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by alisoneberle
Last updated 6 years ago

Social Studies

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The Fossil Record:The fossil record is proof of evolution, as each layer of rock shows a period of time. The fossils contained within each rock layer can be dated to see exactly when they are from. The similarities in these fossils can be studied and it shows the way that creatures evolve over time.

Anitomical Similarities:Homologous structures show the way in which species that seem related could have come from a common ancestor. For example, whales and humans may not seem related, if you look at human arm bones compared to whale flippers, it is clear they have a common ancestor due to the similar structure. Vestigial structures show a common ancestor as well. For example, the fact that whales still have pelvic bones shows that they once had legs that allowed them to walk on land, until they evolved to live in the water.

Ebryology:As embryos, many organisms start off looking almost identical. For example, humans and fish both begin with slits for gills and tails. On human, the gill slits develop into ears and the tails go away, but it shows the way in which seemingly unrelated species all started in the same place but developed differently.

Geography:Sometimes on different continents, extremely similar species are found, as well as identical fossils. This shows us that these animals lived together in the same area at one point. As well, it shows that the continents were once a single land mass long ago (Pangea) that seperated, seperating the species.

Natural and Artificial Selection:Through natural selection, only the animals most suited to their environment will survive long enough to reproduce. This causes species to evolve over time to have the traits required to live as the unsuited ones die off. Through the process of artificial selection, scientists can force the breeding of animals to create ones with the traits desired by the scientists. An example of artificial selection is seen in the breeding of dogs. All breeds came from the common ancestor of a wolf, but were bred to each have different characteristics.

Phylongeny:Through the studying of the genes and chromosomes of creatures and how they are related, scientists can develop a phylogenic tree. This tree shows step by step how certain organisms evolved and which other organisms they are most closely related to.


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