Highly Evolved

[jimlintott]

Armed with a basic understanding of evolution I know that the term highly evolved is silly as evolution has no goals to become better, the goal is simple survival. Whatever works stays whatever doesn't goes.

Now, if I am reading between the lines properly many people who seem to fear evolution fear it because it considers man as just another critter which means we aren't the special work of some magical creator.

I wanted to have a little fun with the term highly evolved though. What criteria could be used to say that one critter is more highly evolved and where on the list would man end up? Would man be number one or number one billion?

So after some thought I have some criteria for judging highly evolved.

1) Has the critter been around a long time and has it been fairly unchanged in that time?

2) How does future survival look? Could it adapt to a new environment easily is its existence fragile?

If I ignore bacteria (which is probably the king of highly evolved) I can think of many critters that are more highly evolved than man. Sharks, crocodiles, ants and wasps all come to mind. Then there are things like coral, sponges, nemetodes(?). It seems that man would fall far down this list.


Without believing in fairy tales how does a rational person put man at the top? (Forget that the word rational probably answers my question.)

So anyone want to play the highly evolved game? Any better criteria for judging it? Is man really the king of beasts?

[Badger]

You forgot cockroaches.

[sphenisc]

I'd disagree with both your criteria.

'Evolve' in its broadest sense means to change. A more highly evolved thing should have the greatest change. If we're talking about extant organisms then they've all had the same amount of time to change, so the one with the greatest rate of change should be the most highly evolved. anything which has been around for a long time with little change is less highly evolved.

A highly evolved thing should also be very precisely adapted to its current environment, if its still pretty much of a generalist - then its rate of evolution to an optimum would seem slow - it's less highly evolved.

This probably shows how meaningless the concept is...

Cheers ;)

[joobz]

Highly evolved?
how about flying, you don't get higher than that. And airplanes don't count. It's got to be a biological ability.

How about long distance fertilization as a highly evolved characteristic. My semen can't float on the wind, so that kinda sucks.

Hibernation as a highly evolved trait. i wish I could sleep through winter and the whole gilmore girls season.

There's that whole changing you sex thing that some fish can do. That seems like it'd save a lot of money and settle some peoples gender issues.

Although I have to admit, opposable thumbs have made self-gratification a lot easier....so, it's kinda hard to top that.


:D :D :D

[jimlintott]

I'd disagree with both your criteria.

'Evolve' in its broadest sense means to change. A more highly evolved thing should have the greatest change. If we're talking about extant organisms then they've all had the same amount of time to change, so the one with the greatest rate of change should be the most highly evolved. anything which has been around for a long time with little change is less highly evolved.

A highly evolved thing should also be very precisely adapted to its current environment, if its still pretty much of a generalist - then its rate of evolution to an optimum would seem slow - it's less highly evolved.

This probably shows how meaningless the concept is...

Cheers ;)

Excellent point. I hadn't really thought of it that way. Isn't man really a generalist though? So we still lose out on the highly evolved front.

[RenaissanceBiker]

"Highly evolved" implies complexity. That is, it has undergone extensive evolution. That does not mean that it is more or less fit to survive than anything else. A sponge is not as highly evolved as a dolphin, yet it may be a better survivor. "Highly evolved" does not mean "better."

[drkitten]

"Highly evolved" implies complexity.

Does it?

That is, it has undergone extensive evolution.

Given the relative generation times involved, this means that bacteria are much more highly evolved than any multicellular organisms. Which in turn implies that "highly evolved" actually implies LOWER complexity, not higher.

A sponge is not as highly evolved as a dolphin,

Why not? It's undergone just as much evolution as a dolphin, and probably substantially more.

[ponderingturtle]

Why not? It's undergone just as much evolution as a dolphin, and probably substantially more.

So the term living fossil that seems to have been unchanged for millions of years is a bad concept? If they fit their niche well enough why would they continue to evolve? How would changes get favored enough to become prevelant?

[Mojo]

If it ain't extinct, it's highly evolved.

[Foster Zygote]

How about long distance fertilization as a highly evolved characteristic. My semen can't float on the wind, so that kinda sucks.
The rest of us are rather happy about that.

Hibernation as a highly evolved trait. i wish I could sleep through winter and the whole gilmore girls season.
As a new father I bet you just wish you could just sleep.

