I've started yet another new thread to discuss just one of the questions I
previously raised and Pete Vincent's reply. (It will need a brief
introduction -- more precisely, five paragraphs! -- before I get to the point.)
> When we know how to divide ourselves into two species who will be
> motivated to do so?
Those who are millions of miles, if not lightyears, away. They won't
be consciously motivated, but it will happen anyway.
There's little doubt that if some of us went into deep space then, over
generations, our existing stock of genes would adapt considerably by
mutations within them. But this doesn't necessarily mean that the
travellers would become a distinctly new species. Several different
space-ship groups in various parts of the planetary system or beyond might
become as different from one another and from us as, say, all the varied
dog breeds have become. But if any travellers returned to earth in, say,
20,000 or 30,000 years' time, they might still be interfertile with with
earth-bound humans -- just as all dog breeds still are, despite enormous
cosmetic differences.
However, evidence is now mounting that new species don't arise from slow
differentiation of mutations within separated portions of the same species
(say, when a species becomes divided by a mountain chain or in a region
that becomes an island by a sea level rise). This lengthy origin of new
species (speciation) is what Darwin -- and all subsequent biologists --
assumed, although no-one was able to prove it. However, it is now being
increasingly believed that new species only arise suddenly and randomly
with, probably, the incursion of a brand new gene. And in sufficient
numbers, too, to constitute a sufficiently large breeding stock from the
word go. If the new species is able to survive then it will either compete
for food with its predecessor (and might cause its extinction) or find
another food-niche of its own.
The reason why one brand new gene might make all the difference is
two-fold. Firstly, at the point of fertilization, the addition of a new
gene within a male or female chromosome would throw all the other genes to
the left of it or the right of it completely out of kilter with its
respective female or male chromosome that it's trying to match with. Thus
an individual with a brand new gene would not be fertile with the previous
stock.
Secondly, it's now being realized that genes don't act singly when in
operation. They also link up with dozens, scores or perhaps hundreds of
other genes. A brand new gene can cause many different changes in the
appearance and behaviour simultaneously. Some effects can be trivial,
others can be significant.
Since Homo sapiens line broke away from the chimpanzee line about six
million years ago, there have been something like 20 hominin species so far
identified from fossilized remains. Other evidence show that we have about
20 genes that the chimps don't have. This isn't proof of the new theory
about speciation but it's suggestive.
If the new speciation theory turns out to be correct then it will clarify a
large grey area in genetics that has existed for 150 years. So my original
question becomes: Will research biologists (and their fund providers) be
content never -- ever! -- to perform experiments in which a brand new gene
is introduced into the DNA of a newly fertilized egg to see whether it will
continue as a healthy embryo, foetus and, indeed, a healthy new-born baby.
If the baby lives and grow into a healthy adult then the chances are that
this individual will belong to a new species.
At the present time, hands would be raised in horror by both the religious
and the non-religious. This must never happen! Every government and every
ethics committee in the world would probably pass legislation to forbid it.
But would this prevent the experiment being tried? I suggest that, sooner
or later, out of sheer curiosity, some biologist or a team in some
university department or corporation will try it. And, if the new species
has new physical or mental abilities which are useful, then the temptation
to introduce the new gene into many more fertilized eggs would be irresistible.
Keith
Keith Hudson, Saltford, England
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