Humans and chimps are genetically more closely related to each other than either is to any other ape. Humans and chimps are a clade within the great apes.
Then there's the way chromosomes sort out. Chromosomes are just chains of genes. These can change over time by fusions of two or by breakage of one into two. But when we look at the chromosomes of great apes...
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Notice that two ape chromosomes look just like one human chromosome. (#2) Otherwise, each chromosome lines up nicely, showing all great apes, including humans, have a relatively recent common ancestor. But even better than that, on human chromosome 2, there are remains of telomeres (chromosome ends) right where they would be if there was a fusion. Now YECs say it was just random chance. But we're talking about thousands of genes. If you calculate the chance of even a thousand things randomly sorting out identically again and again, you're getting into things so unlikely as to be logically impossible.
Then there's the case of the pollicis longus muscle.
J Hum Evol 2012 Jul;63(1):64-78
Or wisdom teeth. They fit nicely into the jaws of other apes, but humans have reduced faces, which usually can't accomodate those teeth evolved for bigger jaws.
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