But it isn’t clever. It’s people engaging in nitpickery without actually answering the underlying question. We’re all smart enough to know what the guy means.
It’s fine for a bit, but it gets tiring. Just pop in and say explain that the question was clumsily worded, reiterate the underlying question and answer it. If you don’t know the answer, why say anything?
Another point about such armor. Against what does it defend? In pretty much the entire history of homo sapiens there is only one predator that matters at all: Homo sapiens. Indeed this seems to be an implicit undercurrent of the OP’s question. Blows to the neck? Only when fighting other humans. No animal predator does this. Before homo sapiens, a few tens of millions of years of savannah dwellers. As above, neck armor would not then have been useful. We are now well past the point where neck armor would have any use at all. And even if there was a case for evolving body armor, we never had enough time. The basic blueprint for mammals doesn’t include armor. It would take a very long time for us to gain enough mutations to make it. And it would require continued competitive pressure to avoid the mutations being quickly lost. Except for the odd street fight that pressure may not have ever existed. However when you next go out to a night club, and the bouncer on the door appears to have no neck, you may have some pause for thought.
The big cats kill by suffocating their victims-- clamping their jaws on the windpipe. Early human ancestors would be particularly vulnerable to those predators.
Before homo sapiens, a few tens of millions of years of savannah dwellers. As above, neck armor would not then have been useful.
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No sure what you mean by a few tens of millions of years of Savannah dwellers. Our ancestors didn’t start living on the Savannah until maybe 5 millions years ago, at most, and probably closer to 2-3M years ago.
The thing is, you don’t need to rip out a human’s throat to make a nice juicy meal out of him. All you have to do is hamstring him and wait for him to bleed out. So adding neck armor would just cause predators to change their strategy slightly. Human’s went in a different direction when defending themselves from predators – they learned to outthink them.
Actually, there would still be some selective pressure against Alzheimer’s, for the same reason that we evolved to live so extraordinarily long in the first place. Even if a 70 or 80 year old human isn’t personally reproducing any more, they can still contribute to the success of their descendants (by teaching all of the useful information so valuable to humans). An elder with Alzheimer’s has a diminished capability to do that, so their descendants will learn less of the tricks for knowing which berries are good to eat, or how to make a better tool, or how to sweet-talk the opposite sex, so their descendants (some of whom will also carry genes for Alzheimer’s) will be at a competitive disadvantage compared to their peers with sharp-minded grandparents.
They’re not attempts to give factual answers, they’re attempts to look clever while not providing any useful information. If you were to ask “why have polar bears evolved to have thick fur?” and I replied “because that’s just how they’ve evolved! Evolution doesn’t have a purpose you know”, my answer is both smart-ass and useless. It gets tiring when 50% of the replies in a thread like this are along those lines.
[QUOTE=Philster]
It is clever. Mocking it doesn’t make it less clever.
Fighting ignorance, dude. Sometimes, ya gotta repeat yourself (re: purpose, etc).
To address your wording: Sometimes, there is no ‘why’ either. We don’t lack things because they would have negative consequences. Sometimes we just lack them. Period.
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I was being sarcastic. It’s not actually clever, it’s banal and obvious. You are right that there are some traits we have developed or not developed randomly, but those are always traits that have very little impact on survival. When it comes to something like the level of neck protection mammals have developed, there will definitely be a reason behind it. “It just happened like that!” is either true but redundant, or false. Either way it’s not a useful answer, even though it’s the most common answer in threads like this.
The very first one of your quotes was a factual correction of an error made in the OP.
evolved traits like ‘the level of neck protection mammals have developed’ do not have to have a reason behind them directly related to the trait. as i mentioned in another thread, some species have survived because they did not live near a catastrophic volcano. their traits survived while possibly superior traits in animals living near the volcano disappeared. “It just happened like that!” is a useful answer, because it is factual. other answers can provide useful examination of the conditions that may affect survival, so long as they are understood to be speculative.
