I am of the personal opinion that Dawkins should have eschewed a number of things, but I find no words or phrases that hint at intentionality in his arguments, beyond in a colloquial sense. They are certainly not intended as such in terms of scientific understanding, nor is such intentionality or purposefulness an “unspoken” requirement or assumption in evolution.
It seems to me that Broom has simply moved Behe’s error away from science and into philosophy. Rather than asking “How can part of a cell function?” he is asking “How can nature build something without a plan?” His earlier claims that Dawkins is in error regarding the eye and vision are not errors on the part of Dawkins, but on the perception of Broom:
Eyes appear to have evolved from simple photo-sensitive cells. His charges against Dawkins are mere semantic quibbling. A single photo-receptive cell can trigger daylight and nighttime responses that enhance survivability. There is no need to speculate on what the “eye” might evolve into. There is no reason to dismiss the “parts” nature of a primitive eye. A cell that triggers motion (or inactivity) when it is struck by light can lead a critter to seek out (or hide from) the sun or its heat. There is no need for a future “eye” to pull the development along in some teleological fashion. Once the organism responds to signals from its photo-receptive cell, a mutation to that cell (to become multiple cells with greater light-sensing capacity or to detect the direction from which the light emanates, for example), can provide the organism with greater chances of survival, leading to natural selection. Despite Broom’s philosophical need to see a purpose in evolutionary changes, there is no evidence that such a purpose is actually required.
They’re not valid. Natural selection is simple, simple and intuitive, and it doesn’t depend on a consciousness guiding it. Why should it? If a change occurs in the atmosphere that causes more sunlight to hit the earth, fish-belly pale folks like me will suffer from folic acid deficiencies and skin cancer. Dark-skinned people will be able to produce sufficient vitamin D even at high latitudes. Suddenly dark-skinned and black people will begin to outnumber white people, and semi-transparent folks like me will disappear completely.
How does that require “intelligence”? It’s just a matter of who reproduces and who doesn’t. There’s no overall brain guiding things - it’s a complex behavior built out of simple parts, like the function in an ant hill. Ants are really, really dumb little critters. But their simple behaviors of following each others’ chemical trails and leaving trails of their own manage to make very simple behaviors add up to very complicated ones. The behavior of an ant colony could even be described, to a certain extent, as intelligent. But there’s still no underlying consciousness, no “thoughts” that propel it. Such with the environment itself. No thought is required for a white person to die of skin cancer, or for a black person to produce adequate vitamin D. It just happens, and enough things “just happening” add up to larger, more complicated patterns.
Using metaphors that ascribe purpose to things is pretty common in science. Our brains aren’t necessarily adept at intuitively relating to the concepts we discuss. So even once we understand that a chemical reaction occurs because two molecules hit each other at just the right angle, at just the right speed, and the reaction occurs because it leads to a lower energy state, it’s easier and more comprehensible to just say that the oxygen atom “wants” a full outer shell. It doesn’t “want” anything, it’s just more stable once it has a full shell. Yet every chemistry professor I’ve known talks about what atoms and molecules want.
Computer programmers do this too - listen to someone describe what their program is doing: it complains, it talks to other programs, it throws a fit when you give it bad input - and the programmers know perfectly well that their creations don’t do any of those things. Hell, they created them - but with any complex system, it’s easy to relate to things on more human terms.
I think this is a rather poorly-done attack on science, but perhaps it really came from a real ignorance on the part of the author.
I don’t see “improved optical performance” as being a non-material constraint. Such a condition as better sight results in better finding food, better seeing enemines and better seeing escape routes. In short, better survival for the possessor of better sight. The non-material thing is the urge to survive which you can argue comes from God if you want to. I would say it evolved because creatures in which it didn’t develop aren’t around any more. I’ll admit that applying this “urge to survive” to one-celled life in the early phase of the beginning is beyond me, but then I’m just a layman.
I think this is just a misleading misstatement. The early flying squirrel isn’t trying to develop a larger flap of skin. It is escaping death so it can go on living and find that other squirrel to mate with.
Baloney. Again, survival is the key. Flies are caught to survive. Not wasting energy in excess silk production means fewer flies must be caught to survive.
He argues that materialists must resort to “images, narratives and metaphors,” but he is basing this claim on analysis of writings, mostly Dawkins, intended for the general and non-specialist public. I suspect that when Dawkins and other evolutionary biologists are writing for scientific publications no such “images, narratives and metaphors” play a part in the argument.
And just another note. If Broom is saying that scientists need to do a better job of explaining I’ll agree. I wasn’t particularly impressed by Dawkin’s book Climbing Mount Improbably. However, that doesn’t mean that non-materialistic ideas must be put into evolutionary theory by scientists when they are thrashing out differences with each other.
