"Wimpification" of humans in human evolution

[JoeTheJuggler]

Originally Posted by Dinwar

I don't disagree, but I do want to emphasize that this is due to several factors that have nothing to do with anything Creationists will try to spin it as. Really, the issue is that we have a glut of choices--there are TOO MANY potential parent species for us to narrow it down to one specific one. We know it almost certainly IS one of these (there's the potential to find a new species and for it to be our ancestor, but given how many ancestrial species we have I'm wagering it's one we've found), the issue is simply figuring out which one is the right one.

Yep. And of course the hominids and pre-hominids that aren't our direct ancestors fit into the picture as well--further confusing the issue of finding smooth directional trends.

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Huh. Hadn't thought of that. It's similar to the difference between reptile and mammal running: reptiles run side-to-side, forcing them to not breath whlie running, while mammals don't have that problem. Used to have two lizards, Corry and Mario, and was always facinated by how long they'dhave to stand still catching thier breath after they got done running short distances. I can see the logic that an additional modification--ie, the ability to completely (well, largely anyway) dissociate running and breathing would be advantageous.

That said, it's pretty similar to the logic behind the aquatic ape theory: we can hold our breath, something that most land mammals can't do but all aquatic mammals can. So I'm a bit hesitant to accept the logic. It certainly indicates that there's something to look at, and even if Homo sapien wasn't the one to do it it may indicate that one of our sister species did.

That's about what I think of it. Fun speculation, and perhaps some ideas for investigation, but nothing much more than that.

And again, these ideas hit home with me as I'm plodding up a long hill and avoiding the inclination to pant but forcing myself by choice to breathe in through the nose for 3 strides and out through the mouth for 3 strides. . . (My own running is even more complicated, but also depends on another effect of bipedalism. I'm a "joggler"--I juggle 3 clubs will running. I generally keep the juggle rate consistent with the running pace, taking advantage of the normal arm swing pattern, but I can dissociate them as well. Unfortunately, what I can't do is simultaneously wipe away that itchy bug that got stuck in the sweat on my face. . ..)

[Dinwar]

Originally Posted by JoeTheJuggler

But again, on the subject of trends or direction in evolution, read Gould's The Full House. He explains how the left limit of simplicity (archaebacteria) is the reason why a non-directional process will eventually give rise to greater and greater complexity.

Right, it's the Left-Hand Wall Rule. We demonstrated that in my intro paleo class, using a shuffled deck of cards (black cards made you take that many steps forward, red ones made you step back, and you can't step through concrete walls). I remember it, because I was the one closest to the wall when we were done--ie, I was the simplest critter. Really left an impact on me--it was the first time I'd ever found statistics USEFUL.

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But there is no directionality in evolution. Species become simpler all the time too. (Parasites, for example.)

That's not entirely true. As a whole, evolution presents no directionality, and the contingent factors certainly confound directionality in individual lineages. However, there IS directionality in individual populations--any population will adapt to a local peak in fitness space (usually the nearest one, but again contingency plays merry havoc with this sort of thing sometimes). The issue is that the environment organisms are adapting TO is always the local environment (ie, those things the individuals encounter) and is always changing.

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Horses did NOT follow a smooth trend from smaller to larger, more toes to fewer toes, and omnivorous to herbivorous molars as is often shown in images like this one:

Exactly what I'm talking about. Each population experienced directional evolution; it's just that when you look at the speceis and family they're all evolving in so many directions that you can't say there's any overall trend.

[JoeTheJuggler]

Careful phylogeneticists will avoid using the terms "primitive" and "advanced" in favor of the terms "ancestral" and "derived" to avoid the implication that there is directionality in evolution.

[JoeTheJuggler]

Originally Posted by Dinwar

Exactly what I'm talking about. Each population experienced directional evolution; it's just that when you look at the speceis and family they're all evolving in so many directions that you can't say there's any overall trend.

I think that's what I mean when I say there is no "directionality". I suppose it would be more accurate to say there is not a single directionality. I mean there is no purposeful movement in any particular direction.

As I said earlier, fitness is circularly defined. There's nothing that is objectively always and everywhere a "fit" trait, other than any trait in a given environment that helps an organism successfully reproduce with offspring that successfully reproduce. . .

ETA: I think this is one of the points the OP is missing.

[Mark6]

Originally Posted by JoeTheJuggler

Careful phylogeneticists will avoid using the terms "primitive" and "advanced" in favor of the terms "ancestral" and "derived" to avoid the implication that there is directionality in evolution.

I often see terms "primitive" and "advanced" used as substitutes for "generalist" and "specialist". As in, tarantulas who attack and eat anything are primitive, orb-weaving spiders who specialize in catching flying insects are advanced.

