The Perpetuation of Living Beings, Hereditary Transmission and Variation: Lecture IV. (of VI.), "Lectures to Working Men", at the Museum of Practical Geology, 1863, on Darwin's Work: "Origin of Species"Huxley, Thomas Henry
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The Perpetuation of Living Beings, Hereditary Transmission and Variation: Lecture IV. (of VI.), "Lectures to Working Men", at the Museum of Practical Geology, 1863, on Darwin's Work: "Origin of Species"
Huxley, Thomas Henry
Darwin, Charles, 1809-1882. On the origin of species; Evolution (Biology)
Now observe what very extraordinary phenomena are presented here.
You have an accidental variation arising from what you may call a
monstrosity; you have that monstrosity tendency or variation diluted in
the first instance by an admixture with a female of normal construction,
and you would naturally expect that, in the results of such an union,
the monstrosity, if repeated, would be in equal proportion with the
normal type; that is to say, that the children would be half and half,
some taking the peculiarity of the father, and the others being of
the purely normal type of the mother; but you see we have a great
preponderance of the abnormal type. Well, this comes to be mixed once
more with the pure, the normal type, and the abnormal is again produced
in large proportion, notwithstanding the second dilution. Now what would
have happened if these abnormal types had intermarried with each other;
that is to say, suppose the two boys of Salvator had taken it into their
heads to marry their first cousins, the two first girls of George, their
uncle? You will remember that these are all of the abnormal type of
their grandfather. The result would probably have been, that their
offspring would have been in every case a further development of that
abnormal type. You see it is only in the fourth, in the person of
Marie, that the tendency, when it appears but slightly in the second
generation, is washed out in the third, while the progeny of Andre, who
escaped in the first instance, escape altogether.
We have in this case a good example of nature's tendency to the
perpetuation of a variation. Here it is certainly a variation which
carried with it no use or benefit; and yet you see the tendency to
perpetuation may be so strong, that, notwithstanding a great admixture
of pure blood, the variety continues itself up to the third generation,
which is largely marked with it. In this case, as I have said, there
was no means of the second generation intermarrying with any but
five-fingered persons, and the question naturally suggests itself, What
would have been the result of such marriage? Reaumur narrates this case
only as far as the third generation. Certainly it would have been
an exceedingly curious thing if we could have traced this matter any
further; had the cousins intermarried, a six-fingered variety of the
human race might have been set up.
Public-domain text, read in full here on John Shaqi.
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