Many of the examples I see for NS are linear and one dimensional:
"Natural selection favored those with better or more photo-sensitive cells because they could detect things that would eat them that those without, or with lesser photo-sensitive cells could and so they copulated and the adaptation was continued. Each successive generation saw better and better photo-sensitive cells until eventually an image was borne."
That's great for simplification, not so much for anything else. Examples tend to focus on one attribute and how it benefits the animal from among the competition. Conversely the competition, because they do not have that attribute, are selected against. Their population dwindles or go extinct.
But organisms are not made of single attributes, but thousands if not more. Given that the underpinning mutations are mostly random and mostly negative. How do you ensure that two attributes simultaneously benefit the animal? What happens if one mutation is positive and the other negative?
For example, a mutation that adds more photoreceptors in the eye, but less hair cell receptors in the ear?
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@John: "How do you ensure that two attributes simultaneously benefit the animal?"
How does who ensure that? Your question seems to be framed from an intelligent design perspective.
I'm no biologist, but I'd say a lifeform that suddenly had 20-20 vision but was deaf or slow-moving would have been somebody's lunch. Random mutation would continue unabated for countless more generations until something with reasonable vision and faster legs appeared. That design (or random combination) would give the animal a real edge and allow it to prosper and produce more progeny. But maybe the climate changes or a volcano pops, and the entire population is lost. So the cycle starts again, over and over for few hundred million years.
It's not linear. It's a zigzag, a maze with twists, turns, and dead-ends.
Right, I've noticed that whenever anyone is talking about evolution, they focus on one attribute as if it were the only thing needing to evolve. In terms of human evolution, we needs eyes, ears, nose, taste buds, etc., etc. The evolution of all these faculties need to overlap and not cancel each other out.
But the end result of all of these attributes that make humans special, including our vision, hearing, taste, and of course language and intellect, is that we have great big heads that make birth difficult and dangerous. I think the evolutionary jury is still out on us.
It's almost as if we'd eaten some kind of fruit that made our heads swell, and now our females are suffering as a result.
Interesting, just to clarify we are not the species with the largest brains, nor are we the biggest babies born. Moreover our skulls are soft and maleable at birth, precisely to facilitate birth.
Regardless, if what you are saying is true, then I'm not sure what evolutionists mean by competition anymore. Where is the competition for the smaller better heads?
What about the size of the head relative to the size of the body? Elephants and whales might have bigger brains, but their bodies are proportionately much larger. The emergence of the head is the most difficult part of human labor. Damage to mother and baby are not uncommon.
"Where is the competition for the smaller better heads?"
Who knows? We're a very young species. And we may have taken charge of that aspect of our own evolution. Caesareans are becoming very common. And then there's sexual selection. Would someone with a very small head be attractive to the opposite sex?
The head size to body size relationship seems pretty irrelevant. A comparison between the head size of the baby and the diameter of the vagina seems more relevant.
If in your example we are taking charge of our own evolution, then I feel like you strayed from my initial premise, which was a critique of natural selection. However, you brought up something else I'd like to criticize, and that is sexual selection. Attraction is a psychological faculty. As such it is a product of the brain, and the brain a product of the genes.
In other words, asking if small heads would be attractive to the opposite sex, is meaningless. Because evolution could have easily made the opposite sex attracted to small heads to begin with. Evolutionists act like the big and colorful feathers of a peacock evolved to attract the peahen, and forget that the dull and colorless feathers of the peahen likewise evolved to attract the peacock.
@John "A comparison between the head size of the baby and the diameter of the vagina seems more relevant."
Isn't vagina size likely to be proportionate to body size? I've never been that close to a whale or elephant, so I'm just guessing.
Perhaps peahens have other attractive qualities that are instantly obvious to the male. The female is probably hardwired to see large colorful tail feathers as a sign of health, so continual selection on that basis would inevitably lead to extremes.
Our attraction seems to be strongly linked to certain dimensional ratios, such as shoulder width to waist width, leg length to torso length, and the relative spacing of facial features. Those formulae are hardwired in our brains, so would we have any choice in accepting or rejecting something that was significantly out of proportion?
Well sure, we do tend to find symmetry attractive. I wouldn't say attraction is strongly linked to it, because there are plenty of other factors involved, and plenty of individual preferences. You may like black woman, and your brother might light blond and blue-eyed woman.
Great, lets suppose attraction is strongly linked to symmetry. Why? Evolutionists like saying that this is because symmetry implies healthiness, or strong genes, or ability to bear healthy children. None of that is true, plenty of studies have failed to find a link between symmetry and health.
