The Mystery Machine and a Another Evolution Question

[NavajoEverclear]

The machine (of which name i do not know and didn't think to ask, and now the one who knows is gone) has to do with a concept i will ask about in a second. So my physics teacher last year (who this year has taken a leave(why or where to no one knows)) showed us this machine, its a box with a rod sticking out of it. You turn on the machine and the rod goes up and down (like a piston i guess) there is a dial to turn up the frequency. An aluminum sheet attaches to the the rod. At high frequencies (that i swore i could feel vibrating my guts and was afraid one of my organs would explode) sand is poured on the sheet and it shifts to fit wave paterns (exactly how it works i dont know, but i saw it), then as he turns up the frequency more that patterns shift (not gradually, but all at once it appears). to different ones rapidly with each increasing increment. Very cool to see, i would love to take this and a generator back a few hundred years and watch people a accuse me of witch craft (or wizard craft, me being male?).

 

Now the evolution question and i'll tie it in with the machine soon.

If evolution is a gradual thing, why are there even seperate species? Wouldn't fossil records show so many extremely slight changes that it wouldn't be possible to classify anything as a species, but in degrees of diversion from an original ancestor? Or does the reason there are seperate species have a mathmatical, structural reason. Such as at a certain point the DNA would suddenly reach a point to make a distinct shift (like the patterns of the machine changed distinctly and suddenly, not suddenly (it had something to do with standing waves, but its the concept of sudden shifting i mean to refer to)). If you still dont understand exactly what i'm asking, i'll put it this way: wasn't our last evolutionary distinct ancestor the neanderthals? If evolution is gradual, wouldn't there be so many gradual improvements from neaderthal to human, that giving any species a name is just a fictional fabricaded label of one level of change that is no more detectibly different than another. Which isn't true because there ARE seperate species.

 

So here it is as simple as possible, and all that other crap is only perhaps uneeeded elaboration : if evolution is gradual, why are there seperate species, instead of everything in between?

[JaKiri]

The machine is a demonstration of standing waves.

 

The definition of species vary, but the usual one is the point at which they can no longer interbreed, which is a very defined point and can happen even between groups that coexist.

 

In addition, neanderthals are not our ancestors.

[NavajoEverclear]

neanderthals are MY ancestors (evidently). Actually i heard their brains were aproximately as big as humans, just composed to work differently. OK so then whatever our last ancestors were (cro magnum? homo erectus? I could look it up, i dont care) why does a distict species even exist , evolution being gradual.

 

You said what defines a species is that it can no longer interbreed, and what causes this change? Is it some mathmatical structural shift within the DNA for some reason. So what makes the transitional species so inferior that their remains are not left behind? How does one species shift into another suddenly? I feel i'm being redundant, i'm just trying to explain what my question meant. You can say that we dont really know the answer if thats the truth.

[JaKiri]

You're unique among the rest of humans if you descended from the neanderthals.

 

And lets look at chess.

 

Lots of gradual, very small changes that result in drastic ones over a period of time.

[Sayonara]

NavajoEverclear said in post #1 :

So here it is as simple as possible, and all that other crap is only perhaps uneeeded elaboration : if evolution is gradual, why are there seperate species, instead of everything in between?

Archaeopteryx as an extreme example. The equine fossil record shows very good intermediate species, assuming of course you start up with the common ancestor and finish with modern horses.

 

Think of it this way. You can see the differences in adaptive biology between, say, Galapagos Finches, because you can look at them and observe their characteristics, diet, behaviour etc.

 

Conversely, two similar fossilised dino skeletons from a sedimentary rock tell you very little about the differences in tissues, organs or behaviour that may have existed between the two animals in question.

[JaKiri]

Oh, and ALL states are transitionary states.

[fafalone]

The current model of evolution includes the puncuated equilibrium theory. Speciation occurs rapidly, followed by long periods of little change, driven by sudden changes in the environment. The odds of something dying and forming a fossil are very small, so intermediate species do not exist long enough to have a high chance of forming one.

[blike]

Oh, and ALL states are transitionary states.

 

Thats what he's saying. If all states are transitionary states, why do we arbitrarily pick certain states and call them species, why not every single state.

 

The answer lies in a combination of faf's post and in MrL's first post.