Which is still wrong.

[Dinwar]

Originally Posted by JoeTheJuggler

Careful phylogeneticists will avoid using the terms "primitive" and "advanced" in favor of the terms "ancestral" and "derived" to avoid the implication that there is directionality in evolution.

Only in formal discussions. After a few beers, they have NO problem with "primitive" and "advanced" (though they're oddly specific for drunk people--"primitive" ALWAYS meens "ancestral", even if they're too drunk to say the words properly).

Originally Posted by Mark6

I often see terms "primitive" and "advanced" used as substitutes for "generalist" and "specialist". As in, tarantulas who attack and eat anything are primitive, orb-weaving spiders who specialize in catching flying insects are advanced.

Which is still wrong.

There's a general principle in the evolution of Earth-like organisms (I have to be careful, because I'm not sure if this is universally true or not and paleontology only deals with a subset of evolution) that lineages start with more generalized forms, then become increasingly specialized. The original mammals, for example, ate pretty much anything. It's only after the branches diverged that they became carnivores and herbivores. Our limbs started off rather genrealized as well--we could use two or four legs to stand, use our forelimbs for locomotion or manipulating objects, etc. Then our limbs became more and more specialized. So specialists tend to be decendents of generalists. So the terminology makes a certain kind of sense, at least in some specific areas.

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I think that's what I mean when I say there is no "directionality". I suppose it would be more accurate to say there is not a single directionality. I mean there is no purposeful movement in any particular direction.

Evolution has been described as Nature trying every available option at once, over and over and over again.

[JoeTheJuggler]

Originally Posted by Mark6

I often see terms "primitive" and "advanced" used as substitutes for "generalist" and "specialist". As in, tarantulas who attack and eat anything are primitive, orb-weaving spiders who specialize in catching flying insects are advanced.

Which is still wrong.

Generalist and specialist aren't terms that necessarily correspond with primitive/advanced and ancestral/derived.

Generalist and specialist refers to the ability of a species to succeed in a variety of environments. (A specialist doesn't; a generalist does.)

Modern sharks are very similar to ancient ones, but that doesn't mean they've stopped evolving somehow. (Or that they no longer participate in evolution because they've found a hugely successful niche in a relatively unchanging environment for a long period of time.) Even though in traditional terms they don't seem to have "advanced" much, they indeed have characters that are derived.

Humans are in fact the ultimate example of an "advanced" but generalist species. We've radiated to occupy darn near every terrestrial corner of the globe.

[Shiner]

G'day all, this is an interesting, if somewhat redundant conversation. I think most of the OPs concerns have been addressed, but if I may.

Ever since we first employed tools our need for strength has been in steady decline. First we had the rock and the stick, as hitting and cutting tools/weapons The lever and the wheel being major contributing factors. The employment of the beast also has obvious implications. As hunter gatherers agility and stamina are more important than strength, but in an agricultural society, especially when employing beasts strength would be an obvious benifit over agility. For a while, then we domesicate the beasts making them managable hence decreasing the need for strength. Then we industrialise our agricultural practices creating a non self-reliant species. . . . . With exceptions to all points thus far.
That's Evolution. . . . . and horses are bigger!

[mike3]

Originally Posted by Dinwar

Right, it's the Left-Hand Wall Rule. We demonstrated that in my intro paleo class, using a shuffled deck of cards (black cards made you take that many steps forward, red ones made you step back, and you can't step through concrete walls). I remember it, because I was the one closest to the wall when we were done--ie, I was the simplest critter. Really left an impact on me--it was the first time I'd ever found statistics USEFUL.

That's not entirely true. As a whole, evolution presents no directionality, and the contingent factors certainly confound directionality in individual lineages. However, there IS directionality in individual populations--any population will adapt to a local peak in fitness space (usually the nearest one, but again contingency plays merry havoc with this sort of thing sometimes). The issue is that the environment organisms are adapting TO is always the local environment (ie, those things the individuals encounter) and is always changing.

Exactly what I'm talking about. Each population experienced directional evolution; it's just that when you look at the speceis and family they're all evolving in so many directions that you can't say there's any overall trend.

So when you look back along a line of descent, and see a trend, that trend is just a bias, i.e. you can look at the evolution towards humans along their "line", and think that life must "evolve towards" humans, but that's only a bias. If you could reconstruct the line at all, you did it after the fact. You could do the same for a modern mollusk, and think that life's "goal" was whatever species of mollusk you picked. But in actuality, there is no ultimate goal, rather there is only change (you could say the immediate goal is to make the organism survive better, but there is no overarching plan, goal, or direction.). Life didn't "goal" since the 3-4 billion years ago when it started, it just changed.

