Solar wrote:
In those 6 million years, 35 million locations of the genome changed, another 5 were removed / added.
That is 40,000,000 / 6,000,000,000 or one change in the genome every 150 years.
You might want to check your maths books again. 6 million years is 6,000,000.
40,000,000 / 6,000,000 is 6.7 changes a year, or about one every 55 days.
Less than one percent of those mutations in the genome actually lead to the mutation of a protein; i.e. it took (on average) over 1500 years for one change to manifest.
You assume that these changes are all selfstanding, and that there was only going forward.
You also assume that there will be only one change made, and that that change will never be undone by a future change.
There's a lot more happening. Consider cancer for a moment. Cancer is a change in a cell that doesn't have a positive effect. It affects a certain type of the DNA, namely the part that controls how often a cell multiplies. It changes the setting from whatever it was (once every month, a week, never) to continually as fast as possible. Just this change alone is counted as cancer. Lots and lots of people die of cancer.
Cancer is lethal because most cells contain a small change from what they should've been. If the change is in something that doesn't matter for that cell, it's harmless. However, if those cells start to spread throughout the body, it'll end up in a place where that bit of the DNA is used. Most of these random variations kill the person to whom they're happening, and even if it's a positive change, you won't have much effect of it. Cancer itself also can be lethal by just plain clogging your arteries.
If the changes happen to your reproductive organs in a way that one of the reproductive cells are modified, and that seed happens to fertilise an egg (or that happens to be the egg being fertilized), and the new combination isn't lethal, then a mutation is born. Note that this isn't a mutant, it's a person like all the rest.
If and only if this new mutation is more functional than the other mutations does it survive. It survives by reproducing more than others.