There's that whole changing you sex thing that some fish can do. That seems like it'd save a lot of money and settle some peoples gender issues.
Speaking as a lesbian trapped in a man's body I think that would be a hoot!

Although I have to admit, opposable thumbs have made self-gratification a lot easier....so, it's kinda hard to top that.
My cats disagree.

[Loss Leader]

I remember reading that the human hand is the most complex bio-mechanical machine in evolution. Surely, that must count for something. Don't ask me what.

[drkitten]

So the term living fossil that seems to have been unchanged for millions of years is a bad concept?

For several reasons.

Perhaps most importantly, because it's simply wrong. Dawkins documents this in one of the Ancestor's Tales (I forget exactly which one); the genes of the so-called "living fossils" such as sharks, alligators, and horseshoe crabs have actually changed as much and in many cases more than animals that have undergone much more obvious morphological change. They've confirmed this by examination of the actual genes.

But it also makes sense theoretically.

If they fit their niche well enough why would they continue to evolve?

Because there's no such thing as "well-enough." It's not a question of outrunning the bear, but of outrunning the other campers. If my brother fits his ecological niche superbly, then it's that much more important that I find every possible advantage I can over him.

Something simple like streamlining there is probably not much room for improvement in; gross body shape is pretty easy to optimize. On the other hand, things like metabolism and efficiency are the sort of things that can be improved without much gross change to the form.

The other big evolutionary change is the predator-prey arms race, or alternatively the pathogen-host arms race. A Devonian shark had evolved to catch Devonian fish, and to resist infection by Devonian germs. Put a Devonian shark into today's oceans and it would probably starve if it didn't die of smallpox first.....

[Mojo]

Like I said, if it ain't extinct...

[drkitten]

I remember reading that the human hand is the most complex bio-mechanical machine in evolution. Surely, that must count for something.

Not much, I'm afraid.

If nothing else, it's patently false. Just as a quick example, the machine consisting of the human hand, wrist, and arm is demonstrably more complex[/i] than just the human hand, since it includes the hand as a subsystem. The human body as a whole is of course still more complex. Where do you draw the line and say this is a machine, but that isn't?

But this also runs into the problem of defining "complexity" in a meaningful way. There are more moving parts in a centipede's exoskeleton, and lungfish have the largest genome of any known animal. Which is the most complex?

[Soapy Sam]

Rasta-men.

[Dave1001]

"Highly evolved" implies complexity. That is, it has undergone extensive evolution.

It's a good spinoff topic: how do we rank the complexity of lifeforms. What's most complex? The top ten? The least complex is probably easier to figure out.

[ponderingturtle]

For several reasons.

Perhaps most importantly, because it's simply wrong. Dawkins documents this in one of the Ancestor's Tales (I forget exactly which one); the genes of the so-called "living fossils" such as sharks, alligators, and horseshoe crabs have actually changed as much and in many cases more than animals that have undergone much more obvious morphological change. They've confirmed this by examination of the actual genes.


Genes or DNA? And how do they tell? Do they have many million year old horseshoe crab DNA?


Because there's no such thing as "well-enough." It's not a question of outrunning the bear, but of outrunning the other campers. If my brother fits his ecological niche superbly, then it's that much more important that I find every possible advantage I can over him.

Something simple like streamlining there is probably not much room for improvement in; gross body shape is pretty easy to optimize. On the other hand, things like metabolism and efficiency are the sort of things that can be improved without much gross change to the form.

The other big evolutionary change is the predator-prey arms race, or alternatively the pathogen-host arms race. A Devonian shark had evolved to catch Devonian fish, and to resist infection by Devonian germs. Put a Devonian shark into today's oceans and it would probably starve if it didn't die of smallpox first.....

So there is nothing really special about nightcap oak then it is just as modern as all other trees?

[RecoveringYuppy]

Given the relative generation times involved, this means that bacteria are much more highly evolved than any multicellular organisms. Which in turn implies that "highly evolved" actually implies LOWER complexity, not higher.
That's if you consider bacteria to be less complex. I'm under the impression that many of the bacteria have larger genomes than us humans. We consume a great many organic chemicals our bodies can't synthesize, while many bacteria synthesize a wider range of their chemicals rather than consuming them. Apparently the genetic codes to describe the biochemistry are more involved than those to grow hands and brains. How would you compare such disparate forms of complexity? Size of the genome would seem to be a fair way to me.