[mike3]

Originally Posted by Dinwar

Right, it's the Left-Hand Wall Rule. We demonstrated that in my intro paleo class, using a shuffled deck of cards (black cards made you take that many steps forward, red ones made you step back, and you can't step through concrete walls). I remember it, because I was the one closest to the wall when we were done--ie, I was the simplest critter. Really left an impact on me--it was the first time I'd ever found statistics USEFUL.

Like this, right? (1-dim random walk):

http://mathworld.wolfram.com/images/...mWalk_1000.gif

Originally Posted by Dinwar

That's not entirely true. As a whole, evolution presents no directionality, and the contingent factors certainly confound directionality in individual lineages. However, there IS directionality in individual populations--any population will adapt to a local peak in fitness space (usually the nearest one, but again contingency plays merry havoc with this sort of thing sometimes). The issue is that the environment organisms are adapting TO is always the local environment (ie, those things the individuals encounter) and is always changing.

Exactly what I'm talking about. Each population experienced directional evolution; it's just that when you look at the speceis and family they're all evolving in so many directions that you can't say there's any overall trend.

Here's a question, now. So, suppose say we did have a method to measure intelligence of early human species, and found them to be less intelligent than humans now. Would this mean anything, or not, in terms of "trends" of any sort, however localized?

[mike3]

Originally Posted by JoeTheJuggler

But again, on the subject of trends or direction in evolution, read Gould's The Full House. He explains how the left limit of simplicity (archaebacteria) is the reason why a non-directional process will eventually give rise to greater and greater complexity.

But there is no directionality in evolution. Species become simpler all the time too. (Parasites, for example.)

But over-simplified "ladder of life" depictions of evolution give a terribly wrong understanding. Horses did NOT follow a smooth trend from smaller to larger, more toes to fewer toes, and omnivorous to herbivorous molars as is often shown in images like this one:

http://upload.wikimedia.org/wikipedi...eevolution.png
Wiki commons image. Permissions released under GNU Free Document License.

So then what is the true meaning and purpose of this picture?

[Robrob]

Originally Posted by mike3

So then what is the true meaning and purpose of this picture?

It shows the evolution of the horse from an early ancestor. It's not saying anything about "complexity" or size. You could do a similar chart for ostriches or hummingbirds. One got bigger, the other got smaller.

[The Norseman]

Originally Posted by Dinwar

If we DO become wimpy it means that wimps are, in the only sense that can be used when discussing biology, objectively better than non-wimps.

I'm officially taking your statement and changing the word 'wimp' to the word 'nerd'. Just because it makes me feel a whole lot better.

[Dinwar]

Originally Posted by mike3

So when you look back along a line of descent, and see a trend, that trend is just a bias, i.e. you can look at the evolution towards humans along their "line", and think that life must "evolve towards" humans, but that's only a bias.

Sort of, yeah. The thing is, each population is going to be subject to a myriad of selection pressures. And each population typically produces a number of ways to get around them. So to pick any single end result and say "This is what the taxa was driving towards" is to ignore the majority of the subpopulations. The exception is chronospecies, where the entire species undergoes directional evolution in the same direction. Rather rare, and extremely odd. Gives taxonomists headaches, which is always fun.

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Like this, right? (1-dim random walk):

Not really; that's just random motion over time. The left-hand wall rule is more random motion with a hard limit at some point. Take thread length on a forum. There has to be at least one post--there's no option to have a thread without one post in it. A thread can be infinitely long, however (this forum limits the post count, but let's assume for the moment that it doesn't). If people randomly posted in threads you'd end up with a lot of very, very short threads, and a few gargantuanly long ones. Furthermore, over time the record-holding thread length would become longer and longer (different threads would hold the record, but the record would increase).

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So, suppose say we did have a method to measure intelligence of early human species, and found them to be less intelligent than humans now. Would this mean anything, or not, in terms of "trends" of any sort, however localized?

There's not enough data to answer that question. If ALL other species were stupider than us, then I'd say no, there is no trend. Or, rather, the trend is for stasis (I studied under one of Gould's students--I'm not allowed to forget that stasis is data ), and we're a fluke. Perhaps a necessary fluke--this fluke may be the only reason we survived while the rest died--but a fluke none the less.

In order for there to be a trend you'd have to find generally increasing intelligence (remember, this is biology--it will ALWAYS be plus or minus quite a bit) in the line that Homo sapien came from. This isn't impossible--similar studies have found various trends in other traits more easily identifiable in the fossil record--but it's a lot more work than people think. This isn't a Master's thesis or a Ph.D. dissertation--this is a career.

