posted
1) Why is there such diversity of life? How does biodiversity mesh with the theory of evolution?
2) Why are humans so far advanced, in terms of mental ability, than any other creature on the planet? We dwarf even our nearest evolutionary cousins... Why such a disparity? Why didn't a different creature evolve intelligence in, say, Australia?
I've asked the second question on this board before, but I don't remember reading anything that completely answered it.
I'm asking sincerely, not as an attempt to prove evolution wrong. For the most part, I accept that evolution is a part of God's plan; I don't have a problem with the earth being a gajillion years old, or dinosaurs being birds' ancestors.
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posted
I'll take a quick stab at each of these. Keep in mind, I am no expert, and did no research on this, just throwing a possible answer out there.
1) Simple explanation is that over a gajillion years as you say, life has had time to evolve into whatever niches are possible to sustain life.
2) This ones a bit tougher, but I have 3 possible explanations. First, I saw on a Discovery or learning channel special that neanderthals or cromagnon man were both a different species from us, as well as marginally intelligent. I think we killed them off.
Second, we are the only species on the planet that requires a high level of intelligence to survive. Basic evolution says traits that promote the survival of your species stick around while others do not. The majority of the other species on the planet are getting along just fine without high level intelligence, and so have no reason to evolve with it.
Lastly, is it really all that remarkable that we are unique in our intelligence? Just recently on the news we see that spider webs evolved in only one place. They have since been passed down to a couple different genus or whatever over the course of time, but it only evolved once in the history of the earth. I'm sure there are a number of other examples out there of traits that can be found in only a single species and you could postulate the same question with the underlying supposition that that species is somehow special or unique because of whatever unique trait they have. Humans are the only intelligent species on the planet, so we are different than all the other animals. Spiders are the only species that spin webs, so they are special and different than all the other spcies on the planet.
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posted
There is such diversity of life because there are myriad niches to fill, and usually multiple species competing to fill those niches.
Intelligence is just one evolutionary strategy. Being more intelligent than our competitors has worked out pretty well for us, but if we weren't relatively physically puny compared to our predators and prey I expect that we wouldn't have evolved intelligence. Also, without thumbs or a dexterous trunk or set of tentacles with which to manipulate the environment, intelligence beyond a certain point is that useful.
[Edit--work was calling, so I didn't have time to finish my thought, or even to realize that it was as incomplete as it turned out to be. My point was that intelligence isn't a trait that is necessarily worth it, for many species. If you were a gazelle, would it benefit you more to be really intelligent, or to be really fast? Evolutionary pressures just haven't selected for intelligence, most of the time. At this point we're a pretty short lived species, as species go; the jury is still out on whether our intelligence is a good evolutionary "choice" for the long haul.]
quote:life has had time to evolve into whatever niches are possible to sustain life
I can accept this answer for the varied environments present-- but within those environments, there are also many, many, many forms of life.
Wouldn't it be more natural for a single (or few) life forms to evolve for each niche, rather than thousands?
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posted
Diversity also stemmed from not just niches, but seperation. As continents drifted, species were seperated and evolved differently.
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Scott, I believe when you want to know what is natural, you look at the natural world. In nature you find a great deal of diversity in each environment. That is natural, much more so than one person's belief on what should be more natural. And notice that I used the word 'niche', not environment. Life has had time to evolve into the many many many niches in each of the many many many environments
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TrapperKeeper, spiders aren't the only creatures that spin webs. Silkworms do so, as do a number of other insects whose names aren't coming to me at the moment. Ever seen a tree that had branches that were webbed into a big globe? That isn't the work of spiders.
In terms of your "to know what is natural, look to the natural world" position, while it's certainly true as far as it goes it doesn't really help in terms of this discussion. You can look to the natural world and see diversity, but that doesn't mean that evolution is the cause of that diversity.
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quote:life has had time to evolve into whatever niches are possible to sustain life
I can accept this answer for the varied environments present-- but within those environments, there are also many, many, many forms of life.
Wouldn't it be more natural for a single (or few) life forms to evolve for each niche, rather than thousands?
Not necessarily. You've often got multiple organisms evolving simultaneously from different ancestoral forms to exploit the advantages of a given niche.
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quote:The majority of the other species on the planet are getting along just fine without high level intelligence, and so have no reason to evolve with it.
Like chimps for example? Posts: 1138 | Registered: Nov 2005
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I'm not an expert by any means. In fact, I don't know any more than any college educated person that happened to take a couple Biology classes and an Intro to Anthropology class. For some reason I decided to take a crack at these questions anyway .
quote:1) Why is there such diversity of life? How does biodiversity mesh with the theory of evolution?
Not only does having a diverse and large number of species mesh with the theory of evolution, it very much depends on it.
The explanation, of course, involves niches. If a new species evolves that fills a niche that was previously unfulfilled, that species will most likely be successful.
Since the ecosystem on earth is so incredibly varied, there are an incredible number of niches that can be filled.
Why are the creatures on earth so different from eachother?
Well, actually, they aren't really all that different after all. The basic chemical components are very much the same. We all store our genetic information in very similar ways, we are all cell based, we all split those cells over and over again in order to grow, and we all use ATP and ADP to give us the energy we need to live. Broken down to the most basic bio-chemical level, us humans are not all that different from plants.
