Evolution, 4th Edition

574 CHAPTER 22

Throughout this book, we have seen how evolution by natural selection sheds

light on almost every area of biology, including the origin and diversification of

humans. Any science that explains so much must have practical uses and implica-

tions for our lives—the main topic of this last chapter. But many people, especially

in the United States, do not accept evolution. So we will come to grips with anti-

evolutionary arguments, and how to refute them (BOX 22A). What is at stake is not

only society’s appreciation of “the single best idea anyone has ever had,” but more:

society’s acceptance of science in general, and of the role of evidence and reason.

Because there is no evidence for supernatural creation of

organisms, opponents of evolution usually try to demon-

strate the falsehood or inadequacy of evolutionary science

and to show that biological phenomena must, by default,

be the products of intelligent design. Here are some of

the most commonly encountered creationist arguments,

together with capsule counterarguments. We emphasize

that these are not arguments against religion as such.

1. Evolution is outside the realm of science because it can-
   not be observed.
   Evolutionary changes have indeed been observed, as we
   have noted throughout this book. In any case, most of sci-
   ence depends not on direct observation, but on testing
   hypotheses against the predictions they make about data.


2. Evolution cannot be proved.
   Nothing in science is ever absolutely proved. “Facts” are
   hypotheses in which we can have very high confidence
   because of massive evidence in their favor and the
   absence of contradictory evidence. Abundant evidence
   from every area of biology and paleontology supports
   the fact of evolution, and there exists no contradictory
   evidence.


3. Evolution is not a scientific hypothesis because it is not
   testable: no possible observations could refute it.
   Many conceivable observations could refute or cast seri-
   ous doubt on evolution, such as finding incontrovertibly
   mammalian fossils in incontrovertibly Precambrian rocks.
   In contrast, any puzzling quirk of nature could be attrib-
   uted to the inscrutable will and infinite power of a super-
   natural intelligence, so creationism is untestable.


4. The orderliness of the universe, including the order
   manifested in organisms’ adaptations, is evidence of
   intelligent design.
   Order in nature, such as the structure of crystals, arises
   from natural causes and is not evidence of intelligent

design. The order displayed by the correspondence

between organisms’ structures and their functions is

the consequence of natural selection acting on genetic

variation. Darwin’s realization that the combination of

a random process (the origin of genetic variation) and

a nonrandom process (natural selection) can account

for adaptations provided a natural explanation for the

apparent design and purpose in the living world and

made a supernatural account unnecessary and obsolete.

5. Evolution of greater complexity violates the second law
   of thermodynamics, which holds that entropy (disorder)
   increases.
   The second law applies only to closed systems, such
   as the universe as a whole. Order and complexity can
   increase in local, open systems as a result of an influx of
   energy. This is evident in the development of complex
   individual organisms, in which biochemical reactions are
   powered by energy derived ultimately from the Sun.


6. It is almost infinitely improbable that even the simplest
   life could arise from nonliving matter. The probability of
   random assembly of a functional nucleotide sequence
   only 100 bases long is 1/4^100 , an exceedingly small
   number. And scientists have never synthesized life from
   nonliving matter.
   It is true that a fully self-replicating system of nucleic
   acids and replicase enzymes has not yet arisen from
   simple organic constituents in the laboratory, but the his-
   tory of scientific progress shows that it would be foolish
   and arrogant to assert that what science has not accom-
   plished in a few decades cannot be accomplished. (And
   even if, given our human limitations, we should never
   succeed in this endeavor, why should that require us to
   invoke the supernatural?) Some critical steps in the prob-
   able origin of life have been demonstrated in the labo-
   ratory (see Chapter 17). And there is no reason to think
   that the first self-replicating or polypeptide-encoding

BOX 22A

Refuting Antievolutionary Arguments

22_EVOL4E_CH22.indd 574 3/22/17 1:49 PM