Download Lecture #2: Introduction to Evolution

Lecture #2: Introduction to Evolution
If you are at all familiar with culture in the United States today, you are aware
that there is a bit of a cultural disagreement—in some circles--about whether
evolution is true. This disagreement is not found in the scientific community,
which universally accepts the physical evidence that evolution is not any sort of
“belief” or ideology. It is merely a physical process of change that we can observe
happening now, in living species. We can infer that this has been happening for a
very, very long time because of many other forms of physical evidence. And it is
this we’ll discuss today.
What is Evolution?
Evolution is defined as change over time. Many things evolve, from car models
to hair styles to languages to religions.
species = similar organisms that can interbreed in nature to produce fertile (i.e.,
able to have their own offspring), viable (i.e., able to live) offspring. To put it
another way, members of different species are reproductively isolated from
each other.
population = members of the same species living in a defined area
ORGANIC evolution is change in the genetic makeup of populations over time.
microevolution – genetic change within a species (no new species created)
macroevolution – genetic change that results in new species
“Nothing in Biology makes sense, except in the light of evolution.”
-- Theodosius Dobzhansky (1900 – 1975)
Theodosius Dobzhansky was a devout Christian who found he could reconcile
belief in a supreme being with the strong evidence for evolution all around us. His
quote above was made in an essay published in American Biology Teacher, where
he created the notion of theistic evolution
Theistic evolution is a concept that asserts that classical religious teachings
about God are compatible with the modern scientific understanding about
biological evolution. Theistic evolutionists believe in a supreme being, that this
supreme being created the physical universe and its laws, and that all life within
the universe evolved as a consequence of those natural laws.
Do You Believe in Evolution?
I pose a question to you: Do you believe in evolution?
Dr. Krempels sez: NO.
This might surprise you. But let me explain how I came to this conclusion.
1. Observable evidence in the earth:
 Radiometric dating and other scientific methods tell us clearly that the earth
is billions of years old (about 4.5 billion, to be more precise).
 If a Supreme Being who actually created the universe and all its inhabitants
in the proverbial seven days, but also decided to create all of this “fake” scientific
evidence to fool us, then I guess the joke’s on us.
 (If so, this Supreme Being has a twisted sense of humor.)
2. Physical evidence in living things:
Living organisms have amazing similarities in their
(1) DNA
(2) physical form (morphology)
(3) embryo development (related species have similar embryo development)
(4) other features (similar proteins, behaviors, etc.)
 These similarities are not trivial, nor are they superficial.
 We can see traits being passed from parent to child in living species today
 Often, traits are passed on in slightly changed form from one generation to
the next.
 We have no reason to believe that this process has not been going on for as
long as the life has existed.

3. Physical evidence from the past
 Fossilized organisms tell us that many species no longer exist, but that they
were very similar to those alive today.
 In fossils, we see a progression of change and complexity over time.
 This can be explained by natural processes we see going on now in front of us.
 It it not necessary to invoke the actions of a Supreme Being to explain this.

4. Physical evidence in Biogeography
 The geographic distribution of living species is congruent with their evolutionary
history and genetic relationships.
 We can see how, as the continents drifted apart (from the giant land mass
known as Pangaea breaking into southern Gondwanaland and northern
Laurasia, and then into the continents we know today), the species carried on
them gradually became different as they were no longer able to share their
genes with each other.