One more time, this is natural selection: things with something that gives them a better chance of surviving have a better chance of surviving. What about that statement doesn’t make sense? What about that statement requires intelligence?
I was going to use this exact example (including oxygen being the element that “wants” a full outer shell). Hmm. It couldn’t be because oxygen is a common electronegative element, and I’m a chemistry/biology educator, and often catch myself doing just that and have to correct myself. No, I think some intelligent force drove us both to think of that example. 
I don’t really want to get into the discussion of definitions because there are others here who have a much deeper and more authoratative understanding of the subject at hand and are better able to tackle that. That is why I started my point with the caveat “The previous discussions over the definition of a ‘species’ notwithstanding,…”. However, I would like to clarify what I said.
To me, evolution is a process that just describes a series of changes in population characteristics that sometimes leads to speciation.
I didn’t say that the human race wasn’t evolving. I didn’t say as a population that we are not changing. Anyone who lives in a house more than a couple of hundred years old and has to duck through doorways can tell you that we are getting taller! I was expressing my view that we are unlikely to speciate – to change so much that our descendents (in general, or of an isolated group) can no longer be said to be the same species as us here and now. For that to happen there must be some selective pressure that forces us to physically, biologically adapt and at the expense of those that don’t. It will require a pretty dramatic turn of events for us to end up competing with our neighbour in a manner that means the winner gets to reproduce and pass on their genes and the loser doesn’t.
Our social structure that cares for all individuals, our technology that allows us to provide ample food, to evade predation, to combat illness, even to adapt our environment to better suit our needs all serve to insulate us from those selective pressures that less advanced animals have to deal with. Just to add to jon the geek’s comments, nobody can predict the future of course but I believe that any dramatic change in our environment, which results in our physical, biological characteristics being more important to our survival than our social and technological skills would more likely lead to our extinction than to our adaptation and speciation.
(I am ignoring one possibility – that our technology doesn’t lead us to engineer steps towards our own speciation through advances in genetic manipulation. I’m not sure if evolution would be the right term for such an eventuality)
Actually, speciation(sp?) is more than probable, assuming there is no faster than light drive, and we do build colony ships. Or, of course, there’s various genetic engineering thoughts… and there’s the Hans Moravec school of philosophy where we build AI descendants.
Oh, to that I completely agree. When and if humanity conquers the stars, we will very likely speciate, because it will be a one-way trip (unless we figure out how to create Morris-Thorne wormholes, of course). I was referring purely to people here on Earth (or even in colonies within the solar system, since it’s likely people would occasionally travel to and from them).
Speciation is also possible through genetic engineering. I even wrote a paper about it for an anthropology class way-back-when. That doesn’t really count as evolution through natural selection, though
I don’t think AI descendants would count as a speciation event. You might say we were creating a new species, but they wouldn’t be genetically related to us.
Probably more to do with nutrition than genetics.
You’ve got to be bit careful when trying to state we have stopped evolving. There seems to be two separate questions here.
Are we still evolving in the sense that given sufficient time a future member of the human race couldn’t succesfully breed with a current (presumably cryogenically stored) member?
Could the human race speciate so that two co-synchronous decendants of the current population couldn’t breed?
As far as the first is concerned the only question you have to ask is do all members of the current population have equal chances of reproductive success and are the chances of reproductive success affected by distribution of genes? I think the answers are no and yes repectively so humans are still evolving.
As for the second, well that would require some degree of physical or social separation (morlocks and eloi?).
I think the answers are “no” and “a little, but less and less all the time”. I think culture has more to do with breeding success in humans than genes.
Yes, it would, and I think those are also lessening. The world is become more and more global, so that even people who grew up thousands of miles apart may end up bearing offspring with one another. The social separation is possible, but I don’t think it’s likely.
[QUOTE=Jon the Geek]
I think the answers are “no” and “a little, but less and less all the time”. I think culture has more to do with breeding success in humans than genes.
QUOTE]
What do you mean by culture? Even within a cultural group breeding success varies and this is biological.
Probably, yes. It was a light-hearted aside and I should have used a better example.
[QUOTE=Xiphos]
You’ve got to be bit careful when trying to state we have stopped evolving.
QUOTE]
With respect, if you are going to refute something I say then you’ve got to be a bit careful that I actually said it.
If you re-read my previous post you’ll come across the words “I didn’t say that the human race wasn’t evolving.”
You seem to be of the opinion that the definition of species includes the inability to successfully reproduce with other species. I’m not interested in debating this - it has already been done in this thread by people who really do know what they are talking about. Suffice it to say others would take issue with that definition.
As you seem to have slightly misconstrued my post, let me summarise my position as succinctly as possible.
