[jtbigwoo]

>> Evolution is a theory that is almost self-evident.

I wish that were the case. To give one example, housecats are so vastly different than monkeys that initial observation wouldn't necessarily point toward a single primitive mammal ancestor. The theory of evolution gets so expansive when you consider billions of years that it's easier to believe in intelligent design.

In a clever twist, many creationists have started claiming that they accept micro-evolution (e.g. the idea that bird beaks would change over generations like Darwin observed) while denying that macro-evolution happens. Thus they can account for the high-school-science-class information that most people get while still clinging to creationism as the overarching truth.

[jostmey]

Sure, it is difficult to initially understand how a house-cat and a monkey once shared a common ancestor. Understanding this fact requires a great deal of knowledge about biology.

But the basic underlying assumptions of Evolution are self-evident. Just assume that you have something that makes copies of itself but does so imperfectly. This means that mutations may form during the copying process. Selection will then act to favor those mutation which are beneficial, and disfavors those mutations which are fatal or detrimental. These basic ideas of how evolution works, which apply to all objects that make (imperfect) copies of themselves, is almost self-evident.

[freehunter]

But the underlying assumptions of creationism hold true as well. If I have a RepRap that's making imperfect copies of itself and evolving, who created the RepRap in the first place? It certainly didn't spawn from nothing.

Sure it's a devil's advocate argument, but that's the issue. Saying something that sounds reasonable to an uneducated person will leave that person believing it's true, because it certainly sounds plausible. If you don't also teach the scientific method and critical thinking, you're not teaching.

[mikeash]

There are really two completely different concepts contained within "evolution".

First there is the concept of gradual change over time in a population of self-replicating entities subject to selective pressure and heritable variation.

Second, there is the theory that all life on Earth descended from a single common ancestor that lived billions of years ago, and the current scale of biodiversity comes entirely from the application of the first concept over the intervening time.

The first is nearly obvious. The second is definitely not.

[pdonis]

The second is definitely not.

Actually, the single common ancestor part is now, since we have DNA evidence.

[mikeash]

It is well supported, but it's not obvious.

[pdonis]

Maybe not for some values of "obvious". But I think it's at least as obvious as "the concept of gradual change over time in a population of self-replicating entities subject to selective pressure and heritable variation", which was the standard for "obvious" used in the post I was responding to. In fact, the average lay person will probably understand the concept of "DNA evidence" more easily.

[mikeash]

Realizing that self-replicating entities with heritable traits subject to selection and variation will evolve over time just takes some thought. Applying it to the natural world just requires that you notice that living things are subject to selection, have variation, and have heritable traits.

DNA evidence requires some pretty advanced science to obtain. The basics of evolution have been known for millennia (that's how you breed plants/animals for specific traits, after all) but DNA evidence for evolution as the source of present-day biodiversity is quite recent.

[pdonis]

Of course DNA evidence is more recent; that's why I said it was obvious now (but wasn't before we knew about DNA). "Obvious" always requires background knowledge; the basics of evolution, as applied to plant and animal breeding for example, were known for millennia to plant and animal breeders, but not to people with no background in those disciplines.

Also, humans have only been breeding plants and animals for ten thousand years or so; would the consequences of self-replicating entities having heritable traits have been "obvious" to a Cro-Magnon 30,000 years ago? They were just as intelligent as we are (at least that's what the data on brain size indicates), but they didn't have our background knowledge.

Finally, saying it "just takes some thought" is vague: how much thought? How much compared to the knowledge and cognitive ability of the average lay person? If you randomly selected lay people and asked them to (1) briefly explain the consequences of self-replicating entities, and (2) briefly explain what having similar DNA means, giving them time to think about each question, which question would they, on average, do better on?