|Our Evolutionary Inheritance|
When creationists say that there
are no transitional fossils to support the theory of evolution, they are implicitly
assuming a kind of evolution that always takes place little by little. This view
of evolution is inherited from Darwin, who did conceive of evolution as a process
that occurs gradually.
But since Gould and Eldredge posited their theory
of punctuated equilibria, we know that evolution can occur in other ways.
Indeed, some species can evolve very rapidly over periods that are brief in geological
terms, followed by long periods of stagnation. Considering the rarity of the conditions
necessary for fossilization, we can understand why there will necessarily be some
“"gaps" in the fossil record. That in no way invalidates evolution
as we understand it today, especially after the important contribution made by
Gould and Eldredge.
Their theory of punctuated equilibria does not constitute
a complete paradigm shift, but it does let scientists revisit Darwin's initial
intuitions about the process of evolution, intuitions that some thinkers were
too quick to freeze into dogma.
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|CREATIONIST ATTACKS ON EVOLUTION|| |
For the past two decades,
United States has been subjected to the growing influence of “"creationists"
who believe that the story of creation as told in the Bible must be taken literally...
in other words, that the universe was created in six days, scarcely 6 000 years
from the fact that the fundamentals of creationism are contradicted by all the
currently available scientific data, many of the criticisms that creationists
commonly direct against the theory of evolution reflect a misunderstanding of
what evolution actually is.
Here are some of the most
common creationist criticisms of evolution, along with the counter-arguments based
on an accurate understanding of this subject.
has never been observed.”
Evolution is basically defined as
a change in the gene pool of a species over time. There are myriad examples of
this phenomenon, such as bacteria that develop resistance to drugs or insects
that develop resistance to pesticides over a short period of time. The emergence
of new species has also been observed both in the laboratory and in nature, especially
among fruit flies. And even if we did not have these direct observations, the
theory of evolution has enabled us to make predictions regarding the fossils of
species that have now disappeared, and in terms of both comparative anatomy and
geographic distribution, these predictions have proven accurate in a multitude
violates the second law of thermodynamics.”
This law states
that the entropy (or “"disorder") in a closed system can only
increase. Creationists simplify this law by stating that order (and hence life)
cannot have emerged from the disorder of the inanimate things found on Earth.
But creationists thereby ignore one major fact: the Earth is not a closed system.
It constantly receives energy from the Sun and sends energy back out into the
universe in such forms as infra-red radiation. In an open system like this, order
(or “"negentropy") can be created locally provided that energy
is degraded on a larger scale, which is the case for the organisms living on Earth.
In any case, the tendency for matter to organize itself is observed even in inanimate
things: snow flakes, sand dunes, tornadoes, and lightning bolts are several good
There are gaps (missing links) in the
First of all, there are some impressive
sequences of fossils that demonstrate the most minute steps in the transitions
from reptiles to mammals and from ancient primates to ancient humans, for example.
The presence of gaps in no way discredits the theory of evolution. Such gaps have
many possible causes, such as erosion of fossil-bearing formations, the rareness
of conditions conducive to fossilization, and the fact that speciation can occur
in a small population or a limited area, or very rapidly (see sidebar).
“The theory of evolution is based on
the idea that life emerged solely by chance.”
Chance, in the
form of the random mutations that are the source of genetic diversity, does indeed
play an essential role in evolution. But to say that evolution is based solely
on chance is to badly misunderstand the equally fundamental role played by natural
selection. It is only by favouring some genetic variants over others that organisms
better adapted to their environment can evolve.
final argument that creationists marshal to try to undermine the theory of evolution
is what they call “"intelligent design". It is based on a more
subtle line of reasoning: that the living world is so complex that only an intelligence
outside our universe could have planned it down to the last detail. But here again,
proper understanding of the theory of evolution would seem to obviate the need
to posit an intelligent design or a “"higher consciousness".