smaller in size than that of modern man.

(b) The volume of brain ranged from 600-700 c.c.

(d) The brow ridges were prominent.

(e) The occipital condyles were ventrally placed and the rear part of the skull was rounded.

(f) The jaws were large with small incisors, large and spatu- late canines, large cheek teeth.

(g) The ilia of pelvis were wider and the limb bones were slender.

(h) The total height was about 5 feet. They used simple chipped pebble tools.

Pithecanthropus erectus—Java man:

Fragmentary remains of Pithecanthropus erectus were discovered in Mid-Pleistocene of Solo River near Trimil, Java since 1891 up to 1945.

The characteristic features are:

(a) The skull was flattish-topped and projected behind.

(b) The brow ridges were solid above the orbits.

(d) The jaws were protruding.

(e) The teeth were arranged in even curve but the canines were projecting.

(f) The femur reflected its upright posture.

(g) The height was about 5 feet. No associated tools were found.

Pithecanthropus (Sinanthropus) pekinensis —Peking man:

The remains of skulls and parts, jaws with teeth and some limb bones of Pithecanthropus (Sinanthropus) pekinensis were discovered up to 1943 from the Mid-Pleistocene caves at Choukoutien (South-west of Peking), China.

The noted features are:

(a) The skull was small and the brain volume was 850-1300 c.c.

(b) The skull was low-vaulted.

(d) The imprint of brain suggested the ability of speech.

Various implements of quartz and other rocks were discovered. The hearths showed the use of fire.

Homo habilis—Transitional man:

The remains of this species were discovered in Pleistocene bed in East Africa. They were the makers of crudely chipped stone tools. They represent an intermediate stage between the Australopithecus and Pithecanthropus erectus. The mean capacity of brain was 680 c.c.

Homo heidelbergensis—Heidelberg man:

One lower jaw of Homo heidelbergensis was discovered in 1907 in sand pit at Mauer near Heidelberg (Germany). The remains were of Mid-Pleistocene period. The jaw was massive with very broad ascending ramus indicating powerful jaw muscles. There was no chin. The teeth were stout and the canines were not enlarged. Associated tools were not found.

Homo neanderthalensis—Neanderthal man:

The remains of Homo neanderthalensis totalling well over one hundred individuals were discovered from the late Pleistocene bed (before or during first Ice Age) in Spain and North Africa to Ethiopia, Mesopotamia. Southern Russia, Gilbraltar, Neanderthal Valley near Dusseldorf (Germany) from 1848-1861.

The Neanderthal man had:

(a) massive long and flat-topped skull.

(b) The forehead was receding.

(d) The nose was broad.

(e) The orbits were large.

(f) The average brain volume was 1450 c.c.

(g) The jaws were protruding but the chin was receding.

(h) The teeth were large.

(i) The attachment sites of occipital region of skull and the cervical vertebrae indicated the existence of powerful neck muscles.

(j) The limb bones were heavy and slightly curved.

(k) The height of males was about 5 feet 3-5 inches.

The females were shorter than males. The Neanderthal man used to live in caves and rock shelters with stone stools and weapons. There was evidence of use of fire. The estimated age was about 100,000 years.

Homo sapiens – Cro- Magnon man:

The remains of Cro-Magnon man of estimated age about 30,000-13,000 b.c. were found in late Pleistocene (close of last Ice Age and later) bed of France to Czechoslovakia, East Africa and Eastern Asia.

The distinguishing features are:

(a) The skull was long and high with no brow ridges.

(b) The face resembled the modern man.

(d) The chin was well developed.

(e) The average brain volume was about 1590 c.c.

(f) The height of males was about 5 feet 10 inches.

They were cave-dweller. They had stone implements and they could make wall paintings and sculpture.

4. Miscellaneous Remains of Man:

(A) Ternifiine man:

Three jaws and skull fragment of Ternifine man were found in Ternifine and Casablanca, North Africa in 1952. These Mid-Pleistocene remains resembled Heidelberg and Peking materials.

