When Kathleen met Richard #5
Kathleen Jones is wrong about African Eve. Does she have any idea how wrong?
Fifth in a series responding to Kathleen Jones’s Challenging Richard Dawkins: Why Richard Dawkins is wrong about God11
The ‘African Eve’
According to Kathleen Jones:
Richard Dawkins’ training as a biologist leads him to formulate the evolution of the human race in matriarchal terms rather than the patriarchal terms still used by many followers of the major world religions…
…Speculation that the first ape that came down from the tree and stood upright was female is widely accepted [by biologists], and has been eagerly seized upon by some feminists. [Emphasis added.]
The explanation is to do with mitochondria:
Human beings, and many other forms of life, are dependent on mitochondria – tiny bodies inside every cell in their bodies – for breaking down food and turning it into energy. … [M]itochondria… are only transmitted from mother to daughter down the generations. A son will inherit mitochondria from his mother, but cannot in turn transmit them to his children. …So a baby gets its mitochondria from its mother, and she derives her mitochondria from her mother, and so on back through history – a great chain of mothers and daughters bearing life. Geneticists have developed the ‘African Eve’ hypothesis: that all human beings can be traced back to one great female ancestor from whom we inherit our mitochondria. So the first Homo sapiens was actually female. [Emphasis added.]
There is some truth in the passages quoted above, but at least one enormous misunderstanding. This is all the more remarkable considering that Jones refers to a specific section of Richard Dawkins’ River out of Eden2 where he explains the ‘Mitochondrial Eve’ claim with complete clarity.
Without replicating that explanation step by step, I would like to highlight where Jones is correct in her summary and where she is stupendously wrong.
Yes mitochondria are only transmitted down the female side. But for some reason she misses out the crucial significance of mitochondrial DNA. Because mitochondrial DNA is in the mitochondria rather than the cell nucleus it does not participate in the chromosomal crossing over which, in organisms which reproduce sexually, shuffles the genetic inheritance of both parents. In theory therefore the mitochondrial DNA could be transmitted from mother to offspring as perfect copies. In practice there is always a probability that copies will be imperfect. So the mitochondrial DNA of all the humans alive today is not the same.
Because of the cumulative effect of copying errors (mutations) the closer two individuals are related the closer their mitochondrial DNA will be. Conversely the more differences there are between one individual’s mitochondrial DNA and another’s the more distantly related they will be on the purely female side – which means the further back you have to go to find their most recent shared female ancestor along the purely female line of inheritance.
Using statistical sampling it is possible to estimate when the individual most probably lived, who was the most recent shared female ancestor of all humans in the world today, along the purely female line of inheritance. That individual is known as ‘Mitochondrial Eve’. Because, for a number of reasons, the balance of evidence suggests that she lived in Africa, she is also known as ‘African Eve’.
At this point it is worth spelling out who Mitochondrial Eve is not. (In the definitions below, as in the paragraphs above, ‘human’ is used as shorthand for Homo sapiens.) Mitochondrial Eve (‘Ancestor 1’) is not:
The most recent shared female ancestor of all humans in the world today along any line of inheritance – ie not the purely female line. This ancestor could be more recent than Mitochondrial Eve.
The most recent shared ancestor of either sex of all humans in the world today along any line of inheritance, and who happens to be female. (If Ancestor 3 is female, then Ancestors 2 and 3 are the same. If male, he would be more recent than Ancestor 2. As it happens, Ancestor 3 is for various reasons much more likely to be male than female.)
The most recent shared female ancestor of all humans who have ever lived, along the purely female line of inheritance. Since many lines of inheritance will have died out (in particular any defined lines of inheritance like the purely female-to-female one), this ancestor is likely to be much older than Mitochondrial Eve.
The most recent shared ancestor of either sex, of all humans who have ever lived, along any line of inheritance, and who happens to be female.
The first human.
Current estimates date Mitochondrial Eve at about 140,000-170,000 years ago, whereas Homo sapiens as a species (represented by Ancestors 4 and 6) is believed to have emerged between 250,000 and 400,000 years ago.
So Mitochondrial Eve is emphatically neither ‘the first ape that came down from the tree and stood upright’ nor ‘the first Homo sapiens’.
As Dawkins explains:
The correct claim is only that Mitochondrial Eve is the most recent woman of whom it can be said that all humans are descended from her in the female-only line. There has to be a woman of whom this claim can be made. The only argument is over whether she lived here rather then there, at this time rather than at that time. The fact that she did live, in some place and at some time, is certain.3
The blurb on the back of Challenging Richard Dawkins says:
This robust and vigorous book analyses Richard Dawkins’ bleak view of the human condition and reveals fundamental flaws and distortions, and a very limited perspective.
On the evidence so far (see also When Kathleen met Richard #1; #2; #3; & #4) I would agree it reveals fundamental flaws and distortions – in Jones’s understanding both of what Dawkins is saying and the perspectives he is arguing from.
1 Kathleen Jones, Challenging Richard Dawkins: Why Richard Dawkins is wrong about God, Canterbury Press Norwich, London, 2007.
© Chris Lawrence 2009.