What is
evolution?
Evolution is a broad, well-tested description of
how Earth’s present-day life forms arose from common ancestors
reaching back to the simplest one-celled organisms almost four
billion years ago. It helps explain both the similarities and the
differences in the enormous number of living organisms we see around
us.
By studying the sequence of changes in fossils found in successive
layers of rock as well as the molecular evidence provided by modern
genetics, scientists have been able to trace how ancient organisms--
through a process of descent with modification—gave rise to profound
changes in populations over time. Many new anatomical forms have
appeared, while others have disappeared. In a very real sense, we
are distant genetic cousins to all living organisms, from bacteria
to whales.
Evolution occurs in populations when heritable changes are passed
from one generation to the next. Genetic variation, whether through
random mutations or the gene shuffling that occurs during sexual
reproduction, sets the stage for evolutionary change. That change is
driven by forces such as natural selection, in which organisms with
advantageous traits, such as color variations in insects that cloak
some of them from predators, better enabling them to survive and
pass their genes on to future generations.
Ultimately, evolution explains both small-scale changes within
populations and large-scale changes in which new species diverge
from a common ancestor over many generations.
Is evolution “just a theory?”
In detective novels, a “theory” is little more
than an educated guess, often based on a few circumstantial facts.
In science, the word “theory” means much more. A scientific theory
is a well-substantiated explanation of some aspect of the natural
world, based on a body of facts that have been repeatedly confirmed
through observation and experiment. Such fact-supported theories are
not “guesses” but reliable accounts of the real world. The theory of
biological evolution is more than “just a theory.” It is as factual
an explanation of the universe as the atomic theory of matter or the
germ theory of disease. Our understanding of gravity is still a work
in progress. But the phenomenon of gravity, like evolution, is an
accepted fact.
Is there “evidence against”
contemporary evolutionary theory?
No. There are still many puzzles in biology about
the particular pathways of the evolutionary process and how various
species are related to one another. However, these puzzles neither
invalidate nor challenge Darwin’s basic theory of “descent with
modification” nor the theory’s present form that incorporates and is
supported by the genetic sciences. Contemporary evolutionary theory
provides the conceptual framework in which these puzzles can be
addressed and points toward ways to solve them.
Is there a
growing body of scientists who doubt that evolution happened?
No. The consensus among scientists in many fields,
and especially those who study the subject, is that contemporary
evolutionary theory provides a robust, well-tested explanation for
the history of life on earth and for the similarity within the
diversity of existing organisms. Very few scientists doubt that
evolution happened, although there is lively ongoing inquiry about
the details of how it happened. Of the few scientists who criticize
contemporary evolutionary theory, most do no research in the field,
and so their opinions have little significance for scientists who
do.
What is intelligent design?
“Intelligent design” consists of two hypothetical
claims about the history of the universe and of life: first, that
some structures or processes in nature are “irreducibly complex” and
could not have originated through small changes over long periods of
time; and second, that some structures or processes in nature are
expressions of “complex specified information” that can only be the
product of an intelligent agent.
Is
intelligent design a scientific alternative to contemporary evolutionary
theory?
No. Intelligent design proponents may use the
language of science, but they do not use its methodology. They have
yet to propose meaningful tests for their claims, there are no
reports of current research on these hypotheses at relevant
scientific society meetings, and there is no body of research on
these hypotheses published in relevant scientific journals. So,
intelligent design has not been demonstrated to be a scientific
theory. While living things are remarkably complex, scientists have
shown that careful, systematic study of them can yield tremendous
insights about their functions and origins (as it has in the past).
Intelligent design necessarily presupposes that there is an
“intelligent designer” outside of nature who, from the beginning or
from time to time, inserts design into the world around us. But
whether there is an intelligent designer is a matter of religious
faith rather than a scientifically testable question.
Why did AAAS
boycott the recent Kansas State Board of Education hearings on
evolution?
The Kansas State Board of Education, which is
dominated by intelligent design advocates, scheduled a series of
hearings beginning May 5 on proposed revisions to state science
standards. AAAS was invited to testify and “provide expert opinion
regarding the mainstream scientific view of the nature of science.”
After much consideration, AAAS respectfully declined to participate,
honoring a boycott called by the grassroots pro-science
organization, Kansas Citizens for Science. We saw little purpose in
a forum where evolution would be juxtaposed against “intelligent
design,” an unsubstantiated alternative that is a matter of
religious faith, not facts. The State Board established a format
which implied that scientific conclusions could be based simply on
the weight of witnesses' opinions rather than on scientific
evidence. We chose to support leaders of the Kansas science
community, who promoted the boycott and described the hearings as
rigged by proponents of intelligent design. In the end, with the
exception of a Kansas civil rights attorney, who pointed out the
farcical nature of the proceedings, only ID proponents testified.
