Merged Icebear's Evolution Thread

[Dinwar]

The Hominidae (/hɒˈmɪnɨdiː/; also known as great apes[notes 1]) form a taxonomic family of primates, including four extant genera:

One quibble: it's pretty obvious that the interbreeding was between H. sapiens sapiens and ancient hominids, which is a non-scientific term meaning the clade that gave rise to humans (Homo, Australopithicus, and the like). Your objection, DC, is somewhat akin to saying that when one discusses reptiles one must include birds: technically true, but missing the point of the statement.

 

[Gawdzilla Sama]

Nonetheless Neanderthal DNA has been shown to be roughly halfway between ours and that of a chimpanzee, neatly eliminating the Neanderthal as a plausible human ancestor.

Can't figure out how they reached this conclusion.

 

[RecoveringYuppy]

NOBODY who understands this stuff claims that natural selection ever creates anything. You could no more create a new species of animal with natural selection than you could construct a building with a wrecking ball.

If you yourself understanding the point that you are "correcting" here then why did you describe natural selection as a mechanism of stasis?

What is the purpose of sex (as opposed to the asexual reproduction which we see in simple creatures)? Sex DOUBLES the cost of maintaining populations. In other words, amongst asexual creatures, each creatures needs to have one offspring to keep population size together; the cost is basically one. For creatures which use sexual reproduction, each creature needs to be involved in procreating TWO like creatures, i.e. the cost is DOUBLED!!

No. Take humans, a simple case, for example. Two humans produce two humans, population is maintained. One human per human. The cost you are claiming here does not double.

 

[Dinwar]

If you yourself understanding the point that you are "correcting" here then why did you describe natural selection as a mechanism of stasis?

It's one of the conclusions from Punctuated Equilibrium. Not that icebear is accurately portraying it, of course.

 

[Maestro]

The Neanderthal genome is reported to be 99.7% identical to modern humans. I was never great at math but that is nowhere near 50%.

 

[ehcks]

The Neanderthal genome is reported to be 99.7% identical to modern humans. I was never great at math but that is nowhere near 50%.

If chimpanzee DNA is 98.8% similar to humans, and neanderthal DNA is 99.7% similar, then.. it's not exactly half-way in between, but it's also not "neatly eliminating the Neanderthal as a plausible human ancestor."

Wait, I did that wrong.

 

[Slowvehicle]

The Neanderthal genome is reported to be 99.7% identical to modern humans. I was never great at math but that is nowhere near 50%.

Yeah, but that's only "after Adam"...math was different "before the fall".

Woo hoo!

 

[RecoveringYuppy]

It's one of the conclusions from Punctuated Equilibrium. Not that icebear is accurately portraying it, of course.

How so?

 

[catsmate]

I've read this and it is clear that you have no idea what you're talking about.

in fact

seems appropriate.

 

[marplots]

Two parents, two offspring. How is the cost doubled?

Also, why did we decide that the unit of description should be parents anyhow? Wouldn't it make more sense to look at populations instead? So, for example, you'd want to think about things like bee colonies where there are scads of drones and workers. Reproduction isn't the whole story, especially when you consider the larger picture may very well decide survival.

 

[bruto]

The Neanderthal genome is reported to be 99.7% identical to modern humans. I was never great at math but that is nowhere near 50%.

Not that it matters much to the basic question of certain posters being utterly and woefully and wilfully ignorant, but I think the contention was that Neanderthals' genome is different by 50 percent of the difference between a person and a chimpanzee. All animals share a huge number of genes, and humans and chimpanzees are already very close. As the famous biologist George Wald succinctly put it, genetically we are more like yeast than unlike it.

This does not, as far as I can see, make Icebear's knowledge of evolution any deeper, or erase his apparent unwillingness to understand what common ancestry means.

 

[Baylor]

Two parents, two offspring. How is the cost doubled?

I don't know about "doubled," but the cost is high....for the female. She needs a fit male with high-quality DNA to ensure sex is worthwhile. That's why in most animal species, you see a small % of males mate with a high % of females. This is obvious to anyone who went to high school.

 

[Robrob]

But, WAIT!! Aren't mutations supposed to be the driving mechanism of evolution itself?? What's wrong with this picture and with a theory which tries to explain our entire biosphere with mutations??

No, evolution is a process. Random mutations, most neutral, some negative and a few positive are "weeded out" by natural selection. The most "fit" survive and populate.

Again, the standard statement of the theory of evolution is that mutations create new kinds of creatures and then natural selection weeds out the unfit from the new kinds. Natural selection itself is a destructive process and an agency of stasis and does not CREATE anything.

So other than restating the obvious, your point? Or are you next going to declare burning petro-fuels is a destructive process and does not MOVE anything?

Go back and read the OP again and try to understand it. NOBODY who understands this stuff claims that natural selection ever creates anything. You could no more create a new species of animal with natural selection than you could construct a building with a wrecking ball.

The standard claim is that mutations create new kinds of creatures, and then selection pares the collection of new kinds down to the "fit" amongst them, i.e. weeds out the unfit.

