A while back (a long while, by now), a friend-of-a-friend mentioned something interesting....

[conuly]

She said that most people she knows who accept the Theory of Evolution ignore "large holes" in it. Now, that may be, and those holes may exist. However, in my experience, most "large holes" mentioned are not, actually, large holes at all - or rather, they're holes in the knowledge of the questioner.

I'm hardly a biologist. However, if you post any complaints you have with evolutionary theory, with one exception... no, two exceptions, I'll gladly start running around to see if I can find answers. Or maybe one of my other friends can answer the problem.

The two exceptions are as follows:

1. I'm not answering that damn chicken or egg question, or any transparent version of it.
2. I'm not answering any question that has to do with the creation of the universe, or the beginning of life. If you say "See, this means there must be a designer", I'll quietly sigh, because the only response to that is "Well, who designed the designer", and before you know it we're having the second-silliest flamefest in history. There might very well have been some sort of original creator(s) or designer(s). I don't know, I don't care, that's onen puzzle we're never getting to the bottom of.

Comments

[literalgirl.livejournal.com]

Well said.

And I don't actually have any questions, but I am glad you are there if I think of any! :-)

[conuly]

The best part of this is that if I can't find an answer, or don't know the answer myself, I can't "disprove" anything, since I admit upfront that I'm not an expert.

The Big Questions

[pockingell.livejournal.com]

Well, you asked for it:

I just realised, I don't really know what the Theory of Evolution is, apart from vaguely understanding that it's along the lines of "small changes occur between individuals, and the changes which allow the individual to survive longer are passed down". What is the actual theory?

Re: The Big Questions

[conuly]

I'm pretty sure that *is* the theory. Hard to see what else could be involved in it. Evolution just means changes through time, and it occurs through the process of natural selection. And pure dumb luck - if a volcano wipes out all the people who carry X gene, that gene is gone from the population, even though that has nothing to do with the survival value of those people, or that gene.

Re: The Big Questions

[leora.livejournal.com]

That's almost it, except it's not really survive more so much as be present more. Longer lifespan means you need to reproduce less to have more of them around, since they stick around. But you can also take the reproduce a lot path. Things that help you make more of you be around will be around more.

It's pretty incredibly obvious, which is why it's ridiculous to argue it. But most people only argue with some of the higher level conclusions.

It's often nicknamed survival of the fittest or survival of the sexiest. Fitness is whatever makes you able to have more of you, which is why it includes counterintuitive things like a peacock's tail that makes it easier for predators to catch it, but gets it babes. And it includes sacrificing your own life to protect your children, at least in certain cases.

And, as Conuly said, luck plays into it. Sometimes something is more beneficial, but it's not very present yet and everything with it happens to get killed in an earthquake. But generally, more helpful traits will become more prevalent. And while there are many random mutations and most are harmful, some will be helpful, and those have a better chance of propogating.

Re: The Big Questions

[rho]

In addition to what conuly and leora have said:

There are actually two big processes going on which are related but very different. One is the changes within a species. Your proto-giraffes are having a hard time, so the ones with slightly longer necks mange to reach more food, so they're more likely to survive, so the genes for having long necks get passed on to their offspring. This is what Leora and Conuly both describe.

Then there's the creation of new species. What actually happens there is that you have one starting species, which then diverges into two, which aren't capable of breeding with each other. This generally happens when there are two separate populations that don't breed, for one reason or another, and then the two populations change sufficiently with respect to each other that it would no longer be possible for them to breed.

The separation can be for any of a number of reasons: a mountain range gets put up in the way, one lot live at the lake bottom and the other at the shore, one lot has females attracted to red mates and the other has females attracted to blue mates, and so on. And equally, the changes between the two populations could be due to a "survival fo the fittest" type effect, or they could just be down to random geetic drift.

So for instance, if we go back to our proto-giraffes, while there was one group staying out on the plains and getting taller, another group retreated into the forests and lived there, and eventually evolved into the okapi.

It's these two effects working in parallel which have led to the great diversity of life on earth today.

