I don't know. It depends on where you draw the "whale/whale ancestor" line.
From Babinski.
Posted on 05/23/2006 4:08:38 AM PDT by PatrickHenry
When ancient whales finally parted company with the last remnants of their legs about 35 million years ago, a relatively sudden genetic event may have crowned an eons-long shrinking process.
An international group of scientists led by Hans Thewissen, Ph.D., a professor of anatomy at Northeastern Ohio Universities College of Medicine, has used developmental data from contemporary spotted dolphins and fossils of ancient whales to try to pinpoint the genetic changes that could have caused whales, dolphins and porpoises to lose their hind limbs.
More than 50 million years ago the ancestors of whales and dolphins were four-footed land animals, not unlike large dogs. They became the sleek swimmers we recognize today during the next 15 million years, losing their hind limbs in a dramatic example of evolutionary change.
"We can see from fossils that whales clearly lived on land - they actually share a common ancestor with hippos, camels and deer," said team member Martin Cohn, Ph.D., a developmental biologist and associate professor with the UF departments of zoology and anatomy and cell biology and a member of the UF Genetics Institute. "Their transition to an aquatic lifestyle occurred long before they eliminated their hind limbs. During the transition, their limbs became smaller, but they kept the same number and arrangement of hind limb bones as their terrestrial ancestors."
In findings to be published this week in the Proceedings of the National Academy of Sciences, scientists say the gradual shrinkage of the whales' hind limbs over 15 million years was the result of slowly accumulated genetic changes that influenced the size of the limbs and that these changes happened sometime late in development, during the fetal period.
However, the actual loss of the hind limb occurred much further along in the evolutionary process, when a drastic change occurred to inactivate a gene essential for limb development. This gene - called Sonic hedgehog - functions during the first quarter of gestation in the embryonic period of the animals' development, before the fetal period.
In all limbed vertebrates, Sonic hedgehog is required for normal limbs to develop beyond the knee and elbow joints. Because ancient whales' hind limbs remained perfectly formed all the way to the toes even as they became smaller suggests that Sonic hedgehog was still functioning to pattern the limb skeleton.
The new research shows that, near the end of 15 million years, with the hind limbs of ancient whales nonfunctional and all but gone, lack of Sonic hedgehog clearly comes into play. While the animals still may have developed embryonic hind limb buds, as happens in today's spotted dolphins, they didn't have the Sonic hedgehog required to grow a complete or even partial limb, although it is active elsewhere in the embryo.
The team also showed why Sonic hedgehog became inactive and all traces of hind limbs vanished at the end of this stage of whale evolution, said Cohn. A gene called Hand2, which normally functions as a switch to turn on Sonic hedgehog, was shown to be inactive in the hind limb buds of dolphins. Without it, limb development grinds to a halt.
"By integrating data from fossils with developmental data from embryonic dolphins, we were able to trace these genetic changes to the point in time when they happened," Thewissen said.
"Studies on swimming in mammals show that a sleek body is necessary for efficient swimming, because projecting organs such as rudimentary hind limbs cause a lot of drag, and slow a swimmer down," said Thewissen, who spends about a month every year in Pakistan and India collecting fossils that document the land-to-water transition of whales.
Researchers say the findings tend to support traditional evolutionary theory, a la Charles Darwin, that says minor changes over vast expanses of time add up to big changes. And while Sonic hedgehog's role in the evolution of hind limbs in ancient whales is becoming apparent, it is still not fully defined.
"It's clear when ancient whales lost all vestiges of the limb it was probably triggered by loss of Sonic hedgehog," said Clifford Tabin, Ph.D., a professor of genetics at Harvard Medical School who was not involved in the research. "But it's hard to say for certain because you're looking at events long after they occurred. As they suggest, there could have been a continual decrease in Sonic as the limbs reduced until the modern version of the animal arrived."
The study itself, combining fossil and developmental data, is notable, Tabin said.
"Whales went through this remarkable transformation to become more like the ancestral fish," Tabin said. "Convergence of evolutionary studies and developmental genetics give us another piece in this growing tapestry of how genetic changes lead to morphological change. It is a remarkable process that was achieved simply and led to profound consequences in how whales were able to survive. Only now in the last five years are we developing this understanding of how the world of evolution is controlled genetically."
###
In addition to UF and Northeastern Ohio Universities College of Medicine, scientists from the Natural History Museum of Los Angeles County and the Indian Institute of Technology were involved in the research. Financial support was provided by the National Science Foundation, the National Institutes of Health and the Indian Department of Science and Technology, New Delhi.
I don't know. It depends on where you draw the "whale/whale ancestor" line.
From Babinski.
I assumed that they were horsing around, fell off the Ark, and had to swim for it!
