As a biochem major, I can assure you that evolution very much exists, and please don't try to deny it. If you want evidence, there are actually E. coli lab kits that you can use to show how evolution works in a short amount of time, as natural selection can be seen on a microscale.
Just by knowing how natural selection and genes work you can deduce evolution. Genes have the potential to change, depending on parental inheritance and random mutation. This means that a member of a species can have small differences than the rest. Over time, as genes change due to generations of different ancestors, the species itself changes, and after perhaps millions of years there is a chance that a part of that species will branch off due to being very unsimilar to the rest.
With natural selection, only the organisms best suited for their environment survive. If one member of a species has better sweat-producing capability due to superior eccrine glands, while another member is greatly inferior in terms of perspiration production, and both face a drought, the one with the better eccrine glands will survive and spread its genes while the other dies, and is unable to reproduce and spread their inferior genes. After a while, there will be no more members of that species in the area that has poor eccrine glands, and thus through genetics the species would have changed, ever so slightly. Over millions of years, this cycle repeats itself, and organisms change drastically, in function and appearance, as only the ones able to best adapt in their current forms survive and pass on their characteristics.
You're Gonna Carry That Weight.
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