 Science is based on knowledge gained by observation of physical evidence.
 Religion is based on faith in that which cannot be observed.
 Unlike religious dogma, scientific inferences are subject to revision as new
data become available.
 So, to answer your question: No, I do not believe in evolution. I accept it as
the most logical explanation for observable fact.
 Belief is not an issue.
Is Evolution “Only a Theory?”
Question: Some say that evolution is “Only a Theory.” Is that true?
Answer: NO.
Remember: in Science, the word “theory” has a very specific meaning. It is not
the same as the meaning of “theory” in everyday language (which sort of means
“a guess”). Science operates under a set of rules. Remember our discussion (The
Scientific Method) about the difference between (1) hypothesis, (2) theory, and
(3) law in science.
Evolution is none of these. It is a PROCESS and an OBSERVABLE FACT.
Hypothesis
A hypothesis is an educated guess, based on observation. Usually, a hypothesis
can be supported or refuted through experimentation or more observation. A
hypothesis can be disproven, but not proven to be true.
Theory
A scientific theory summarizes a hypothesis or group of hypotheses that have
been supported with repeated testing. A theory is valid as long as there is no
evidence to dispute it. Therefore, theories can be disproven. Basically, if evidence
accumulates to support a hypothesis, then the hypothesis can become accepted as
a good explanation of a phenomenon. One definition of a theory is to say it's an
accepted hypothesis.
Law
A law generalizes a body of observations. At the time it is made, no exceptions
have been found to the law. Scientific laws describe things, but they do not
explain them. One way to tell a law from a theory is to ask if the description
allows you to explain “why” something happens. (If it does, it’s a theory; if it
doesn’t, it’s a law.)
Example: Newton’s Law of Gravity allows you to predict that a dropped object will
fall, but it doesn’t explain why.
As you can see, there is no 'proof' or absolute 'truth' in science. The closest
we get are facts, which are indisputable observations.
Note, however, that if you define proof as arriving at a logical conclusion based on
evidence, then there is “proof” in science. But if you mean that proving something
implies that it can never be wrong, then that’s different. And the word “proof” can
mean different things in different branches of science. So be very careful when
you use these words.
What is theoretical about evolution?
Evolution is not a religion, belief, or ideology.
Definitions of ideology a : a systematic body of concepts especially about human life or culture
b : a manner or the content of thinking characteristic of an individual, group, or
culture
c : the integrated assertions, theories and aims that constitute a sociopolitical
program
Evolution is none of these. Evolution is a process of change that we can observe.
The only thing theoretical about evolution is how it happens.
So it’s really not correct to call someone an “evolutionist” or “Darwinist”, as these
terms imply a type of ideological belief that those who accept evolution as fact
simply do not have.
So why did Darwin say we evolved from monkeys?
Well…that’s just it. HE DIDN’T.
Darwin’s contribution to the study of evolution was providing a scientifically
testable mechanism by which it happens: NATURAL SELECTION.
Here’s what Darwin actually said (distilled down into four tenets):
1. Overproduction: Organisms are capable of producing huge numbers of
offspring
2. Heritable Variability: Those many offspring carry variable traits that are
heritable.
3. Limited Resources: Those variable offspring must compete for limited
resources.
4. Differential Reproduction: Those whose heritable traits make them better
at acquiring resources will leave the most offspring.
The precise definition of evolutionary (Darwinian) fitness is the
proportion of genes you leave to the next generation (compared
to other members of your species).
Any physical/heritable trait may be:
adaptive – it increases the likelihood of leaving offspring
maladaptive – it decreases the likelihood of leaving offspring
neutral - doesn’t affect the likelihood of leaving offspring
Common misconceptions about evolution:
1. Evolution is a theory about the origin of life.
INCORRECT. Evolution is the process by which life changes, not the way it got
here.
2. Evolution is a process by which species become better over time.
INCORRECT. Evolution has no value system. It’s merely a process by which
different species become better adapted to the particular habitat in which they
live. A species evolutionary fitness is determined by its success in its habitat.
3. Evolution is driven by organisms’ need for a particular trait.
INCORRECT. Organisms do not evolve traits because they need them. Instead,
individuals that have accidental mutations that give them traits that make them
better able to exploit and live in their environment will leave more offspring, and
over time, the population will start to have more individuals with those adaptive
traits.
4. Darwin said that humans evolved from monkeys
INCORRECT. Darwin said no such thing, nor would any serious scientist of today
claim that. No living species can be considered ancestral to another living species.
Instead, it is correct to say that humans and monkeys (and chimps, gorillas,
orangutans, etc.) all evolved from a common ancestor that didn’t really look
exactly like any of them. All these related species have changed over evolutionary
time and have their own specializations. (That also means that there’s no such
thing as a “most highly evolved species.” Every successful species is evolved to
survive and reproduce in its habitat. That’s all we’re saying.)
If you’re sitting here, you—like any other living thing alive right
now--are the product of successful ancestors. And if you’re
lucky, you’ll be somebody’s ancestor yourself some day.