It is my opinion that while the human (like any other) population continues to evolve, that is it’s variety and characteristics will change over generations, speciation in the human race is unlikely to occur any time soon. My rationale is that we have acquired the ability to insulate ourselves from the process of natural selection AND we are unlikely to see the isolation of part of the population.
I may be wrong on this and I’m open to be corrected. If you can see a scenario in which the human population, or any isolated part of it, would be subjected to severe selective pressure and forced to adapt physically/biologically to the point where it could be designated a new species I would be interested to hear it.
Human breeding success is becoming less and less biological. What you think and how you live have far more to do with attracting a mate than biology. Even people who are biologically incapable of reproduction can now reproduce through artificial insemination.
I’m sure there are still some genetic factors influencing human reproduction, but they’re less than they were even 50 years ago, and far less than they were 100,000 years ago.
This is why memetics interests me a lot, although I admit I don’t know much about it, and don’t know if it’s anywhere near actually developing into a real science. Something like memes have a lot more to do with successful human reproduction than genes do, and the ratio of “meme” importance to gene importance is increasing all the time.
Jon the Geek: ‘It’s likely that evolution of the human species is slowing down. We can adapt to the environment through technology, without having to do so genetically. Certainly allelic frequencies are changing, but, without some sort of large scale disaster that we can’t adapt to through technology, it’s unlikely that we will speciate.’
Somnambulist: ‘*t is unlikely that we are likely to evolve into something we would call a new species anytime soon. This is because, for the time being at least, we have elevated ourselves above the process of natural selection. We have become very good at providing survival resources (food, water, shelter, etc.) for a significant proportion of the population.’
A thought occurred to me. (Cue gasps of astonishment from some and dread from others.)
With greater human control of the natural world (especially the terrestrial part) than ever before, and with shrinking habitats for many creatures in the natural world (especially the terrestrial part), is it likely that fewer creatures will speciate (in the next x million years, excluding the possibility of a natural catastrophe)?
Given what I see (perhaps mistakenly) as their greater resistance to human control/influence, is it the lower orders, such as insects, that are most likely to evolve and speciate?
That’s a non-sequitor. If a person reproduces through artifical insemination, then by definition the person is capable of reproducing. After all, there’s a baby to prove it!
How the person reproduces is irrelevant. Natural selection only cares about whether reproduction happns, not how it happens. A person who reproduces is fit, whatever the means used to do so. A person who does not reproduce is unfit, regardless of how well their reproductive system might work if they tried to use it. A woman who produces three children via artifical insemination is reproductively fit; a woman who takes birth control pills until she goes through menopause is reproductively unfit (even though her plumbing may be in perfect working order and she’d easily get pregnant if she stopped the pills). The former produced offspring, the latter didn’t - and from the standpoint of evolution that is all that matters.
Remember, selection occurs in reference to the enviroment an organism lives in. We no longer live in the Pleistoscene; traits which would have made an individual incapable of passing on their genes 20,000 years ago may have no negative effects today, and visa-versa. A Cro-Magnon man who developed juvenile-onset diabetes at age six would have died in childhood; a modern person who develops juvenile-onset diabetes may live to old age and produce several children. Diabetes is no longer the barrier to reproduction it once was. Conversely, no one in the Pleistoscene needed to learn to read, so there was no selection pressure against dyslexia. That’s certainly not the case now; in Western societies, not being able to read can be fatal (and it certainly makes you less desirable as a potential mate). That’s a new selection pressure our distant ancestors never had to deal with, because written language was not part of their enviroment.
There are as many genetic factors influencing human reproduction today as there were 50 years ago or 100,000 years ago. They’re just different genetic factors.
But did their genes have anything to do with whether they reproduced? Does a genetic factor influence whether a woman chooses to undergo artificial insemination? Does a genetic factor influence whether a woman chooses to stay on birth control through her entire reproductive lifespan? I am contending that these are social decisions, not genetic. The woman’s genes now have less to do with whether she will reproduce than they once did.
I’m not saying humanity isn’t changing, but I still contend that these changes have less and less to do with genetics.
I’m going to end this hijack, though. I may start a new thread, but feel free to do so yourself if I don’t get to it
Actually, it likely increases their chance of speciation. We are adapting the environment to make it more comfortable for us, but that doesn’t mean it’s more comfortable for other organisms. Add to this that we’re isolating them into pockets (just passing a road through a forest might divide one population into two completely separate populations, for example), and I think it’s likely that speciation will occur.
Probably not. That greater resistance to human influence means we’re having less impact on them. It’s the organisms that are being split into isolated populations that are most likely to speciate (or, if the change is too fast, as it very well may be, to simply die out).