[drkitten]

Genes or DNA? And how do they tell? Do they have many million year old horseshoe crab DNA?

No, they use reconstructive techniques to triangulate on the most probable common ancestral genes of modern species For example, we know that the 'eyeless' gene in fruit flies is very similar (but not identical) in both form and function to the Pax6 gene in mammals -- and of course, different mammals have slightly different forms of Pax6. Similarly, alpha, beta, and zeta hemoglobin are very similar but different in detail.

So we take the Pax6/eyeless gene equivalent from a hundred different species -- everything from spider crabs to spider monkeys -- and we reconstruct an evolutionary tree based on it. And then we do the same with hemoglobin, and the same with .... When we do this, we discover that genes for horseshoe crab eyes are about as far from the reconstructed ancestral genes as are the genes for mouse or fruit fly eyes. And shark hemoglobin is as far from ancestral hemoglobin as is dolphin hemoglobin.


So there is nothing really special about nightcap oak then it is just as modern as all other trees?

Genetically so? Not really. It's "morphologically" special, I guess, in that the morphology hasn't changed much in umpteen zillion years. But that doesn't mean its biochemistry hasn't changed radically.....

[Crazycowbob]

Highly evolved?
how about flying, you don't get higher than that. And airplanes don't count. It's got to be a biological ability.

How about long distance fertilization as a highly evolved characteristic. My semen can't float on the wind, so that kinda sucks.

Hibernation as a highly evolved trait. i wish I could sleep through winter and the whole gilmore girls season.

There's that whole changing you sex thing that some fish can do. That seems like it'd save a lot of money and settle some peoples gender issues.

Although I have to admit, opposable thumbs have made self-gratification a lot easier....so, it's kinda hard to top that.


:D :D :D

Why can't advances in technology count?

I think the biggest problem here is that so far every one has come up with different deffinitions for "highly evolved", and what's worse, is that most of them could be acceptable.

I've often seen evolution as stated "a species ability to adapt to it's environment" by natural selection, generally. If this is the case, I'd deffinately put humans at the top, since they not only have adapted to their environment, but have come to the point in which they can adapt unsuitable environments to fit them.

Which brings me to a question I have...
If our understanding of nature, and ability to manipulate it, has evolved, how is that not also evolution of our species as a whole? Does evolution of a species have to refer to genetics alone? After all, our understanding of the world over the last century has dramatically increased our lifespan and ability to thrive, even in what were once inhospitable conditions, wouldn't that be considered evolution, even though not at a genetic level?

Just my take on the situation,
Educationalizing welcomed! :D

[ponderingturtle]

No, they use reconstructive techniques to triangulate on the most probable common ancestral genes of modern species For example, we know that the 'eyeless' gene in fruit flies is very similar (but not identical) in both form and function to the Pax6 gene in mammals -- and of course, different mammals have slightly different forms of Pax6. Similarly, alpha, beta, and zeta hemoglobin are very similar but different in detail.

So we take the Pax6/eyeless gene equivalent from a hundred different species -- everything from spider crabs to spider monkeys -- and we reconstruct an evolutionary tree based on it. And then we do the same with hemoglobin, and the same with .... When we do this, we discover that genes for horseshoe crab eyes are about as far from the reconstructed ancestral genes as are the genes for mouse or fruit fly eyes. And shark hemoglobin is as far from ancestral hemoglobin as is dolphin hemoglobin.


How does this prove how much change horseshoe crabs have had in say the last 100 million years?


Genetically so? Not really. It's "morphologically" special, I guess, in that the morphology hasn't changed much in umpteen zillion years. But that doesn't mean its biochemistry hasn't changed radically.....

And how do you know how much its biochemistry has changed? The process above seems to be assuming change to prove that there was change. You are measuring the separation, but you are assuming that both moved at the same rate to get there, thus showing that both moved.

It looks like you are basically assuming your conclusion.

[RecoveringYuppy]

How does this prove how much change horseshoe crabs have had in say the last 100 million years?

One such measure across two leaves of the tree wouldn't prove anything about the specific rate along one branch of the tree. But we've measured so many pairs from so many disparate parts of the tree that it would be impossible to construct scenarios where any one branch can be said to be an unchanging "reference" branch.

