The
history of science contains many cases of theories that were oversold
by eager apostles. One of the main cases today involves the
overselling of the theory of natural selection. In this case many of our biologists are representing as “settled science” the
idea that natural selection is the main cause for evolution. The
evidence for evolution is good, but the evidence is quite weak that
natural selection is the main cause of evolution in large organisms.
Let
me clarify the difference between evolution and natural selection.
Evolution is the idea that over very long periods of time, species
very gradually undergo changes, developing novel adaptions to their
environment, with such adaptions sometimes becoming sufficient for
one species to evolve into a different species. Natural selection is
a hypothesis about the cause of evolution. Natural selection says
that evolution occurs mainly because organisms that are more fit to
survive tend to reproduce more. Darwin introduced both the basic
idea of evolution and the theory of natural selection at the same
time, in a book entitled On the Origin of Species by Means of
Natural Selection. But it is quite possible to believe in
evolution without believing that natural selection is its main cause.
The
modern theory of natural selection is all centered around the idea of
random mutations. The idea is that the blueprint of a species (found
in its DNA) undergoes random changes called mutations, which might be
produced by something like a cosmic ray hitting the DNA stored in a
cell, or a random “copying error” when the DNA is not copied
exactly right. In some cases, it is claimed, these random changes
result in a change that is actually beneficial. When such a thing
happens, it is claimed, natural selection causes the organisms that
had such mutations to reproduce more often than some other organisms
in that species which did not have such a mutation. It is claimed
that this causes the mutation to be inherited more and more often in
later organisms belonging to that species. Such a process, it is
claimed, it so powerful that it can account for all kinds of
astonishing adaptions in organisms.
Now
the question is: what evidence is there for this theory that natural
selection is the main force behind evolution? Although there is lots
of historical evidence for evolution (found in the fossil record),
there is no significant historical or fossil evidence that natural
selection has been the main cause of evolution in large organisms. Think
for a moment of the difficulties of ever getting such evidence. In
almost all cases when we have a fossil record of some organism that
existed eons ago, we don't have DNA from that organism. Even if we
had that DNA (from a few dead organisms), it would still not be
enough to figure out the history of DNA changes in a species from long ago, and whether or not natural selection was the cause of evolution in a
particular species.
It
turns out that getting evidence for natural selection requires an
incredibly hard procedure. This procedure has been attempted on some
small organisms with very short lifespans (such as bacteria and fruit
flies). The procedure might go something like this:
- You start out with a population of organisms of some type, and you carefully record the DNA of all of those organisms.
- You track the evolution of these organism over many generations, while applying some factor that causes lots of mutations. The DNA of these organisms must be checked at very many times.
- You attempt to determine whether useful new adaptions are being evolved, and attempt to determine whether such adaptions (this new functionality of evolutionary novelty) are being produced by natural selection and random mutations.
The
experiments that have been done along these lines have produced very
modest results. The study here studied 600 generations of fruit
flies, finding no change more dramatic than a 20% shorter life cycle.
Another
experiment is Richard Lenski's long-term experiment on bacteria,
which has tracked more than 60,000 generations of bacteria. The
results of this experiment have been modest, with the main result merely being that the
bacteria seem to have developed an ability to digest citrate that it
did not have before. Documenting such an adaption is “peanuts” compared
to demonstrating that a significant and complicated structural
innovation (such as the human eyeball or a wing) did occur because of natural selection (something that no
one has ever demonstrated).
Even
Lenski's meager result is subject to doubt, as a large fraction of
scientific experiments are not replicated when another experimenter
tries to replicate them (and in the case of Lenski's experiments, it
will be decades before we can determine whether someone is able to
replicate his results).
There
is a simple reason why experiments of such a type can never show that
natural selection is the main cause of evolution in large organisms.
The shorter the life cycle of an organism, the more likely it might
be for it to evolve beneficial changes because of natural selection.