Evolution is a process driven by natural selection, so what is it you are complaining about?

 

[Mojo]

Evolution and sex

Yes please.

 

[pakeha]

....Worst case on the planet is Saudi Arabia:

https://www.google.com/search?clien...tic+diseases&sourceid=opera&ie=UTF-8&oe=UTF-8

...

I had no idea of this situation in the Arab world.

And yes, I agree with Loss Leader

I think you need to read a book about evolution. ...

There's a lot of on-line material, too, icebear.

 

[Dancing David]

What is the purpose of sex (as opposed to the asexual reproduction which we see in simple creatures)?

You do know there are organisms that reproduce asexually?

I wonder what benefit there is in mixing genes and random variation?

I also am aware you will not respond to this, but answer the second question.

Hints:
-diseases in mono culture crops, which have more variation that asexual clones.
-what mechanism allows clones to adapt to changing environments.

Just for your knowledge, aphids and yeast are two creatures, besides amoeba that reproduces asexually.

 

[Dancing David]

Go back and read the OP again and try to understand it. NOBODY who understands this stuff claims that natural selection ever creates anything. You could no more create a new species of animal with natural selection than you could construct a building with a wrecking ball.

The standard claim is that mutations create new kinds of creatures, and then selection pares the collection of new kinds down to the "fit" amongst them, i.e. weeds out the unfit.

Bold words that essentially demonstrative of your closed mind.

Weeding out the unfit matters little, what matters is the numbers of successive generations from those that breed successfully. maybe you you should start with some ToE written after 1960.

Nothing creates 'a new creature' in a single step, but please continue to show you closed mind so openly.

 

[Dinwar]

How so?

Gould and Eldridge found that many species are remarkably stable through long stretches of geologic time. I've seen their reports (Gould's papers are largely available free online, with a quick Google search, if you want to see them yourself), and even got the chance to look at some of the species they worked with, and can attest to the accuracy of their observations. I've also seen it demonstrated in species neither considered, which further supports this notion.

The reason for this, according to those researchers and later ones (and from my own research, I can say confidently that it makes sense), is that organisms will quickly adapt to reach a local fitness high. Once there, the organism can't easily adapt any further--they're at the local high, so any adaptation will reduce their fitness. There are numerous mechanisms by which this can happen, but natural selection is constantly culling the population, creating selection pressure that attempts to push the organisms back to that local fitness high. In other words, organisms rapidly adapt to their environment, and most of the time any subsequent shift in the population will result in the organisms being less fit.

This isn't universally true. Chronospecies are species that evolve wholesale into new species, and this obviously can't happen if the population is under confining pressure. And if the environment shifts significantly the organisms adapt, follow the environment, or die. But for many organisms, natural selection is a conservative force for most of the lifespan of the species.

The real issue--one that people on all sides of the PE debate tended to forget--is that biology is incredibly complex. PE, phyletic gradualism, and other modes of evolution--even hopeful monsters--play a role. The question is, WHAT role? In other words, which modes of evolution are dominant under what conditions? PE works well as a model for mollusk evolution, but not so well for foraminifera (or, as I said before, chronospecies). Hopeful monsters do from time to time arise (six-legged frogs and the like), but they tend to not survive very long and are almost irrelevant to evolution today (in the Tonian, however, who konws?). Plants and bacteria and archea play by their own rules; these models of evolution (and pretty much any you'll ever see on this forum) were developed for animals, so there's no reason to assume they apply. Etc.

 

[Mister Earl]

"My ignorance is just as good as your knowledge."

 

[Wowbagger]

As I see it, the purpose of sex is to prevent genetic mutations from driving complex species to extinction within a few generations.

What it does is add more variety to gene combinations in the gene pool. More variety means more chances to overcome changes in the environment, as species become more complicated.
For example, it plays a role in preventing a single gene line from becoming overly exploited by another.

It doesn't have much to do with preventing genetic mutations from happening.

But, WAIT!! Aren't mutations supposed to be the driving mechanism of evolution itself?

It's not just mutations.

There are LOTS of other ways variety is added to the gene pool, as well: Transpositions, recombinations (through sex, as I mentioned), deletions, insertions, activations and deactivations from other genes, etc.

Again, the standard statement of the theory of evolution is that mutations create new kinds of creatures and then natural selection weeds out the unfit from the new kinds.

That's a tad naïve.

More accurately: Variety is added to the genome in the reproduction process, and Natural Selection weeds out those that are less fit among that variety. This could include some of the "new kinds" of creatures, but also a large number of the older ones.

Natural selection itself is a destructive process and an agency of stasis and does not CREATE anything.

When you alternate the process of reproduction (with mutations and other things adding variety to the pool) and natural selection, over and over and over again... for many, many generations, the results are going to be species that don't look or act very much like their ancient ancestors.

But, the changes across each of those single generations are going to be very subtle. Lots and lots of small changes, over time, become what appear to be big changes, when you compare the "start" with the "end".

Understand now?