I often hear evolutionists claim that they “know how macroevolution occurs” and how this claimed knowledge explains the evolutionary history of life on earth. If they really have this knowledge, I would like an evolutionist to explain how, for example, one would actually go about breeding ancient reptiles to eventually produce a bird (hypothetically speaking, of course).
I assume that if you were breeding ancient reptiles, you would breed them the same way you breed any domestic animal in order to emphasize the traits you want to see.
I’m not sure what specifics you’re looking for – perhaps you could give some more information about which parts of evolution you’d like more understanding of.
I would probably start with an ancient winged dinosaur, maybe one with feathers.
I suspect Edgar was interested in the evolution leading from a dinosaur less obviously in the line of descent to birds. But for that we’d just need to pick an earlier forebear of the group that went on to develop feathers. Of course the process would be much slower than any human breeder could have hoped to achieve in his lifetime. Isn’t the short answer to the question regarding macroevolution essentially many, many instances of microevolution?
It’s all there in the Current Biology article. I doubt that Edgar is interested in bird evolution, but I am, so I thought it would be fun to look at that nice review.
Sure, but even then, one reason that morphological innovation is so interesting in this context is that it suggests the possibility of rare, large evolutionary changes of the kind that is discussed in (for example) evo-devo circles. When we look closely at wings, for example, we see standard vertebrate forelimbs with bird specializations. But when we look at feathers, by contrast, it’s less clear; maybe they were something new and special. There have been some very recent advances there, suggesting that feathers predate birds by millions of years, but it still seems unclear where they came from, biologically. My point simply being that a picture of smooth, continuous, nearly imperceptible change adding up to macroevolution is potentially too simple even though it’s mostly correct and even though from a rate-of-change perspective, it’s completely correct.
[Edit: PDF sent on request]
Interesting article. It makes sense that feathers preceded birds, as evidently they were in place and adapted to new use for flight rather than the opposite progression. In like manner, skin was adapted by bats for flight. It really could be no other way.
In the OP question, to me the idea of deep time is the starting place, as without it you can not have evolution. That is probably why AIG fights the idea of deep time so religiously (pun intended).
It seems to me that any evolution performed by nature (natural selection) could theoretically be performed by humans (artificial selection), given enough time. So how would you start breeding ancients reptiles to develop an avian heart, to become warm- blooded and to develop wings?
I’m no expert and not a biologist (more like a bumbling amateur, really), but it’s my understanding that each time you select from the population to isolate a specific feature, it significantly reduces the genetic diversity within the population, so I imagine the chances of doing this for multiple features would be rather low, simply because you’re running out of genetic diversity. My understanding is, selecting for one feature usually means it reduces the chances of selecting for other features.
Plus there is the problem of harmful mutations (that result in weak, sick and unfit animals) arising when the genetic diversity becomes too low - a problem that is well known to dog breeders, for example, and which actually limits how radically dogs can be bred from the “original” dog. In other words, I think in trying to breed dino’s into birds, one will encounter the same genetic problems as any all animal breeders have encountered.
That’s sort of cheating. As far as I know, the earliest dinosaurs didn’t have wings or feathers. How would you breed these original dino’s to evolve wings and feathers? Then how would you breed these winged, feathered dinosaurs to become warm-blooded and to evolve an avian heart?
I don’t set a time in the OP - let’s assume unlimited time (the original breeders sadly wouldn’t be alive to see the end product - if there is an end product).
Yes, that’s the theory; but thousands of years of animal breeding demonstrates that there are genetic limits to how much an animal can “evolve”.
How so? DNA sequencing says otherwise, that genetic changes are far more deep.
Rats you didn’t try to learn anything from @sfmatheson. Did you get a copy of the paper he shared, The Early Origin of Feathers? If you are curious about warm-bloodedness here is a Google Scholar search for ‘Origin of endothermy birds.’ Its an interesting question, but only when one is willing to learn on the topic and not insist ‘well you can’t explain this or that, therefore I’m right in whatever I want to be true.’
Dog breeders are working to limit genetic diversity. They do this by inbreeding to produce a “pure bred” dog. This also results in the retention of harmful genetic characteristics but since the dogs are being supported and fed by the humans this isn’t a problem. Dog breeding is not a good model for evolution because it doesn’t work like natural selection. Ask any vet and they will tell you the healthiest dog is going to be a mutt.
Is it wise to judge the limits of natural selection which has been in play for billions of years on what has been possible for humans to achieve through deliberate selection in the couple of thousand of years we’ve been at it. Also keep in mind that no human breeding project has ever had as its aim to breed something as different as possible from the starting stock. Early human efforts were always about enhancing the traits we already liked while smoothing out those we didn’t. In natural selection, a population of an organism is culled by changing environmental pressures so that those which survive will be those most likely to pass along the needed traits. No breeder is required. Natural selection is more elegant than that.
I haven’t seen that data. Can you provide a reference?
Strong selective sweeps, in which a gene or trait is fixed rapidly in a population, do typically result in reduced genetic diversity in the vicinity of the selected gene (in the genome) but will only affect overall genetic diversity if the sweep is incredibly fast. Even then, diversity recovers over time. So it is incorrect to claim that selection strongly reduces genetic variation, and it is even more wrong to suggest that reduced diversity after a hard selective sweep would be permanent.
Are you kidding? Ask any dog breeder what happens when the genetic boundaries are explored - the result is weak, sick, deformed and unfit animals. That’s common knowledge. Your macroevolutionary imaginings seem to be divorced from reality.
"In his recent book, The Greatest Show on Earth: The Evidence of Evolution , Richard Dawkins observes airily that human beings are "distant cousins of bananas and turnips." Yet minutely observant plant breeders, "daily and hourly scrutinizing" their productions (to quote Darwin on natural selection), are unable to turn purple roses into blue ones." (Tom Bethell, Natural Limits to Variation, or Reversal to the Mean: Is Evolution Just Extrapolation by Another Name, evolutionnews.org)
"The available data of biology indicates that in contrast to evolutionary theories, there is sufficient evidence to suggest that biological change has limits." (Lane P. Lester and Raymond G. Bohlin, The Natural Limits of Biological Change, 1984, p.149)
That is certainly true, when you have inbreeding and lack of genetic diversity. It is well known that severe genetic bottlenecks often lead to extinction for that reason. Cheetahs are at risk due to that lack of diversity, as are Tasmanian devils. This is well known to evolutionary scientists. However, it does not follow that it indicates a limit as to evolution, just that some lineages do not make it.
The answer to my question, then, is ‘no’.
Thought this was cool-
Just ran across this. Pretty basic, but a good primer.