Inference from evidence is also part of science. Not everything is replicable, nor needs to be. We see adaptation through natural selection happening today, and we see the fossil record changing from non-flying to proto-flying to flying organisms. The inference can be made without (impossibly on human timescales) replicating the sequence.
Common descent isn’t an assumption Bill. It’s a well established scientific fact. That’s only been explained to you about five dozen times by now, every time you trot out the same stale argument.
Note there are two competing models for the origin of flight in birds: the ground-up hypothesis and the tree-down hypothesis. Each has some evidence and it’s possible both occurred in different proto-bird lineages.
Abstract: The origin of avian flight is a classic macroevolutionary transition with research spanning over a century. Two competing models explaining this locomotory transition have been discussed for decades: ground up versus trees down. Although it is impossible to directly test either of these theories, it is possible to test one of the requirements for the trees-down model, that of an arboreal paravian. We test for arboreality in non-avian theropods and early birds with comparisons to extant avian, mammalian, and reptilian scansors and climbers using a comprehensive set of morphological characters. Non-avian theropods, including the small, feathered deinonychosaurs, and Archaeopteryx , consistently and significantly cluster with fully terrestrial extant mammals and ground-based birds, such as ratites. Basal birds, more advanced than Archaeopteryx , cluster with extant perching ground-foraging birds. Evolutionary trends immediately prior to the origin of birds indicate skeletal adaptations opposite that expected for arboreal climbers. Results reject an arboreal capacity for the avian stem lineage, thus lending no support for the trees-down model. Support for a fully terrestrial ecology and origin of the avian flight stroke has broad implications for the origin of powered flight for this clade. A terrestrial origin for the avian flight stroke challenges the need for an intermediate gliding phase, presents the best resolved series of the evolution of vertebrate powered flight, and may differ fundamentally from the origin of bat and pterosaur flight, whose antecedents have been postulated to have been arboreal and gliding.
Yep, definitely a fascinating area: and, as this abstract notes, bird flight was most likely preceded by pterosaur flight and succeeded by bat flight (since birds preceded mammals), which use different modes for non-feathered wings.
It’s very likely that there are multiple independent evolutions of the capacity for flight, rather than a single landmark event leading to all later varieties.
I agree that inference can be part of science. What mechanism are you inferring accounts for what you are observing. Are you inferring that reproduction and associated variation alone can account for a set of cellular sequences (DNA) that can produce flight?
Are you aware of how Darwin inferred common descent?
I would argue that reproduction alone is not a powerful enough mechanism to go from non flight to flight. It was impossible for Darwin to understand the obstacles for the molecular innovative changes required.
I would argue that the Creator responsible for the diversity of life could resurrect one of His creations.
Do you think a flying creature was born to a non-flying creature?
Common descent as a whole concept is not really what’s being considered here: there was already a vast number of living organisms by the time flight arose.
I realised, too, that we had neglected to talk about insect flight, which I’m presuming arose before reptilian/avian and mammalian. Moths, butterflies, flies, bees or their ancestors, who used various kinds of membrane for their wings.
Insect flight predates all three of those too. Sadly the Creationist you’re dealing with doesn’t understand the purposes of scientific modeling. He seems to think a fine grained model is necessary as “proof” a supernatural miracle didn’t occur.
Are you aware Darwin has been dead for 140 years and science has learned exponentially more about common descent since then?
Since nobody says or thinks evolution happens by reproduction alone you can stop worrying. Why do Creationists always forget the feedback from natural selection in their "EVOLUTION IS IMPOSSIBLE!!’ claims?
Sure an omnipotent supernatural being COULD do anything with magic. There’s just no evidence such a being ever did.
These different creatures are very different. The origin of insect wings are very different then the origin of wings composed of flight feathers. As flight has originated several times the difficulty of describing the molecular origin from reproduction alone makes the evolutionary hypotheses seem very unrealistic IMO.
Of course it will seem unrealistic with the goofy strawman version of evolution you keep pushing. The scientific world doesn’t share your ignorance based delusions.
As Timothy has noted, I’m not sure where this ‘reproduction alone’ concept is coming from. Evolution is the tension between genetic novelty (mutation, gene transfer, etc) and natural selection, operating on populations of organisms over time in the context of ecological niches.
Debunking a concept that is not evolution does not constitute debunking evolution.
But to be fair, you haven’t debunked even that, except by assertion that you find it implausible.
I don’t think there is anything to debunk at this point as there is no testable model for the origin of flight for insects, mammals or birds.
On what do you base the inference that flighted animals can be produced from non flighted animals? How many organized DNA nucleotides do you think it takes to produce a flight in a feathered bird?
Could it be as many a several hundred million? They need to produce specific bone structure coordinated with muscle structure coordinated with wing structure coordinated with feathers structured for flight.
This is why the population genetic models start with populations of animals.
Note this Bill claim comes immediately after I posted a model of the ground-up model for the evolution of avian flight. Of course to Bill “testable” means having to repeat every last step in the million+ year history of flight evolution down to the molecular level.
Bill, can you think of any extant animals which have a step between non-flight and flight, like gliding?
