Could you hold your own in an evolution debate?

Charles Darwin and Alfred Wallace each came up with the theory of evolution independently, at about the same time, but Darwin is remembered primarily due to his scientific treatise, "On the Origin of Species."

Homo sapiens has been around for at least 200,000 years, based on remains found in Africa. They were hunters and gatherers.

Many fossils are found preserved in sedimentary rock or in tar pits. Looking at the changes which happened to organisms in the past helps scientists understand how a species has evolved.

Radioactive dating uses information we know about elements like carbon and their rate of decay into isotopes over time. By looking at how many of these isotopes are present, scientists can estimate the age of just about anything.

Mutations are not all good or bad: the vast majority of mutations are silent, meaning they do not cause any noticeable differences. Occasionally, mutations confer an advantage (such as resistance to a disease) or disadvantage (such as causing a disease).

Changes to DNA happen all the time; some have no effect and some do. The nucleotides in DNA contain four nitrogenous bases (abbreviated A, T, G, and C); if some are deleted or added, for example, it could change what that segment of DNA does.

Evolution's domain is the development of new species from the old via many changes over time. It does not cover how life came to exist in the first place, or what will eventually happen to life on Earth.

In common use, the word "theory" often implies that one is surmising or guessing at something. In science, "theory" is only used to describe a thoroughly-proven body of knowledge. The basic tenets of evolutionary theory are just as well-proven as the existence of the atom; the discipline as a whole continues to evolve as our methods improve.

Mice and humans are genetically similar enough for mice to be used successfully as test subjects, to learn more about cures for human diseases. However, chimpanzees and humans show the closest relationship, with 99% of our DNA shared.

According to descent with modification, new species come from old species. Differences are spurred on by changing conditions and may occur gradually or in spurts.

Bacteria with a mutation that protects them from an antibiotic will survive, then spread that resistance to other bacteria when they reproduce. This results in a population of antibiotic-resistant bacteria.

Many events can influence the direction evolution takes: a famine might cause birds with a certain set of traits to die out while others are able to survive. Mass migrations and geological events can divide populations and influence which genes are passed on.

An alligator leg and a bat wing are examples of "homologous structures," body parts that appear to have developed due to a common ancestor. The bones which have developed in an alligator leg, bat wing, or even the human arm are all remarkably similar.

Galapagos, because of its isolation and cyclic weather, was the perfect place for Darwin to observe the results of evolution. The finches of Galapagos, for example, had several beak types that allowed them to specialize in different food sources on the island.

It's amazing how much data can be retrieved just from one skull: scientists can look for information about brain development, eating habits, and even whether the animal could have had speech (in the case of early humans, at least).

Darwin's natural selection is where we get the saying, "survival of the fittest." He believed that the organisms best suited for survival would pass those traits to future generations, driving the refinement of the species.

Easy examples of vestigial structures in humans are the tailbone and the appendix. Creatures with a tailbone most likely descended from creatures that once had a tail.

DNA is unstable and decays quickly, making it unlikely that anyone could find real DNA in a fossil. We do have the next best thing, though: proteins from blood cells and blood vessels have been discovered in 68-million-year-old dinosaur bones.

Proteins, DNA and RNA contain a wealth of information that scientists can use to track the evolution of various species and determine which are related and by roughly how much. Highly similar sequences and functions suggest recent common ancestry.

Neanderthals were early members of the human race, but modern humans don't appear to have Neanderthals in their ancestry. Some scientists think the Neanderthals were wiped out by modern humans, either through war or disease.

Many types of cats and dogs are the result of selective breeding. Breeders use the principals of evolution when selecting which animals to breed for certain traits.

New species can take thousands of years to develop or a few decades. "Punctuated equilibrium" is a term that describes evolution that occurs in spurts; a population can be stable for long stretches of time, then suddenly shift in just a few years, due to a change in environment.

The term "allele" is used to describe variations of the same gene. For example, genes for hair color might result in brown hair, black hair, blond hair, red hair, etc. The genes still code for hair color, but the color itself differs.

For the frogs to be members of the same species, they must be able to breed successfully. This is not the case if their offspring either fail to be born or cannot reproduce themselves. Sexual incompatibility is a hallmark of speciation.

Social Darwinists tried to apply the idea of natural selection to human populations, arguing that the human race would be improved if people with "undesirable traits" were prevented from breeding. Darwin never encouraged social Darwinism and modern evolution has nothing to do with it.

Similarities between species can be the result of common ancestry or the effect of similar environmental pressures. Scientists often evaluate differences in embryological development and DNA to determine which was the cause.

There are many examples of coevolution - some driven by competition and predatory behavior, some driven by symbiotic relationships. For example, rough-skinned newts produce a poisonous substance on their skin that prevents most animals from eating them. Garden snakes, however, developed a resistance to the substance so that they can still eat the newts.

Interestingly, changes to mating rituals can easily cause speciation because the animals using an altered mating ritual are less likely to mate with the ones using the old ritual. This segregates genes and primes the stage for speciation.

The study of genetics has revealed a wealth of information about the mechanisms that drive evolution. Studying patterns of inheritance, DNA, etc., is critical for understanding what causes evolutionary phenomena.

The word comes from two Latin words that together mean, roughly, "belonging to men" or "belonging to human beings." Hominids were the precursors to modern human beings.

Some religions openly preach against evolution, but the Catholic Church is notably accepting of the theory. It holds that evolution could be the method God used during creation and that God could have simply given the first humans souls when the time was right. Pope John Paul II famously said that "truth cannot contradict truth," meaning that if evolution is true, there is a way it can coexist with faith.

Chimpanzees have not only opposable thumbs, but opposable toes as well! Humans, on the other hand, can walk regularly on two feet. Apes must travel on all fours most of the time, because of their C-shaped spines.

Non-random mating, immigration and emigration, small population size, natural selection, and genetic mutations can all disrupt a population's genetic equilibrium. As a result, some traits will become more prominent and some will become less prominent.

While evolution explains the mechanism necessary to get from ape to human, the exact path evolution took is still missing information. There are several models to explain current findings which are adjusted as new data comes in.

While many pieces of evidence support the theory, the strongest reason to believe all humans descended from one small group is the fact that mitochondrial DNA has undergone relatively few changes. The hypothesis states that the group which produced modern humanity would have been in Africa just 100 to 200 thousand years ago.