From an evolutionary perspective, the way the differences the organisms on earth developed can very easily be shown in a taxonomy diagram. The farther back the split occured, the less any organism resembles another organism. We split from apes pretty recently, and so are very similar.
None of this is anything more than what you would get from an eighth grade biology book, but it seems pretty self explanatory to me, so I guess I am having trouble understanding what to explain in more detail.
quote:2) Why are humans so far advanced, in terms of mental ability, than any other creature on the planet? We dwarf even our nearest evolutionary cousins... Why such a disparity? Why didn't a different creature evolve intelligence in, say, Australia?
Intelligence may appear to be a super-successful trait, but in a biological sense, its not really.
Every trait involves trade-offs. In order for humans to have advanced intelligence, one thing we needed was a big head. This means that we needed to do most of our development outside of the mother's womb, making both the infant and the parent incredibly vulnerable for the first several years of the infant's life. That alone is a huge trade-off.
A lot of things had to come together at once in order for intelligence to be the huge advantage it is for us humans.
You can take a wolf, and make it super-smart, but what good would that do? The wolf still lacks ability to make tools, and (debatably) still lacks the ability to make language. What possible advantage would a wolf have with human-like intelligence? Could it catch a rabbit any better? Perhaps, but being able to run a little faster would be more of an advantage. Considering the trade-offs, if the wolf cubs had to spend the first couple of years of their lives completely helpless, it would make for a very short-lived species.
I'm not sure that intelligence would ever have developed in humans if our ancestor apes didn't already evolve the opposable thumb. Being able to create and wield tools gave the intelligence trait a clear evolutionary benefit, which eventually outwieghed the trade-offs.
If apes had opposable thumbs, why didn't other species which were off-shoots of apes evolve intelligence? Actually, there were several that did. We aren't sure why they died out, but one thought is that homo-sapiens were simply the most successful, and they filled the niche.
Edit: Okay, that took a while to write, and so many have already answered. Interesting that Noeman's answer is so similar to my own .
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posted
Someone tell me why we, of all creatures, have evolved to the point where we have the ability to destroy nature itself? If nature is truly about balance, than there must be more to our species than simply an evolutionary edge in the form of intelligence, no?
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quote:The majority of the other species on the planet are getting along just fine without high level intelligence, and so have no reason to evolve with it.
Like chimps for example?
Yeah, exactly like chimps--they're very well suited for their environment.
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posted
If there were only one species fulfilling a needed function, kill that species and an ecosystem would collapse. Evolution is not just about traits that advantage the individual in competition against other individuals. Overlapping with another species' capabilities is a survival trait.
Also, think of how evolution describes species arising; the common vision is a spreading tree of life. Think of how every existing species is a possible source for a new species (and it doesn't disappear when a new species splits off, for whatever reason). Even if speciation doesn't occur very often, it results in incredibly diversity over time; its like compound interest.
Regarding humans, as mentioned, there have been several intelligent species we know of other than homo sapiens. They were all closely related, of course. However, the others all died out between us killing them and coopting their societies through mating. We were more adapted, and once there were significantly more of us it pretty much became inevitable.
Also, that there is no other species even close is something of a conceit. Every year we make new discoveries in what 'lesser species' are capable of learning/doing/thinking, up to and including some fairly advanced grammatical and metaphysical concepts (dolphins seem to understand sentence structure and selfness really well, for instance). Now, we've certainly accomplished more, in at least the sense we consider important . However, that's easily explained in the same way its explained why we all use CDs and DVDs instead of laserdiscs, despite laserdiscs being nearly as capable. Advantages, even small ones, matter, and there are certain sorts of advantages that are even more advantageous the more individuals have them (or are them, in the case of homo sapiens). See my previous note about killing or integrating all the competitors.
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quote:Someone tell me why we, of all creatures, have evolved to the point where we have the ability to destroy nature itself? If nature is truly about balance, than there must be more to our species than simply an evolutionary edge in the form of intelligence, no?
First, no, we can't destroy all of nature. We may be there in a few centuries, but we aren't there yet. If we set off every nuclear bomb on earth, not only would we not even come close to killing off all the bacteria and other micro-organisms on earth, but we wouldn't even have managed to kill all the insects, plants, and I'm sure several other species. Not to even mention all the life in the oceans. They wouldn't even notice the change.
We could wipe out the large land-animals, but that's about it.
Someday maybe we have the technology to move an asteroid into earth's path or something, but we aren't there yet.
Secondly, you appear to believe that evolution is some-sort of sentient process with goals and safe-guards.
Its not, its just how things happen. There's no collective consciousness which controls any part of it. So many people seem to have the idea that it does, however.
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posted
Why on earth would nature be about balance? Its not like nature is some metaphysical entity enforcing rules. Evolution is not a theological imperative, its a process that occurs due to some very simple realities, resulting in great diversity and adaptation. There's nobody going down a list for every new lifeform and saying "lets see, able to survive, unlikely to try to ascend to a higher plane of existence, won't destroy the earth," et cetera.
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quote:In terms of your "to know what is natural, look to the natural world" position, while it's certainly true as far as it goes it doesn't really help in terms of this discussion. You can look to the natural world and see diversity, but that doesn't mean that evolution is the cause of that diversity.
I was actually under the impression that evolution was the prominent theory to explain what evidence we find in the natural world.
