“One common objection is the assertion that anatomy is not independent of biochemistry, and thus anatomically similar organisms are likely to be similar biochemically (e.g. in their molecular sequences) simply for functional reasons. According to this argument, then, we should expect phylogenies based on molecular sequences to be similar to phylogenies based on morphology even if organisms are not related by common descent. This argument is very wrong. There is no known biological reason, besides common descent, to suppose that similar morphologies must have similar biochemistry. Though this logic may seem quite reasonable initially, all of molecular biology refutes this “common sense” correlation. In general, similar DNA and biochemistry give similar morphology and function, but the converse is not true—similar morphology and function is not necessarily the result of similar DNA or biochemistry. The reason is easily understood once explained; many very different DNA sequences or biochemical structures can result in the same functions and the same morphologies (see predictions 4.1 and 4.2 for a detailed explanation).
As a close analogy, consider computer programs. Netscape works essentially the same on a Macintosh, an IBM, or a Unix machine, but the binary code for each program is quite different. Computer programs that perform the same functions can be written in most any computer language—Basic, Fortran, C, C++, Java, Pascal, etc. and identical programs can be compiled into binary code many different ways. Furthermore, even using the same computer language, there are many different ways to write any specific computer program, even using the same algorithms and subroutines. In the end, there is no reason to suspect that similar computer programs are written with similar code, based solely on the function of the program. This is the reason why software companies keep their source code secret, but they don’t care that competitors can use their programs—it is essentially impossible to deduce the program code from the function and operation of the software. The same conclusion applies to biological organisms, for very similar reasons.“
What Science would you like? The science of feathers perhaps?
Much of Evolution is presupposition and extrapolations with little or no backing to them. I have seen some of the ludicrous explanations of fossils that claim to prove that dinosaurs are the parents of birds. And I watched with incredulity a documentary that claimed to show the development of birds which was purile to say the least. How David could keep a straight face is beyond me, but he actually seemed to believe it.
Well if you compare the basic mode of moving on land then that must be correct. 2 or 4 limbs is common across various genomes. But I am not sure whether this helps much when trying to decide whether we are directly related to chimps or not. Perhaps we need to concentrate on the differences rather than the similarities? (and whether Evolution could bridge the “gap” or not)
Richard
PS I am aware of the dislike of the term “gap” in Evolutionary circles. And am not keen on the “God of the gaps” either
That would mean you to have seen it. And to cite specific examples. However, it assumed that feathers evolved with no flight intent. That wings could involve for the purpose of gliding to the floor, so that the growth of the sternum, and the over all mass to size ratios just sort of fall into place. And the metabolism needed to generate flight? It becomes a solution, not a random deviation. Basically it ignored the over all physiological uniqueness of birds. And maybe someone could explain why beaks are so necessary for the survival of Avians? (Baring in mind how big a change it is to move from an integrated mouth to a beak)
It’s not assumed. It was once a hypothesis, and that hypothesis has gained experimental support. The earliest feathers we see in the fossil record are down-like feathers that cannot have supported powered flight. There’s also some cool evolution-devo stuff known about the genes involved - the evidence we have supports the idea that feathers are modified and exapted scales.
Watching a BBC nature special isn’t going to give you the evidence - it’s going to give you (at best) a cursory lay-level summary.
I don’t know a single example of a genome that codes for 2 limbs. Can you provide a reference?
Let me help. You can’t, because there’s no such thing. [content removed by moderator] You are using a pop-level TV show as a foil for proclaiming doubt about evolution. Has it occurred to you yet that the forum is populated with people who know a lot about evolution and who would be willing to answer well-articulated questions? Might that be a more fruitful–and respectful–approach to engagement on the forum?