Re: The Big Questions

[ahsirakh.livejournal.com]

Actually, there are many possible parts in the theory which you can believe in (behold: the Wikipedia article! (http://en.wikipedia.org/wiki/Evolution)), which is why saying one believes in the existence of evolution is vague, and one trying to slam evolutionary theory tends not to succeed because they usually only attack a single prong of all evolutionary theory, which comprises numerous prongs of theory.

Re: the chicken and the egg, I think it's a cute question which is pretty much agreed on if microevolutionary theory, even by natural selection alone, is to be believed: the egg came first. The original chicken and the egg paradox relied on the assumption that chickens can only be hatched from eggs laid by other chickens, but chickens could very well have evolved from "other species" (the quotation marks are based on how you treat the human divide of species). This means that the chicken oculd have come into conception with the right mix of genetic traits in an egg from chicken-like species resulting in a chicken as we know it.

[atdelphi.livejournal.com]

Ooh, I've got one - not really about a 'hole' in the theory, but rather about making the argument for the theory itself (keeping in mind that I'm the least scientific person in the world.)

Now, I know the reason it's referred to as a theory is because macroevolution, due to the obvious time spans involved, hasn't been directly observed. Rather like the way that our 'knowledge' of the earth revolving around the sun was only a theory until we actually sent satellites out to snap pictures.

My question is: are there any other pieces of scientific knowledge that the general public takes for granted that are really only 'theories'? I could definitely use an example to trump those who smugly play the "Why do they call it a theory, then?' card.

[rho]

Atomic theory would be a good one. Or quantum theory. Or the theory of relativity. Slightly more esoteric, we have things like game theory. Or if we allow a little bit of linguistic leeway, how about pythagoras' theorem, which is occasionallyr refered to as pythagoras' theory?

The "it's just a theory" brigade annoy me immensely because they completely ignore the way that the word is used scientifically. In a scientific context, it can mean a framework and system for understanding things just as much, if not more, than it can mean a hypothesis or conjecture.

[conuly]

Gravity.

[leora.livejournal.com]

All accepted scientific knowledge is a theory. That the Earth revolves around the sun is a theory. A theory that Einstein, in fact, gave us reason to question with his theory of relativity. Now we know it may be more accurately described as saying from one point of view, the Earth revolves around the sun, but other points of view are equally valid but generally less useful.

The only difference between theories is how much support/evidence we have for them. There is no absolute knowledge in real science. Everything can be theoretically disproven. And our long-held ideas about Newtonian physics were shown to be incomplete. They're a good model, but not a perfect model. Pretty much everything is assumed to be an imperfect model, but we use the best ones we can create and improve them as we go. That's what science is.

Faith is the only thing that tries to claim absolute truths. And it can do so because it has absolutely no requirement to have any evidence to support it whatsoever, and generally is able to throw away any evidence that conflicts as irrelevant. That is why faith makes claims of absolute knowledge and science does not.

[maladaptive.livejournal.com]

Gravity is a theory. We know something holds us to the ground, but is it really gravity, or did a supreme being tie everything down with really stretchy strings?

[theshiversbaby.livejournal.com]

If the T. of E. is correct, there must be an incredible number of stages in development for each species as the species slowly evolved. For example, there should have existed all of the steps between some early form of, oh I don't know, elephant that we'll call "Proto Elephant," and the elephant as we know it today, "Modern Elephant" (yes, I realize there is more than one kind of elephant, I'm just oversimplifying for the purpose of clarification). Assuming that Proto Elephant is quite different from Modern Elephant, this process must have taken quite a long time and a large number of developmental stages.
Two questions: a) Do you think this is correct?
and b) If so, why haven't we found more skeletons supporting this fact? I'm mean, obviously we've found skeletons of things we classify as separate species - in the case of humans, for example, we've found Homo habilis, Homo erectus, etc. But we don't seem to have found many skeletons between these stages. They all seem to belong to distinct species. Why? Does this mean that every stage of development, no matter how miniscule, could be classified as a different species? If so, we should be a few thousand species beyond Homo sapiens, then.

[theshiversbaby.livejournal.com]

[Edit: I guess we're really Homo sapiens sapiens. Right? And I may have messed up some capitalization. I'm not a biologist in the least.]