Also, I didn't say that spiders were the only creatures that spin webs, I said it only evolved in one place.
quote:Originally posted by fugu13: Also, think of how evolution describes species arising; the common vision is a spreading tree of life.
One minor quibble--while the "tree of life" is certainly the most common way of describing the interrelatedness of species, it implies an upward climb, and a hierarchy of life that doesn't really exist. I like the shrub metaphor better, myself.
quote:Also, that there is no other species even close is something of a conceit. Every year we make new discoveries in what 'lesser species' are capable of learning/doing/thinking, up to and including some fairly advanced grammatical and metaphysical concepts (dolphins seem to understand sentence structure and selfness really well, for instance). Now, we've certainly accomplished more, in at least the sense we consider important
This is a very good point. Without thumbs/trunk/tentacles, a species can't really do that much with their intelligence that will demonstrate it to us in obvious ways. It's entirely possible that dolphins or whales are much more intelligent than we currently give them credit for. Certainly as we continue to observe and analyze their calls they seem to bear halmarks of language (syntax, proper names, and so forth), which is certainly something that is associated with intelligence.
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posted
Can someone define 'niche?' How does a species evolve to fulfill something that it (as a species) has not needed to fill before?
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quote:Originally posted by TrapperKeeper: By Noeman
quote:In terms of your "to know what is natural, look to the natural world" position, while it's certainly true as far as it goes it doesn't really help in terms of this discussion. You can look to the natural world and see diversity, but that doesn't mean that evolution is the cause of that diversity.
I was actually under the impression that evolution was the prominent theory to explain what evidence we find in the natural world.
Oh, it is. It's just that if you're explaining something about the natural world to someone who for the most part accepts evolution as how organisms came to be, but isn't utterly sold on it, the "that's just how it is" approach isn't a very productvie one.
quote:Also, I didn't say that spiders were the only creatures that spin webs, I said it only evolved in one place.
quote:Originally posted by TrapperKeeper:
Spiders are the only species that spin webs, so they are special and different than all the other spcies on the planet.
That's the last sentence of your first post, by the way, and is what I was responding to.
Something to consider is that if intelligence and having opposable thumbs are linked as strongly as we think they are, this itself is a huge inhibitor of developing the trait.
This is because in order to have workable hands, you can only have two legs (barring the evolution of a third set of limbs, which would carry its own considerable evolutionary baggage). The reason this is a rare trait in the animal kingdom is that, in general, bipedal motion is a pretty crappy trait.
Its horribly inefficient, and its SLOW. Proportionate to its size, a four legged animal is usually far faster than a human. Furthermore, the development in the skeletal structure and nervous system involved in bipedal motion involves many inefficient intermediaries.
In the prey versus predator dynamic, being fast is of huge importance. (That is unless you are a very large animal, in which case you need four legs to hold you up.)
The way apes were able to develop opposable thumbs is to escape the need for speed by going vertical. Apes are rather slow animals (except over short distances), but they can escape any predators by going into the trees.
So opposable thumbs were something of an evolutionary rarity because they generally are not a good trait. Since extreme intelligence needs the opposable thumb to be of much advantage, it pretty much only could have come from apes.
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posted
Something I don't think anyone has mentioned...
Evolution is a scramble to survive. The reason there can be multiple species filling the same niche is because they all manage to survive there.
Cow's, chickens and pigs all fill the "Them's good eatin'" niche. That is their biggest survival trait, and one they share. They die as individuals but their species goes on because "Yum!" They all fit in that niche without compitition.
We are the only one in the Intellgence niche because we kill anyone who competes with us.
We killed (or bred away) the neanderthals, we killed our own species when we wanted their territory, we even kill less intellegent animals that compete with us for food. Bugs that eat our crops and preditors that eat our farm animals.
We even MAKE new species to fight our fight for us. Domesticated cats to fight mice and rats for instance.
posted
X, do you think that it is opposable thumbs in particular that intelligence is tied to, or just an ability to manipulate the environment? I'd think the latter, but I haven't read anything about it one way or the other.
Also, where do cetaceans fit in with that idea? Do you see them as exceptions that prove the rule?
quote:Since extreme intelligence needs the opposable thumb to be of much advantage, it pretty much only could have come from apes.
Or elephants, or squid or octapus, unless it's thumbs in particular that are important for some reason. And of course, pandas have developed a pseudo-thumb. It doesn't provide all of the capability of a real, jointed thumb, but it works in a pinch.
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quote:Can someone define 'niche?' How does a species evolve to fulfill something that it (as a species) has not needed to fill before?
Okay, take a species of small birds. They generally get by on eating insects. Say a certain type of beatle which is poisonous to other birds.
A new species of beatle evolves from the one the birds enjoy, which has a hard outer shell which these birds cannot penetrate with their beaks. However, this makes the new beatle slower, and not as able to get the best plant life.
Bang, two different beatle species. They are competing against eachother, but both have advantages and disadvantages over eachother. Are they in the same niche? That's hard to say. They both eat the same food, but you could consider them sub-niches. I don't think scientists are in total agreement on what defines a 'niche'.
Now take these birds. Say they grow in numbers (as all species attempt to do) and start eating larger and larger quantities of the non-hard-shelled beatle. They reach a population ceiling when the beatle population starts to wane, largely getting replaced by the new beatle species.