Originally Posted by The Norseman

I'm officially taking your statement and changing the word 'wimp' to the word 'nerd'. Just because it makes me feel a whole lot better.

"Age of the Geek, baby!" ~Leverage.

[I Ratant]

Originally Posted by mike3

So then what is the true meaning and purpose of this picture?

.
It's means the environment for the horse line to fit into changed so that larger horses could survive better than the smaller sizes.
The opposite occurs also, with smaller "winning" the race to survive.
There's no "meaning" beyond that indication of the environment being adapted to by the animal.

[yog_sothoth]

Humans are wimpier now? A unit of modern special forces would be able to annihilate any number of stone age soldiers. Heck, Sarah Palin in a helicopter and armed with a rifle could defeat the mightiest cave man.

[I Ratant]

Originally Posted by yog_sothoth

Humans are wimpier now? A unit of modern special forces would be able to annihilate any number of stone age soldiers. Heck, Sarah Palin in a helicopter and armed with a rifle could defeat the mightiest cave man.

.
Man-on-man?
Clubs and rocks?

[mike3]

Originally Posted by Dinwar

Sort of, yeah. The thing is, each population is going to be subject to a myriad of selection pressures. And each population typically produces a number of ways to get around them. So to pick any single end result and say "This is what the taxa was driving towards" is to ignore the majority of the subpopulations. The exception is chronospecies, where the entire species undergoes directional evolution in the same direction. Rather rare, and extremely odd. Gives taxonomists headaches, which is always fun.

Not really; that's just random motion over time. The left-hand wall rule is more random motion with a hard limit at some point. Take thread length on a forum. There has to be at least one post--there's no option to have a thread without one post in it. A thread can be infinitely long, however (this forum limits the post count, but let's assume for the moment that it doesn't). If people randomly posted in threads you'd end up with a lot of very, very short threads, and a few gargantuanly long ones. Furthermore, over time the record-holding thread length would become longer and longer (different threads would hold the record, but the record would increase).

So if you had something similar to that graph, but with hard limits on how far along the y-axis it could go, would that be more like it (not a simple "clipping", but hard limits implemented into the random motion process itself that generated the graph)?

Originally Posted by Dinwar

There's not enough data to answer that question. If ALL other species were stupider than us, then I'd say no, there is no trend. Or, rather, the trend is for stasis (I studied under one of Gould's students--I'm not allowed to forget that stasis is data ), and we're a fluke. Perhaps a necessary fluke--this fluke may be the only reason we survived while the rest died--but a fluke none the less.

In order for there to be a trend you'd have to find generally increasing intelligence (remember, this is biology--it will ALWAYS be plus or minus quite a bit) in the line that Homo sapien came from. This isn't impossible--similar studies have found various trends in other traits more easily identifiable in the fossil record--but it's a lot more work than people think. This isn't a Master's thesis or a Ph.D. dissertation--this is a career.

"Age of the Geek, baby!" ~Leverage.

But I thought you were saying there are no trends in evolution, period. Also, I'm wondering: how exactly do you define a "trend", anyway, in this context? But if there was no "generally increasing intelligence", does that mean there could have been ancient hominids just as smart as us? If no trends for "strength" or "wimpiness", just as "wimpy"?

[Dinwar]

Originally Posted by mike3

So if you had something similar to that graph, but with hard limits on how far along the y-axis it could go, would that be more like it (not a simple "clipping", but hard limits implemented into the random motion process itself that generated the graph)?

Something like that, yeah. Put a hard limit at 0 and run a random walk again.

You can also do the Drunkard's Walk--a hard wall on one side, and a gutter on the other. In other words, it can't go below X(z), but once it goes above X(q) it stays at X(q) indefinitely.

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But I thought you were saying there are no trends in evolution, period.

You're trying to make it a simple cut-and-dried question. It's not. If you follow an individual lineage there are often trends--but when you look at larger taxa each trend from individual lineage cancel out, and there's no trend. It's a huge number of experiments trying everything all at once--each experiment can be directional, but the suite isn't.

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But if there was no "generally increasing intelligence", does that mean there could have been ancient hominids just as smart as us?

Of course. There could be ancient hominids that make our geniuses look like morons.

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If no trends for "strength" or "wimpiness", just as "wimpy"?

Sure. Some were less robust than us. Some were more so. Depends on which lineage you're looking at how robust it is.

[Dancing David]

Originally Posted by mike3

Like this, right? (1-dim random walk):

http://mathworld.wolfram.com/images/...mWalk_1000.gif



Here's a question, now. So, suppose say we did have a method to measure intelligence of early human species, and found them to be less intelligent than humans now. Would this mean anything, or not, in terms of "trends" of any sort, however localized?

Depends on the definition of intelligence.