The Fossil Record, Speciation, and Mutation Rates


(Dcscccc) #1

hi prof davis. first- about the evolution of whale see my discussion with dr venema in this post:

http://biologos.org/blog/biologos-basics-video-7-how-evolution-works-part-2

now about the fossil record. prof dawkins for example claim that even one fossil in the wrong place will falsified the evolution theory (like a human with t-rex). but in reality we find a lots of such fossils. for example: we find a tetrapod footprint that is date more then 15 milion years earlier then its transitional form:

its like to find a human fossil even before apes.

so the fossil record actually contradict the evolution prediction.


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(Chris Falter) #2

I think you have a misunderstanding of the scientific process. Well-established theories constantly get tweaked as new data are added to the catalog of findings. Surprising new data don’t necessarily prove the established theory was wrong; they just imply that the theory needed a better articulation of details, mechanism, timelines, etc.

Here are some examples from other scientific disciplines:

  • Pluto was once regarded as a planet. Additional data have shown that it is not. Does that mean that the theory of a heliocentric solar system has been overturned?

  • Satellite observations in the latter half of the 20th century surprised geophysicists, who had not previously suspected that the southern hemisphere is ever so slightly larger than the northern. Does that mean the earth is flat?

With regard to the 395 million year old trackways, it is important to note that we don’t even have a fossil skeleton of the creature(s) that left them. Thus it is imprudent to draw strong conclusions about where the critters fit in the phylogenetic transition from lobe-finned fishes to tetrapodes. I.e., we don’t have enough evidence to conclude that the trackways occur 15 million years too early.

There have been a whole lot of fossil discoveries that initially forced recalibration of the contemporary accounts of evolution. The theory got recalibrated to incorporate the new data, and thus continues to thrive. Much like the theories of the solar system and of the shape of the earth.

If a fossilized homo sapiens was discovered to be 395 million years old, now that would be something truly revolutionary. A fossil that shows a transition occurred 15 million years earlier in Poland than it did in Canada is not the same thing.

If you see this in a timely fashion, I would ask for your prayers as my wife and I make our weekly Tuesday evening visit to a maximum security prison to evangelize and disciple the men there, as part of our church’s outreach.

Thanks, and have a glorious day in Christ!

Chris Falter


#3

These seem to me to be rather ridiculous examples, Chris. Not at all parallel to the kinds of things that dcscccc is bringing up. Pluto not being large enough for a planet? The earth is flat…? What?

Fossils out of order create serious problems for the evolutionary tree. Even if there are explanations made, it means the predictive power is reduced. Complex organs (irreducibly complex) also cause problems for an evolutionary pathway. This doesn’t mean that perhaps an explanation cannot be made, but this is on an entirely different order than your examples.


(Dcscccc) #4

hi chris. you said:

“If a fossilized homo sapiens was discovered to be 395 million years old, now that would be something truly revolutionary. A fossil that shows a transition occurred 15 million years earlier in Poland than it did in Canada is not the same thing.”-

not realy. first we can just say that this fossil somehow get to the wrong layer. maybe even fall into a deep cave or somthing. so even a fossil of homo sapiens date about 395 my cant disprove the evolution theory.

secondly- where is actually the limit? what about homo with dino?

have a good day


(Chris Falter) #5

Hi JohnZ -

My essential point was that discovering a new piece of data that doesn’t quite fit with the previous theory doesn’t imply that we should just throw out the old theory altogether. I picked extreme examples because they are easier to understand.

In the current discussion, dcsccc was quite willing to discard the entire theory of evolution because a fossilized trackway in Poland showed the transition from lobed-fin fish to tetrapod happened somewhat earlier there than it did elsewhere. I was urging him to instead consider another possibility, namely that

(a) the local conditions in Devonian Poland might have been different than elsewhere, and thus more conducive to an earlier transition to land, and

(b) the lack of fossil skeletons make the construction of a phylogeny for the track-leaving Polish tetrapods rather difficult.

Lots of fossil discoveries have been initially surprising and forced revisions of timelines. Feathered dinosaurs. Australopithecus sediba. Early docodont diversity. But paleontologists have been able to incorporate them into the story of the evolution of life. The Polish trackways are no different.


(Chris Falter) #6

Hi dcscccc - Discovering fossil evidence of homo sapiens during the Jurassic or Cretaceous would be truly revolutionary, yes. Nobel Prizes would surely follow.

Do you have any specific evidence in mind?


#7

However, what does an earlier transition do to the time required for mutation rates? I also find it interesting that it is the lack of fossils that establishes the limits for transition links. But lack of fossils, as shown in this example, does not mean that the link is absent. In other words, there is little justification for not putting every single species in the tree at least 50 million years earlier than the first fossil is found. This particular one added 15 million yrs, but how do we know there are not others still waiting to be found, or even if there are no fossils, that the species did not exist 50 mill yrs earlier, leaving no fossils or fossil footprints behind?