[conuly]

1. Yes
2. Skeletons don't last as long as we might think. If they did, we'd be standing knee-deep in dead bodies all the time. Also, classifying them is a pain in the insert body part. Look at the fuss made over the new "hobbit" skeletons found a few months ago! Are they a "new" species? Or just part of this species? We don't know. Were Neanderthals, in fact, a different species, or did they mate with our own ancestors, and add their genes to the population? We don't know.
3. Does this mean that every stage of development, no matter how miniscule, could be classified as a different species?

The standard definition has to do with the ability to produce viable offspring. Since we can't determine that from fossils, we can go to an alternate definition, which has to do with genetic similarity. Except we can't, because we don't know how similar we have to be to be the same species, and I'm fairly ...

Sorry, I'll type up a better (and complete) reply after feeding the kid.

[conuly]

...fairly certain that you can't extract much DNA from fossils anyway. That's what makes them fossils. So, really, when people talk about extinct species, they're making guesswork. They don't know where one species belonged or another did.

Think of a clock - one with only four numbers, 12, 3, 6, 9. You know that one revolution of a second hand is a minute, one revolution of a minute hand is an hour. Let's say that we are at the 12 spot, and some ancestral species is at the 3 spot. We measure time with the minute hand. At what point in the evolutionary cycle does it stop being the ancestral species and start being some "intermediate" species?

[ladytalon.livejournal.com]

There are actually a heck of a lot of fossil elephants known. And one is referred to as the proto-elephant--it's nearly unguligrade, has a flexible nose but no trunk, and is sort of small-hippo-size. It took about 50 million years to get to where they are today.

In paleontology, it is actually sometimes difficult to determine where the "new" species starts, for a species which has a good record. Some ammonite lineages, for example, evolve very quickly, and though you can definitely say "the one that's 75 million years old looks very different from the one that's 70 million years old and those are definitely distinct species" there's still the problem of what to do with the ones in between. (IT doesn't help that some ammonites are sexually dimorphic, so males and females ended up being classified as different species.) What usually ends up happening is that we pick a midpoint and say that everything before that time is species A, and everything after is species B. We take measurements of various things so that we can determine the species--species A has a great than 3 mm ruffle on one side of its suture, and species B has a ruffle less than 3 mm long.

[leora.livejournal.com]

First of all, your premise is false. Evolution includes the concept of random mutations. It is possible to have pretty much any degree of change just happen. It's highly unlikely, but it's possible. Given millions of years, many unlikely things will happen.

Second of all, there is only a tiny degree of difference genetically between humans and other primates. I don't recall with which species this was stated, probably homo erectus, but I know it was with one of the close but not quite humans where if you cleaned one up and put it in modern clothes, it'd pretty much look human. It could pass on a busy street.

People keep talking about the missing link, and I keep wondering - which link is missing? We have countless links.

Also, as was stated, lots of things get destroyed over time. We don't expect a perfectly seemless record of history left in the ground. We expect gaps. Not every animal is going to get conveniently trapped in a tar pit for us.

Finally, by the very nature of evolution, it is very hard to draw boundaries. To say, this is no longer a FOO and now a BAR. It's partly the seamlessness of it that makes it so hard to trace the path. Is this an unusual homo erectus showing the normal variation for a homo erectus or is this a something else? Am I a human showing the normal variation for a human, or am I an early stage of some other species? If the theory of evolution is correct, then it will be very hard for people to answer those questions. And thus it will be very hard to draw the clear straight path, especially as there isn't really a clear straight path but a bush, a bush that sometimes intermingles its genes back together, that splits off shoots, some of which die and some become new species and some mix back. It's tangled and it should be tangled.

[appadil.livejournal.com]

Re: the "incredible number of stages" in a species development, that's not neccessarily always true. Yes, you can get mutations accumulating slowly one gene at a time, but you can also get really RADICAL changes really quickly. Case in point- the transition between protostomes that build their digestive tract mouth-to-anus (most invertebrates) to deuterostomes which go anus-to-mouth (echinoderms and all vertebrates). That's not the sort of change you can really have transition stages for- it's all or nothing.

