Transcript Misconceptions about Evolution and the Mechanisms of Evolution

Misconceptions about
Evolution and the Mechanisms
of Evolution
Adapted from Understanding Evolution, a
website developed by the University of
California Museum of Paleontology with
support provided by the National Science
Foundation and the Howard Hughes Medical
Institute.
Unfortunately, people have
misconceptions about evolution
•Some are simple
misunderstandings
•Some are ideas that
develop in the course of
learning about evolution,
possibly from school
experiences and/or from the
media.
•Other misconceptions may
stem from purposeful
attempts to interfere with
the teaching of evolution.
Evolution and How it Works
•Misconceptions are unfortunately very
common.
•Most of these misunderstandings have to do
with assumptions that evolution proceeds in a
particular direction or that individual living
things can choose to adapt.
“Evolution is a theory about the origin of life.”
•Evolution deals mainly with how
life changed after its origin.
•Science does try to investigate
how life started but not as the
central focus of evolutionary
theory.
•Whether or not we understand
how life began, we do understand
a lot about what happened during
the history of life.
“Evolution is like a climb up a ladder of
progress; organisms are always getting better.”
•Natural selection weeds out individuals that are unfit in a particular
situation.
•For evolution, “good enough” is good enough. No organism has to
be perfect.
•They are not marching up a ladder of progress but need to be fit
enough to survive and reproduce.
•Other taxa may have changed and diversified a great deal—but that
doesn’t mean they got “better.”
•What works “better” in one location might not work so well in
another.
Fitness is linked to environment, not to progress.
“Evolution means that life changed ‘by chance.’ ”
•Chance is certainly a factor in evolution, but there
are also non-random evolutionary mechanisms.
•Random mutation is the ultimate source of genetic
variation
•Natural selection, the process by which some
variants survive and others do not, is not random.
•To say that evolution happens “by chance” ignores
half of the picture.
“Natural selection involves organisms ‘trying’
to adapt.”
•Natural selection leads to adaptation, but the process
doesn’t involve “trying.”
•Natural selection involves genetic variation and selection
among variants present in a population.
•An individual has genes that are good enough to survive
and reproduce, or it does not.
“Natural selection gives organisms what
they ‘need.’ ”
•Natural selection has no
intentions or senses.
•If genetic variation allows some
individuals to survive a particular
challenge better than others, they
will have more offspring in the
next generation, and the
population will evolve.
•If not in the population, the
population may still survive (but
not evolve much) or it may die
out.
•But it will not be granted what it
“needs” by natural selection.
Evidence Regarding Evolution
Many of the misconceptions about the evidence
supporting evolution have been planted in the minds
of the public through antievolution propaganda.
The following notions may appear compelling at first
glance, but are easily debunked with a little
information.
“Evolution is ‘just’ a theory.”
Scientific theories are explanations that are based
on lines of evidence, enable valid predictions, and
have been tested in many ways. In contrast, there
is also a popular definition of theory—a “guess”
or “hunch.” These conflicting definitions often
cause unnecessary confusion about evolution.
“Evolution is a theory in crisis and is collapsing
as scientists lose confidence in it.”
Debate is not whether evolution (descent with modification)
took place, but how it took place.
Details of the processes and mechanisms are vigorously
debated.
Evolution is sound science and is treated accordingly by
scientists and scholars worldwide.
‘Project Steve’ and bogus lists
of scientists who don’t
support evolution
“Gaps in the fossil record disprove evolution.”
There are lots of transitional forms.
What counts as transitional? When has something
changed ‘enough?’
That transitional fossils are not preserved does not
disprove evolution.
Science actually predicts that for many evolutionary
changes there will be gaps in the record.
“Evolutionary theory is incomplete and is currently
unable to give a total explanation of life.”
Evolutionary science is a work in progress.
New discoveries & new hypotheses made to explain them—
just like other sciences
We can’t know everything about evolution but…
We do know a great deal about the history of life
Evolution is the only well-supported explanation for life’s
diversity.
“The theory of evolution is flawed, but
scientists won’t admit it.”
No support for creationists
claims about flaws.
Usually they are
misunderstandings of
evolution or
misrepresentations of
evidence.
Scientific refinement
process doesn’t mean there
are flaws.