Heck, a number of the responses here border on neatly answering the OP’s question in the negative: why do humans have no neck armor? Well, the fact is that humans do have neck armor – sure as they have protective cups for the genitals and safety goggles for the eyes and bulletproof vests and oven mitts and so on. And they’ve got soft weak hands with no claws worth mentioning – and they carry wicked sharp knives, sure as they’ve pioneered some interesting breakthroughs in the knife-on-a-stick department for to spear animals from a distance.
A samurai used neck armor just like a medieval knight did, and either could tote a shield for extra protection thereabouts – sure as a cop with riot gear does nowadays, in clear plastic and everything. We evolved those options, y’know? Who needs to evolve armor when you can evolve armorers?
Yes, I know. ‘Evolution doesn’t have a purpose’ and all that. But when someone asks a question about why humans have developed a certain trait, they’re not asking whether evolution has a purpose. They’re asking why that trait has survived the evolutionary process, what survival advantage it confers compared to its mutant competitors. Granted some traits do have no effect on survival advantage and may have been propagated at random (male nipples for instance), but those traits are rare, and most of these types of threads aren’t asking about them. This one certainly isn’t.
Just because an answer is factual does not make it useful if it’s redundant. It’s like answering the question, “Why do polar bears have thick fur?” with “Because they do”. It’s factual but it’s also completely useless. Clearly the useful answer is going to be something like, “it keeps them warm”. But these threads always get littered with smart-ass comments along the lines of the former.
ok, i understand what you are saying. but i perceive a wide-spread misconception that evolution has a purpose, and that it can be determined what factors resulted in evolved traits. so as i mentioned, note the speculation, and the reasons can be interesting, but rarely conclusive.
also, the polar bear case doesn’t correspond to this one at all. foremost, its easy to see why thick fur is currently an advantage for polar bears. the neck question is far more general in nature. very few animals have or have had neck armor. so another answer might be, ‘because none of our ancestors had neck armor genes to inherit, and no mutations for neck armor occurred.’ you probably find that equally pointless, but that’s how it is.
[QUOTE=ed malin]
ok, i understand what you are saying. but i perceive a wide-spread misconception that evolution has a purpose, and that it can be determined what factors resulted in evolved traits. so as i mentioned, note the speculation, and the reasons can be interesting, but rarely conclusive.
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You’re probably right, I’m maybe being a little unfair. Some people occasionally do have a misconception about how evolution works and it can’t hurt to clarify it. But it does get to me when someone makes a thread asking why a specific trait has survived the evolutionary process and the first 15 answers are all variants on, “because it has! Evolution doesn’t have a purpose you know!”. That’s not a helpful answer.
I think the two cases are actually very similar. Lots of evolutionary biologists (Richard Dawkins for one) constantly make the point that people who know a bit, but not a lot, about evolution overestimate how likely it is for traits to survive at random. Dawkins thinks that almost every trait humans have developed is finely-tuned for survival, and the idea that something major like a lack of tougher neck protection could have survived millions of years of evolution, across billions of individuals, without being tested for its survival value is unthinkable.
When it comes to something major like this (in fact, when it comes to nearly any trait we have), it has been tested against its mutant competitors over and over again, and there is a reason it has won. That ‘reason’ is what the OP is asking for, and what these threads are generally asking for.
ok, this could get good. i’m going to see what dawkins has to say before responding directly (on the off chance that somebody who has spent a lifetime studying this area knows more than i do from thinking about it occasionally).
there is commonality in a lot of questions about evolution, but a ‘why does animal have trait’ question can be much more directly addressed than a ‘why doesn’t animal have trait’ question.