Yes, I have seen this claim. But Feathers do not fossilise, so the evidence is inconclusive at best. I have also seen some rather monstrous examples of claimed early creatures, some of which belong in fairy tales. Whether feathers are adapted scales is less important as to the possibility that feathers have any Survival advantage other than in flight. Claiming feathers as a display rides headlong against “Survival of the Fittest”. Or do you not understand what a feather is? Scales exist in almost every colour imaginable and Chameleons are the pinnacle of this. A “pretty” feather just does not cut it, in the real world (as opposed to rose coloured Scientific glasses)
Feathers aside. The basic construction of a bird belies a bit by bit construction. The main components are too interdependent. The high metabolic rate would shorten the life of a creature that did not need it. The clumsy wings have no use outside of flight. The wings need both the muscles and the metabolism to drive them. The bone construction would be a disadvantage in land creatures. The beak is almost essential yet the transition from mouth to beak is almost impossible using normal Evolutionary techniques. (Duck billed platypus is probably an exception)
Why is it that every Evolutionist seems to have forgotten all they ever knew about physiology and / or Ecology?
I guess if you are desperate enough you will find your “Missing” pieces.
God does not need such things of course, He is not limited to “Small deviations”.
My colleagues at Current Biology were excited, along with almost everyone in the world, by this discovery, a spectacular fossil discovery on top of scores of others. One of many news reports here. I think most people on the forum know that feathers fossilize, but wanted this great discovery to get some love.
I am not in a position to validate nor invalidate what Science has now deemed as fact.
It seems that what I learned as a youth has been updated. However, the function of these “feathers”, assuming they are real, seems less certain and speculative. Perhaps people do not want to ruin what seems to be a “break through”.
In all seriousness, though, if you’re running off knowledge from when you were young, then you will be very out of date with current evidence. I’d suggest taking some time to learn before making claims about what is or isn’t possible for evolution to accomplish. One place to start (since you’re here on BioLogos) would be the BioLogos “Evolution Basics” series I wrote a few years ago. Cheers.
You misunderstood me. I was talking about the number of limbs used to walk with not the number of limbs that any creature has.
How many limbs do you use to walk with?
You wrote gibberish about “genomes” and “whether this helps much when trying to decide whether we are directly related to chimps.” We’ll have more interesting and productive conversation when you do some reading to get a basic understanding of evolution, of genomes, of fossils, and so on. Dennis pointed you in a good direction. Good luck, and have fun.
Richard, feathers, and in particular downy feathers would be very helpful in temperature regulation, perhaps in camouflage, protection against the elements and perhaps more and were later adapted to signaling and later to gliding and flight. Today, flightless birds still have feathers to their benefit. And ours, as it would be upsetting to be chased by a herd of naked ostriches.
The basics have not changed. Evolution still works on a basic principle no matter what “evidence” has been discovered. The “scope” of the Evolutionary process has not changed either. Only the interpretations of evidence and the wild claims that people seem happy to make about what “time” can accomplish. There are somethings that a “simple” change cannot do. And some changes that need more than a “simple” change to accomplish. Evidence will not change these facts.
I have already been criticised for reacting to a “put Down” I do not wish to go there again.
One thing that is sometimes not intuitive from the perspective of where we sit, is that evolution (in the commonly held sense) takes place with whatever genetic parts are hanging around, with no long range goal in mind. It proceeds based on whatever is a successful adaptation at that time for that time. Perhaps the downy feathers elongate because they shed rain better, or shade the tender skin better so that trait is passed down . They change color to hide better or confuse predators. Only later are they used for gliding, then better muscle attachments become advantageous. The downside of evolution this way is that we wind up with backs not optimal for upright posture, weird pathways of nerves, and muscles that do little or nothing.
Featherless chickens are ugly enough, I just thought featherless ostriches would be even more disturbing.
Hi Richard - it’s going to be difficult to have a meaningful conversation about evolution if you’re not willing to learn a bit about what it actually is (as biologists understand it) and what the current lines of evidence are for it (fossils, genome sequences, and the like). I’d encourage you to have a gander at that series I posted up there ^ as a starting point. Best, Dennis