Aren’t
scientists really just afraid to debate proponents of intelligent
design?
No, scientists actually thrive on debate, but only
according to the norms and standards of scientific investigation and
discourse. Scientists are bound by existing facts while the
opponents are not constrained by sticking to the verifiable evidence
and data.
Scientists see no point—and much danger—in pitting a scientific
concept like evolution against a non-scientific article of religious
faith like intelligent design. By agreeing to debate evolution,
scientists would be offering proponents of intelligent design a
veneer of scientific respectability that has not been earned in the
rough-and-tumble of everyday science. They also buy into a situation
where the public might expect an either-or outcome between science
and religion.
Doesn’t fairness require that
alternatives to contemporary evolutionary theory be taught in the public
schools?
No. This is not about fairness. Science requires
adherence to standards of research conduct and process. Intelligent
design has not met those standards and should not be taught in
science classrooms. If anything, it is unfair for proponents of a
non-scientific claim to try to force their views into science
classrooms.
Still, it appears that scientists are arrogant or elitist when they
refuse to participate in debates.
Scientists recognize that they can appear aloof by refusing to
appear in debates with intelligent design advocates in any and all
forums they demand. But scientific inquiry and debate is not subject
to the same ground rules as a media talk show. Scientific discourse
demands experimental evidence.
Scientists, including officials at AAAS and other groups, have been
very willing to talk to reporters, community groups and others about
their reasons for supporting evolution and their misgivings about
proposed school board actions in Kansas and elsewhere. We trust the
good judgment of parents and community leaders when all of the facts
are known.
Are
scientists trying to stifle discussion of intelligent design?
We do not want to censor discussion of intelligent
design in the proper setting but the school science classroom is not
that setting. Nor do we want to portray evolution as some
carved-in-stone dogma. Science is an ongoing process, with new
evidence accepted and weighed constantly. Intelligent design
advocates have yet to contribute in a scientifically rigorous manner
to that process.
AAAS has worked hard to guarantee that children get a first-class
science education. We’ve helped set the objectives for what should
be taught and learned in science classrooms. We want to prevent an
erosion of the quality of science education. In the case of Kansas,
that would be unfortunate at a time when the state is trying to
attract high-tech industry and it, like other U.S. states, is trying
to nurture more homegrown science talent.
Are
science and religion inherently opposed?
No. Science does not take a position on an
intelligent designer, which is a matter of religious faith, and is
not testable scientifically. AAAS and other scientific groups do not
want to create the impression that religion and science are
inherently in conflict. They live together quite comfortably,
including in the minds of many scientists.
Science and religion ask different questions about the world. Many
individual scientists are deeply religious. They see scientific
investigation and religious faith as complementary components of a
well-rounded life.
Can
science stimulate religious thought?
Yes. A particular religion’s understanding of the
world provides the context from which questions of meaning emerge. A
development in science may provide a new more reliable explanation
of the structure and processes of the world. This may be different
from the understanding of the world that is presumed in a particular
religion. What may appear to be a conflict between science and
religion is actually a contrast between earlier and more recent
understandings of the world (e.g., between an earth-centered
universe and a sun-centered universe) and can be a constructive
stimulus for religious inquiry. In fact, Jewish, Christian, Muslim,
Buddhist and Hindu scholars have sought positive ways to relate
evolutionary theory with their religious traditions.
Is the
science classroom the appropriate place to discuss the religious
interpretations of science?
No. Religion is a subject of inquiry in
historical, philosophical and social studies, not in science. So,
discussion about religion is most appropriate in the social studies
or humanities curriculum, not in the science curriculum.
Have
scientists underestimated the impact of the intelligent design movement?
Many scientists probably have been caught
unawares, in part, because they don’t see an inherent conflict
between science and religion. They often are more comfortable in the
laboratory, doing science and communicating it to students, than
they are in the public arena. But it is clear they can no longer
afford to ignore the political reality of the intelligent design
movement and its effort to sway school boards and curriculum
committees in many states and communities. The AAAS is determined to
remain engaged on this issue and encourages other scientific groups
to do so as well, particularly at the grass roots level.
What are
the stakes?
The risk, if intelligent design is incorporated
into school curricula, is to undermine scientific credibility and
the ability of young people to distinguish science from non-science.
And that is what matters more, in the longer term, than the specific
battles over intelligent design versus evolution. In Kansas,
advocates of "intelligent design" are attempting to redefine what is
and is not science, in direct conflict with the science standards
recommended by both the National Academy of Sciences and AAAS in
earlier work. They are pushing the board to reject a definition that
limits science to natural explanations for what's observed in the
world. They want to define it so that science will include
supernatural explanations.
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