Haven't had one of these in awhile, and this place is getting boring, so let's do it.
Let's look at a normal chromosome.
Where red are Telomeres, gray is the centromere and blue are the genes. Throughout all life, chromosomes have this structure (except for HC2): Telomeres on the end, centromere in the middle.
Then you get to HC2:
Here we have two telomeres on the ends, two telomeres in the center, and two centromeres on the first and last quarters. Obviously, at some point in the past two chromosomes merged to form a single combined chromosome. This is why the great apes have 24 sets of chromosomes, but humans only 23.
What's so special about this fact is that humans aren't the only ones to have this structure: Neanderthals and Denisovans share the conjoined HC2 as well.
Since the rest of nature shows us that chromosome merger is not a common occurrence (it hasn't been seen anywhere else), Occam's razor dictates that we inherited the conjoined chromosome from the same ancestor the Neaderthals and Denisovans did.
So how can this be explained away by those who don't believe in evolution?