Today, we look for an historical Eve in her garden.
The University of Houston's College of Engineering
presents this series about the machines that make
our civilization run, and the people whose
ingenuity created them.
Stephen Jay Gould has become
a fine public voice in matters of biology, geology,
and evolution. He writes complex ideas down in
words that you and I can fathom. Now he talks about
a new notion of a common ancestor.
Humanoids have been around over two million years.
This new ancestor is only a tenth that age -- only
200,000 years. Older humanoids might've been our
cousins. But they weren't ancestors.
Advocates of that idea call the new ancestor Eve.
Why Eve and not Adam? The answer has to do with the
basis of the theory.
Certain of our cells carry building blocks called
mitochondria. Both our mother and father
contributed to our genetic makeup. But only our
mother gave us our mitochondria.
Mitochondria are useful in tracking kinship. Some
years ago, Argentine grandmothers fought to get
back children who'd been kidnapped by the
dictatorship. They used a mitochondrial DNA test to
identify the children.
Now ethno-biologists put mitochondrial data into
computers. They can do their calculations many
ways. But every path leads to one specific ancestor
or another. One path leads to the bones of certain
200,000-year-old African women. Since we can't yet
trace male genes, we give those women the
collective name of Eve.
Some people wonder if there's a Biblical angle on
all this. But looking for a single mother of our
species misses the point. This Eve opens much
deeper questions about our place in the scheme of
things. Gould says we're really just an
afterthought in evolution. In his words,
We are a thing, a singular event, an item of
history -- not the predictable result of necessary
improvement. Homo sapiens is one of the twigs [on
the tree of life], not [a] grand, overarching
predictability.
We'd rather've been shaped by millions
of years of competitive selection into a
large-brained super-animal. We want to be the focus
of history, not one of its byroads.
But then, this Eve doesn't offer a scientific
answer to the question of our place in the cosmos.
Besides, another theme entirely is rising in
scientific circles.
It is that our Earth might be a single system.
Maybe we're elements that participate in sustaining
the Earth that sustains us. Maybe Earth is far more
than a backdrop against which we played the drama
of evolution. Maybe we have to see our own
progression as part of the changing equilibrium of
Earth as a whole.
If that's the case, this new Eve takes on a very
different meaning. For then our presence on Earth
represents the solution of some problem -- not the
result of a competitive skirmish for survival.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
Gould, S.J., Eve and Her Tree. Discover,
July 1992, pp. 32-33.
Lovelock, J.E., Gaia: A New Look at Life on
Earth. Oxford: Oxford University Press, 1987
(an updated reprinting of a 1979 book.)
Joseph, L.E., Gaia: The Growth of an
Idea. New York: St. Martin's Press, 1990.
Gibbons, A., An About-Face for Modern Human
Origins. Science, Vol. 256, 12 June,
1992, pg. 1521. (The tracing of our origins to an
Eve in Africa is under severe attack. However, the
notion of a very specific, and fairly recent,
ancestor is quite alive.)
For more on the idea of Earth as a coherent system,
see Episodes 699 and
700. I'm grateful to
Professor Blaine Cole, UH Biology Department, for
his counsel on this episode.
The Engines of Our Ingenuity is
Copyright © 1988-1997 by John H.
Lienhard.
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