Question by Alt: National Geographic v. Charles Darwin? “Adam” and “Eve” of the DNA Project.?
How could Dr. Spencer Wells ever hope to identify ONE pair of humans to give start to all of us? (see more details on the NatGeo DNA project at www.nationalgeographic/genographic)
This sounds very much like a attempt to “prove” the holly or extraterrestrial start of human civilization, contrary to the Darwin’s theory… If they did not mean to diminish Darwin’s theory, how can they be able to trace the Pair of Humans. They may only trace at least a tribe or two, AND THEN they may trace it back to supermonkeys and even dolphins or something in the ocean! Not just ONE pair of humans, especially and if only Dr. Spencer Wells admit that the DNA is THE biological HISTORY book/code, not a book of revelation.
Paul, a superb answer, it resolves the “pair” might not been the “pair’. And, indeed, I suppose the DNA research did not mean to call those left over people “non-humans”. Let’s say it was just another misformulation of the goal.
Yet, your answer still leaves the question open as to “How can they tell that a human being BEFORE “Adam” or “Eve” may be called NON-humans?
Am I correct to suppose that Dr. Well is actually looking for HISTORICALY earliest humans WHO left their traces in our DNAs, but NOT the EARLIEST HUMANS !
O.K., Secretsauce, then How can we assume that there was only ONE ancestrial female and ONE ancestrial male to the entire humankind even separated in time?
There must be hundreds of such ancestrial “parents” to the modern world population. And those “parents” should have lived not only at different points in time, but varied in locations – many in Africa, some in Arab peninsula, some in Central Asia, and still some younger “ancestrial parents” in all corners of the world!
To use “Adam” and “Eve” even figuratively is quite misleading. A better allegory perhaps might be “to look for an apple (not “adam”) and a berry (“not “eve”) to a plump (not “kain”)”.
(Note: fruit names above were used in joke to illustrate the idea)
Answer by Paul B
Your answer is answered in great depth in the Nature article referenced in this abstract:
To summarise, you don’t inherit DNA from all of your ancesters. In fact, you don’t even inherit DNA from all of your great grandparents.
Every generation you back, you double the number of ancestors. Before long, the number of your ancestors exceeds the number of humans on the planet. This means that something has gone wrong with the maths – namely that you have ignore the consequences of marriages of distance cousins.
When you take this into account, it is fairly likely that in the last couple of thousand years, there was someone who was the ancestor of every person currently alive. However, the chance of us inheriting any DNA from this particular person is rather small.
In order to go back to someone who everyone inherits DNA from, you have to go back much, much further in time.
The “Adam” and “Eve” genetic studies only aim to find the “ultimate male ancestor” and the “ultimate female ancestor”. They trace the “Y-chromosone” (inherited solely from your father), and the “mitocondrial DNA” (inherited solely from your mother), to form unique son -> father and daughter -> mother linkages going back through time.
This means that a father who only had daughters, or a grandfather who only had granddaughters will never be located via a survey of this type: they didn’t contribute any Y-chromosone DNA to subsequent generations.
It is likely that, in the dim and distant past, there was a small tribe of humans (or possibly several tribes). By change, only some of males had male offspring. Only these male DNA will pass to future Y-chromosones – the existence of the other males will be lost to the “Adam” project. Equally by chance, two of the the “Adam” males had the father – in this case, you can call the father the “Adam”, and the sons the “Cain” and “Abel”.
Going backwards in time, the number of “Adams” can only decrease. But this doesn’t mean that the tribe was getting smaller – only that the number of members with male-lineage descendents decreases. In a similar way, a decrease in the number of “Eves” will be expected.
I hope that this makes it clear. There was never a single “Adam”, and a single “Eve”. It is just by chance that there is only one “Adam” whose male-lineage descendants survive to the present day, and that there is only one “Eve” whose female-lineage descendants survive likewise. In fact, the chances are that “Adam” never met “Eve”, let alone had children by her…
What do you think? Answer below!