Question about evolution.. genetics

[Trytostaydead]

Instead of studying, me and my friends entered into a debate about evolution. Mind you, we're all in the same comparative anatomy classes, we all took genetics, molecular, cancer and all those wonderful classes.. but the one issue we could not resolve was the question of genetics.

When we're asked to compare species and trace their goddamn evolution (it is not a fun thing to do on a test) based on homologs and such, the differences are too well defined, even between the transitionary species that exist in that grey zone between phylogenies.

Now, that might be great and all and one might argue that that shows evolution in the works, but from a genetic point of view, unless we're talking about bacteria and viruses, those genetic leaps are mind-boggling.

Granted, mutations occur in tremendous amounts.. but most are caught by your own built in safetyguards and quickly weeded out and repaired. Most genetic mutations that do survive are usually unnoticeable or do something harmful. As a little background most mutations come in the form of DNA damage from UV radiation, free radical formations and such which often lead to deleterious effects on the DNA (cancer being one of many wonderful by-products).

The argument though, was the changes occuring.. such as the formation of wings. If we take for granted that evolution is a very very slow process and we take it from the beginning. We have to assume that only one animal had a mutation that gave it the beginnings of a wing, probably looking nothing at all like a wing let alone function like one. We then have to assume that this one animal survives and passes its genes on (probablility goes way down again). Then its offsprings likewise have to flourish and pass down the gene, the gene will have to be constantly passed down and modified through probably millions of years through most likey SINGULAR mutants until it reaches the primitive form of a wing.

Even reaching the primitive form a wing, the bird probably as yet cannot fly yet. To reach flight, at least glide.. the wingspan should probably reach a certain length and the bones should at least become somewhat aerodynamic. Then, the act of flight itself is a hazardous undertaking. The few animals with the proper mutations need to be able to survive with such gangly appendages, and even then you get to the most hazardous part of flight.. LANDING. The mutations involved would need extensively modified legs and hips. Then for POWERED flight, extensive modifications of not only skeletal, but muscles as well (and believe me, the muscles in the pectoral area of a bird go through extensive modification)

The probability of physical mutation, the probability of it surviving, the probability of the trait being passed down, the probability of offspring surviving times god only knows how many times is mindboggling. Then we get into the discussion of population. If mutation that gives rise to a new species is singular and most likely extremely minor at best, it still means it has to breed and populate by incredible proportions.

The question is, why don't we see any of these intermediate stages? The fossils dug up are usually unique derivatives (like four winged birds) or have well defined characteristics that seperate them on the phylogenetic tree. Perhaps they were lost in time, either way.. until those missing links are found.. at least from a genetic point of view.. it's mind-boggling. A few hundred million years of evolution is probably the outcome of a lot of lucky breaks and probably divine intervention.

[Mr Bean]

Look at Gliding Animals, there is your trasinonary fossels right there

[Trytostaydead]

Look at Gliding Animals, there is your trasinonary fossels right there

Read what I wrote again. Even reaching the gliding animals is a feat onto itself. And even then, we should see non-functional forms of wings.. truncated forms of wings, arms with wings, animals with multi-limbs.. etc etc

[Lagmonster]

The argument though, was the changes occuring... such as the formation of wings...Even reaching the primitive form a wing, the bird probably as yet cannot fly yet.

Limited mindset, kid. The answer is obvious: A wing isn't USED for flying right away. An animal with a partially-evolved wing doesn't try to fly with it. One organism's partially evolved wing is another organism's fully evolved bug-catching-net, or body blanket. You're thinking too narrowly; what you percieve as an underdeveloped system had a different purpose originally.

Edit: As for transitionals, apply the same mindset. Each fossil is a fully developed version of itself, for its time, in its environment. There is no 'half organisms'.

[Darth Wong]

Most arguments against transitional fossils can be stymied by simply asking them to define what they would accept as a transitional fossil.

[Mr Bean]

we should see non-functional forms of wings.. truncated forms of wings, arms with wings, animals with multi-limbs.. etc etc

We do, there are birds with useless Wings in existance now, There are Birds which have Flippers instead of wings, We have Insecets with everything from stubs to full fleged wings, There are thousands of examples, just Dig up your avarage bird watching book and flip back to "Unusal" birds to find all your trasinatory fossiles


Also note the fact that complete bran new Limbs are possible with Mutant like the six legged South African Frogs first discovered in the 1860s and were first dimissed as accidents but they discovered quite abit of them, You can find tons of modern day frogs with an extra limb or what-not as they are espcilly vurnable to enviormental changes and mutantions

[Mr Bean]

Also as always Talk Origens is always helpful

A useful link for you
http://www.talkorigins.org/faqs/faq-tra ... .html#bird

[Trytostaydead]

Most arguments against transitional fossils can be stymied by simply asking them to define what they would accept as a transitional fossil.