During this time, a new species of that bird evolves which has a stronger beak, and can now eat the hard-shelled beatles. They can eat both species of beatles, and so become the dominant bird species in the very tiny sub-niche of the consumers of this beatle species.
Does the original species die off? Perhaps. Its niche has been filled by a more successful species. Its future doesn't look good. But perhaps a member of the original species develops the ability to eat a different type of beatle. Perhaps the new bird species developed in Australia, and while it replaces the original bird species there, there are still members of the original species in other places in Asia.
Does any of this make sense? Posts: 5656 | Registered: Oct 1999
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posted
A niche is not metaphysical (nothing is, in evolution). It is a heuristic for thinking about the process of evolution. Its basically just 'something that can be done'. For instance, being a bottom feeder might be called a niche, particularly in a particular aquatic context (ponds, or maybe even a specific pond, say).
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quote:X, do you think that it is opposable thumbs in particular that intelligence is tied to, or just an ability to manipulate the environment? I'd think the latter, but I haven't read anything about it one way or the other.
I would say that yes, it is the ability to manipulate the environment, and that opposable thumbs are the best adaptation by far (that we have seen) to accomplish this.
quote:Also, where do cetaceans fit in with that idea? Do you see them as exceptions that prove the rule?
I don't really know . Like I said, I am no biologist. I'd think that the intelligence which has developed in dolphins is tied to their evolutionary need to communicate and act in a well-coordinated group. The same is true of Orcas (I've heard they can team up and even take down a blue whale!).
When speaking of intelligence, however, I was referring to human-level intelligence. Granted, it is impossible to determine just how much smarter we are than dolphins, but I don't see dolphins ever evolving to the point of being able to get to the moon or to perform experiments on the nature of light. I think it may help if I defined "intelligence" in the way I am using it as "the ability to create and employ tools in a way which radically changes the environment and enhances a species survival abilities". That is the trait which I think opposable thumbs (or their equivalent) may be necessary for.
quote:
quote:Since extreme intelligence needs the opposable thumb to be of much advantage, it pretty much only could have come from apes.
Or elephants, or squid or octapus, unless it's thumbs in particular that are important for some reason. And of course, pandas have developed a pseudo-thumb. It doesn't provide all of the capability of a real, jointed thumb, but it works in a pinch.
Octopus I would say had a pretty decent shot at it developing advanced intelligence (by the definition used above). They may have been limited by their environment, however, in their inability to use fire (but that of course comes pretty late in the game). I'd be very interested in reading any studies dealing with octopuses and their capacity for tool use. If a creature with similar tentacles had been able to evolve on land, I'm not so sure that it would have been apes who got their first.
As for elephants... I suppose I could see their trunks evolving to the point which they could make tools. Still not nearly as good as a pair of hands though.
Put a human brain in an ape's body, and he can still probably build you a house with a hammer and nails. Not true of putting a human's brain in an elephant's body. Or even an octopus.
I think that at some point, intelligence could have evolved for other forms of hypothetical environmental manipulation, but at the time that humans evolved, the only one out their was the opposable thumb.
A certain jungle has fruit-bearing trees full of thorns - so the monkeys that survive/d are those with, say, thicker skin or a bit less sensitivity to pain or with methods of getting the fruit without climbing the trees, etc. These monkeys eventually fill that niche and, eventually, a bunch of armor-plated, numb, rock-throwing monkeys. They are also polka-dotted and sing arias as mating calls, but the reasons for those traits hasn't been discovered.
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quote:I think it may help if I defined "intelligence" in the way I am using it as "the ability to create and employ tools in a way which radically changes the environment and enhances a species survival abilities". That is the trait which I think opposable thumbs (or their equivalent) may be necessary for.
Are we limiting this discussion to proven and observed species? Because the Decolada would satisfy your use of the word "intelligence" without having opposable thumbs.
While I can understand the usefulness of your definition of intelligence in the context of this discussion, I think it is very limited when comparing general intelligence of different species since there are many different aspects of human intelligence that cannot be easily categorized as an ability to "change the environment and enhance a species survival abilities."
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quote:While I can understand the usefulness of your definition of intelligence in the context of this discussion, I think it is very limited when comparing general intelligence of different species since there are many different aspects of human intelligence that cannot be easily categorized as an ability to "change the environment and enhance a species survival abilities."
But if you have such a broad definition, then the answer to the question "Why hasn't intelligence evolved in other animals besides humans?" is "It has, as shown by species X, species Y, and to a lesser extent species Z".
That discussion is quite a fun one, and yes, a different definition would need to be agreed upon. But that doesn't appear to be what Scott was asking about.
Edit:
quote:Are we limiting this discussion to proven and observed species? Because the Decolada would satisfy your use of the word "intelligence" without having opposable thumbs.
My definition is by no means perfect. For one I would add "and can concieve of new tools for new environmental needs at will". Does this qualification eliminate the Decolada? Perhaps not. Like I said, my defintition isn't near perfect. Perhaps someone else could think of a better one?
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quote:X, do you think that it is opposable thumbs in particular that intelligence is tied to, or just an ability to manipulate the environment? I'd think the latter, but I haven't read anything about it one way or the other.
I would say that yes, it is the ability to manipulate the environment, and that opposable thumbs are the best adaptation by far (that we have seen) to accomplish this.