I just realized this today: our bungs have protection. We can clench our butt cheeks to “defend” or “armor” our bungholes. However, I think compared to the neck, the bung is far less important.
ok, i’m going back over what i can get find for dawkins. the term ‘finely-tuned’ is a little open ended. dawkins has used other common terms to describe evolution that can be imprecisely interpretted (by me, not necessarily you). i think dawkins is looking at the very long evolutionary process in humans, and some traits of humans won their competitions very far back in the process. also, i don’t think he was including hypothetical traits like neck armor in the process. there aren’t a lot of neck armor genes in the history that we know about, and there may never have been a competition. i understand dawkins ‘selfish gene’ concept, and give it great credence, but environments can change faster than evolution, and something useful now may become useless later. and i’ll keep mentioning the catastrophic volcano scenario. there may have been animals with a great neck armor gene that were wiped out by events that have nothing to do with gene competition. but you make an excellent point about dawkins view that totally useless traits are unlikely to arise purely by accident. traits do not survive based only on simple usefulness, there is competition for genes to fit into the entire genome (hope i’m using those terms properly). so a gene for neck armor would have had to do much more than just protect the neck (especially since neck injuries don’t seem to be a major cause of humans dying before they reproduce).
There is a reason we don’t have better neck protection than we do. It gives us some sort of survival advantage. When you’re talking about a major trait like this, in the context of millions of years of evolution and billions of individuals, that much is certain. What that advantage is, I don’t know. I suspect it means we have more mobility in the neck, allowing us to assess and respond to our environments more effectively at high speed. But “evolution doesn’t have a purpose” is not a useful answer in itself and I wish people would stop offering that redundant fact as a clever suggestion of what the advantage is.
i still ask, survival advantage compared to what? compared to hypothetical neck armor? that’s not convincing. compared to previous actual neck configurations, then yes, you’re logic is impeccable.
This is false logic. You are starting from the premise that every trait possessed - and, more oddly, not possessed - is necessarily adaptive. The former is questionable, the latter is downright unsupportable.
There are, in fact, several possible reasons why we do not posses neck armor. The simplest reason is that the starting point for such never appeared at any point in our ancestry, and was therefore never improved upon. This, in turn could be simple luck of the draw (i.e., the potential for such exists and has simply not arisen), or it could be a result of developmental constraints that pretty much ensure that such will never arise without significant changes to our bauplan (i.e., the potential for such does not exist within our current genetic structure). Given the paucity of neck armor within vertebrates in general, I would lean toward the latter, myself.
Unsupportable, maybe. But this is the exact point I’ve been making, and it’s the point evolutionary biologists like Dawkins make continually: people see that evolution is random and they overestimate how likely it is that certain traits might simply never crop up. But the idea that the “starting point for neck armor” never appeared over millions of years, across billions of individuals, is borderline unthinkable. We’re not talking about luck of the draw, we’re talking about the luck of billions and billions of draws, where any result that conveys a survival advantage will become more likely in future. When it comes to a major trait like this, that clearly has a direct effect on survival, there is a reason we don’t have it, and that reason involves a survival advantage.
I can’t see how you’ve come to your final conclusion either: vertebrates, in general, do not have much neck armor. Particularly mammals. Do you honestly think it’s likely that traits for greater neck armor have simply ‘never appeared’ in most mammalian species, over millions and millions of years? The odds of that must be impossibly small. Do you honestly that it’s physically impossible for us to develop better neck protection? Or do you think it’s more likely that there’s a survival reason that we haven’t, and that most other mammals haven’t either? I think the latter is so likely it’s obvious. And that’s the same argument biologists like Dawkins make about almost every trait we have.
Utter nonsense. First off, natural selection is not a guarantee of anything. It’s a stacking of the deck, so to speak, in favor of certain traits, but it is by no means an assurance that anything that is favorable to an organism will necessarily evolve.
Second, I take it you are unfamiliar with concepts surrounding morphogenesis? There are absolutely developmental constraints on organisms which limit the directions in which they can vary - and which new mutations can even arise. Contrary to popular belief, organisms are not free to vary in any conceivable fashion.
Er, yes. I believe that was my point, actually.
I believe that the reason we have not is because of internal, developmental constraints, not because such a trait evolved in the past and was selected against. The fact that in all of mammaldom, few, if any, have actually evolved such, that would certainly point more toward “constraint” than “tried it, didn’t work”.