I think you misunderstand science. A scientist does not 'support' any theory. A scientist looks at data and formulates a hypothesis. Should data come along at a later point that refutes the original hypothesis, so be it, formulate a new hypothesis. Scientists around the world will try to test the hypothesis will all known data to either disprove or substantiate the hypothesis. This is how knowledge grows.
Religion does not seek to prove or disprove it's self. Religion uses the the same 'reasoning' that a parent who is frustrated with a child. When asked one to many times, the parent will just say "because I said so". That method does not work for science.
If you cannot see the difference between this and religion I understand why you do not understand the relevance of similar bone structures, DNA or other facets of science have on our history. As an example, it is hypothesized that whales and other sea mammals were once land based mammals due to certain bone structures. Their flukes have five digits which are thought to be remnants of hands/paws that evolved into flukes when the animals evolved into sea based creatures. There are also fossil records that show remnants of rear legs as well which have all but disappeared on to days creatures. Looking at similar bone structures is quite important in determining their relation to other creatures that existed before and after the existence of the creature in question. This is how times lines and genealogies are determined.
