I assume you mean that humans are a particular species of ape, as in, a human is an ape, but not all apes are human. Otherwise, you and I have extremely different definitions of what a human is to say the least. You cannot train a gorilla to perform arthroscopic surgery, nor can a chimpanzee expound on philosophy and moral dilemmas. They're very different from us.
Evolution is not a straight line, it is a tree or bush.
True, but if you look at the tip of the highest branch of any tree, you can still trace a single line all the way down to the root.
But we came from a common ancestor, all the great apes and diverged along different branches, some of them ending in extinction.
So what was this common ancestor?
Here is a list of relatively close ancestors of apes and humans: Starting some 80 million years ago: Tree shrews, Lemurs Lorises Tarsiers Cebids Old World Monkeys Gibbons Oranutan Gorilla Human Chimps. Chimps branched off after Humans started evolving from the common ancestor of humans and chimps about 7.7 million years ago. Chimps branched about 3.4 million years ago.
Anthropoids branced from ancestral primates about 70 million years ago and apes as a whole about 23 million years ago.
Let's cut to the chase. It is the period from the point this common ancestor appeared +/-7.7 million years ago to the present that my questions are concerned with. Repeating the analogy given above, we should be able to start at the tip of the highest branch of the tree -- us -- and trace backward in a single line, if not to the root (microbes) then to a thicker main branch (this ancestor). What was this ancestor, and roughly how many basic successful mutations were there between it and us? There are only three possible answers to this question:
1) a specific number;
2) an approximate number;
3) we really don't know.
I don't know how I can make this question any clearer.
What you have to understand about genetics is that mutations and other content changes in genetic material build up whether expressed in the phenotype or not.
Fair enough, but I knew that already. This is stuff taught in basic biology in grade school and high school. Genetic traits skip generations due to various combinations of dominant and recessive genes, etc. But for the purposes of this conversation, I am only concerned with those expressed phenotypes.
Thus, there are many areas of genetic material that can be activated by various type of switch type genes. So if life has been evolving for a billion years, we have a billion years of genetic variations throught the whole system.
That would seem obvious. But I am only interested in this common ancestor of 7.7 million years ago to the present, as in, this ancestor eventually gave rise to this phenotype, which then gave rise to this one, then that one, etc.
And while we're at it here, let's take a poll. There seem to be 3 basic positions represented in here:
1) Atheist/agnostic.
2) Pure creationist, believes Earth is no more than about 10,000 years old.
3) Believers in God who believe the Earth is much older than that and who at least allow the possibility that evolution was God's way of creating the variety of life we have now.
Which are you? I would consider myself more or less a 3.
However, some 3's in here appear to be clinging so tightly to evolution that they are speaking as if the physical world of matter is all there is, which is to say they are much more a 1 than a 3, which is to say they don't REALLY believe there's a God but think it's a "lovely idea".
If you are a 3, then just as with a 2, by definition you have to allow for the possibility of supernatural intervention by an omnipotent metaphysical Supreme Being whenever He bloody well feels like it. This means you have to allow for things that cannot and will not ever be explained by science, which deals only with the physical and by definition cannot address the metaphysical.
Using physical science to explain the metaphysical is much like a man standing under a streetlight looking for his car keys. Another man approaches and asks "What are you doing?"
"I'm looking for my car keys."
"Where were you when you dropped them?"
"Over there," he points to the gutter over in the dark away from the streetlight.
"So why aren't you looking there?"
"Because the light is better over here."
***
So everybody, are you a 1, 2, or 3?
"Repeating the analogy given above, we should be able to start at the tip of the highest branch of the tree -- us -- and trace backward in a single line, if not to the root (microbes) then to a thicker main branch (this ancestor)."
A straight line going back 2.2 million years from Homo sapiens to Homo erectus to Homo habilis with the common ancestor Australopithecus afarensis at about 2.7 million years (common to Australopithicenes and Homo.
I don't know if they know precisely what differences in DNA sequence and alleles there might have been, because there is no DNA available, to my knowledge.
I don't know why you think the number of mutations between one and the other is that important. It is obvious there are major differences in skeletal structure, especially cranial development.
There is a gap in fossils from 8 mya to 4.4 mya. So we don't have common ancestor information for the gorilla, chimp, human split. But using the molecular clock and DNA-DNA hybridization some conclusions can be drawn.
The difference in amino acid sequences in albumin of chimps, gorillas and humans is only about 1.2%. With this and a simple formula that indicates the relationship between time and distance, a divergence date of about 5MYA can be estimated. Much of the difference between apes and humans are attributable to just a few regulator genes. We are not as genetically different as we look.