Evolution confusion??

[GeorgeyGal]

Kittys thread also got me thinking, re evolution, just 1 e.g. a fish evolved to have legs and breath on land thus evolving to land mammals so why do we still have fish, why havent they all evolved!? Its really hard to explain as I have no idea scientifically how to word this, does anyone else wonder this also or know what I mean, or is it just me?

One answer the foodchain! But how would nature determine this!

 

[smokey]

Same reason as we still have monkeys, only certian species evolved to that point and others either didnt or went down a different route

 

[Lina]

Because evolution is a myth, thought of by someone with a great fantasy!

 

[KittyVentura]

Because evolution is a myth, thought of by someone with a great fantasy!

Is that a serious reply?

If so it is extremely rude. If I were to call your beliefs "myths, thought of by someone with a great fantasy!" you'd think I was out of line. Most athiests believe fully in evolution, typically one goes hand in hand with the other.

 

[Nibblenic]

Because one strain of species went one way and the other went another.

Also most species have a relevant place in the food chain or in aiding other animals.

There are millions of species that have become extinct especially in the smaller anials like fish/insects/small animals

 

[smokey]

And because of those smaller ones becoming extinct many larger one died out as well.

Did anyone ever find the missing link from apes to humans?

 

[SKATERBUN]

I suppose because that lucky fish had a dominant gene that eventually made it grow legs and the others did not...
like smokey said it would of been a particular species and maybe didnt reproduce with other creatures outside of this species.

 

[Elhaym]

I see what you're getting at. Sometimes evolution is thought of as a chain, with single cells at one end and complex mammals at the other and all animals evolve along the chain.

But really you need to visualise it as a huge branching tree, with many branches splitting into others. So for example, humans didn't evolve from monkeys, but rather both humans and modern-day monkeys evolved from a single common ancestor.

Hope this makes some sense, I am crap at explaining.

 

[aragornlover8]

Evolution isn't quite as cut and dried as a lot of people think. It's a really gradual process based entirely on genetic mutations. The species that survive are the ones with the mutations most advantageous in a particular environment.

I'll make up an example...
Imagine a rodent-like creature (let's call it RodentA) living in a wooded area. These rodents are all attracted to nectar. However, there are other rodents living in the area who are attracted to the same food source as RodentA. Due to a weird genetic mutation, RodentB is born. RodentB has a long snout and can reach the nectar in vase-like flowers. Because this is a virtually untapped resource, RodentB is very successful. RodentB mates with RodentA, and those born with RodentB's characteristics survive. Those born with RodentA's characteristics are less likely to flourish, given the competition for resources that was previously mentioned. So RodentB surpasses RodentA. In a period spanning several generations, RodentB exists, while RodentA is more likely to have become extinct.

I'm not sure if this helps anyone. I just think a lot of the confusion surrounding evolution is that people think of it in overly simplified terms. Creature A doesn't become Creature B. It's a little more complicated than that.

 

[smokey]

But over time creature A does become creature B even if it is indirectly and through offspring, they are still the sum of their ancesters

 

[aragornlover8]

But for a period of time Creature A and Creature B do live simultaneously.

 

[freckleonear]

Evolution isn't quite as cut and dried as a lot of people think. It's a really gradual process based entirely on genetic mutations. The species that survive are the ones with the mutations most advantageous in a particular environment.

I'll make up an example...
Imagine a rodent-like creature (let's call it RodentA) living in a wooded area. These rodents are all attracted to nectar. However, there are other rodents living in the area who are attracted to the same food source as RodentA. Due to a weird genetic mutation, RodentB is born. RodentB has a long snout and can reach the nectar in vase-like flowers. Because this is a virtually untapped resource, RodentB is very successful. RodentB mates with RodentA, and those born with RodentB's characteristics survive. Those born with RodentA's characteristics are less likely to flourish, given the competition for resources that was previously mentioned. So RodentB surpasses RodentA. In a period spanning several generations, RodentB exists, while RodentA is more likely to have become extinct.

