Home » The Design of Life » Just up at The Design of Life blog: African Eve

Just up at The Design of Life blog: African Eve

Was one woman who lived 150,000 to 200,000 years ago the ancestress of all of us? Science may not be sure, but pop culture is.

Part One: Our Mitochondria: A piece in the puzzle of our origins?

Part Two: What Does Our Mitochondrial DNA Say About Human Ancestry?

Part Three: African Eve – when pop culture falls in love with science

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6 Responses to Just up at The Design of Life blog: African Eve

  1. 1

    There really is no controversy about the fact that there was a mitochondrial Eve. The hard question is how long ago she lived.

    The following is from our friends at talk.origins. They call it a proof which technically it is not, and credit it to Dennett, although many others made the very same argument before him.

    Consider all the humans alive today on Earth. Put them into a set S.

    Next, consider the set of all those women who were the mothers of the people in the set S. Call this set S’. A few observations about this new set S’. It consists of only women (while set S consists of both men and women)—this is because we chose to follow only the mother-of relationship in going from set S to set S’. Also note that not every member of set S’ needs to be in set S—set S consists of all people living today, while some of the mothers of living people could have died, they would be in set S’ but not in set S. Third, the size of set S’ is never larger than the size of set S. Why? This is because of the simple fact that each of us has only one mother. It is however overwhelmingly more likely that the size of set S’ is much smaller than that of set S—this is because each mother usually has more than one child.

    Repeat the process of following the mother-of relationship with set S’ to generate a new set S”. This set will consist of only women, and will be no larger (and very likely smaller) than set S’.

    Continue this process. There will come a point when the set will consist of smaller and smaller number of women, until we finally come to a single woman who is related to all members in our original set via the transitive-closure of the mother-of relation. There is nothing special about her. Had we chosen to follow the father-of relation, we would have hit the Y-chromosome Adam. Had we chosen to follow combinations of mother-of and father-of relations, we would have hit some other of our common ancestors. The only reason why the mother-of relationship seems special is because we can track it using the evidence of mitochondrial DNA.

    Thus there must exist a single woman who is the matrilineal most-recent common ancestor of every person in set S.

    Also important to keep in mind is that while the final set S’* has only one member (the Mitochondrial Eve), she was by no means the only living woman on Earth during her lifetime. Many other women lived with her, but they either did not leave descendents who are still alive today, or did not leave descendents via the matrilineal line who are still alive today.

  2. I also read a good analogy of how we would all be descended from one woman in the book “Before the Dawn.” At least, I think it was that book. I’m too lazy to open it up and try to make sure right now.

    Anyway, the comparison was using a more familiar analog of last names. Mathematically, as time progresses, more and more last names would run out of progenitors. As the scale of time increases, it is inevitable that there will eventually result in one last name. Of course, this would have to be on a large enough scale of time.

    This does not mean that the first person with that last name is at the head of the family tree for every person, ever. It means that their lineage is the last one remaining after all the other lineages got filtered out.

    Okay, I gave in. It IS in “Before the Dawn” by Nicholas Wade in the Eden chapter. It’s a pretty easy-to-follow analogy, explained much better than I could do. The book is pretty interesting. Sorry for digressing…

  3. http://www.icr.org/article/3858/

    At the International Conference on Creationism there is going to be some creationist research on Mitochondrial Eve presented —

    The “Eve” Mitochondrial Consensus Sequence Robert W Carter, Dan Criswell, and John Sanford

    They’re calling the consensus sequence “Eve 1.0″ :)

    Schedule for the ICC2008:

    http://www.icc08.org/schedule.htm

  4. Also check this one out from David Brooks, who apparently now dabbles in philosophy of the mind as well as science:
    http://www.nytimes.com/2008/05.....3JQN1puPbA

    Right up Denyse’s alley!

  5. From the above link:

    “After analyzing the differences found among the sequences in their dataset, they discovered that more than 83 percent of the mitochondrial genome had not changed in all of human history, and in over 99 percent of the locations where a change has occurred, only a small minority of people carried that specific change. In other words, most changes that have occurred are minor and rare. On average, human mitochondrial DNA differs from the original Eve consensus sequence by only 21.6 nucleotides (a nucleotide is a “letter” in the DNA alphabet). This is a small number when one considers that there are more than 16,500 nucleotide letters in the human mitochondrial genome.”

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