Evolution: The Basics

In recent years it has become apparent that most in the United State and most of the people in the world have little to no understanding of what evolution is, the theory of evolution is, the facts of evolution are and even how science works. So I write this article in the hopes of explaining evolution in a short simple yet informative way for those who have little to no understanding of the basics of evolution.

⇒What evolution is and is not
What evolution is not:

• All of science.
• Other fields or theories of sciences.
  • Cosmology.
    • The Big Bang Theory.
    • Star formation.
    • Planet formation.
  • Geology.
  • Chemistry
    • Abiogenesis (origin of life).
• Origen of the universe.
• Atheistic (it has nothing to do with the existence or non existence of a god or gods).
• A lie.

What it is

• A filed of biology.
• A fact and a theory.
• Descent with modification.
• Change in allele frequencys with in a geen pool over time.
• Changes in populations over multiple generations.

⇒Fact and Theory
Evolution is a fact and a theory. Now this can be confusing to most people, in colloquial language a "theory" is guess or conjecture but in science the words "fact" and "theory" do not mean the same things as they do is colloquial language. In science a "fact" is a confirmed observation and a "theory" is a model that makes testable predictions that have been tested and shown to be accurate.
The fact of evolution is the observation of evolution (Changes in populations over multiple generations), these observations have been made in the lab and in nature.
The theory of evolution explains the fact of evolution with mutation and natural selection

⇒Mutation
Mutations are random changes in the nucleotide sequence of DNA, these nucleotide sequences are what code the genes and genes are what determines your height, eye color, how many fingers you have whether you have 2 arms and 2 legs etc.
Mutations have two causes. 1. damage to DNA. 2. an error in the copying DNA when a cell divides.
The effects of mutations can be positive, negative or neutral. Most mutations are neutral (have no effect), some are negative (decreasing an organisms chances of survival and reproduction) and some are positive (increasing an organisms chances of survival and reproduction).
The effect of a mutation that is not neutral whether positive or negative can vary widely, for example: one mutation could slightly increase a persons chances of getting cancer while another could cause a person to be born with out arms.

⇒Natural Selection
Natural selection is the process where traits that increase the chances of survival and reproduction are "selected" for and build up in a population and traits that decrease the chances of survival and production are weeded out.
Traits are determined by genes and (as said above) genes are determined by the nucleotide sequence of DNA.

⇒Speciation
A species is roughly defined as a group of organisms that can naturally mate and produce fertile offspring. Speciation is the point were two populations that could initially mate and produce fertile offspring diverge enough genetically that they are no longer able to produce fertile offspring.
Speciation occurs when an initially single populations splits into to two or more populations. Random mutations build up in the populations until the populations have genetically diverged to the point where individuals from one population can't mate with an individual from another and produce fertile offspring.

⇒Micro And Macro
In simple terms microevolution is variation within a species while macroevolution is variation above the species level. A population adapting to changes in its environment is microevolution, changes to a population large enough that if an individual from the currant population mated with an individual from the ancestral population they could not produce fertile offspring is macroevolution.
Both microevolution and macroevolution are driven by the same mechanism: mutations. (see mutations⇑).

⇒Branching Tree Of Life
Rather than being a ladder with humans on top and bacteria at the bottom, evolution is a tree. As noted above in the Speciation section⇑ populations can split and evolve into different species. Populations split and evolve into new species, those species (if they survive) can split again evolving into new species. This creates a branching tree of life (metaphorically speaking) rather than a ladder. All existing species can be traced back to common ancestors who can be traced to common ancestors even further back.

⇒Links

• Evolution
• Understanding Evolution
• PBS - Evolution
• How Evolution Works (videos)
• New Scientist - Instant Expert: Evolution
• Strange Science - Evolution