Doubting Didymus

Quite, but nonetheless, you cant pass nurture down the generations, unless you are talking about memes.

Nature and nurture create individuals, but only nature (consisting of the genetic instructions) can evolve.

RufusAtticus

Remember, that for every rule in biology there is an exception. Offspring inherit more than genes. Wolbachia is a great example of Lamarkian inheritance.

The key word here is "evolve" as in "evolution." There are many different ways to express evolution, some more restictive than others. I think the most accurate and scientificly open is the following.

• Evolution is the change of properties of a population or frequencies of such properties between generations.

It states nothing about the mode of inheritance, just observations of descent with modification. Thus even changes in traits like culture are evolution.

[ October 16, 2002: Message edited by: RufusAtticus ]</p>

Doubting Didymus

But you wouldn't classify heritable change as distinctly different from other kinds of change?

By your definition, if I cut of the legs of my neighbors cat, then the cat species has evolved. If I dye every sheep in the world blue, then the sheep species has evolved toward blueness.

These changes in the properties of a species might be 'evolution' in a technical, trivial sense, but they are not what is normally meant by evolution in the biological sense.

RufusAtticus

Note the last two words in my description.

Doubting Didymus

"Between generations".

Okay, but doesn't that still restrict evolution to heritable changes?

Please fill me in here, as I have never quite got my head around non-heritable factors in evolution.

Would I then be justified in saying that, if a change in the environment occurred that caused the clouds of New Zealand to precipitate blue ink, thus staining blue every sheep, then the sheep could be said to have evolved blueness? Considering that this environmental factor will cause blueness in every generation, does it, or does it not fit your definition?

RufusAtticus

Although your example is extreme, I would argue that evolution has indeed happened. You used to have white sheep, now you have blue sheep. Has the gene pool changed? No. Has the population changed? Yes.

The issue here is that on some level, you can't separate environment from genes. Or rather isolate heritable factors for poplation change from everything else. That is why I tend to describe it as broadly as I do.

Compare the following descriptions.
<ol type="1">[*]Evolution is a change in a gene pool.[*]Evolution is the heritable change of properties of a population or frequencies of such properties.[*]Evolution is the change of properties of a population or frequencies of such properties over time, i.e. between generations.[/list=a]

Now, (1) makes too many assumptions about the nature of inheritance; (2) leaves open the question of how do you determine wheather a change is heritable or not; (3) doesn't have these faults. The significance is that even non-heritable change can be significant enough to affect the future evolution of heritable traits.

Oolon Colluphid

Hey guys, as usual, the more you learn, the more you learn you need to learn. I’ll bow out. Once again I’m out of my league once the serious science starts. (Any fool (including this one) can kick holes in creationists. Trust scientists to muddy the waters by pointing out that life ain’t that simple . ) Still, one last attempt...

I’ll assume you simply missed off a ‘ ’ there... I’d hate to have to say something like “right y’are milord, whatever you say milord’ &lt;tugs forelock&gt;”

Well, yes of course they are... but sorry, but I was under the impression that they were mainly passed on through the genes that make bodies which express the phenotype (in conjunction with environment yadayada...). I must have missed something in all those textbooks that gave me that impression (not impossible -- they aren’t such rivetting reading that I’ve made it right through any of ’em yet!).

Well take it up with him then. I am allowed to be blinkered (though happy to have them removed) since my degree is Classics, and I last did biology officially at A Level back in 1986. I’m surprised if Dawkins is blinkered though. My only evidence is that what he says nearly always rings true to me, whereas his ‘opponents’ don’t. So take it up with him for misleading the public!

If you can find anywhere where I’ve suggested that genes are diseases, I will happily leave this forum for ever in shame. It’s not ‘interesting’ (implying ‘revealing’) in the slightest. As with neurological disorders, disorders are a useful way of seeing how the stuff works normally. I could have picked on positive phenotypic effects, but I couldn’t think of any clear-cut examples off-hand, and didn’t want to use hypotheticals. Not having sickle-cell anaemia, not having phenylketonuria, etc, didn’t make the point as well. But if you want one, how about nylon oligomer digestion in bacteria?