Bacteria such as those in Lenski's experiment have a lifespan about
130,000 times shorter than a human lifespan, and can double their
population in only about an hour. It is all too possible that
natural selection is sufficient to cause useful adaptions in very
short-lived organisms such as bacteria, but is not sufficient to
cause useful adaptions in large, long-lived organisms such as
animals as large as a dog or larger.
But
isn't there some way, in theory, that you could prove natural
selection by using large long-lived animals such as mammals? Yes, in
theory there is. But it has never been done, and would be a nightmare
to do, as it would take ages.
Imagine
how the project might be executed. After building some special
testing environment (perhaps some special large building), you would
start out with a population of some large species with a lifespan of
more than decade. You would take samples of the DNA of each organism
in such a population. You would then monitor such a population over
many generations, frequently taking DNA samples to see how the DNA
was changing. Since a generation for such organisms would take at
least a year, the project would have to probably last for thousands
of years. All in all, it would be a project more difficult than
landing men on Mars. No one has ever done such a project, or even
one tenth of such a project.
It
would seem that for reasons such as these, the theory that natural
selection is the main explanation for the evolution of large animals
is one that simply is not very susceptible to experimental
verification. But what about some other approach? What about some
approach in which we get the predictions of the natural selection
theory, and then try to verify that such predictions are coming true?
But
that doesn't work either. The reason is that the modern theory of
natural selection is all centered upon the idea of blind chance. The
theory assures us that natural selection will do random stuff we
can't predict. So there is not much of a way to match up reality with
the predictions of natural selection. For example, natural selection
does not give us any predictions about what a particular organism
will evolve to in the future. So there is no way to exactly match up
predictions and reality when trying to get proof for natural
selection.
So
from the standpoint of being verified, the theory that natural
selection is the main driver of evolution in large animals is on
incomparably weaker ground than other scientific theories which do
make a host of exact numerical predictions that are repeatedly
verified to the letter. Using a theory such as the theory of
gravitation, one can make very precise predictions such as the
prediction that a particular object released from a particular height
will hit the ground 14.5 seconds after it has been dropped. Such
predictions have been verified countless times. But the theory of
natural selection has no such record of predictive success. Some of
the things that are sometimes claimed as “successful predictions”
of the theory (such as the discovery of something like DNA) are not
actually predictions uniquely predicted by the theory. A nonbeliever
in natural selection would have been just as likely to have predicted
that something like DNA existed before it was discovered.
Eager
to try to prove that natural selection is an important determinant of
human traits (or the main determinant), some scientists have resorted
to statistical analysis of DNA (the genome). But such studies may not
be mathematically sound. In 2009 Phys.org published this article
stating the following:
Scientists
at Penn State and the National Institute of Genetics in Japan have
demonstrated that several statistical methods commonly used by
biologists to detect natural selection at the molecular level tend to
produce incorrect results. "Our finding means that hundreds of
published studies on natural selection may have drawn incorrect
conclusions," said Masatoshi Nei, Penn State Evan Pugh Professor
of Biology and the team's leader.
Likewise
the paper here states, “Many of
the statistical methods for detecting natural selection are
unreliable.”
The study Genome-Wide
Scans for Footprints of Natural Selection
notes, “a puzzlement arises when we inspect how modest is the
replication for discovery of different genomic regions between
algorithmic approaches or between different studies.”
Given
these items, one must wonder whether scientists scanning the genome,
eagerly looking for faint traces of natural selection, are much
different from UFO enthusiasts scanning photos of Mars and
occasionally claiming to have found something important. Given a
mountain of data, sufficient time and a huge toolkit of statistical
methods to choose from, it is not too unlikely that you may be able
to find “faint traces” of exactly whatever it is that you were
hoping to find. I may also note that finding some statistical trace
of natural selection would not by itself prove that natural selection
is the main thing driving evolution in larger organisms such as man.
It is entirely possible that natural selection is a relatively minor
effect in species with long lifetimes, and the main thing propelling
evolution is something else.