 

Firstly, when groups of animals can no longer interbreed with each other (because of physical, temporal, or other barriers) they have become separate species. That is how we define species.

 

If evolution is gradual, wouldn't there be so many gradual improvements from neaderthal to human

 

Assuming humans descended that way, there would be. However just because their is a change, doesn't mean its a new species. When the change prohibits interbreeding, however, it is a new species. A few physical changes to things such as proportions usually won't result in a new species. Think of all the different shapes, sizes, colors, and proportions of humans. We are not all different species.

 

The second part of your answer comes from faf's reply.

[Sayonara]

I should really have read the question ;-)

[YT2095]

Neat machines

I`ve seen similar effect in vibratory seives, used for seperating ingredients into different mesh sizes (pyrothechnic use) they make paterns too, a bit like sand dunes

I`ve done a similar thing with an 18" sub and polystyrene balls hooked up to a sig-gen, get the right freq and they seem to stay almost still, alter it a bit and the patern changes and some freq`s all hell breaks loose and they get chaotic and start bouncing out. I recon it would make a neat excutive toy for a desktop if you could make it look good with lots of chrome and perspex

[Skye]

The original question can be summed up with an analogy: Why are there distinct branches on a tree if the tree is constantly growing gradually?....At some point a single branch becomes two, in trees because of hormones, in species because of reproductive isolation. Also, the point at which a single species diverges from it's ancestors is entirely arbitrary, though it can be explained with a evolutionary genetics model, like punctuated equilibrium.

 

'Intermediate' species do exist in a way, usually classified as sub-species. They are able to physically interbreed with other sub-species, but don't, often because they are seperated.. but not always. While of the same species, they are distinguishable in appearance. Neanderthals (who lived in Europe/Middle East I think) were probably able to interbreed with what are considered to be our ancestors, but based on some genetic comparisons they didn't (or not to a noticeable degree). Had they lived and become physically incapable of breeding with the our ancestors, they would now be a seperate species, if they started interbreeding we probably would have merged.

[JaKiri]

Actually, you don't need reprductive isolation for two species to form, if you mean physical isolation,

[Skye]

They're different things, and either can exist without the other.

 

Physical isolation is one thing which can lead to reproductive isolation, but some some populations are reproductively isolated while occupying the same range. There are also more complicated situations, classic example: population A and population C are physically isolated but both breed with an intermediate population B, so you get indirect gene flow between A and C via B, which can prevent speciation between A and C.

[NavajoEverclear]

Thanks for the input guys, good info in your posts. Don't know what else to say . . . . now for that vacation . . . .

[Radical Edward]

NavajoEverclear said in post #1 :

Now the evolution question and i'll tie it in with the machine soon.

If evolution is a gradual thing, why are there even seperate species? Wouldn't fossil records show so many extremely slight changes that it wouldn't be possible to classify anything as a species, but in degrees of diversion from an original ancestor? Or does the reason there are seperate species have a mathmatical, structural reason. Such as at a certain point the DNA would suddenly reach a point to make a distinct shift (like the patterns of the machine changed distinctly and suddenly, not suddenly (it had something to do with standing waves, but its the concept of sudden shifting i mean to refer to)). If you still dont understand exactly what i'm asking, i'll put it this way: wasn't our last evolutionary distinct ancestor the neanderthals? If evolution is gradual, wouldn't there be so many gradual improvements from neaderthal to human, that giving any species a name is just a fictional fabricaded label of one level of change that is no more detectibly different than another. Which isn't true because there ARE seperate species.

 

there are a number of barriers between species

 

1) premating (i.e. they won't mate)

2) postmating (they will but it doesn't work, different mating behavious

3)prezygotic: the gametes don't fuse

4)postzygotic: the offspring doesn't form properly or is sterile.

 

so speciation can form through a number of methods, though as has been pointed out, the strict separation is when they can no longer breed and produce (fertile) offspring. Different species are generally chopped up from their common ancestor either by geography, or through adaption to different niches in the same geographical area. The speciation then occurs either through an accumulation of mutations (either DNA or chromosomal differences), or behavioural changes required to adapt to that environment.

 

you missed one sort of speciation though, and that is when new species are formed through hybridization of two parent 'species'.