I thank you for the post, and there was no sarcasm intended, after going to your reference I see that they referred to the Neanderthal man as fully human, were does he enter into the time scale, and they are saying that in fact we are all descendent's of Noah, after the great flood, but the U.S.Dept. of geology says that if you covered the worlds land mass with all the water not in the oceans (3,426 million cubic miles, 1 mile = 1 trillion gallons) the worlds land mass would be covered to a depth of approx. 1 inch ( taking that you can stick water on mountains) anyway 1 inch is hardly enough to get your feet wet, I suggest Noah might have done better going to high ground as the animal population at the supposed time of his being would weigh in at about 87,000 tons, and to build a ARK out of wood to carry such a cargo would have a combined weight of about 190,000 tons some engineer this Noah, even with Gods help it defies all engineering logic,like I said before there are still people that believe that the earth is flat, and I personally believe in numbers as it is difficult to make 2+2= 7( notice that is NOT two by two )
I'll leave that to the continuum descretizer contingent (CDC).
LOL...this thread is still going on? Scubie, I know you're well intentioned...but...
I thought it was over too! Al as much as wrote me off twice, and I was fine with that, but then I see he felt he needed to educate me on wheat and grass. So I (maybe foolishly) answered his last.
As far as jerry goes...he sent me another post claiming I didn't answer his first question, then posing another. I try to be accomodating. 8^)
I'm stuck at work, and the one thing I can occasionally do is monitor FR, so I'm suseptable to getting pulled into a "quagmire."
Hope you are having a good day.
Sincerely
"I thought it was over too! Al as much as wrote me off twice, and I was fine with that, but then I see he felt he needed to educate me on wheat and grass. So I (maybe foolishly) answered his last.
As far as jerry goes...he sent me another post claiming I didn't answer his first question, then posing another. I try to be accomodating. 8^)
I'm stuck at work, and the one thing I can occasionally do is monitor FR, so I'm suseptable to getting pulled into a "quagmire."
Hope you are having a good day.
Sincerely"
Ahh, yes...the wheat and grass. I'm still awaiting the link for that reference. Keep 'em flyin'!
<< Ahh, yes...the wheat and grass. I'm still awaiting the link for that reference. Keep 'em flyin'! >>
Au contraire! I said you could google it. There are many links you could use. And YOU said you would look into it.
It's not a silly question. It goes to the heart of your claim that speciation does not occur.
I need something more specific on it. Couldn't weed thru all the "near hits".
This is about as close to what you were saying (maybe it's because I can't stand Google and don't use it). http://www.genetics.org/cgi/content/full/168/2/1087
The jist or conjecture is wheat and human share a common series of evolution with each other.
However, Haung's conclusion was "However, recent data suggest that most domestication-driven, agronomic, and end-use traits, as well as those genes involved in landmark speciation events such as polyploidy, are crop and species specific."
I agree, if it were plausible, it would be species specific. I wouldn't expect wheat to evolve into an elephant, but some other plant form specific to wheat--but would still be a species of wheat. Kinda like you can't cross breed apples and oranges. Different species, I'm guessing.
<< The jist or conjecture is wheat and human share a common series of evolution with each other. >>
It wasn't conjecture. It was merely pointing out a parallel -- not a common series.
<< The jist or conjecture is wheat and human share a common series of evolution with each other. >>
Why can't domestic wheat interbreed with emmer grass?
Because domestic wheat is a descendant of wild emmer grass, through mutations and natural and human-directed selection. Now, domestic wheat is a different species.
IOW -- speciation.
If you would like more examples of speciation, just let me know. If you would like to continue holding your hands over your ears and closing your eyes tight -- that only says something about you, not the evidence.
"Because domestic wheat is a descendant of wild emmer grass, through mutations and natural and human-directed selection. Now, domestic wheat is a different species."
This proves wheat is of the same kind. Much like wolves probably begat dogs. But if the DNA has been artifically manipulated, then it's a different issue.
What's your take on Haung's conclusion?
<< This proves wheat is of the same kind. >>
So -- speciation does not occur -- but when it DOES occur, it's okay, because it's the same "kind."
I have been asking creationists for ten years to define "kind." I get a lot of evasions -- and when I do get answers, I get things like "species" -- or "genus" -- or "order" -- or even "family."
What is a "kind" and where do we find a definition like that in science?
"What is a "kind" and where do we find a definition like that in science?"
I doubt if you'll find that term in scientific circles. It's Scripturely based.
"So -- speciation does not occur -- but when it DOES occur, it's okay, because it's the same "kind."