There
are also very substantial reasons for doubting that natural selection
is the main thing that caused evolution in humans. The best reason I
know of is the inability of natural selection to explain dozens of
human mental faculties and traits that do not seem to be adaptions that contribute to reproductive success. Consider
this question: what is it intellectually that makes a human different
from a monkey? There are many things: we have good language ability;
we're good at math; we have morality; we are spiritual; we have esthetic abilities that allow us to create and appreciate art; we
have inner lives and introspection; we can form abstract ideas and
ponder philosophical questions; and so forth. But none of these
things are biological adaptions that improve an organism's likelihood
of surviving until reproduction. So none of these things can be
explained by natural selection. It would seem, in fact, that natural
selection theory predicts that such things as these should not even
exist.
Human traits hard to explain by assuming natural selection
So
far from just being a case of natural selection not making
predictions that we can verify, the problem seems to be that natural
selection theory would seem to make counterfactual predictions about
human nature – that you should not have any important
characteristics unless they make you more likely to survive until
reproduction (in other words, that you should not have most of the
things that make you different from a monkey).
The
difficulty of using natural selection to explain the origin of man's
mental capabilities is compounded by the fact that about 200,000
years ago the population of humanity was believed to be small, as few
as 10,000. The fewer organisms there are in a population, the more
unlikely that there will be enough mutations for natural selection to
produce something useful.
I
may point out here that you could not counter these arguments merely
by pointing out some evidence that natural selection occurs. Let's
consider three different ideas that can be listed in a table.
Hypothesis 1 | Natural selection occurs. |
Hypothesis 2 | Natural selection occurs, and is the main cause of new adaptions or features in small organisms with short lifespans (bacteria, fruit flies, etc.) |
Hypothesis 3 | Natural selection occurs, and is the main cause of new adaptions or features in large organisms such as humans. |
You
do not prove Hypothesis 3 by merely proving Hypothesis 1 or
Hypothesis 2. Since the reproduction rate of tiny organisms may be
thousands or tens of thousands of times greater than the reproduction
rate of large organisms, you don't prove Hypothesis 3 by proving
Hypothesis 2. So you can't successfully rebut this post by merely
citing something that supports Hypothesis 1 or Hypothesis 2.
Given
all these problems with the idea of assuming that natural selection
is the main cause of evolution in large organisms, why is such an
idea being sold as “settled science”? Why are we being
dogmatically assured by so many biologists that they understand what
caused the appearance of man's higher traits? I think it's a
case of premature triumphalism. After first figuring out that
evolution is occurring, our biologists should have merely said to
themselves: we have completed one lap, but there are still 10,000
laps to go before we understand this. But instead scientists crowned
their heads with laurel leaves (and put gold medals around their
necks) after completing the first lap – by assuming that the first
major book on evolution had also figured out what the cause of it is.
It is all too plausible that the actual cause of evolution is some
principle or principles far more complex and vastly more deep than
the simple idea of natural selection. If we ever understand such a
principle or principles, I suspect we will find that it is also the
explanation of the origin of life, something entirely unexplained by
the theory of natural selection.
It
is entirely possible that the main thing driving evolution is some
natural mechanism far deeper and more sophisticated than natural
selection – some mechanism involving undiscovered laws of nature or
undiscovered information processes (or both) that tend to work in a
teleological or anti-chaotic manner, causing more and more complex
things to emerge from simpler things. Nature could have embedded
within it some kind of programming (or something that acts like
programming), some wellspring of emergence that acts as an antithesis
to the Second Law of Thermodynamics, causing ever-increasing order as
time passes. Such a principle might be behind the evolution of man's
faculties, the origin of life, and the physical ordering of the
universe since the time of the Big Bang.
Postscript: See the link here for a 2-sentence statement signed by hundreds of scientists and PhD's. The statement states exactly the following:
We are skeptical of claims for the ability of random mutation and natural
selection to account for the complexity of life. Careful examination of the
evidence for Darwinian theory should be encouraged
Postscript: See the link here for a 2-sentence statement signed by hundreds of scientists and PhD's. The statement states exactly the following:
We are skeptical of claims for the ability of random mutation and natural
selection to account for the complexity of life. Careful examination of the
evidence for Darwinian theory should be encouraged
No comments:
Post a Comment