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What is evolution and where is the supporting evidence for it?
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The theory of evolution states that individuals within a species show a wide degree of variation,
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and those individuals with characteristics best suited to their environment are more likely to survive and reproduce.
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This theory grew from studying the variations and similarities in living animals and plants,
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but also very importantly by studying fossils.
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The study of the number and placement of fossils within certain types in areas of rock is known as the fossil record.
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This record gives us an indication of the types of animals and plants that existed in the past.
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For many millions of years ago, right up until around 10,000 years ago, fossils of single celled organisms, such a sign of bacteria from Australia,
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have been found in rocks that are more than 3.5 billion years old.
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Paleontologists are people who study fossils.
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By comparing fossilized body structure and fossilized tracks of movement, they painstakingly pieced together the story of how animals and plants have changed and evolved over time.
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Importantly, by comparing fossils from different species, paleontologists can look for similarities in structure to try and work out which species are related to which others
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This work has enabled scientists to visualize how some species have evolved from others.
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The discovery of transitional fossils has greatly assisted paleontologist understanding of how their evolutionary process occurred.
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For example, in 1988 scientists found a 370 million year old fossilized fish with a hand like fin,
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suggesting a transition from sea dwelling creature to land.
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Look at this picture of fish fingers.
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Meanwhile, the discovery of transitional reptile fossils, with mammal like jawbones,
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has enabled paleontologists to date the emergence of early mammals to about 245 million years ago.
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Mammals did therefore live alongside the dinosaurs.
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The fossil record has enabled scientists to track the path of human evolution from great apes,
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and has even allowed us to identify where humans and chimpanzees went their separate ways.
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Our last common ancestor lived about 5 to 7 million years ago.
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Since that time, over 20 hominid species have been discovered.
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Tracing the lineage of plant and animal species using fossil record is not an exact science.
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The lack of transitional fossils makes this all the harder, leading to significant gaps in the fossil record.
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Because the formation of fossils is a rare event, many transitional species have just not formed fossils.
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However, as new fossils are being discovered all the time, we can expect at least some of these gaps to eventually be filled.
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In this video, you have learned what the fossil record is and how it has contributed to our understanding of evolution.
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You have also learned about problems with the fossil record.
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Can you find any other examples online or in books of transitional fossils?