Why do you think that an arm ending in a thumb equipped hand is better for this than an elephant's trunk?
quote:
quote:Also, where do cetaceans fit in with that idea? Do you see them as exceptions that prove the rule?
I don't really know . Like I said, I am no biologist.
Yeah, I'm not a biologist either, although I kind of think I missed my calling by not becoming one of one flavor or another. I definitely don't have anything more than a layman's knowledge of all of this.
quote:I'd think that the intelligence which has developed in dolphins is tied to their evolutionary need to communicate and act in a well-coordinated group.
That seems pretty plausible to me. Fish accomplish this through other means, of course, but I could definitely see a mammalian species developing the mammalian predisposition for intelligence to accomplish this end.
quote:The same is true of Orchids (I've heard they can team up and even take down a blue whale!).
Man, those are some tough flowers!
quote:When speaking of intelligence, however, I was referring to human-level intelligence. Granted, it is impossible to determine just how much smarter we are than dolphins, but I don't see dolphins ever evolving to the point of being able to get to the moon or to perform experiments on the nature of light.
Sure. They just don't have the necessary equipment to manipulate their environment, and as long as they stay in the water they aren't likely to evolve it, since they have a more immediate need for those appendages as flippers (and since hands would make them less and hydrodynamic)
quote:I think it may help if I defined "intelligence" in the way I am using it as "the ability to create and employ tools in a way which radically changes the environment and enhances a species survival abilities".
Hm. I don't really see that as intelligence, per se. I see that more as the combination of intelligence and some kind of nimble environment manipulator than intelligence itself. Given your definition, wouldn't that autmatically make dolphins very, very unintelligent?
quote:
quote:Since extreme intelligence needs the opposable thumb to be of much advantage, it pretty much only could have come from apes.
Or elephants, or squid or octapus, unless it's thumbs in particular that are important for some reason. And of course, pandas have developed a pseudo-thumb. It doesn't provide all of the capability of a real, jointed thumb, but it works in a pinch.
Octopus I would say had a pretty decent shot at it developing advanced intelligence (by the definition used above). They may have been limited by their environment, however, in their inability to use fire (but that of course comes pretty late in the game). I'd be very interested in reading any studies dealing with octopuses and their capacity for tool use.[/quote]
I would be too. Another problem for them would be that they couldn't say, knapp flint, since water would slow down the rock they were wielding too much to chip off bits of the flint. Or so I'd assume. If they do develop human-level intelligence I expect that their expressions of it will be remarkably different than our own, simply because of the constraints placed on them by the environment (for lots of other reasons too, but that's the one I'm thinking about right now).
My coworkers are bugging me to stop typing and join them for lunch. More when I return!
As for elephants... I suppose I could see their trunks evolving to the point which they could make tools. Still not nearly as good as a pair of hands though.
Put a human brain in an ape's body, and he can still probably build you a house with a hammer and nails. Not true of putting a human's brain in an elephant's body. Or an octopus.
I think that at some point, intelligence could have evolved for other forms of environmental manipulation, but at the time that humans evolved, the only one out their was the opposable thumb. [/QUOTE]
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quote:Originally posted by fugu13: If there were only one species fulfilling a needed function, kill that species and an ecosystem would collapse. Evolution is not just about traits that advantage the individual in competition against other individuals. Overlapping with another species' capabilities is a survival trait.
Ack! No! Wrong! Evolution cannot plan ahead that way; if an ecosystem depends on a single species, and that species gets wiped out, that's just too bad. Moreover, it doesn't work at the species level anyway, it works at the level of individuals. There's no particular advantage for an individual in having a capability that overlaps with those of another species; indeed, it's a bit of a disadvantage, since they now compete for the same stuff.
To answer Geoff's original questions : About the diversity, we can run the thought experiment of what would happen if there was not considerable diversity. What happens is that mutations have a harder time killing things off. For example, consider a largish monkey, whose normal mode of transport is brachiation. It's pretty well adapted to life in the trees. Now suppose a mutant is born, with, say, rather heavier muscles - such mutants are known among humans, they tend to become weight lifters and athletes. Unfortunately for the mutant monkey, it's now too heavy to swing through the branches! So it's forced to live on the ground. Well, if that happens in a world with gorillas, the poor monkey doesn't stand a chance; all its adaptations are for life in the trees, except for this matter of the heavy muscles. Poof, one dead mutant. But in a world without species diversity, that is, no gorillas, why, it has just invented for itself a niche! In other words, the less diversity, the smaller the deviation required to create a new niche.
This is known as adaptive radiation; we see it happening in the fossil record in the Cambrian Explosion, which occurs just after a major disaster wipes out 95% of the then-existing species. As you can imagine, this wasn't exactly good for species diversity at the time. (Though it was all one after ten million years, to be sure.) We could also see it happening in cichlids in Lake Victoria, until thy were knocked back pretty recently by human interference. You could Google for them, they're pretty interesting as an example of adaptive radiation.
I have to go and can't deal with human brains right now. It's too early in the morning for that, anyway.
posted
Forgive me if I don't nest the quotes. As evidenced by your post, its becoming difficult to manage in an orderly way .
quote:Why do you think that an arm ending in a thumb equipped hand is better for this than an elephant's trunk?
