Allright, forget the fossils

I've been reading a lot of threads here arguing over transitional fossils, radiometric dating, fossilzation rates, etc. etc....So forget the fossils... How much evidence for evolution is there that can be gained just by examining the mophology and genetics of existing species?

Thread moved here from the Proposed New Topics forum.

Here is one way of looking at the Theory of Evolution.You can arrange organisms by their morphology, so that they form a tree.You can arrange organisms by their ancestry, so that they form a tree.You can arrange organisms by their genetics (DNA), so that they form a tree.ToE says that these are all the same tree.The primary evidence for ToE is in genetics and reproductive biology, which demonstrates the processes by virtue of which these are the same tree.Secondary evidence is in the form of using ToE to make predictions, and checking whether those predictions are confirmed. The basic idea behind predictions is simple. Given any one of morphology, ancestry, genetics you can locate the organism in the tree. Then, from the location in the tree you can predict the other two (of morphology, ancestry, genetics).The best secondary evidence comes from field biology - examining species found in nature, where morphology and genetics can be checked, and ancestry can be partially checked.Here is how fossils fit in. They provide partial information on morphology. Dating of the fossil gives partial information on ancestry. With these two you can find an approximate location in the evolutionary tree. That allows the estimation of other information about the organism that was fossilized. It is mainly an exercise in the tentative reconstruction of natural history. It is indirectly supportive of ToE in that the method works.

How is this determined? You make it appear to be independent but I don't think it is.

In many cases it cannot be determined. But it surely can be in the lab or in laboratory like conditions (plant and animal breeding for example).

You claim that you can organize "organisms" ( ) by ancestry. You use the term in two other places suggesting that all organisms are included over a wide time frame. Your answer here seems to involve only very few specific critters over a short time.You seem to suggest that I can tell ancestry by knowing who gave birth to who. How does that technique fit into the bigger picture you gave at first?

I was trying to describe ToE in terms of data analysis.Science idealizes. We say that the temperature is a real number. But when I read a thermometer I only get a range of possible values, due to the presence of measurement error. If we take statistical thermodynamics seriously, then there is no exact real number for a temperature, at best there is a probability distribution. Still, the idealization works well and is simple to apply.In the same way, the idea of a tree of organisms is an idealized picture. The data is usually blurry, giving an approximate location in the tree. We typically collapse a whole species into a blurry spot in the tree.But the idealized picture still explains how the prediction works. The consequence of blurriness is that if the data is blurry, then the predictions are blurry. This is the crux of the creationist-evolutionist debate.The tree we can build from "who gave birth to who" is a local tree. Based on reproductive biology, we can see that every organism fits into such a small local tree.Side note (for the lurkers): I should clarify that "tree" is being used here in the mathematical sense (from graph theory), not the thing growing in your back yard.What reproductive biology cannot tell us, is whether there is one huge tree containing all organisms, or there are multiple disconnected trees. ToE claims a single tree, and creationists claim multiple small trees. That's their argument of "micro-evolution but not macro-evolution".If there are multiple disconnected small trees, then prediction should work as I described it within any of those small trees. But there is no obvious reason to expect prediction to work across trees. That prediction works quite well overall, is therefore strong evidence for a single large tree.

quote:

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There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one;

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From Darwin page 459 "Origin of Species".Aside from the above which is really neither here nor there, the ToE doesn't suggest on it's own that there is one or multiple trees.What we find when examining life is that the evidence says there is only one major tree with extant forms today (that we recognize anyway). This isn't part of the theory it is a consequence of applying the theory to the evidence we have at hand.All of which may only be saying what you have already said in your post. However, the pedantic nit is that it is not a consequence of the theory but simple what we observe in life here today.

just because darwin doesn't suggest it, doesn't mean anything. darwin is not the first and last word on evolution.

Darwin did suggest both one or a few trees and I noted that what Darwin had to say is, indeed, neither here nor there (not the last word).However, the theory doesn't say that there has to be one tree any more than it says how the evolving life has to have started. What I said was that we observe that life today shows very strong evidence of being part of one tree. (There is still the small chance that there is a "few" trees but most have clearly been pruned and are very small if they are there at all.

i would argue that if abiogenesis is possible, then it is likely that there are more than one tree. but the trees i looked at in my biodiversity class looked pretty well organized.. but then i'm not sure of a few things. that's life. (haha)

There are different statements of the theory, and they might not all agree on this.As far as how the theory is used, it doesn't much matter whether it is one tree or few trees (say a tree per phylum). I agree with you that the evidence favors one tree.

Why not forget the morphology? There is plenty to read in the 89 years of Genetics (journal) published at http://www.genetics.org/contents-by-date.0.shtmlThe answer is: lotsMick

Mick, you evil person! Now I have another free online journal to eat up all my hours!!

"ToE" claims that the organisms we see today are the result of natural selection operating on changes over time on populations that all arose from one individual. The argument over ToE is over one tree versus unknown number of trees. Evolution is not denied by creationists who realize some form of super evolution had to occur with the ark pairs to give us the diversity of organisms we see today. In order for ToE to be correct there needs to be ONE tree because the genetic evidence for it is the same genetic mechanisms throughout all life-forms (minus the pesky virii :-)). This seems to be the case. However I'd also like to point out that in many areas of biology (this includes academia), the emphasis has shifted so much to genetics that there are very few morphologists anymore. After all, who wants to be an old museum specimen (I'm very proud of my morphologist self thank you :-D) when you can be the superman molecular biologist? As a result, especially with the impressionable youngsters, the benefits of genetics are always told and many of the pitfalls are left out. For example, which tree do we trust when the genetics give one that differs from the morphological one? Why would we trust a specific tree? For those who don't think this occurs a great source is:
Losos, J.B., T.R. Jackman, A. Larson, K. de Queiroz, and L. Rodriguez-Schettino. 1998. Contingency and determinism in replicated adaptive radiations of island lizards. Science 279:2115-2118.
Other problems are which sequence is truly representative? How does this sequence change over Earth History and is it reliable in all organisms. What about selfish genes and gene hopping? What degree of convergence occurs in genes? Where is embryology in all this?The trees we get using ToE are all based on the assumption that there is one tree. Trees are not evidence in any form but are the completed proposal of history. In the literature the tree (route evolution took) is argued, not whether or not using one tree is justified. They work because so many of the methods assume that like organisms are related to one another (both morphologically and genetically) If both sides say that the common genetic mechanisms exist because of either common descent or common designer, how can you really predict anything differently in this realm? This is by the way, without the aid of fossils and radiometric dating as given below. This is also done without taking behavior and ecology into consideration..Later