Stuff like that is possible because of homeobox or HOX genes- genes which regulate and trigger other genes. It might take a lot of mutations in normal genes to double a body segment or erase an eyeball or so on, but a change to a single HOX gene has massive effects. In humans, polydactyly is caused by a HOX mutation... in fruit flies, scientists have been able to produce all kinds of mutants, most notably flies with legs for antennae.

[maladaptive.livejournal.com]

Re: chicken and the egg.

The egg came first, if you want to get to the nitty gritty. There was some point when a creature that's NOT a chicken laid an egg that became what we know of as the chicken.

Of course, it doesn't really happen this way, because there is no dividing line between chicken and not; evolution's just too slow for that. But on a technically, yes, that's the answer to the question. :P

[literalgirl.livejournal.com]

Well said.

And I don't actually have any questions, but I am glad you are there if I think of any! :-)

[conuly]

The best part of this is that if I can't find an answer, or don't know the answer myself, I can't "disprove" anything, since I admit upfront that I'm not an expert.

The Big Questions

[pockingell.livejournal.com]

Well, you asked for it:

I just realised, I don't really know what the Theory of Evolution is, apart from vaguely understanding that it's along the lines of "small changes occur between individuals, and the changes which allow the individual to survive longer are passed down". What is the actual theory?

Re: The Big Questions

[conuly]

I'm pretty sure that *is* the theory. Hard to see what else could be involved in it. Evolution just means changes through time, and it occurs through the process of natural selection. And pure dumb luck - if a volcano wipes out all the people who carry X gene, that gene is gone from the population, even though that has nothing to do with the survival value of those people, or that gene.

[atdelphi.livejournal.com]

Ooh, I've got one - not really about a 'hole' in the theory, but rather about making the argument for the theory itself (keeping in mind that I'm the least scientific person in the world.)

Now, I know the reason it's referred to as a theory is because macroevolution, due to the obvious time spans involved, hasn't been directly observed. Rather like the way that our 'knowledge' of the earth revolving around the sun was only a theory until we actually sent satellites out to snap pictures.

My question is: are there any other pieces of scientific knowledge that the general public takes for granted that are really only 'theories'? I could definitely use an example to trump those who smugly play the "Why do they call it a theory, then?' card.

[rho]

Atomic theory would be a good one. Or quantum theory. Or the theory of relativity. Slightly more esoteric, we have things like game theory. Or if we allow a little bit of linguistic leeway, how about pythagoras' theorem, which is occasionallyr refered to as pythagoras' theory?

The "it's just a theory" brigade annoy me immensely because they completely ignore the way that the word is used scientifically. In a scientific context, it can mean a framework and system for understanding things just as much, if not more, than it can mean a hypothesis or conjecture.

[theshiversbaby.livejournal.com]

If the T. of E. is correct, there must be an incredible number of stages in development for each species as the species slowly evolved. For example, there should have existed all of the steps between some early form of, oh I don't know, elephant that we'll call "Proto Elephant," and the elephant as we know it today, "Modern Elephant" (yes, I realize there is more than one kind of elephant, I'm just oversimplifying for the purpose of clarification). Assuming that Proto Elephant is quite different from Modern Elephant, this process must have taken quite a long time and a large number of developmental stages.
Two questions: a) Do you think this is correct?
and b) If so, why haven't we found more skeletons supporting this fact? I'm mean, obviously we've found skeletons of things we classify as separate species - in the case of humans, for example, we've found Homo habilis, Homo erectus, etc. But we don't seem to have found many skeletons between these stages. They all seem to belong to distinct species. Why? Does this mean that every stage of development, no matter how miniscule, could be classified as a different species? If so, we should be a few thousand species beyond Homo sapiens, then.

[theshiversbaby.livejournal.com]

[Edit: I guess we're really Homo sapiens sapiens. Right? And I may have messed up some capitalization. I'm not a biologist in the least.]

[maladaptive.livejournal.com]

Re: chicken and the egg.

The egg came first, if you want to get to the nitty gritty. There was some point when a creature that's NOT a chicken laid an egg that became what we know of as the chicken.

Of course, it doesn't really happen this way, because there is no dividing line between chicken and not; evolution's just too slow for that. But on a technically, yes, that's the answer to the question. :P