What are homologous structures?
Horses, humans, birds and whales all have homologous features. But what is that? Take a look at the forelimbs of a horse, a human, a bird and a whale (they use to have legs! I know, weird right?!) they all have very similar bone structures yet all have different functions.
What is embryology?
Is the study of development of embryo's. It starts from the moment the "egg" is fertilized to the fetus stage.
This is a picture of different species in different embryonic stages.
What is vestigial features?
What does the human appendix do for me? Why do whales have hip bones? Features that organisms have but do not function, or we don't use are known as vestigial features. Scientists believe that millions of years ago, vestigial features were actually useful. Take a look at some modern snakes and whales, they have hipbones, which is evidence that suggests that they used to have legs! (Can you imagine a whale walking on land?)
What is biochemistry?
How do scientists know that the closest related mammal to a human being is a chimp? Because scientists us Biochemistry to compare biochemicals of different species. Proteins are molecules that make up structures in organism, so using biochemistry scientists are able to differentiate between species, and find relations. (Use page 146 in the bio text book too look at figure 5) Scientists are also using biochemistry to try and peace together the order of evolution. What came first, the chicken or the egg?
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