Explaining human evolution

By: ERIN O'NEILL


posted on: September 10th, 2018

Evolution is the theory that modern species have developed over time from earlier ‘ancestor’ species. This explains why modern species look and act differently to species that came before them. Reasons for this development are usually to do with developing adaptations. This means when one organism (a life form) has characteristics or abilities that make them better at finding food or avoiding predators than others. These can be internal (inside the body such as better resistance to diseases) or external (outside the body such as colour or size). Evolution theory includes humans. Countless skeletons and remains have been found all over the world which suggests that we have descended from earlier species.

THE THEORY OF HUMAN EVOLUTION

There is overwhelming evidence for the theory that modern humans descended from earlier hominin (early human) species, which in turn descended from a common ancestor that we shared with the chimpanzee. This evidence comes in the form of early skeletons scientists have found, and our genetic similarities to chimpanzees. Genes are the building blocks of the body and contain the information that determines everything from the size of our brain to our eye colour.

The scientific name for us as modern humans is Homo Sapien and we are the only surviving species of early human. The term ‘Homo’ refers to a genus (category of similar species) that included other types of early human such as Homo erectus, which is extinct and older than Homo Sapiens.

These early humans of the Homo genus first developed from another genus called Australopithecus. This genus in turn was related to the lineage of pan, from which chimpanzees are also descended. It is very important to remember that modern humans are not chimpanzees or directly descended from chimpanzees. Our species is descended from a common ancestor. This means an old species evolved into early humans, and separately evolved into an ancestor of the modern chimp.

Humans evolved to have very different behaviours and looks. These include increased brain size and an adapted grip. One of the most important differences is humans’ bipedalism (an ability to walk upright on two legs).

EARLY AFRICAN HUMANS

The early humans of the Homo genus first appeared in Africa. That means that the first modern humans, Homo Sapiens, came from Africa.

Homo Sapiens first emerged about 200,000 years ago. We know this because of bones found near the Omo River in Ethiopia. 60,000 years ago Homo Sapiens began to migrate throughout the world.

500,000 years ago, there were a few different species of early human in the genus Homo. Another name for these other types are archaic humans. The archaic humans included the Homo neanderthalensis and were different to Homo Sapiens, but had a close common ancestor. Homo Sapiens proved themselves to be better adapted and outlived other the archaic humans, which went extinct perhaps as recently as 10,000 years ago.

One of the ways early human species adapted was through using tools. The earliest tools include using rocks to crack open food, which developed to using hammers and anvils. The oldest tools were found in Kenya and are 3.3 million years old. As the tools are older than the earliest humans of the Homo genus, it suggests that they were used by an ancestor of early humans that was similar to an ape.

WHO IS ‘LUCY’?

Lucy, also known as Dinkinesh, is a nickname for bone fossils from a female skeleton found in Ethiopia. Lucy was a Australopithecus afarensis from 3.2 million years ago. This means that her genus was the Homo genus’ ancestor.

Lucy represents an example of human evolution from a common ancestor to chimpanzees. This is because she has a small skull and rib-cage similar to apes. At the same time she had a valgus knee, which means that she was bipedal and walked upright like early humans. The length ratio from her arm to thigh was 84.6%, which compares to 71.8% for modern humans, and 97.8% for common chimpanzees. This represents the evolving human body from extinct great apes.

BELIEF IN EVOLUTION

The theory of evolution is not contradictory to the existence of God. The evidence for evolution in all species is very concrete. Many people believe in this evidence alongside being very religious. This is because evolution explains how humans have evolved. It does not explain how the first life or the universe was created, or by who.

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