I think this comes down to the fact that there are two hands, and only one trunk. Sure, an elephant's trunk can act very similar to a human arm, but they only have one of them.
Like I was mentioning, put a human brain in an elephant's body. How good would they then be at creating tools? Could they make a hand-axe out of stone, wood, and rope? I wouldn't think they could do so alone. Perhaps two elephant-humans together could do it. In doing so, they would need a fully formed communication system. So it appears that in order for elephant trunks to function as human hands, you'd also need human vocal chords. If an elephant had two trunks, I could see them as being roughly as functional as a hands. You could argue that the elephant could use its mouth to stabilize something while the trunk is the manipulator, but that's still not nearly as good as a set of two hands.
quote:Hm. I don't really see that as intelligence, per se. I see that more as the combination of intelligence and some kind of nimble environment manipulator than intelligence itself. Given your definition, wouldn't that autmatically make dolphins very, very unintelligent?
That's the thing about these discussions. Intelligence is impossible to define, really. We can bludgeon it into a working definition like I tried to do above in order to define what separates human intelligence from other animals, but its never a really great definition no matter how you define it.
I think adding the "and can concieve of new tools at will when encountering a new environmental need" makes my defintion a little better, but its still pretty lacking.
I think the problem here is the inherent lack of the ability to define intelligence by what intelligence produces. Sort of like defining a disease by its symptoms.
Here are basically the two observable aspects of intelligent behavior:
"The ability to create and use tools to manipulate their environment in a meaningful and highly adaptive manner. This includes the ability to concieve of new tools at will when a new environmental need arises."
"The ability to communicate in a meaningful way with other members of the species in order to perform complex tasks as a group."
Dolphins clearly show very little of the first behavior, but clearly display aspects of the second behavior.
Does that make them intelligent? I certainly can't say .
Posts: 5656 | Registered: Oct 1999
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Xavier: It seems wolves already have (relatively speaking) more inteligence than most living organisms. Brain mass is relatively larger and their method of hunting is a good deal more sophisticated i.e hunting in packs.
It almost seems pointless to speculate if there are diminishing returns or in fact no returns to increasing a wolf's inteligence. Can we really do more then speculate what a wolf would do with that inteligence?
As for the inability to create tools, well I guess I can agree that its likely a wolf would be handicapped in that department. But what about survival tools that increased inteligence brings? The ability to anticipate the actions of a threat. The ability to modify behavior on the spot as opposed to the slow adaptability of instincts?
Though a working language such as what humans posess may be impossible (I don't know). Wolves could still make their hunting methods even MORE effective by even the most simple system of snarls, grunts, barks, etc.
Perhaps a wolf with greater inteligence does not catch rabbits any better, but it does not have to be exclusive to rabbits. What if focused on larger game? It could avoid traps more efficiently. If it was attacking a farmers sheep it could calculate how often it could get away with carrying off the farmers sheep before it was hunted. It could recognize the superiority of a farmers gun, as well as the mechanism behind it and would instead avoid the farmer more so then a less smart wolf that might confront the farmer (instinct to protect its territory).
Obviously this is all speculation and I must confess that I enjoyed your concept of the wolf with human inteligence alot Xavier. It almost makes me want to think what other animals could do with that inteligence. Many of your other points such as the the neccesity for greater development outside the womb as a tradeoff for a bigger head were very much worth considering.
What about animals then that are so large that their brains could be larger than human beings and yet they are not? Why were many of the dinosaures so stupid? Why can't a blue whale surpass the inteligence of a human being by over 100 times?
Posts: 14316 | Registered: Jul 2005
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Cephalopods are relatively shortlived and solitary, so that socialization and social learning hasn't developed in them the traits that we would recognize as human-like intelligence.
There is one controversial study asserting capacity for social learning in octopi, but it has not been duplicated.
However, cephalopod intelligence is an excellent example of an area we may be rather ill-equipped to evaluate. Octopus brains are larger for their body mass than most higher mammals, but the brain structure and entire nervous system is vastly different from ours. Their sensory inputs are measurably greater than ours, including hairs that sense distant movement in the water, and the ability to see polarized light (however, they may be colorblind). They learn (mazes, punishment/reward) but also forget. They have remarkable navigational skills, and range widely on the sea floor but always returning to a 'home' location. Their sense of propriocentricity is vastly more three-dimensional than ours, translating into a sort of 360-degree ambidextrousness. And some squids that school use rapidly changing displays of body color in ways that suggest communication.
Owners of octopi speak readily of their pets' personality, creativity, playfulness, 'wants', etc. It's unclear how much of this is anthropomorphizing. Who can say, if we really understood the way they 'think', how much more might be going on.
Posts: 431 | Registered: Oct 2003
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quote:Intelligence is impossible to define, really. We can bludgeon it into a working definition like I tried to do above in order to define what separates human intelligence from other animals, but its never a really great definition no matter how you define it.
I think adding the "and can concieve of new tools at will when encountering a new environmental need" makes my defintion a little better, but its still pretty lacking.
When comparing human intelligence to that of other species, I think an appropriate definition should include sapience, or at the very least, sentience. Although, I'm not really sure how you can adequately test that in other species when you can't really communicate with them.
Posts: 1256 | Registered: May 2005
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"I can accept this answer for the varied environments present-- but within those environments, there are also many, many, many forms of life."