Tricky question that's trying to be answered by both sides. But it gets mindboggling when we see entire losses of certain bones, muscles wrapping through new holes, bone fusions, and modifications to accomodate specific traits.

[Lagmonster]

It's not that mind-boggling. I think you're just looking at vast gaps in the record and wondering what fills them, and that's good science.

What is BAD science is to point to the gaps and say, "Well, damned if *I* can figure out what goes here. I guess we better just give up and say God poked this here joint into a reverse alignment."

Remember that, kid.

[Trytostaydead]

It's not that mind-boggling. I think you're just looking at vast gaps in the record and wondering what fills them, and that's good science.

What is BAD science is to point to the gaps and say, "Well, damned if *I* can figure out what goes here. I guess we better just give up and say God poked this here joint into a reverse alignment."

Remember that, kid.

Just saying, it's rather mindboggling in most aspects. We cannot conceive millions of years, let alone billions of years.. we can just quantify it and label them. My main beef is not about evolution, it's about how evolutionists like doing a kuma-tae (bloodsport baby) against creationists when evolution theory itself is perhaps the fastest evolving thing out there. With new molecular research being done.. some you just have to go, "now, shiver me timbers.. how the FUCK is that possible?"

[Ted C]

Even reaching the gliding animals is a feat onto itself.

Why? It follows directly from a leaping stage.

And even then, we should see non-functional forms of wings.. truncated forms of wings, arms with wings, animals with multi-limbs.. etc etc

Unless I'm mistaken, fossil dinosaurs with wing-like forelimbs have been found.

[Cyborg Stan]

Oh dear. Gliding is easy. Simply have the gene that signals for cell death between limb bones turned off during development. Such a thing is benefical simply by being used as a small parachute, and thus allows the individuals survive falls better or simply to be able to jump and survive longer things between branches.

Now, for feathers - it is now thought that they are modifications of scales, that grew outward rather than collapsing inward (which I think gets you hair), which is possible with a simple mutation. It wouldn't be useful for flying, but it is useful for insultion - even given warm-blooded dinosaurs, it still could trap in heat, lessening the metabolism needed to stay warm and increase the temputure range of the dinosaurs that had them. IIRC, there's a fossil of a dinosaur with their arms covering a nest, presumably warming them but making no sense if there weren't feathers there at one point. I'll have to look. Then, either you'd get dinosaurs that glide from trees, or another school of thought is dinosaurs that leap, from catching insects in mid-air. In any case, you'd use the arms to balance, and in either case, you'd move them to catch a bit of air. (For leaping dinosaurs, I suppose the thought of chickens come to mind.) With the new use of pushing against air, stronger pectoral muscles would come along as well more aerodyanmic feathers. I suppose feathers are preferable as a flight surface compared to skin, so the possible flaps between the limbs would not be favored compared to a single strong limb to hold the muscles and the feathers. (The wings of a bird and a bat are very different.) After short bursts of powered flight it's merely a matter of degree to full-fledged flight.

Of course, other ways of getting wings, such as the skin-membranes of bats, which are probably just rodents that once had the auto-cell-death turned off and went through a gliding stage, and insects, which probably had things that started out as temputure control membranes. (Broad side to sun to heat up, Thin side to cool, open and close for other characteristics.) that also served as help for catching air. (Infant spiders can do this via their own silk....) with muscles that got in to help control direction. Full-fledged flight is even easier with insects because of their size.

[LadyTevar]

Then, either you'd get dinosaurs that glide from trees, or another school of thought is dinosaurs that leap, from catching insects in mid-air. In any case, you'd use the arms to balance, and in either case, you'd move them to catch a bit of air. (For leaping dinosaurs, I suppose the thought of chickens come to mind.) With the new use of pushing against air, stronger pectoral muscles would come along as well more aerodyanmic feathers. I suppose feathers are preferable as a flight surface compared to skin, so the possible flaps between the limbs would not be favored compared to a single strong limb to hold the muscles and the feathers. (The wings of a bird and a bat are very different.) After short bursts of powered flight it's merely a matter of degree to full-fledged flight.

The Italics are my own addition, because when I read this thread that thought came to my mind as well. Being from a rather rural area, I have had the amusement of watching a young chicken run up a tree.

Yes, run. Not fly, although the wings are flapping. The young bird is actually clawing his way up the tree with it's legs, going nearly perpendicular to the ground.

Recently I saw a show on either Discovery or Learning Channel that discussed this as part of the evolution of winged dinosaurs. The wing flapping the young chicken did actually acted to push its mass closer to the tree, allowing the vertical run without tipping backwards. The point was that it's not true flight, it's merely using the wings as a stabilizer and climbing aid, very useful when escaping the fox.