Hmmm. Well, if you say so. I’ve heard from a variety of sources (hence its believability) that there’s too much political ideology mixed in, so I’ve not bothered previously. But okay... &lt;doubtful&gt;

Ah, the power of Dawkins’s teachings + textbook browsing + Google!

Erm, gimme a chance, I’m still dipping into Scott Gilbert! (Hope he hasn’t noticed .)

Eh-err! All I said was that I tend to agree with him, because (to me) everything fits better from his perspective.
Well, if you think he’s wrong, explain why, so us educated lay folks can see how we’ve been misled!
TTFN, Oolon

pudsey warrior

Maybe it's because I'm a Brit, but I often find what Dawkins writes and says fascinating. To me, he interprets Darwinism better than most and explains it as clearly as anyone. However, what I also find somewhat frustrating is that macro-evolution still has to be taken 'on trust', unlike micro-evolution. Of course Dawkins' explanations for these lack of contemporary demonstrations of macro-evolution are plausible, but I would prefer to see 'hard evidence'. (Wouldn't we all?!!) I think there is still much more work to be done here, i.e. to provide evidence of how 'small successive steps' can successfully function at the macro level. It seems to me to be more than reasonable to describe Dawkins’ the basic ideas outlined in ‘The Blind Watchmaker’ as a conceptual approach. Gould et al. could see limitations with Dawkins and hence posited punctuated equilibrium.

Personally, I'm not convinced by Gould's approach to solving some of the problems that Dawkins appears to leave unresolved. Punctuated equilibrium seems to be like an admission that Darwinism is ‘in trouble’, that evolution cannot proceed through a series of small successive steps. On the other hand, although Dawkins doesn’t necessarily meet all the challenges or difficulties raised by his own view of Neo-Darwinism, (he makes no claims to be omniscient), his position is well-argued.

To oversimplify matters, I believe that Dawkins represents a classic Darwinian viewpoint, whereas Gould, Goldschmidt, Mayr et al. have initiated different Evolutionary models. The theory of Evolution itself has been continually evolving and there appears to be no sign that this theory is in recession!

seanie

Punctuated equilibrium is no such thing. It may be misrepresented as such but it's not. It's still evolution through a series of small sucessive steps. It simply that from the perspective of geological time, and long periods of stasis, this evolution appears extremely rapid.

It still can sit quite comfortably within Darwinian theory.

Oolon Colluphid

What did you have in mind that’s left unresolved? Dawkins isn’t writing about palaeontology, comparative anatomy etc, which is where you get the macroevolution evidence; he writes to explain how neodarwinism can explain complexity. He’s explaining that the theory works, with examples, not providing detailed evidence. Look in textbooks for that!

Nah, that’s the creationist take on it. Punk Eek was posited to explain apparent sudden jumps in the fossil record. However:

a) there are plenty of smooth fossil transitions too, so it does not indicate that “Darwinism is in trouble”, merely that there may be more going on than simple smooth changes (things long recognised anyway, such as allopatric speciation), and

b) PE seems only to be different to a straw man version of Darwinian microevolution anyway, that of slow steady changes -- what Dawkins has called constant speedism -- which nobody thought was right anyway. Note too that a couple of hundred thousand years could be enough for even quite drastic morphological change, yet be nigh on undetectable in the fossil record, which would then have the appearance of a jump, a punctuation event.

That’s why I tend to agree with him. Whenever I’ve seen or read him answering questions, he always comes up with sensible, rational answers. (Live, he’s an impressive speaker. When questioned, he pauses for a moment, repeats the question back in measured tones to check he’s got it (with eyes closed or gazing into the distance), then responds with concise rationality.)

Cheers, Oolon