One thing to remember is that evolution doesn't have a conscious mind. The most widely accepted modes of evolution don't really do anything but get rid of *bad* mutations - those that are not beneficial to the species' survival - and allow *good* mutations, that give the animal some kind of competitive edge, to propagate.
Mutations happen all the time, in every species. Most are so small or insignificant that no humans will ever notice them.
If Mutation A in Species A allows it to be successful and exploit a resource, then Evolution isn't going to say to Species B, "Sorry, dude...Species A is already exploiting that resource via Mutation A. You'll have to find somewhere else to live." If Species B happens to have a beneficial mutation that will also allow it to exploit the resource, then it's fair game. A and B now become competitors for the resource, but because mutations are always occurring in their offspring, they may both be successful at exploiting that resource, despite the presence of one another and other species, as well.
"Wouldn't it be more natural for a single (or few) life forms to evolve for each niche, rather than thousands?"
No - because *nature* has made multitudes of life forms evolve for each niche, therefore it is "natural" for multitudes to evolve for each niche. Sorry, couldn't resist.
There actually are many different niches that are only utilized by one or two different species. They're too many for me to list, sadly. But examples of very specific, unique evolution are out there.
It's also a pretty darn good thing that many different species are sharing various niches. If the Spotted Loobycat hunts on the east side of the Berserko Mountains and its prey of choice is the Little Purple Deer, it's a good thing for the Loobycat that there are also less tasty but still plentiful Nine-Toed Sloths, Buzzybirds, Corn Frogs, Cave Goats, and Hoary Leaf-Mice inhabiting the same area. If the Little Purple Deer ever face troubles that cause them to migrate out of the area, or ever are hit by a disease that makes them much less plentiful or wipes them out altogether, the Loobycat can still survive on the many other species that have evolved to live on the east side of the Berserko Mountains.
Diversity almost always makes far more sense than compartmentalized specialization - yet, as I said, relatively few species per niche do exist in some places on Earth.
...yet more are constantly evolving, so how long will that last? Posts: 1006 | Registered: Jun 2006
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KoM: no, you are wrong, likely due to misreading. I never implied any planning ahead at all. However, if something adapts in a way which better ensures the survival of its community as a whole, the community as a whole will survive better than other communities, making the individual survive better, considered in a broad scope.
No planning necessary at all for community-survival-improving adaptations to be selected for.
Posts: 15770 | Registered: Dec 2001
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Also, for question #2 - the info about Neanderthals was great. There was a point (proven via the fossil record) when there were several types of homonids living at the same time. What caused Homo sapiens to become the one remaining species? Some kind of bottleneck occurred, and the Homo populations were dramatically reduced.
Personally, as an atheist, I'm comfortable ascribing Homo sapiens' prominence post-bottleneck to sheer chance. Many folks are not comfortable with the idea of accepting our brilliant minds and our good fortune as the dominant species on Earth to pure, goofy luck. Even many atheists don't dig this point of view, because it's creepy to think about how close we came to never exising as modern humans at all! But why Homo sapiens surviving the bottleneck over the other Homo species? Who the heck knows?
New info also points to the loss of Neanderthals due to interbreeding with Homo sapiens. http://cogweb.ucla.edu/ep/Neanderthal.html Maybe they did co-exist (and they CERTAINLY were *highly* intelligent, skilled, thoughtful, superstitious, aware...so like Homo sapiens in every way but the brow ridges and the long femurs and humeres), and maybe our ancestors mated with them, and they became us, and we became them, and living humans really aren't as exclusively Homo sapiens as we think we are?
In any case, equally intelligent, wholly different species *did* live side-by-side with us for a time.
posted
I thought the bottleneck theory was heavily modified? That is, I thought it wasn't so much a bottleneck as a dominant group spreading its genetics (and coincidentally its mitochondria ) to all the existing populations of homo sapiens.
Posts: 15770 | Registered: Dec 2001
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"Someone tell me why we, of all creatures, have evolved to the point where we have the ability to destroy nature itself? If nature is truly about balance, than there must be more to our species than simply an evolutionary edge in the form of intelligence, no?"
We're always just on the edge. A virus could destroy 90% of the human race at any time. We just don't know when it will happen.
Nature isn't about balance; it's about survival. Many other species have wiped out other species and destroyed their environments; we just have the intelligence to realize what we are doing (and the jackassery not to stop when we can).
Elephants mow down whole forests for no apparent reason during their musth, turning treed areas into savannah. That's not any fun for the tree-dependent creatures that live in a patch of forest that becomes a male elephant's punching bag for a few weeks. Who knows how many predators have eaten every one of a prey species that wasn't fast enough or dully colored enough to avoid detection? We may never know that answer to that. Rabbits were introduced to Australia, but they quickly turned millenia-old grasslands into deserts. If nature were about balance, Australian plains should have found a quick and easy way to bounce back from the rabbit fiasco. After all, it's not improbable that a pregnant rabbit could arrive on a grassy island via non-human means (washed up on a raft of flood debris, perhaps) and do the same to any similar environment without human help.
Survival is the story of nature, never balance. Balance is a bonus when it occurs.