(B) Mount Carmel man:

Remains of 13 individuals including complete skeleton were discovered in Mount Carmel, Palestine (Israel). These upper Pleistocene remains showed characteristics of both Neanderthal and modern man, but slightly taller.

(C) Swanscombe man:

The remains (occipital and parietal bones) were found in Swanscombe, Kent, England in 1936- 1937. They were of Mid-Pleistocene age. The bones were thick and the brain volume was estimated to be about 1300 c.c.

(D) Solo man (Homo soloensis):

The remains of eleven partial skulls and two femurs of Pleistocene age were discovered from Solo River near Ngandong, Java in 1933. They had low forehead and heavy brow ridges. They exhibited many features which were more modern.

(E) Rhodesian man (Homo rhodesiensis):

The remains of Rhodesian man of late Pleistocene age were found in 1921 at Broken Hill, Rhodesia (South Africa). A similar skull was also discovered in 1953 in Capetown. The remains consisted of one skull, upper jaw, parts of limb bones, pelvis, sacrum, etc. The brain volume was about 1300 c.c. The characteristics of face, brow ridges, orbits, palate and limb bones were much like those of modern man.

(F) Other remains:

The other fragmentary remains of man include that of:

(i) skull fragments of Pithecanthropus robustus from Java (1938);

(ii) portions of a huge jaw of Meganthropus palaeojavanicus from Java (1941) and

(iii) three huge molars (five to six times the bulk of those of the present day’s man) of Gigantopilhecus blacki in 1935-1939.

These molars were possibly collected from caves in South China.

5. Biological Trends in Human Evolution:

The evolution of man involves the following significant changes:

(a) Switch over from the four gait apes to the bipedal gait of man.

(b) Perfection of hand for tool making.

(d) Change of diet from fruits, hard nuts, hard roots to softer foods.

(e) Increase in their ability to communicate with others and development of community behaviour.

6. General Consideration on Human Ancestry:

Since the discovery of the ‘missing link’ between apes and men in 1894 by a Dutch anatomist, E. Dubois, a large number of fossils of man have been brought to the limelight. All the newer finds as well as the older ones are being interpreted by different authorities in different ways. The scientists of the past described the fossils in terms of ‘individual types’ rather than ‘populations’.

They gave a scientific name of their new find and placed it in a separate species and in a separate genus, whenever applicable. But the modern Anthropologists and Zoologists are trying hard to discard nearly all the names of ‘genera’ which were coined in the past.

They recognise that the ancestors of man have progressed mainly along a single evolutionary line and at times this line became branched -to give two or three related species (Fig. 1.29). During the past 600,000 years it consisted of a single species having a common gene pool with a number of races.

The remains of ‘Southern apes’ (Australopithecus) have been claimed to be forerunners of man. These creatures were more like apes than man in respect of their intelligence and way of life. They could walk erect and the architecture of limb and body skeleton was much like those of modern man.

An intermediate fossil form, Homo habilis, an intermediate form between Australopithecus and the ancient species of man (Java and Peking man), was discovered from the same bed containing East African Australopithecus.

This fact gave evidence that the Australopithecus was the direct ancestor of man and they persisted side by side with their derivatives—the earliest men. The transition from apes to man was a gradual process and the series of fossils portrays a gradual but complete transition from apes to modern man.

Comparative studies on morphology and chemistry of protein have proved that Homo sapiens, gorilla and chimpanzee arc closely related to each other than other anthropoid apes like orangutan and gibbon.

Homo sapient, gorilla and chimpanzee have possibly, evolved from a group of apes common in Eurasia and Africa during Miocene. The immediate ancestor of Homo, as stated earlier, was the Australopithecus which lived between Pliocene to Pleistocene in North Africa and Eurasia.

The earliest man, Pithecanthropus erectus, was widespread in Eurasia during Pleistocene possibly evolved into modern man by series of gradual stages without splitting into separate species (Fig. 1.30). The main characteristics which differentiate man from apes evolved at different rates.

The use of tools appears to have evolved first which preceded the increase of size of brain. Both these were accompanied by the change from four- footed gait to bipedal erect posture.