We also have old DNA for some species (Neanderthal being in the news quite a bit the past decade for this reason) that allow us to prove that modern DNA has changed in the recent past. The simplest assumption is that DNA has been changing similarly in the past.

There's general agreement of the shape of the tree from several different lines of evidence, and some of those lines of evidence contribute thousands, even hundreds of thousands, of points of evidence: The family tree was first noticed by Linneaus, Lamark and others than noted that the fossils fit the tree, early 20th century biochemists established that proteins and immune responses fit the tree, now late 20th century biochemistry is establishing that DNA, the direct agent of inheritance, also fits the tree. That's a mountain of evidence, no assuming the conclusion here.

[Dave1001]

does complex basically mean non-homogeneous?

If so, what's gram-for gram the most complex life form?

[ponderingturtle]

One such measure across two leaves of the tree wouldn't prove anything about the specific rate along one branch of the tree. But we've measured so many pairs from so many disparate parts of the tree that it would be impossible to construct scenarios where any one branch can be said to be an unchanging "reference" branch.

I am not sure where you are going with this. Do horseshoe crabs have common ancestors with anything else for the last 100 million years?

As a general rule I can see how that would work, but it still looks like you are assuming that they changed to support the theory that they changed.


We also have old DNA for some species (Neanderthal being in the news quite a bit the past decade for this reason)

We can't have old enough DNA on Neanderthal to address what I am talking about, because they where not around more than a million years ago.

that allow us to prove that modern DNA has changed in the recent past. The simplest assumption is that DNA has been changing similarly in the past.


But that does not say anything useful about so called living fossils. Have we checked modern horseshoe crabs vs horseshoe crabs from 100,000 years ago?

There's general agreement of the shape of the tree from several different lines of evidence, and some of those lines of evidence contribute thousands, even hundreds of thousands, of points of evidence: The family tree was first noticed by Linneaus, Lamark and others than noted that the fossils fit the tree, early 20th century biochemists established that proteins and immune responses fit the tree, now late 20th century biochemistry is establishing that DNA, the direct agent of inheritance, also fits the tree. That's a mountain of evidence, no assuming the conclusion here.

Yes, that all fits nicely, but how does that prove the amount of biochemical change in something that has had no morphological change? Just because it holds for animals that have morphologically changed (like various species of shark and crocodilian have change quite a bit even if the over all body plan is the same, no one would mistake a cayman for a alligator).

[RecoveringYuppy]

Yes, that all fits nicely, but how does that prove the amount of biochemical change in something that has had no morphological change?
Ahh, I see your question. And now understand your focus on direct comparisons of DNA within the lineage. I don't know if we have such comparisons available. I would only point out that we're fairly sure that many many genetic variations lead to the same morphology. So we'd expect that the creature would keep "evolving" if only in the sense that they are finding all the possible genetic combinations that lead to the same morphology.

[drkitten]

And how do you know how much its biochemistry has changed?

I'm not sure what you mean by this question. We know that something changed from the DNA evidence; the horseshoe crab form of the ey/Pax6 gene is observably different from the inferred ancestral form.

We also know that the morphology hasn't changed much.

If not morphology, then what? BIochemistry is an obvious catch-all term to describe the functioning instead of structure of organisms, but if you don't like the term, suggest something else?




The process above seems to be assuming change to prove that there was change. You are measuring the separation, but you are assuming that both moved at the same rate to get there, thus showing that both moved.

Er, no. We infer the starting point, not by assuming that evolution occurs at the same rate (as a matter of fact, it's relatively easily provable from the data that it doesn't), but on the basis of probability theory. If you assume, for example, that horseshoe crabs are genetically identical to their 100million year old ancestors, then you are forced to accept a highly improbable set of parallel mutations that happened at roughly the same time in all other studied lineages.

It's rather like the old joke where a sergeant calls for a volunteer to take one step forward, and everyone else in the platoon takes one step back. That kind of coordinated action among independent organisms is impossible when we're talking about evolution, so we instead infer that the person in front took a forward step instead of everyone else taking a backwards one. This becomes more and more certain an inference the more people there are in the platoon -- with only two people, I can't make any inference at all, but with two hundred (big platoon, I know) I can be fairly confident.