Scientific method is mean
to point out any real flaws.
“Evolution is not science because it is not
observable or testable.”
•Evolution is observable and testable.
•Science is not limited to controlled
experiments Actually, much is
accomplished by gathering evidence
from the real world and inferring how
things work.
•Multiple lines of evidence allow valid
and useful inferences
“Most biologists have rejected ‘Darwinism’
(i.e., no longer really agree with the ideas put
forth by Darwin and Wallace).”
•Evolution generally proceeds at a slow, deliberate pace but can
proceed at a relatively rapid pace under some circumstances.
•In this sense, “Darwinism” is continually being modified.
•Modification is how things work in science.
•No credible challenges to the basic Darwinian principles so far.
•Scientists have not rejected Darwin’s natural selection, but
have improved and expanded it.
‘Project Steve’ and bogus lists of scientists
who don’t support evolution
The statement:
Evolution is a vital, well-supported, unifying principle
of the biological sciences, and the scientific evidence
is overwhelmingly in favor of the idea that all living
things share a common ancestry. Although there are
legitimate debates about the patterns and processes of
evolution, there is no serious scientific doubt that
evolution occurred or that natural selection is a major
mechanism in its occurrence. It is scientifically
inappropriate and pedagogically irresponsible for
creationist pseudoscience, including but not limited to
"intelligent design," to be introduced into the science
curricula of our nation's public schools.
As of a year ago, 688 scientists with some version of
Steve in their name had signed the document.
Implications of Evolution
Evolution has one implication—it explains the
history of life.
Other implications allegedly derived from
evolutionary theory have been used to support the
denial of evolution or to justify inhumane behavior.
.
“Evolution leads to immoral behavior. If
children are taught that they are animals,
they will behave like animals.”
•Humans are animals.
•We share anatomical and
biochemical traits as well as
behaviors, with other animals
•Some behaviors are specific
to particular animals.
•Linking immoral or
inappropriate behavior to
evolution makes no sense.
•Morality is not based on what
is, but on what ought to be.
“Evolution supports the idea that ‘might makes
right’ and rationalizes the oppression of some
people by others.”
•“Social Darwinism” arose
from a misguided effort to
apply lessons from
biological evolution to
society.
•Pre-existing prejudices
were rationalized to
promote social and
political agendas.
•The “science” of Social
Darwinism was refuted.
•Biological evolution has
stood the test of time, but
Social Darwinism has not.
Evolution and Religion
The alleged incompatibility of religion and evolution
has been used as a way of persuading people to
deny the history of the Earth.
“Evolution and religion are incompatible.”
•Religion and science
(evolution) are very
different things.
•In science only natural
causes are used to explain
natural phenomena.
•Religion deals with beliefs
that are beyond the natural
world.
•The misconception that
one has to choose between
science and religion is
divisive.
Teaching Evolution
Misconceptions about what should be taught in the science
classroom stem from confusion about the nature of science
itself.
Science is about figuring out how things work and relies on
empirical knowledge, not faith.
Antievolutionists have tried to confuse science and
religion, leading to the following misconceptions in the
minds of some members of the public.
“Teachers should teach ‘both sides’ and let
students decide for themselves. ”
“Evolution is itself ‘religious,’ so requiring
teachers to teach evolution violates the First
Amendment.”
•Evolution is science.
•The study of evolution relies on evidence
and inference from the natural world.
•Thus it is not a religion.
Why is Evolution Relevant and
Important to Study?
Solving biological problems
•Biological systems evolve, which means that variables
always change and history always matters.
•If we don’t take evolution into account, our solutions to
biological problems are likely to fail.
•Understanding evolution helps solve biological problems
that impact our lives.
Understanding how diseases
evolve helps us administer
vaccines most effectively.
Understanding the evolution of insects
helps us devise more effective methods
of pest control.
Medical Science
Vaccine
development
A researcher
examines a gel used
in DNA analysis
Agriculture & Economics
The mass production of genetically-similar
foods (like the grain being harvested here, and
these red onions) makes our groceries
inexpensive, but leaves them vulnerable to
diseases and pests.
Irish Potato
Famine
Grape
phylloxera
Conservation
Kemp's Ridley sea turtle
Right whale
Hairy-nosed wombat