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Microevolution
Name: James
Location: N/A
Country: N/A
Date: N/A
Question:
I am writing a paper about macroevolution and have come across a
common theme a number of times. Since my research materials typically
date from the 1980's, I was wondering if you could clue me in on some
new developments. The question refers to the fossil record, which
seems to show rather sudden appearances of well-developed life forms
rather than more gradual change. The materials I have go on to
explain the absence of transitional forms, but is there any new hard
evidence linking the branches on "tree of life"? Also, if proto-life
became simple life (such as viruses), which became bacteria, which
became eukaryotes, etc., how come none of this can be reproduced in
the laboratory? One would think that if time and chance could do
something blindly in a billion years, intelligent designing could do
so in far less. Thanks. I'm looking forward to what you have to say.
Replies:
What you must first realize is that evolution takes a long time.
No, not a long time -- a LONG time. Longer than a person can
comprehend. Can you imagine a million years? Folks are surprised by
what can transpire between Presidential elections, let alone what can
happen over their own adult lifetimes, which is barely half a century.
The situation is similar to that of quantum mechanics: Your intuition
about space, based on macroscopic events (what happens to baseballs),
is useless and misleading when it comes to microscopic events (what
happens to atoms). Similarly, your intuition about time, based on
microscopic events (what happens in your life), is useless and
misleading when it comes to macroscopic events (what happens over
geological eras). Of course this is hard to swallow -- it would not
be rational to distrust your intuition. You may buy it in the case of
quantum mechanics only because the theory leads to hard facts and
devices, such as transistor radios. The same is true about evolution:
reasonable people accept the theory because of the hard facts and
devices it produces, such as vaccines, antibiotics and knowledge of
how to breed faster racehorses.
Given this limitation, there are two ways to establish the links
between branches of life -- to demonstrate evolution. The first is by
observing the fossil record, the forms of life now existing, and use
rigorous logic and reason --- while abandoning the dangerously
misleading promptings of ``common sense'' --- to deduce those links.
It takes a lot of mental training and practise to be able to do this,
just as it takes a lot of physical training and practise to do
something your body does not find intuitive (playing tennis).
I am not sure what you mean by the lack of transitional forms in
the fossil record. Isn't Archaeopteryx a transition between dinosaur
and bird? Isn't Australopithecus a transition between ape and man?
Given how very few animals get themselves fossilized -- it takes
rather unusual conditions at death -- it's a miracle the fossil record
is as useful as it is.
You can also observe evolution in action in species with very short
generations, such as bacteria and viruses. Want to observe a species
being created? Consider AIDS, which did not exist before 1959. Want
to observe a species altering significantly in response to natural
selection? Consider antibiotic-resistant tuberculosis.
As for reproducing things in a laboratory, it depends on what you
mean. A host of new species have been created by man since he began
manipulating his environment. Consider domestic cats, dogs, cows,
pigs, horses, wheat, rice, and corn. New species of bacteria are
created all the time in response to pressure from antibiotic use.
But perhaps you mean created de novo, from scratch, atom by atom.
This could be done, but it would be unbelievably time-consuming and
expensive, and so no one has even tried. What would be the point? If
you want a new breed of cat or corn, it's far cheaper to start from an
existing form and modify it. Only someone with a real philosophical
ax to grind would consider a project as quixotic as building a
bacteria out of carbon atoms. Scientists and engineers have better
things to do -- designing and building the host of technological
widgets that make modern life possible. Nor are the folks who foot
the bills -- taxpayers, consumers -- willing to fork out a couple of
trillion dollars so all doubting Thomases can have unequivocally
proven what a little rigorous thought makes evident already.
I expect you are quite correct, in that intelligent designing could
cut the time required for building life forms from scratch way down
from the three hundred million years needed by blind chance. I doubt
it would take more than 0.001% as long, tops.
Grayce
First of all, there are lots of "transitional forms" in the fossil record.
What there isn't a lot of is gradualism. For the most part, new life forms
appear, remain little changed for a while, and then disappear. Apparently,
once an organism is well-adapted for success in its environment, it's hard
to make small changes that don't make it much less fit. Exactly why this
is we don't know for sure.
As for "new hard evidence linking the branches of the tree of life," how
hard do you need? I guess you want something newly discovered since 1990.
Don't forget, though, that when Darwin proposed his hypothesis of evolution
by natural selection, the mechanism of heredity was not known! Knowledge
of DNA, and the genetic code, and the similarities between the genes of
closely-related organisms all came long AFTER Darwin's theory.
Furthermore, they all support and help to explain it.
As for the fact that we haven't made evolving life in the laboratory yet, I
think that you're expecting too much of your species. Let's say, as a
first guess, that it took blind Nature a billion years to make evolving
life on earth. You know how long a billion years is? The first fossil
record of animals of any of the modern phyla came with the Cambrian period,
about 600 million years ago. How much faster do you want us to go? Even
if you give us an advantage of a factor of a MILLION in speed, it would
still take us a thousand years to catch up to the billion-year
accomplishment of getting any kind of life at all. And how many of us do
you want to work on the problem? I don't know of any scientists who are
explicitly trying to create a living cell in the lab. I know of some who
are trying to understand and model certain aspects, such as movement,
transmembrane transport, self-duplication, and so on, but nobody is even
attempting to put it all together yet. And why should we be able to yet?
A hundred years ago, we didn't even understand the basic structure of the
atom. Fifty years ago, we had no idea how DNA told the body how to put
proteins together. We have made tremendous improvements in knowledge, but
we're nowhere near done. We still haven't made a black hole in the lab, we
still can't make a self-sustained controlled nuclear fusion reaction, and
we haven't synthesized life.
I won't even hazard a prediction of when life will be synthesized. So much
more needs to be understood before it can happen.
Richard Barrans Jr., Ph.D
James
I only have a brief comment. I see evolution not simply as species
modifying themselves either quickly or slowly to adapt to the environment,
but more a case of there being a variety of characteristics of species, and
those which make the species the 'fittest' for survival in the particular
environment surviving 'better' than the others. In this way, offspring in
the future would be more likely to contain the optimum characteristics for
survival while those with other options would be les likely to survive and
therefore less likely to appear in future populations by passing the same
characteristics to their offspring.
As far as reproducing this in the lab, I see that we could influence items
we perceive to offer enhanced survivability in the future....we already do
this in inoculating against disease, promotion of good diet, prescription of
vitamins etc. for promotion of good health and prevention of certain disease
arising from a lack of required nutrients. You might be thinking more along
the lines of other adjustments to the environment and would it be possible
to head-off changes in our environment with our own (enhanced) "evolution".
For example....if the ozone lay continues to be degraded by consumption of
chemicals here on earth, we might be interested in creating characteristics
that would enable us to survive against the predicted higher incidence of
skin cancers. This might eventually lead to a genetic change in our skin,
but more likely what would happen is that the survivability of those who are
fair skinned would be adversely affected by skin cancer, and due to their
early demise, the genes for those who are not fair skinned and can more
successfully deal with less of an ozone layer protection would be passed on.
The difficulty in this is predicting first where the environment is and
where it is headed, and then predicting what will be those issues which will
be beneficial or detrimental to our survival as a species. We can make some
short term predictions, but evolution works with the wisdom of the ages.
Thanks for using NEWTON!
Richard R. Rupnik
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Update: February 2012
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