Origin and Evolution of Man

The journey of human evolution, Homo sapiens, has been a topic of great biological interest. The idea that man is a creation of a super­natural power prevailed for a long time. However, biologists view the process of human evolution using knowledge on morphology, physiology, embryology, and fossil records. 

Man is placed under the family Hominidae of the order Primate. They differ from other anthropoid apes by having: a larger-sized brain with a greater functional ability (Maximum in Gorilla = 650 c.c., Minimum in Man = 1000 c.c.) The braincase is larger than the face region.

The face is flatter with a less protruding lower jaw. There is a continuous growth of long hair on the head which is spare and short on the body. Generalized hands with well-developed thumbs and long legs with a non-opposable big toe. Man is terrestrial by nature and walks erect on two feet. They surpass all animals by possessing the exclusive ‘human features’.

History of Man

Our evolutionary history is written into our genome. The human genome looks the way it does due to all genetic changes that affected our ancestors. The exact origin of modern humans has always been a topic of debate.

Modern humans (Homo sapiens), are Latin for ‘wise man’. The human species is the only surviving species of the genus Homo but where we came from has been a topic of much debate. We originated in the African continent in the past 200,000 years and evolved from their most likely recent common ancestor, Homo erectus, meaning ‘upright man’ in Latin. It is an extinct species of the human race that lived between 1.9 million and 135,000 years ago.

Two key models have been put forward to explain the evolution of human beings, mainly the Homo sapiens, namely the ‘out of Africa’ model and the ‘multi-regional’ model. The ‘out of Africa’ model at present is the most accepted model. It proposes that Homo sapiens evolved in Africa before they migrated across the world.

The ‘multi-regional’ model proposes that the evolution of Homo sapiens took place in several places over a long time. The mixing of the various populations eventually led to the single Homo sapiens species we see today.

Earliest Ancestor

Ardipithecus was one of the earliest ancestors who have been discovered with the fossils and are known as Ardipo way back more than around 4.4 million years old. The details regarding the evolution of human beings are still debated as the evidence of fossils of many ancestors is quite vague. In fact, instead of the human evolution tree, a more accurate analogy can be drawn to an evolutionary bush.

Charles Darwin has never implied the fact that humans have evolved from the apes, although many of his fellow mates have insisted that he had. Moreover, the concept of a missing link between the apes and humans was being considered preposterous by many scientists. This is because we have evolved alongside the great apes. However, we already have a common ancestor who has lived roughly around 7 million years ago. Moreover, the points of evolution in the presence of nodal fossils have a meaning that humans are being evolved gradually as opposed to a sudden change.

Evolution of Man

The earliest anthropoids, Parapithecus, Propliopithecus, etc., represented by the remains of jaws were first discovered in the Oligocene bed of Egypt.

The fossils of anthropoids of the Miocene period show considerable diversity with some possessing pre-human features. They may have evolved into the human line and others leading towards the great apes. Dryopithecus, an anthropoid fossil, is regarded to stand close to the point of divergence.

The process of evolution involves a series of changes that can cause those species to either adapt to the current environment or become extinct. Evolution is considered the result of changes that are being made in the genetic material of humans. It does not contribute to changing a single organism but contributes towards the changing of the entire group of organisms belonging to the same species.

Man has been originated through several stages and these stages are explained below - 

• Dryopethicus - Dryopithecus is considered to be the earliest known ancestor of man. They were found in some parts of Africa, Asia, and Europe. It has been known that the evolution of man began from him. Dryopethicus was being followed by Australopithecus.

• Australopithecus - Australopithecus could walk upright and they were 1.2 meters tall. They have inhabited the mainland of Africa. They used to have human-like teeth and had large jaws. 

• Homo habilis - Homo habilis used to have a height of around 5 feet and they could even make use of tools. It has been believed that they were able to speak. 

• Homo erectus - It has been considered that Homo erectus was more evolved than beings. They used to have larger brains and they were also upright. They were the ones who invented the fire and were carnivorous. They also had a prominent speech. 

• Homo sapiens - Homo sapiens are known as modern men. Home sapiens had developed the power of thinking and using the tools. They were omnivorous and were able to produce art. Their brain size was reduced to 1300 cc.

The Evolution of Humankind

Discoveries of remains of earliest ancestors and races give an idea of the process of human evolution. The major forms, as recorded until date, are as follows:

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

They bear the following characteristics:

1. The skulls are smaller in size than that of modern man.

2. The volume of the brain ranged between 600-700 c.c.

3. The forehead was higher than in apes and the face was protruding.

4. The brow ridges were prominent.

5. The occipital condyles were ventrally placed and the rear part of the skull was rounded.

6. The jaws were observed to be large with small incisors.4

7. It also had large and spatulate canines and large cheek teeth.

Pithecanthropus Erectus- Java Man

Fragment remains of Pithecanthropus erectus were discovered in the Mid-Pleistocene of Solo River near Trimil, Java from 1891 until 1945.

The features are:

1. A flattish-topped skull and projected behind.

2. The brow ridges were solid above the orbits.

3. The brain volume was between 775-900 c.c.

4. The imprint of the brain indicated the ability of speech.

5. The jaws were protruding with teeth arranged in an even curve.

Pithecanthropus (Sinanthropus) Pekinensis - Peking Man

The remains of skulls and parts of the skeletal structure 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:

1. The skull was small and the brain volume was 850-1300 c.c.

2. The skull was low-vaulted.

3. The brow ridges were stout.

4. The imprint of the brain suggested the ability of speech.

Signs of implements of quartz and other rocks have been discovered. The hearths showed the use of fire.

Homo Habilis-Transitional Man

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

Homo Heidelbergensis-Heidelberg Man

One lower jaw of Homo heidelbergensis was discovered in 1907 in a sandpit at Mauer near Heidelberg (Germany). The remains were of the Mid-Pleistocene period. The jaw was massive with very broad ascending ramus which indicates that they had powerful jaw muscles. There was no chin. They also had stout teeth and the canines were not enlarged. Associated tools were not found.

Homo Neanderthalensis - Neanderthal Man

The remains of the Neanderthal man from the late Pleistocene bed (before or during the first Ice Age) were first discovered in Spain and North Africa to Ethiopia, Mesopotamia., Gibraltar, Neanderthal Valley near Dusseldorf (Germany), Southern Russia from 1848-1861.

The features of the Neanderthal man are:

• Massive long and flat-topped skull.

• The forehead was receding with heavy brow ridges.

• The nose was broad.

• The orbits were large.

• The average brain volume was 1450 c.c.

• The jaws were protruding but the chin was receding and they had large teeth

• The attachment sites of the occipital region of the skull and the cervical vertebrae indicate the existence of powerful neck muscles.

The females were shorter than the males. The Neanderthal man lived in caves and rock shelters made with stone tools and weapons. There was also evidence of the use of fire. The period is estimated around 100,000 years ago.

On the earth, homo sapiens are the most important species on our earth which is the result of over 7 million years of evolution. The traces of the evolution of humans have been obtained through the records of fossils and through the studies of physiological, morphological, and embryological. 

Human beings belong to the family which is known as the Hominidae of the order Primates. Apes like humans also belong to the same order that is Primates. With the passing of time, the ancestors of this order evolved and they started becoming more and more different.

It is believed that the first-ever ancestors of humans originated in Africa and eventually migrated towards Asia, Europe, and the rest of the world.