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Page 3 of Part 2: Who Was Mitochondrial Eve’s Husband?

People often issued a challenge: Y chromosome Adam and mitochondrial Eve they were born tens ofthousands of years away, how could a couple? They really can not be husband and wife. Mitochondrial Eve is the Y chromosome old grandfather's wife, while the Y chromosome Adam married the following mitochondrial Eve grandchildren many generations of women.

Ⅰ. Mitochondrial Eve: our maternal “most recent common ancestor”

1. The time period when our maternal ancestors lived

 (1) Evidence-based estimation: The relationship between  mitochondrial DNA mutations and the dates when these events happened, it is obvious that regardless of how many generations we back track the maternal ancestors, we must  rely on three evidences: a. There must be at least two who reproduced into ethnic groups of the present time; b. There must be difference in mutations in these two individuals’ mitochondrial DNA; c. There is a known “mutation rate”.

Three conditions must be fulfilled: a. There are two base points representing the two ethnic groups lasting until the present time; b. The two base points separated by a predetermined distance which represents “the difference in the mitochondrial DNA mutation”; c. There is a certain upward slope representing the “mutation rate”. One can depict two intersecting straight lines on account of these three conditions. The point of intersection can represent our deduced ancestors.

(2) We must be aware that out of the intersection of our maternal ancestors who regardless of whether they were the oldest or youngest, they must have at least two daughters. Moreover, they descendants must have reproduced until the present time. The only way to be sure of these two base points, because it is to search from the blood samples of modern human beings. If our maternal ancestors only had one daughter or just one daughter’s descendants reproduced up to the present time, then we cannot deduce her existence or the period of time she lived ( Please see Figure 2-11 The Mitochondrial lineage tree in last page).

2. Mitochondrial Eve was our “most recent common ancestors” by deducing

“Our most recent ancestors” can be abbreviated MRCA. There must be other females who lived at the same time as mitochondrial Eve. However, their descendants failed to survive up to the present time. Nonetheless these females must be the female siblings of mitochondrial Eve from the same maternal genetic. Their mitochondrial DNA sequence must be very similar to that of mitochondrial Eve.

Obviously, mitochondrial Eve should have a mother, grandmothers or else who gave birth to her? How it is that we cannot deduce them? The reason is because her aunts, grand aunts and their descendants did not survive until the present time. It is impossible to deduce if the condition, namely, “ the  need to have at least two daughters and their descendants must survive until the present time”, is not met.

Moreover, we need to pay attention to the fact that in order to be our maternal ancestors, the females must of 23 pairs of chromosomes and their mitochondrial DNA must be basically the same as ours.

Ⅱ. How much of a difference is there between mitochondrial Eve and us?

1. The difference is less than one in one thousand:

Figure 2-15 Semiconservative replication of DNA

Each one of the human chromosome contains a long chain of DNA double helix. The two chains each contain a string of nucleobases.  The pairing of these nucleobases are strictly complementary following the pairing rule as follows: A pairs with T and G with C. If the left side is T, then the right side must be A and not G or C, or T. This pairing is similar to a zipper. During “Semiconservative replication”, the process is similar to opening the zipper then giving the left side of the zipper a new complementary pairs on the right side which must be the same as the original “right side of the zipper”. Likewise, to give the right side of the zipper a new complementary pairs, the left side must be the same as the original “left side of the zipper”.  In this way, the replication of a complete zipper which is exactly identical with the “mother” zipper.  

This is the mechanism by which the DNA Semiconservative replication operates in order for the chromosome and mitochondrial DNA sequences could be accurate passed on from one generation to the next regardless of how many times the human cells undergo division. “Incredibly, DNA synthesis can occur as fast as 100 nucleotides/second and must be as accurate as 1 wrong base in 10^9 nucleotide additions. . . . .”[Reference 5]

2. The wonderful DNA repair function

(This section is borrowed from the textbook of the Chinese University” Modern Molecular Biology and Genetic Engineering” Reference 6)

Even though the DNA replication process is a high fidelity process, however, invariably there exists a small amount of uncorrected error in the replicated progeny DNA. In order to avoid a large amount of mutations leading to the death of the body, DNA has a special repair function which occurs simultaneously during the strict replication of the DNA sequence. Unlike other molecules, DNA is very special because it can make self repair after replication-related damage or errors. The DNA repair function is another guarantee for the speedy and stable replication process. The different types of DNA repair are listed belo>repair ; (2) excision repair ;(3) Direct repair; (4) recombination repair;(5) error-prone repair; et.