If plausable--is what I said. That would mean from a mircoevolutionary concept--it might be feasible, in my opinion. (note: I said might, which means I would entertain the thought). But from a macro perspective, no. I don't believe there's compelling evidence suggesting a macroevolutionary process is "creating" new and different life forms--separate and genetically different from the "parent".
As far as the wheat and emmer grass studies, the fact that man has done much in "breeding" different strains may be one reason these are incompatible. Any of us in Kentucky can tell you that thoroughbreds are pretty much tapped out as "designer" racing horses. In fact, some are so inbred, that they're ineffective, can't reproduce, too fragile, etc. Probably because the bred has not benefited from genetic drift and diversity.
Just my hunch.
"What is a "kind" and where do we find a definition like that in science?"
"I doubt if you'll find that term in scientific circles. It's Scripturely based."
No, you won't find it in science, so why are you insisting on using it to refute a scientific conclusion? And since you still have not defined it -- scientifically OR biblically -- it has no real meaning.
This creationist argument -- "the kinds are fixed, and it is impossible for evolution to pass the barrier between them" -- cannot stand up under even the slightest scrutiny. Creationists have never been able to tell me -- or anyone else, as far as I can tell -- what the created kinds are.
If kinds are distinct, it should be easy to distinguish between them. Instead, what do we find in nature? We find what is called a 'nested hierarchy' of similarities, with kinds within kinds within kinds. Pick a "kind" -- and we find that this "kind" fits nicely into larger and larger "kinds" that are inclusive of that one.
No matter where you posit your barrier for how much is included -- there will be many groups that overlap the boundaries of that barrier. While this pattern fits the prediction of evolution, it directly violates the "biblical" principle of "fixity of the kinds."
In fact -- this idea of a barrier between "kinds" is not even taught in the Bible. All the Bible says is that the different "kinds" were created, and that they reproduce "after their kind." This does not contradict evolution, since evolution does not posit that individuals evolve -- only populations, after a cumulative amount of mutations and selections.
The Bible nowhere says that "kinds" cannot change and grow into more variety of "kinds," nor does it give any hint concerning any "barrier" that prevents evolution from passing beyond the "kind" level -- whatever that is.
I have two questions:
1) What is a "kind"? Same question I asked before, which you did not answer.
and
2) What is the scientific mechanism that erects a barrier between kinds, so that evolution can work up to that point, but no further?
So-o-o-o-.....whales started out as water dwelling creatures, evolved into landlubbers (landblubbers?) and then re-evolved back into water creatures?
Can one use the words "evolved" and "creatures" in the same sentence?
"1) What is a "kind"? Same question I asked before, which you did not answer."
I don't define it, the Scriptures do.
My guess would be a more defined taxonomic classification based upon observation or physical evidence of the animals themselves. Whereas we know a coyote/dog when we see it. And can observe this is a "kind" of canine and it's characteristics attests to the evidence of such. And we know that dogs can't breed with aligators. Nor would I expect a wolf breeding with a cockerspaniel produce a new "kind", such as a bird.
The creation by God of distinct "kinds" is described in 1 Corinthians 15:38-39 implies that transmutations between kinds is precluded, or at least superfluous.
1 Corinthians 15:38-39 (Holman Christian Standard Bible)
38 But God gives it a body as He wants, and to each of the seeds its own body.
39 Not all flesh is the same flesh; there is one flesh for humans, another for animals, another for birds, and another for fish.
Otherwise, I guess you could google it! LOL!
"2) What is the scientific mechanism that erects a barrier between kinds, so that evolution can work up to that point, but no further?"
Because God created life "each according to its kind" as specified in Genesis. See also, again, 1 Corinthians 15:38-39. The same reason we cannot breed with apes, they are of a different kind. If we were of like kind, then this would be possible. But we're not. We may share similar DNA, (what? something like 96%? Can't remember)etc, but this doesn't tell us anything. Clouds are 100% water. Watermellon is approximately 98% water. Are we to conclude they have a similar "make up" and should expect to observe mellons in the sky?
I supposed God could evolve Man as you implied. Nothing is impossible for God, but I've not read anything suggesting this. I guess you could argue the term "creation" in general terms and that God used a process. However, the references in the Scriptures clearly use the term "create". Until there is anything compelling that is "discovered" and goes through a proper peer review, I'll still remain within the word of the Gospel otherwise.
I've tried to honestly and respectly respond to your questions based on my belief system irrespective of the so-called evidence that you've embraced--and haven't been a wise guy or silly like I was earlier. Now I have a couple of questions--
1. Why is it you would discount the word of God and why would you believe that God did not do the things as described? Is God a liar? If God created Man in His image, then why are the Scriptures that difficult to understand/believe--especially in light of the "Y chromosone Adam" discovery?
2. Why is it important to put your faith in what Man tells you rather than an all encompassing God?
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