The Early Man: Origin, Evolution and Adaptation

Origins of Human Beings

A number of theories have been put forward to explain the origin of human beings

• The creation theory.
• The mythical/ traditional theory
• The evolution theory

The Creation theory

The Jews, Christians and Muslims recognize the creation story as narrated in the first book of Bible and in Qur’an.
It says that the whole universe was created by God.
That God also created man, woman and all living things and all non-living creatures.
Man was created in God’s own image and woman created to provide man with companionship.

The Mythical Theory

Among African communities, there are myths about their origin all of them pointing to the fact that the first man was created by God.
Some examples include;

1. Among the Agikuyu, their God (Ngai) created the first man, Gikuyu. He the provided him with a wife, Mumbi. He gave him land at Mugurwe wa Gathanga.
2. One of the myths among the Nandi state that the first two people, male and female came from the knees of a giant man, when the knees began swelling and later burs for the two to come out from each of the either knees.

The Evolution Theory

Charles Darwin, an English man living between 1809 and 1882 questioned the acceptance of the creation theory.
In 1859; he published his ideas in a book titled The Origin of Species by Means of Natural Selection
Clearly the theory of evolution was not accepted but it helped to make people aware of the new ideas concerning the origin of man.

What is Evolution?

Evolution can be defined as the process of change in living organisms over a number of years, frequently involving the beginning of new species from earlier species.
According to Charles Darwin, man transformed from simple life slowly over millions of years through environmental mutation, natural selection, isolation and adaptation.

Mutation was a stage of abrupt change.
Natural selection is an instinct by which the stronger species out compete the weaker for resources.
Adaptation is where the surviving species isolate themselves from others as they adapt to new environment through body changes and technological changes e.g. ability to grow crops and make shelter.

Points on Darwin’s Theory of Natural Selection

• All organisms or creatures are uniquely different and this uniqueness is based on heredity factors which an organism has from birth.
• Although many young organisms are produced, few manage to develop to maturity.
• The organisms that manage to grow to maturity and reproduce are those that are able to constantly adapt to the existing environment
• Isolation and adaptation is the final stage in the evolution process
• The theory of evolution holds that Humans belong to the animal kingdom and that man has evolved over the years
• Man is a primate just as apes like gorillas, chimpanzees and monkeys. However, man belongs to the family of hominidae, while apes belong to the family of pongidae

Evolution and Adaptation of Man

The earliest Mammals lived on trees because; there was more supply of food o trees such as insects, leaves and birds’ eggs; and they were more secure from their enemies while up on trees
Archaeological evidence points at East Africa as the cradle of mankind for the following reasons

• Evidence from archaeologists’ show that the earliest apes first evolved around lake and rift valley areas. And if man evolved from apes, then the first man must have appeared in east Africa.
• The savanna landscapes found in east Africa favored evolution while the conditions elsewhere (forests and deserts) Were unfavourable.
• The bones and weapons and tools which archaeologists are finding are proofs to this. These findings are widespread in Olduvai Gorge, Olorgesaillie, and Ngorongoro and around lakes of east Africa.
• The discovery of remains of early hominids and their material culture which form a pattern of human evolution prove this. E.g. we can trace the evolutionary process from Dryopithecus to Ramapithecus to Australopithecus to Homo habilis to Homo erectus to Homo sapiens.

Archaeological Sites in East Africa
Kenya; Rusinga Island, Fort Ternan near Kericho, Kariandusi near Elementaita, Gambles cave, Olorgesaillie, Kobi For a near Lake Turkana, Hyrax Hill and Njoro River cave.
Tanzania; Olduvai Gorge, Eyasi Simila, Apis Rock and Garusi
Uganda; Nsongezi, Napak, Magosi, Paraa, Ishanga, Mweya and Nyabusora
Ethiopia; Omo River Valley and Hadar.

Changes that Occured

1. The tail which no longer had any value in the savanna disappeared.
2. Man became more upright as there were no more impeding vegetation as was the case of too much foliage and intertwining vegetation in the forests and also to reduce surface area onto which solar isolation had effect. These also enabled quicker movement.
3. The leg and foot formation changed to enable the weight of the body to be supported and balance to be achieved while moving or at a standstill.
4. Gradual use of front limbs (hands for holding objects) enabled man to make tools which made work easier. The limbs also found another role of protection from other predators.

There were changes which Homo sapiens underwent as a break-off from apes to modern man as follows;

1. The skull size of the early human beings became larger indicating bigger brains. For example, Australopithecus, who lived between 5 and 1 million years ago, had a brain capacity of 530cm³. Homo erectus who lived later on had an improved brain capacity of between 775cm³ and 1225cm³.
2. Their jaws and teeth became more powerful compared to earlier forms indicating their use in tearing and cutting tough fibres and even the need for defence as a weapon. The size of the jaws and teeth became smaller.
3. They developed a refined speech as compared to earlier forms.
4. They were taller with less hair on their body.
5. The forearms and hands underwent some changes. They developed a thumb for grasping objects. Their arms and hands became shorter, more appropriate for an upright posture.
6. Their leg and foot formation also changed. Their feet and toes were smaller than earlier hominids in order to support the weight of the rest of the body while motionless or mobile. The toes were no longer in need for holding onto branches.