Evolution os a tough subject to learn about for two main reasons:
it is based on a number of misunderstandings
it is strongly tied to religious beliefs.
Therefore, we really need to start with a metaphysical approach to the controversy surrounding evolution.
We have been presented with a confusing array of just what evolution means, and we have allowed ourselves to become distracted about the nature of scienc e and religion. We also have added in confusion with the meaning of words used to describe the process.
So Let's Start with BASIC Definitions:
Right from the dictionary:
A gradual process in which something changes into a different and usually more complex or better form.
Change in the genetic composition of a population during successive generations, often resulting in the development of new species. The mechanisms of evolution include natural selection acting on the genetic variation among individuals, mutation, migration, and genetic drift.
By far the simplist definition (and the one we'll be using in this course) is this:
Evolution is a change in the heritable traits within a population across generations.
We can understand this because we already know what most of these words mean.
We know that heritable traits are characteristics that can be passed from parent to child through DNA.
We also know that a population is a group of organisms that lives locally to one another in a specific area.
And we know from our recently completed genetics section that generations are represented by parent and children.
So, evolution is nothing more than changes passed from parent to child in organisms.
But what about religion?
Let's start here with definitions of what science and religion really are:
Science is the study and understanding of the natural world.
Science is based on fact and can be quantified (counted or measured).
Religion is the study of the supernatural world, and is based on faith.
Faith cannot be proved, but must be accepted without proof.
No matter what people will try to tell you, science has no direct commentary on religion, as it is a completely different subject.
This is a science course, so we will explore and investigate facts in our class, and draw conclusions from the facts we can get. This process need not conflict with any belief system. We investigate what can be measured, and what can be known. Faith and belief will be kept separate from our discussions in class.
A religion course can explore matters of faith. This is not that course. You can speak with clergy or philosophers for help in reconciling these concepts.
Introduction to Evolution
So, what did we learn?
Here are questions to guide your viewing of this video.
Are hairy ears dominant or recessive based on the pedigree shown? How can you know?
This is a review of the Mendelian Genetics section we've just completed.
What is the difference between Natural and Artificial Selection? (the wolf/dog section addresses this)?
What does "Reproduction with Variation" mean?
Are there guiding forces in Evolution?
Why is it important that organisms don't produce exact copies of themselves when they have offspring?
Let's start with a video:
More confusing definitions:
We use language in our daily lives differently than in science, which adds even more confusion to learning about evolution. We have all heard someone say "I have a theory about...", and we know that they are saying "I have an idea about ...". A theory in science is different from your idea about why Mary likes John (or something like that). We have a misunderstanding of what a scientific theory is, so we should define that as well.
Scientific Theory: an explanation acquired through testing and confirmed through observation and experimentation. Scientific theories are not directly observed, but are inferred from facts and experiments, and are used to predict and explain how the natural world works.
We frequently have a misunderstanding of what a Scientific Law is as well.
Scientific LAW: A scientific law is a statement based on repeated experimental observations that describes the natural world. A scientific law implies a causal relationship involving its elements. A scientific law differs from scientific theory in that laws do not propose a mechanism or explanation of phenomena: they are merely distillations of the results of repeated observation.
There is still concepts that we need to clarify. We need to be sure that we can understand what we mean when we make a statement.
Evolutin is dependant on three conditions:
There must be Variation in a population
The variation must be Heritable
The variation must provide an advantage
So let's make sure we know what each of these conditions mean:
Variation in a population: Individuals in the population must have different versions of traits. Without variation, all individuals will have the same trait value and cannot be distinguished with respect to that trait.
A trait that we have looked at a lot in genetics was Dimples - and we saw there were variations - an individualmay have dimples or not have dimples. This is an example of variation.
Heritability: The variation must be heritable (transmitted from parent to offspring).
Advantage: There must be an advantage to the survivabilioty of individuals with the trait. Having Dimples or not offers no advantage for survival, so would not effect evolution, but long necks in giraffes does offer an advantage. Giraffes that can pass the trait of longer necks on to their offspring would have an advantage over giraffes that could not.
So can we start learning about evolution?:
What is Evolution?