Posts: 1006 | Registered: Jun 2006
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It might be worth noting that diminishing returns do not necessarily prevent a trait from evolving. For example, peacocks' tails are plainly not very useful; a much shorter, less colourful appendage would be way handier in evading predators. Nonetheless, the thing evolved, because it signals to females that "Hey, look at me, my genes are so good I survive even when carrying this dang thing around!" There is a theory that this is also what happened to human brains.
On the subject of 'balance', nope. If a species evolves capable of wiping out everything else, and therewith itself, well, too bad. In nature, excreta occurs. You should note, this is not theory, it has happened at least once. There was a time when cyanobacteria were everywhere. Nowadays you only find them in cracks and deep-sea vents, that kind of thing, where there's no oxygen. But two billion years ago, they totally dominated; in fact, nothing else existed. Then one of them invented photosynthesis. It was a disaster. Not only was the new metabolism more active, its waste product was a poison that killed everything that didn't use oxygen, leaving it as free biomass for the killer to scoop up! 99.9% of the species on Earth died. The atmosphere is now 20% oxygen - oxygen, one of the most reactive elements! Chemically speaking, that's so far out of equilibrium, it's unbelievable.
Posts: 10645 | Registered: Jul 2004
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"I thought the bottleneck theory was heavily modified? That is, I thought it wasn't so much a bottleneck as a dominant group spreading its genetics (and coincidentally its mitochondria [Wink] ) to all the existing populations of homo sapiens."
That's one of the things that's still debated. In any case, whatever happened *diminished genetic diversity,* which is in itself the definition of a bottleneck. (That is, it doesn't have to be a cataclysmic event - just something that reduces the gene pool and makes it "easy" for the dominant strains to be observed in every present-day individual).
However, I personally feel that the cataclysmic bottleneck theory is the most sound. A supervolcano erupted in Sumatra 70k years ago - there is, of course, ample geological evidence of this - at as near to the point of the genetic reduction as we are able to trace with current technology - and the eruption coincides with the loss of other species, too. Big ol' volcano wiping out lots of species seems more likely to me than lots of hot and bothered Homo sapiens guys, but that's just me. Posts: 1006 | Registered: Jun 2006
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quote:Originally posted by fugu13: KoM: no, you are wrong, likely due to misreading. I never implied any planning ahead at all. However, if something adapts in a way which better ensures the survival of its community as a whole, the community as a whole will survive better than other communities, making the individual survive better, considered in a broad scope.
No planning necessary at all for community-survival-improving adaptations to be selected for.
But there is no reason for the help-the-community gene to be selected for. In fact, it might possibly cost the organism something, and therefore be selected against. So there's no passing on of the trait of co-operation, which is needed for real evolution at the community level : Even if you have a strongly cooperative ecosystem right now, it is entirely possible for it to be invaded by parasitic cheater genes, and become a dog-eat-dog community.
Posts: 10645 | Registered: Jul 2004
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You guys are doing an awesome job of answering Scott!
A few further thoughts regarding human intelligence.
I believe it is true that other species (specifically dolpins, et al.) may be closer to us in 'base factors' of intelligence, or intelligence potential, if you will, than we have so far proven -- and in addition they may have realized that potential (types of thinking, learning, and communication) in ways that are hard for us to recognize, because they are so alien (see my post, above, about octopi).
Even the so-called lower animals (birds, smaller mammals, livestock, etc.) may have more of the attributes (emotions, sense of self, memory, rudimentary reasoning, communication, etc.) than we give them credit for. (It becomes difficult to go down this path and remain a carnivore.)
These are some of the ways that non-humans may be closer to us. There are also ways in which humans may be closer to non-humans. I believe we usually overestimate the degree to which our success, cleverness, social structures, and other behaviors are distinctly attributable rational thought and our vaunted brainpower. We are animals, too, and what we call instinct in wolves and sheep is still a large part of us.
Which brings me to evolution. All of the above noted, the modern human brain IS remarkable. Consider the fact, for example, that a lifelong concert musician will have physically discernible structures in their brain associated with music learning.
It is helpful to remember that adaptability itself is a product of evolution. For example, the mechanisms of DNA are susceptible to just so much mutation. And just so much mutation is susceptible to being expressed in a given organism (rather than buried in unexpressed or repressed gene sequences). These factors themselves have been mediated via evolution -- if the mechanisms were more reliable, species change could not occur and environmental changes would kill everything. If the mechanisms were more unreliable, life would bloom into a chaotic and ultimately self-destructive profusion of unsuccessful experiments.[1]
Early hominid evolution -- along with bipedality, tool use, language -- must have favored not only certain aspects of raw brainpower, but some inherent advantage of faster, and heritable, brain development. Our brains today, capable of tremendous feats of complex reasoning, invention, visualization, memorization, social networking, calculation, language, and abstract/conceptual imagination, are heirs of that accidental advantage.
[1] It's worth noting, relative to global warming AKA accelerated climate change, that this balance is synchronized with typical global patterns of climate change and continental drift. If the earth never changed, the more stable model would have worked; if the earth changed more rapidly (i.e., present day), a more "unreliable" or mutative model might have developed.
Posts: 431 | Registered: Oct 2003
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An interesting illustration of evolution to fill niches is Madagascar. There are 50 species of lemur filling all manner of niches on the island - and lemurs currently exist nowhere else. The island's environment allowed for their evolution and survival, whereas mainland Africa did not.
Posts: 3960 | Registered: Jul 2001
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