Evolutionary Debate

POSTED BY: AnthonyT
UPDATED: Tuesday, February 20, 2007 16:16
VIEWED: 20170
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MRIG

Wednesday, February 7, 2007 6:33 AM

Quote:
Originally posted by AnthonyT:

Thanks for all the input, guys.

Is it really true that no species has ever evolved into another species within the verifiable scope of human observation?

Not even bugs or rats or such? I mean, they reproduce like crazy, so I'd imagine they're the most likely candidates for observed evolution? I'm supposing you need thousands of generations.

What about my chijuajua (sp?) Or a toy poodle? Or one of those long, short dogs with the floppy ears? I've often heard that humans have bred these dogs from a common stock animal, selecting desirable traits. There sure are a lot of different and distinct kinds of dog with very different physical attributes.

Are they all the same species as a wolf? Just how different do you need to get from your source animal before you can be said to have 'evolved' into something new?

Is it at all possible to ever observe an evolutionary process, or will evolution always be a theory just because we can't see it from start to finish? (Takes too long, even for little critters?)

--Anthony

"Liberty must not be purchased at the cost of Humanity." --Captain Robert Henner

Sorry for double-posting, I'm still figuring out the details of how this forum works.

I don't know of any examples of seeing one species branch out into another within recorded human history. Considering how long it takes, and how recent we are, there might not be any. Speciation takes not only the ordinary mechanisms of evolution but also geographic isolation. Darwin saw different species of finches on different islands in the Galapagos, which had clearly originated from one common ancestor. Because the islands prevented them from interbreeding, they became seperate species. Most of the evidence for evolution we don't see firsthand. Scientists piece together a picture of what happened with clues left behind in the same way that forensic investigators do to a crime scene.

However, nature doesn't have a precise line for "species." Dogs, for instance, used to be classified as all the same species, Canis familiaris, which evolved by human breeding from wolves, Canis lupis. Apparently it's since been renamed a "subspecies" of wolf. However, each breed shows more variation, so my dachshunds(the long ones with the floppy ears--I have two) are the same species as your chihuahua (I can't spell it either, I looked it up. Same with "dachshund"). However, there are clearly differences between the two. Both of them are also the same species as a wild dog or a gray wolf.

The definition I've heard is that two animals are considered the same species if they can mate and produce fertile offspring. Thus, two breeds of dog are the same species, but horses and donkeys are not, because mules are sterile. But, of course, this line is quite blurry and difficult to categorize.

Evolution will always be a theory, but that's not a bad thing. In science, a theory is a step up from facts, because theories explain facts. The question is how well-supported a theory is. Evolution is an example of a well-supported theory. Intelligent Design is also a theory, but it's not a very good one, because it isn't well-supported.

Another key element that all scientific theories must share, but ID doesn't have, is called falsifiability. What this means is that if the theory is wrong, there is some way to show that it is wrong. If we found a fossil rabbit in the Precambrian, that would falsify Evolution. However, if similar evidence comes up against Intelligent Design, a proponent of ID can always say "the Designer put it there," or something similar, meaning that ID can't be falsified.

The fact that we can't see Evolution happen from start to finish doesn't mean we can't figure out what happened, in the same way that fingerprints and DNA evidence can catch a murderer even without witnesses. So if someone says that Evolution is "only" a theory, they aren't using the word "theory" properly.

Whew. I really need to stop caring so much about evolution, so tha

FLETCH2

Wednesday, February 7, 2007 7:04 AM

Quote:
Originally posted by MRig:

Yeah, that makes sense. A mutation doesn't have to be positive, it just can't be negative. However, it's hard for me to imagine a mutation that isn't one or the other, because anything that wastes energy is negative. Thus, if a mutation makes some minor, inconsequential change for a small increase in energy cost, it is still negative and detrimental to survival.
.

I can give you an example. Sickle Cell anemia is a genetic mutation that can be very painful and before modern medicine highly fatal. These days most folks that have it have an ancestors that come from Africa, where the mutation is quite common. Why is this? Well Sickle Cell gives some protection against the Malaria parasite. Malaria tends to attack the weaker members of societies, principally the very young and the very old where as Sickle Cell tends to become more debilitating the older a person gets.

As a result we have the following situation. Children born without the mutation have an increased chance of dying young because Malaria kills the young and the Sickle Cell mutation offers some protection. This means more kids with the mutation manage to grow up and survive to produce children than kids without it. Of course those survivors with Sickle Cell won't live as long as the survivors without it, but since they live long enough to pass on their genes to the next generation that doesn't matter.

So here we have a mutation that while decreasing the lifespan of the organism actually increases it's chance of breeding successfully. It has both positive and negative effects.

TRENCHMONKEY

Wednesday, February 7, 2007 5:06 PM

Quote:
Originally posted by AnthonyT:

Is it really true that no species has ever evolved into another species within the verifiable scope of human observation?