This goes back to my peacock example. There is no logic behind attraction, at least not in the way evolutionists want there to be logic.
"The head size to body size relationship seems pretty irrelevant. A comparison between the head size of the baby and the diameter of the vagina seems more relevant."
Nope. The vagina is all soft tissue and quite 'stretchy'. A narrow pelvis with ligaments that don't stretch well, however, can cause problems.
As for the brain....I am not sure overall size is as critical as other factors like the folds and forebrain. I'll look it up when I get a chance.
Well yeah, that's true. It also looks like caesarian sections are done for many reasons, but heads being too large or the mother's pelvis being too small is very rarely the reason: http://americanpregnancy.org/labor-and-birth/cephalopelvic-disproportion/
Besides the rarity, it also appears to be caused by specific disorders and deformities, even diabetes. It isn't cause by just being human.
Why are so many questions on this forum ambiguous? Wait don't answer that I already know.
There's actually only one threshold for success that the mutation would need to achieve for it to be positive and that is does it make you more effective at procreation? So whether the mutation made you more efficient at sex, gave you longer on earth to procreate more, made you more desirable to the opposite sex or shortened the time required between pregnancies,the effect is the same. You genetic material was more likely to be passed down.
This is actually the leading hypothesis for what happened to neanderthal I believe. We can see that neanderthal and homo sapien coexistence. From fossil and bone data we can see that far from being lumbering brutes, neanderthals were bigger, faster, stronger and based on cranial analyses had bigger brains than us, they occupied societal groups, probably before us and there's even evidence that they formed primitive religion. Unfortunately we were better in the sack so we became the dominant species and they died off.
So the only thing that matters (the most important at least) is reproduction?
Basically yeah.
I asked so I could be clear of what he was saying lol. Example:
Him: My stomach is rumbling.
Me: Are you hungry?
You: Yes I'm hungry.
@Benjboi: we were better in the sack"
We have around 2% Neanderthal DNA, so some us got into the sack with some of them.
I'm a bit skeptical about this procreation idea, though. Lots of other factors could have given us an edge, such as communication skills, disease resistance, and adaptability to climate change.
True, we did get into the sack and did the bad thing with our neanderthal cousins.
It's also true that all of the things you mention have us competitive advantage but they all amount to one thing, more time or opportunity to do the hunka chunka.
Take something like communication skills, on the face of it there's no link. But something like that would mean you were better equipped to work as a pack, which in turn means your less likely to die, which means you've got more time to hop on the good foot and do the bad thing.
I'm not saying that the physical act of procreation has to get better (although my wife might disagree :)) I'm simply saying that for a mutation to be successful it has to result in a greater likelihood that those favourable genes are passed down.
It seems like all you did was replace one thing with another, without actually answering anything.
To rephrase things in your terms: In human we needs eyes, ears, nose, taste buds, etc., to have more time or more opportunities to do the hunka chunka. Therefore, the evolution of all these faculties need to overlap and not cancel each other out. Do you agree?
Nope.
You're thinking that humans are the "goal" of evolution. We are not. We are just the product of the culmination of these various evolutionary traits.
No animal "has" to evolve all, or even any, of these traits. We are just the things that happened to.
First of all, if I was thinking that humans were the goal, I would have said that humans are the goal.
Second of all, if what you are saying is true, and no animal has to evolve any of these traits, then what do you make of the notion of competition? It becomes irrelevant and inconsequential to talk about competition if animals don't have to evolve any of these traits, right?
First, you do.
Second, no.
Explain how both things are simultaneously possible.
Both what?
Competition and the irrelevance of what traits are evolved.
I never said mutations were irrelevant.
I wrote nine words, none of which was mutations. Forget it. I just want you to explain what you meant by your statement:
"No animal 'has' to evolve all, or even any, of these traits. We are just the things that happened to."
Which is almost the opposite of what Algebe said:
"I'd say a lifeform that suddenly had 20-20 vision but was deaf or slow-moving would have been somebody's lunch."
So what did you mean?
Evolution involves mutations.
How are those two statements contradictory?
Forget it, I lost interest in your conversation.
I know the feeling.
It's hard to talk about evolution with someone who freely admitted they don't want to learn about it.
:D
I agree lostlocke, I don’t see a contradiction.
The difference is phenotype vs genotype.
Natural selection, selects for phenotypes. Eyes, ears, nose and mouths, are phenotypes. I don't care if he doesn't think mutations are irrelevant, because mutations are already irrelevant if they don't cause phenotypic changes. I only care about his statement:
"No animal 'has' to evolve all, or even any, of these traits."
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