#8

Hi JohnZ,

I can’t unpack this question. Mutation rates are expressed as mutations per unit time, so I have no idea what you are trying to convey when you write “time required for mutation rates.” Can you clarify?


#9

What I meant by my rather convoluted question is that the earlier appearance of a species (transition from ancestor) presumably means a shorter time for mutations to occur that allow for the the new species to be selected.


#10

OK. Wow. If I’m understanding you now, you have an enormous misunderstanding of speciation.

In addition to selection not happening on species, and speciation not being the discrete event you seem to be describing, there’s no waiting around for mutations to occur.

Indisputable fact: populations have existing genetic variation (polymorphisms). This fact is measurable and true regardless of anyone’s beliefs about their randomness. Are you with me so far?

Obvious conclusion, but only if you understand mechanisms: there’s plenty of raw material for selection to act upon for many generations if God reduced the mutation rate to zero.

Your huge misunderstanding here is that there is some static state of a population just waiting for mutations to occur. All natural selection requires is variation that we already know exists, not new mutations. It’s far more likely that recombination will create a new genotype with selective advantage than mutation will.

Remember, the reviled Darwin knew nothing about mutations. He merely saw the indisputable fact that there is heritable variation in populations. Darwinian evolution is more simply and accurately described as heritable variation+natural selection.


(Dcscccc) #11

chris. why actually? we can just say that the this species evolve earlier then we thought. so even this kind of fossil will not disprove the evolution.


#12

You are right about that, but still you have missed the point. Evolutionary theory postulates that mutations are the source of the variation, and that mutation rates are more or less constant, ie. similar to what they are today. You are right that natural selection works on existing variation, but… without the random mutations, there would not be sufficient variation to develop new distinctive species or kinds. There would only be various strains within species.


(Christy Hemphill) #13

I thought speciation happened because a segment of a population became isolated from the other decendants of their ancestors, either because of geography (islands/lakes, etc.) or because individuals with certain traits gravitated to a different ecological niche as part of competition for resources. Over time, certain traits (for which the genes existed in the ancestor population) get weeded out or become more prevalent in the different groups, until after enough generations, the two populations will not interbreed. That’s how I’ve heard it explained for the honeycreepers in Hawaii or the Lake Victoria cichlids, for example.


#14

You’re not making sense. Insufficient polymorphism would lead to extinction.


#15

You are absolutely correct, Christy, but JohnZ appears to want us to view speciation as something that happens linearly to a single population, instead of the branching you described, driven most often by environmental changes.


(Dcscccc) #16

joao. how many mutations you think we need to a 100 amino acid functional protein?


#17

I do.

Of course it is population genetics. Don’t recall doing the second statement. “Evolutionary evolution”?

You’re suggesting that today’s mutation rates are not indicative of ancient mutation rates? Well, that’s a start.

You’ve missed the point.

Again missed the point.

You are changing the subject.


#18

This is entirely incorrect. Christy’s description is correct, but speciation on this basis will be the result of a loss of genetic information, reducing the variation and polymorphism, not increasing it. Just because two populations do not interbreed due to isolation, does not mean that they cannot. When we discover that they can interbreed, then we have difficulty with the definition of species, and debate whether they are merely different strains, instead of different species.

Nor is the change driven by environmental changes, but rather by certain individuals finding their niche in various environments. Ie. different “cats” in the jungles vs in the artic vs in the dessert. Due to isolation they do not interbreed, but under certain circumstances, some of them can interbreed.


#19

[quote=“johnZ, post:45, topic:748”]
This is entirely incorrect. Christy’s description is correct,…[/quote]
Well, if I say that Christy is absolutely correct and you say that what I say is entirely incorrect, then Christy’s description cannot possibly be correct–if you’re correct.

Fascinating! Do you have any data, John? Why “variation and polymorphism”? What’s the difference between those genetically?

Correct. However, the isolation allows to take them in different directions so that they eventually cannot. That’s non-Darwinian, btw.

I don’t see anything to debate about, John, except that Darwinian theory predicts that lines between species will be fuzzy. What does your hypothesis predict?

Geographic isolation is obviously an environmental change.

Not necessarily. It’s a faulty metaphor because the individuals aren’t doing any “finding.”

Those are much further apart than species. Are you familiar with higher taxonomic classifications? Do you realize that Felidae is a family?

[quote]Due to isolation they do not interbreed, but under certain circumstances, some of them can interbreed.
[/quote]Do you really think that a lynx can interbreed with a jaguar?


#20

Wrong. A half truth is often no better than an outright falsehood.

Don’t you kjow?

Drift is the result, not the cause.

Yes.

Not really.

groups are made of individuals. white cats find their niche in snow covered areas. the yellow and brown off-types do not find their niche there.

Yet some of them can interbreed.