How did every animal develop with the same basic system?

But it’s not just shortcuts. Sometimes nature appears to be taking the scenic route - and driving it at night.

If an intelligent designer was designing a flying mammal from scratch, he’d start with a blank page and design a set of wings. Nobody would choose to make wings out of highly distorted finger bones.

It’s a little more complicated than that. There are at least 25 different genetic codes, but it seems obvious that they have evolved from one another, since they each contain minor variations from an older variant;

The fact that there is more than one possible code seems significant, because it seems to indicate that there are many genetic codes which are both possible and viable, but our biosphere only utilises a very small subset of them, all of which are causally linked.

Well, sort of. It’s closer to say evolution is a process of random mutations, and if a change is beneficial for the organism’s current environment, it is likely to be passed on, and may eventually either outcompete the unmodified original species or split into a new species. Evolution is a process of adapting to the immediate present, does not necessarily render a species fit for future situations, and in fact frequently creates species which are vulnerable to environmental changes.

Why not? What’s a better design for a flying animal that size?

Kinda … If there was a designer, the designer would be the extremely crazy scientist… it requires such bizarre random behaviour to design such wacho systems, its bizarre and yet would require extreme intelligence, the complexity of the cannibinol receptors, the hormones, the pheromones… you couldn’t imagine designing it, its just too bizarre…

But evolution explains it nicely.

A big part of it, I understand, is Hox genes. The idea is that most animals sort of draw from the same “toolkit”, which is where most of our similar DNA is from. But Hox genes act as a sort of regulatory blueprint that control where, to what degree, and at what stage of development certain pieces of that toolkit manifest. By playing with Hox genes, researches have been able to do things like replace fruit fly eyes with legs and other freaky things. Hox genes essentially “point” to our more core genetic material and explain how it should be expressed.

That doesn’t mean all animals have exactly the same core genes and Hox genes are the only differences, but the way I understand it is that we all share extremely, extremely similar cores and differences in these surface-level blueprints account for the bulk of the difference.

Not too far removed from something Chrstian radio host Todd Friel has said. He was playing a game he called “What If?” with Christopher Hitchens (and getting utterly destroyed by him) and describing God’s (hypothetical) interventions in Hitchens’ life as:

“He’s allowed you to live your life”
“He’s kept you together by the power of His word”
“He’s kept you alive”
“He causes you to breathe”

…which sounds like Friel believes God engages in, indeed has to engage in, constant and minute physical maintenance of every human being. If that was the case, why would we have or need lungs or any other organs to maintain life, as you say?

What is the point of this What If “game”?
“What if I am absolutely right about God and you are absolutely wrong? Huh? Huh? Huh?

Why sacrifice your forelegs to make a wing? Why not just have wings come out of your back, like insects, dragons, angels, or fairies? (In fact, the latter three show that humans could design a better flying organism.) All flying vertebrates have had to make compromises as to manipulation of food or other locomotory capacities because they had to utilize their forelimbs to make wings. Insects haven’t had to make that compromise, giving them much more flexibility.

Yeah, but can you replicate the insect model on the scale of birds and bats? Human designs of dragons, angels and fairies generally stop short of describing the inner workins, and to my recollection attempts at fitting the necessary muscles into the bodies of those designs, as rendered today, fail to give a functional flyer.

I’m not saying it can’t be done, or that I don’t agree that keeping the forelegs would be a win, just that I’d like to see an actual working design before I sign off on the alternate plans. :wink:

If the point was to make Friel look stupid as Hitch casually disintegrated him… mission accomplished.

It was funny how Friel kept pathetically reminding Hitchens “Remember, we’re playing What If” when Hitchens went off script or, more accurately, turned out to have a brain. Friel can’t handle the unexpected, accustomed as he is to being spoon-fed.

In fact, I’ve seen it suggested that the reason flying birds outcompeted the pterosaurs was that, since the birds only used up one pair of limbs on making their wings instead of both like the pteros did, they were better able to walk.

I think the point here is that birds, bats, pterosaurs, and all the other flying critters are clearly modified forms of some non-flying animal. Starting from scratch you would come up with very different designs.

Wll, sort of, but even for insects, the origin of wings mounted in the aft thorax wasn’t flight, but likely for the purpose of radiating excess heat. Once the surfaces evolved to a sufficient size, insects could spread geographically faster than other organisms, and further modifications allowed for directionally controlled flight, until we get to the profusion of highly optimized wing structures (for individual niches) that insects demonstrate today. That these designs are so varied and functional isn’t any evidence of “intelligence” in design, of course; it is just a natural, statistical consequence of the variety of species evolving across the distribution of all physically possible modifications to the existing planform and fratures, with those that provided the most reproductively successful benefit in the overall context of the environment (which includes not being so succesful that it competes itself right out of a food source or other resources) resulting in numerical superiority.

Those optimizations, however, are limited in having to start from the existing morphology; hence why all mammals have some combination of four limbs (or deprecations therefrom), two eyes, two ears, and one nose and mouth. It also explains why mammals grow gils in embryonic forms but reabsorb them later in natal development. It would be better, for instance, for ruminants to have eyes mounted on stalks so they could observe their surroundings while eating, but that isn’t a readily available evolutionary path so it hasn’t happened with any mammal; instead, the eyes have just moved to the sides of the head, and ruminants instinctively halt their eating and pop their heads up on a regular frequency in order to look for predators. It’s not the best solution of all, but the best one available from the starting plan, and works well enough to benefit bison, elk, and deer.

By the way, natural selection isn’t just for the evolution of life. An entire field of optimization theory–genetic algorithms–uses guided selective testing to identify optimal solutions that our “intelligent” brains cannot otherwise see. An intelligent designer with the patience and resources of a supernatural being would likely use the same methodology to develop an optimal product. The assumed precepts of so-called Intelligent Design actually do nothing to establish the existance of a god of any kind; they simply highlight the limitations of imagination and scale of evolutionary action in the minds of the beholders.

Stranger

Well, it’s worth pointing out that insects already have less compromises to make than vertebrates because they have fewer weight problems (related to flight). If you took a bird and gave it forelegs it would obviously be able to function more effectively on land, but they’d just be dead weight in the air.

Microsoft isn’t all-knowing and all-seeing with unlimited resources (that’s Google).

Possibly. I’d like to see some though.

Well, if we’re hypothesiying a fallible designer bound by the limits of finite resources, sure.

That’s not what the usual ID advocates are really thinking of, is it?

And yes, the OP fails to begin with in that not even a majority of kingdom Animalia are of the tetrapod design. There are an abundance of phyla with a variety of radically different designs.

I was going to suggest “Why Evolution Is True”, also by Coyne.

Excellent point. I’ll need to remember that for future use.

I won’t give you credit, though. :slight_smile:

In fact, the flying insect (or arthropods in general) is a perfect example of the “Design” failure. The tiny arthropods breathe using air tubes carrying oxygen deep into their bodies. This is adequate for smaller, cold-blooded animals, but does not scale well thanks to the square-cube law. This put an upper limit on insectoid sizes. Should insectoids be inclined to evolve to larger sizes, they would need to develop lungs - but they would be competing with birds, who already occupy the “big flyer” niche more efficiently. Of course lungs means a bigger and better circulation system to pass that oxygenated blood through the body… and so on. Maybe if they were not competing with birds, they might evolve to be bigger with better breathing functions - but for now, someone else is eating their lunch.