Right. Exactly. You didn’t answer my question, except implicitly: you do seem to assume that flight started when suddenly an utterly non-flying organism gave birth to a fully-adapted modern bird. That is, that all those genetic changes happened at the same time.
Rather, an insect perhaps developed some flatter limbs and found that that allowed it to somewhat direct its fall when it fell out of a tree or off a rock, and that that allowed it to hunt prey or avoid predators. Over multiple generations, that adaptation came to dominate the population based on natural selection, and the insects with the broadest limbs were more successful. And so on.
The evolution of flight - which occurred multiple independent times with different organisms of different scales at different times - occurred across multiple generations of very small adaptations being selected for, not by one single leap.
The point stands: when you don’t understand evolution, the thing you debunk is not evolution, and your debunking is irrelevant to evolution.
Here it comes right on cue folks. The old hoary “what good is half a wing!” Creationist gem.
Here is a 15 year old paper testing the WAIR (wing assisted inclined running) model for the evolution of avian flight. Note the authors specifically state how their work tests the hypothesis, something Bill swears doesn’t exist.
Abstract: The use of incipient wings during ontogeny in living birds reveals not only the function of these developing forelimbs in growing birds’ survival but also the possible employment of protowings during transitional stages in the evolution of flight. When startled, juvenile galliform birds attempt aerial flight even though their wings are not fully developed. They also flap their incipient wings when they run up precipitous inclines, a behavior we have described as wing-assisted incline running (WAIR), and when they launch from elevated structures. The functional benefit of beating these protowings has only recently been evaluated. We report the first ontogenetic aerial flight performance for any bird using a ground bird, the chukar partridge ( Alectoris chukar ), as a model species. We provide additional ontogenetic data on WAIR, a recently described locomotor mode in which fully or even partially developed flapping forelimbs are recruited to increase hindlimb traction and escape performance. We argue that avian ancestors may have used WAIR as an evolutionary transition from bipedal locomotion to flapping flight.
From the paper:
As a rebuttal to [Darwin’s (1859)] explanation of the origin and diversification of life, St. George Jackson [Mivart (1871)] posed a challenge: “What use is half a wing?” With this simple question, Mivart challenged Darwin to explain the adaptive role of intermediate forms within an evolutionary continuum, prompting Darwin to expand on the concept of functional shifts within structural continuity ([Gould 1985]). This concept of transitional functional and structural stages is the basis for exaptation, an integral component of modern evolutionary theory ([Gould and Vrba 1982]). A response to Mivart’s question is that if the wing of a flying bird is a product of small, gradual structural changes, these transitional forms must have had some function during the evolution of powered flight. But how do we assign and test a hypothetical function or propose an adaptive value for a transitional form that we find preserved only in the fossil record? This dilemma has spurred volumes of publications on the origin of flight, which have characteristically centered around two well-entrenched schools of thought. The first, known as the arboreal theory, proposes that flight evolved from tree-dwelling ancestors and predicts a gliding intermediate phase ([Marsh 1880], [Bock 1965], , [Feduccia 1996], , [Xu et al. 2003]). The other, known as the cursorial theory, considers ancestral birds to be terrestrial dinosaurs that developed powered flight “from the ground up” ([Williston 1879], [Nopsca 1907], [Ostrom 1979], [Caple et al. 1983], [Chatterjee 1997]. However, none of the historical theories regarding the evolution of avian flight adequately explains the functional value of a transitional wing to a protobird.
Perhaps new insight into this arena can be gained from studies on the behavior and ontogeny of extant species, both juveniles and adults, that exhibit locomotor patterns similar to those of avian ancestors (i.e., cursorial bipeds). Extant animals represent models relevant to explaining the functional strategies of intermediate ancestral forms because of the similarities between ontogenetic wing structures and the wings of potential transitional forms. More simply, where else can one find an incipient avian wing but on a baby bird? Thus, extant ontogenetic transitional forms provide observable, logical functional explanations of putative adaptive intermediate stages, as required for hypotheses structured in a historical-narrative arena ([Bock 1985]), and only by looking at these extant models can we take origin hypotheses into the experimentally testable realm. In this article, we explore the ontogeny of locomotor performance and its relationship to wing development in an extant model in order to gain insight into the origin of avian flight.
I am not debunking evolution. There is a solid theoretical basis for population genetics.
I am claiming that the origin of flight and other innovations are not part of modern evolutionary theory. Common descent explains similarities as reproduction produces similar features. Common descent does not explain the innovative differences is animals.
I have not made this assumption. Time, generations and populations cannot explain the origin of large novel functional DNA sequences. An intelligent Creator of the diversity of life can.
Like always the scientific evidence presented shows you’re dead wrong. Would it hurt you to once, just once, do a little research before making these frankly silly Creationist claims?
Of course they can when you consider well known evolutionary processes. Your lack of knowledge about the basics of evolutionary biology doesn’t make all our scientific understanding magically vanish.
So can invisible magic pixies. But since there is no positive evidence for the magic pixies or an Intelligent Creator we have no reason to consider them.
It’s your argument and it assumes only two supernatural options. Ha.
Not begging the question to answer which one I’d choose based on logic. Stop arguing with yourself so much.