Blinn

Darwin knew that there was variation, but he did not know what created variation.

SanDiegoAtheist

To add a bit to this...

The only reason why DNA when first discovered was thought to pose a problem for evolution was because they hadn't discovered the methods by which variation was introduced into DNA. Once they figured out that:

a) DNA is imperfectly copied, and in such a way that it can increase in size, and
b) that multiple methods can cause mutations causing changes to the base-pair sequencing

all of a sudden there was absolutely no problem with it anymore.

Darwin didn't predict DNA per se...but DNA has exactly the characteristics that Darwin predicted for the mechanism of heredity. Pretty good prediction for 100 years before the fact.

Cheers,

The San Diego Atheist

RufusAtticus

Actually it's more along the line of Mendelian genetics supported Darwin's mechanism of Natural Selection and DNA supported Mendelian genetics.

~~RvFvS~~

Peregrine

Somewhere on my computer is a quote from a biologist about a Tennessee law making it illegal to teach evolution as fact (the law of course was ruled unconstitutional, but I digress).

He jokingly applauded making it illegal to teach evolution as a fact, because "as well all know, theories are more important than facts." Facts are whats and theories are whys. It is important to know that the earth revolves around the sun and that objects fall at the same rate in a vacuum. But it is more important to know why, and that is the job of theories.

Daggah

And what 'serious problems' did it cause?

Oh wait, I seem to remember trying to debate you about DNA and protein sequences, and how they strongly demonstrate evolution - you chickened out, as I recall.

Mageth

Ah yes, the old we are right and you are wrong argument. Btw, evolution did not predict DNA, a nd DNA posed serious problems for what was then the dominant theory of evolution.

So?

Darwin did emphasize the importance of inheritance and variation, and thus "predicted" some mechanism for passing down characteristics and for acquiring new heritable characteristics; he just didn't know the mechanism and didn't correctly understand inheritance and the causes of variability.

The discovery of DNA resulted in a more complete, more correct, and stronger theory of evolution (which is what you'd expect in science), so I don't really see what the "serious problems" are or were, or what your point could possibly be.

randman

"he just didn't know the mechanism and didn't correctly understand inheritance and the causes of variability.

The discovery of DNA resulted in a more complete, more correct, and stronger theory of evolution (which is what you'd expect in science),"

That's fine, but I c an't let people go around and pretend evolutionary theory predicted DNA. After the fact predictions don't count for a lot. Now, admitting significant modifications have been made, and have made evolutionary theory more consistent with the facts, that is fine, but the attempt by many is to pretend evolutionary theory had been right all along, and it has not.

RufusAtticus

Put it this way, Randman.

Although Natural Selection didn't predict DNA, it did predict many of the attributes of DNA.

~~RvFvS~~

fando

Semantics are the hardest thing to tussle with. We need more words than the catch-all "evolution".

lpetrich

Actually, one could make a stronger case for Mendelian genetics having done that. Darwinian evolution and Mendelian genetics are consistent with each other, however.

And it would be interesting to see if anyone had ever speculated on what properties are necessary for a molecule to carry hereditary information -- speculation done before nucleic acids were shown to have those properties.

That speculation has to come before Watson and Crick started working on the structure of DNA, otherwise, it may be "contaminated" with knowledge of what the answer ought to be.

I know that proteins had often been thought to be the carriers of heredity before nucleic acids were shown to be those carriers, but I am not familiar with what speculations had been made about what special structures or whatever that they must have had in order to carry heredity.

[ June 08, 2002: Message edited by: lpetrich ]</p>