The already very precise DNA sequence replication is made every more precise by the aforementioned repair mechanisms. However, during the replication process, very small “mistakes” are created. These “mistakes” are the “mutations” which is inherited by the next generation. Because of this, during the 200,000 years and thousands of generations of inheritance of modern humans, we have an explanation of why the difference in our DNA is merely thousandth. Even more amazing if the fact that within this difference is included all the mutation markers in Y chromosome as well as the mitochondrial DNA. Because of these genetic markers, not only can we trace our ancestors but also depict mankind’s migratory routes and history. Thus, from this viewpoint, these “mistakes” are no longer “mistakes”.

For example, M168 genetic marker’s letter ‘T’ remains unaltered on the same locus at the DNA sequence the Y chromosome that include 50 million nucleotide. This truly amazing inheritance relies on the aforementioned accuracy of DNA replication.

As mentioned before: there is “ the accuracy rate is one mismatched nucleobase pair in the replication of one billionnucleobase pairs” (Reference 5).Therefore, every time during the replication of the six billionnucleobase pairs within the cells (three billion from father and three billion from mother), the replication error is merely six letters. There are no more than 50 cell divisions in every human being during his or her lifetime. Therefore, each generation, only 300 “mistakes” or mutations are accumulated.

From mitochondrial Eve until today, 200,000 years have lapsed. After 10,000 generations of inheritance, there must be around three million “mistakes” or mutations. It being accumulated about three million in one cell. The ratio is around 0.5 (3 million ÷ 6,000 million) which is exactly the difference between Michelle and mitochondrial Eve. One can even predict that after another 200,000 years, the difference may increase by another 0.5.

Mutation cannot be the motivating force of evolution. From the mere difference of only 0.5 between mitochondrial Eve and modern humans, one can see that even mankind’s microevolution did not happen because of mutations. Needless to say, one cannot across the gap between the ape’s 24 pairs of chromosomes and the 23 pairs of chromosomes in humans because on human DNA mutations.

V. There is no human microevolution

Why is there no microevolution in humans?

As mentioned earlier, we have seen that DNA difference is merely 0.5 in one thousand between the mitochondrial Eve (200,000 years ago) and modern humans. This difference is even smaller than between difference peoples living in different regions of the world. From this fact we can be certain that in the last 200,000 years, microevolution has not occurred in humans.

Let us take another look at the August 22, 2000 report in the New York Times science section entitled “Do Races Differ? Not Really, Genes Show) which states:

“Dr. Venter and scientists at the National Institutes of Health recently announced that they had put together a draft of the entire sequence of the human genome, and the researchers had unanimously declared, there is only one race — the human race.

.

Dr. Venter and other researchers say that those traits most commonly used to distinguish one race from another, like skin and eye color, or the width of the nose, are traits controlled by a relatively few number of genes, and thus have been able to change rapidly in response to extreme environmental pressures during the short course of Homo sapiens history.”

Dr. Venter is one of the world leaders in genomic research. He is the chief expert who has done the most in the actual human genome project. Among the samples from five Individuals in the world genome research project, one sample came from Dr. Venter.

In sum, from the times of Y chromosome Adam and mitochondrial Eve, microevolution has not occur in humans.

Reference：

1.Dorit RL, Akashi H, Gilbert W.  “Absence of polymorphism at the ZFY

  locus on the human Y chromosome.” Science 268:1183–1185 1955。

2．Underhill PA, et al. “Y chromosome sequence variation and the history of human populations”, Nature America Inc.2000.

3. Cruciani F, et al., A revised root for the human Y chromosomal phylogenetic tree: the origin of patrilineal diversity in Africa. Am J Hum Genet. Jun 10 2011

4.Anatole A. Klyosov, et al.,Re-Examining the “Out of Africa” Theory and the Origin of Europeoids (Caucasoids) in Light of DNA Genealogy, Advances in Anthropology,2012. Vol.2, No.2, 80-86

5. Morgan, David. The Cell Cycle: Principles of Cell Control. New Science Press Ltd., London, 2007; pp 58-60.

6. HiYing Li，” Modern Molecular Biology and Genetic Engineerin

g”，the textbook of the Chinese University，Published by Chemical Industry Press