I have Some memory of an article in New scientist in the later half of last year that talked about a verifiable case not sure though will look it up over the weekend (New scientist is weekly so migfht take some time)

I dont suffer from madness, I enjoy it.

FREMDFIRMA

Wednesday, February 7, 2007 6:12 PM

Quote:
Is it really true that no species has ever evolved into another species within the verifiable scope of human observation?

I dunno, you could make a good case for some of our posters for human evolution (or would that be devolution?) into Troglodyte.

-F

CITIZEN

Wednesday, February 7, 2007 6:20 PM

Quote:
Is it really true that no species has ever evolved into another species within the verifiable scope of human observation?

Why would that be hard to believe? We've only been here five minutes.

More insane ramblings by the people who brought you beeeer milkshakes!
No one can see their reflection in running water. It is only in still water that we can see.

CHARLIETHEBLOODY

Wednesday, February 7, 2007 6:54 PM

Quote:
Originally posted by TrenchMonkey:

I have Some memory of an article in New scientist in the later half of last year that talked about a verifiable case not sure though will look it up over the weekend (New scientist is weekly so migfht take some time)

that sounded familar so I had a search and this came up from the review of the year:

Review 2006: Evolution in action
23 December 2006
From New Scientist Print Edition.
Bob Holmes

STUDYING evolution is a lot like studying tigers. You know your subject is there by the traces it leaves, but you don't often see it in the flesh. This year, though, evolutionary biologists were treated to not one but several glimpses of evolution in action right before their eyes.

Take the little lizard known as Anolis sagrei. When researchers introduced a larger, predatory lizard onto the tiny Caribbean islands where they live, A. sagrei immediately began to evolve longer legs for speedier escapes. But then the little lizards learned to flee into the branches of shrubs, where the predator could not follow - and within six months evolution had changed tack again to favour shorter-legged lizards, which are better climbers.

However, such changes are small beer compared with the hard stuff of evolution: making new species. Yet here too evolution put on a show in real time. Biologists reported not one, but two butterfly species that arose abruptly from hybridisation between existing species, a form of instant speciation formerly known only in plants.

Biologists also witnessed evolutionary misfires, where new species in the act of diverging from a parent species failed to retain their distinct identity and merged back again through hybridisation. These failed speciations are probably common - indeed, our own genome bears traces of a failed divergence from chimpanzees before the split finally happened. However, some experts suggest that human activity may make such failures more common by homogenising habitats and erasing ecological differences that once kept new species distinct.

From issue 2583 of New Scientist magazine, 23 December 2006, page 13

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"I'm an artist, with an e and a beret."

RUE

Wednesday, February 7, 2007 7:55 PM

Thanks both.

There was an article (probably too long ago to be googled successfully) about a North American (?) bird that was evolving into two distinct species at the eastern and western ends of its range (species that could not interbreed), whereas the middle range was an intermediate between both.

ANTHONYT

Wednesday, February 7, 2007 11:07 PM

Evolved into a duplicate post...

--Anthony

ANTHONYT

Wednesday, February 7, 2007 11:07 PM

Quote:
Originally posted by citizen:
Quote:
Is it really true that no species has ever evolved into another species within the verifiable scope of human observation?
Why would that be hard to believe? We've only been here five minutes.

More insane ramblings by the people who brought you beeeer milkshakes!
No one can see their reflection in running water. It is only in still water that we can see.

Well, it's hard to believe because of scale. Sure, I don't expect to be able to witness evolution on something like a tiger or a moose, because these are long-lived creatures.

But I hear there are bugs whose entire lifecycle is like a couple of days. I'd think a scientist or team of scientists should be able to simulate evolution in such bugs by selective breeding (pretending that their choices are 'natural selection') and manually forcing the hand of hundreds of thousands of generations of bugs.

I mean, like you said, humans have only been here for five minutes. So something that lives a lifespan 1/15,000 as big as ours ought to show its evolution 15,000 times faster. 70 years of breeding little bugs that live for a couple of days would be like nearly a million years of human evolution. Which means like maybe we can go completely from one species to another in a single human lifespan.

So is there any work being done to go from one species of X to another in order to create definitive verifiable proof of what some people call macro-evolution?

I think it'd be cool.

--Anthony

"Liberty must not be purchased at the cost of Humanity." --Captain Robert Henner

ERIC

Thursday, February 8, 2007 1:11 AM

Quote:
Originally posted by AnthonyT:

But I hear there are bugs whose entire lifecycle is like a couple of days. I'd think a scientist or team of scientists should be able to simulate evolution in such bugs by selective breeding (pretending that their choices are 'natural selection') and manually forcing the hand of hundreds of thousands of generations of bugs.

Don't need a team of scientists- I once did exactly this in elementary school on a science field trip with a plastic vial of fruit flies. It's a classic exhibition activity in kid-oriented scientific institutions.

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