Human Evolution

Human Evolution Mr. H. Jones

History of Human Evolution  Human evolution is the theory that humans evolved from   

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primates or ape like creatures. The idea began in 1856, when a skull was found in the Neander Valley in Germany that seemed half ape, half man. This fuelled the debate and the search for more skeletons stepped up. In 1859, Charles Darwin published On the Origin of Species which theorised that all living things had a common ancestor. In 1863, Thomas Huxley argued strongly for human evolution from apes but many did not support him including Alfred Russell Wallace. In 1871, Darwin published The Descent of Man, applying the theory of natural selection to human evolution. Since 1856, many hominid skeletons have been found all over the world.

A Common Ancestor  It is believed by many

scientist that Apes and Humans have a common ancestor.  Most scientists believe that this ancient ancestor may have existed between 10 and 7 million years ago.  But there is little fossil evidence to support this.  This common ancestor may have been Orrorin tugenensis which lived 7 million years ago.

Hominid Groups  Today, the family Hominidae (Bipedal Primates) has

grown to include several genus„ including:  Ardipithecus, the most apelike hominids.  Australopithecus, small-brained slender hominids with

mixed fruit/vegetable diet.  Paranthropus, small-brained robust hominids with a

grassland vegetable diet.  Homo, large-brained hominids with an omnivorous diet.

Ardipithecus ramidus  Evolved 4.4 million years ago.  First fossils found in 1992 but a recent, almost complete, 

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fossil (Ardi) was found in Ethiopia. The most primitive hominid ever found, this species has more chimpanzee-like features than any other human ancestor. Ardipithecus ramidus may have walked upright. Ardipithecus stood four feet (1.2 m) tall and weighed a little under eight stone (50 kg). But many of Ardi's features are far more primitive than those seen in modern apes, suggesting chimpanzees and gorillas have evolved considerably after they split from the common ancestor they shared with humans.

Ardi – Artists Impression

Australopithecus afarensis  3.5 to 2.9 million years ago.  This species includes "Lucy," the 3.2 million year old

fossil found by Donald Johanson in 1974.  A. afarensis had a small braincase and relatively large teeth and chewing muscles; similar to those of chimpanzees.  However, their teeth, as well as their leg and pelvis bones, exhibit human-like characteristics.  They ranged in height from 1m to 1.5 m and walked upright.  In 1975, 13 other A. afarensis fossils were discovered in Ethiopa, in an area called site 333.

Australopithecus afarensis – “Lucy”

Homo habilis  2.5 to 1.6 million years ago.  Homo habilis, which actually means "handy man," is

apparently the first species to make and use primitive stone tools.  About 1.5m tall and weighing 45kg, H. habilis had a

brain that was larger than any Australopithecus brain, but smaller than the Homo erectus brain.  First fossil found in 1960 in Tanzania.  Much debate as to whether H. Habilis should be part

of the genus Australopithecus.

Homo habilis

Paranthropus robustus  Also referred to as Australopithecus robustus.  2.1 to 1.2 million years ago.  Believed to be roughly the same size as A.

afarensis  But P. robustus had a larger, heavier, thicker (hence the name robust) skull, as well as a jaw and large teeth that were well adapted to chewing.  They share some cranial characteristics with modern gorillas.  Similar sized brain to that of a modern chimp.  First fossil found in 1938 in Southern Africa.

Paranthropus robustus

Homo erectus  Means “upright walking man”.  1.8 million years to 300,000 years ago  The first example of Homo erectus, known as "Java

Man," was discovered in Indonesia in 1893.  Fossil remains of Homo erectus have since been found throughout Africa and Asia, making it the first wideranging hominid.  Despite the primitive appearance of its skull, the erectus skeleton is very similar to that of modern humans, although more robust (thicker and heavier).  Homo erectus was probably the first hominid to use fire.

Homo erectus

Homo heidelbergensis  1 million to 200,000 years ago  Homo heidelbergensis had a brain that was larger than H.    

erectus but smaller than that of a modern human. The brain was enclosed in a skull that was more rounded than H. erectus. Fossil remains of Homo heildelbergensis have been found in Africa and Europe. H. Heidelbergensis were probably the first European hominids and probably the first in the British Isles. First fossil found in 1921 but many more are being uncovered in La Sima de los Huesos ('The Pit of Bones') in northern Spain.

Homo heidelbergensis

Homo neanderthalensis  230,000 - 30,000 years ago  First fossil found in 1856.  Averaging five and a half feet in height and possessing short

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limbs, Neanderthals were well-adapted to living in a cold climate. Attached to their robust (thick and heavy) bones were powerful muscles. Homo neanderthalensis, had a jutting nose set in a large face with massive brow ridges and no chin. They lived across Europe and the southwest of Asia, from Britain in the West to Iraq in the East. The Neanderthal's brain was larger than the brain of living humans, although its shape was longer from front to back and not as rounded in the front.

Homo neanderthalensis

Homo sapiens  120,000 years to present.

 Also known as Homo sapiens sapiens.  Homo sapiens living about 40,000 years ago (classed Cro-

Magnon) made elaborate tools out of bone, antler, ivory, stone, and wood, and produced fine artwork in the form of carvings and cave paintings.  First "Cro-Magnon" specimens found in 1868.  Around 75,000 years ago, Homo sapiens faced extinction with the eruption of the volcano Toba in Sumatra, which caused a worldwide temperature drop.  Homo sapiens reached the Near East by at least 90,000 years ago, Australia by at least 50,000 years ago, Europe by 40,000 years ago and the Americas by 12,000 years ago

Social Evolution  Social evolution refers to the development of culture 

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amongst modern humans. Culture includes such items as writing, drawing, music, technology, religion and science. The social evolution of Homo sapiens has accelerated over the past few thousand years, particularly with the development of language, both written and spoken. The ability to learn from past generations separates us from most animals and has allowed us to succeed as the dominant species of earth. Social evolution is not linked to natural selection, and many attribute our social and cultural evolution to the soul and our consciousness.

What‟s Next  The human population is still evolving, but evolution is 

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too slow for us to notice. Some suggest our use of technology is slowing down evolution, we do not need to change but can use technology to allow us adapt to our environment. Genetic mutations do occur, but modern medicine is ensuring the worse genetic disorders are treatable. However, more defective genes are being passed onto the next generation. In the future, if we master the genetic code, we may be able to control our own evolutionary path, by selecting the traits we want for the next generation?