I'm not sure if this helps anyone. I just think a lot of the confusion surrounding evolution is that people think of it in overly simplified terms. Creature A doesn't become Creature B. It's a little more complicated than that.

That's a brilliant explanation of microevolution. However it doesn't really apply to macroevolution, which is one species turning into a completely different species.

Personally I cannot accept the theories of macroevolution. One of the biggest problem for me is Michael Behe's theory of irreducible complexity. If a fish managed to evolve lungs, it would drown. The only way to get from a fish to a land animal is to change at the very least the gills into lungs, the single circulation into double circulation and the 2 chambered heart into a 3 or 4 chambered heart all at the same time. It can't happen one small step at a time because the organism simply wouldn't survive. Bearing in mind that mutations don't really add new genetic information (the closest you're likely to get to that is gene duplication followed by point mutations), I find macroevolution rather difficult to believe.

 

[punk_pig]

If the ocean were suddenly to become inhospitable to life then creatures that had randomly mutated to live on land would be all that existed BUT this is not the case, the sea still offers many niches for different kinds of fish etc. feeding on different things. The land was just another resource which could be exploited by those creatures who had the advantageous mutations. As mentioned above though the fish currently living in the ocean aren't necessarily the same species that mutated to produce land animals, they too have been evolving their own mechanisms for surviving in the sea. Nd not every member of a species will produce a mutation, they don't all decide to evolve as one. E.g if my next door neighbour evolved wings (I know it's more complex than that) it wouldn't mean I would evolve them too, neither would it make me necessarily obsolete.

I don't think I explained that very well...

Wanna really blow your mind?? Sea mammals like whales evolved from land dwelling mammals that had lived on land for thousands of years!!

 

[aragornlover8]

If the ocean were suddenly to become inhospitable to life then creatures that had randomly mutated to live on land would be all that existed BUT this is not the case, the sea still offers many niches for different kinds of fish etc. feeding on different things. The land was just another resource which could be exploited by those creatures who had the advantageous mutations. As mentioned above though the fish currently living in the ocean aren't necessarily the same species that mutated to produce land animals, they too have been evolving their own mechanisms for surviving in the sea. Nd not every member of a species will produce a mutation, they don't all decide to evolve as one. E.g if my next door neighbour evolved wings (I know it's more complex than that) it wouldn't mean I would evolve them too, neither would it make me necessarily obsolete.

I don't think I explained that very well...

Wanna really blow your mind?? Sea mammals like whales evolved from land dwelling mammals that had lived on land for thousands of years!!

I nearly peed myself with excitement when I learned that.

 

[aragornlover8]

Evolution isn't quite as cut and dried as a lot of people think. It's a really gradual process based entirely on genetic mutations. The species that survive are the ones with the mutations most advantageous in a particular environment.

I'll make up an example...
Imagine a rodent-like creature (let's call it RodentA) living in a wooded area. These rodents are all attracted to nectar. However, there are other rodents living in the area who are attracted to the same food source as RodentA. Due to a weird genetic mutation, RodentB is born. RodentB has a long snout and can reach the nectar in vase-like flowers. Because this is a virtually untapped resource, RodentB is very successful. RodentB mates with RodentA, and those born with RodentB's characteristics survive. Those born with RodentA's characteristics are less likely to flourish, given the competition for resources that was previously mentioned. So RodentB surpasses RodentA. In a period spanning several generations, RodentB exists, while RodentA is more likely to have become extinct.

I'm not sure if this helps anyone. I just think a lot of the confusion surrounding evolution is that people think of it in overly simplified terms. Creature A doesn't become Creature B. It's a little more complicated than that.

That's a brilliant explanation of microevolution. However it doesn't really apply to macroevolution, which is one species turning into a completely different species.

Personally I cannot accept the theories of macroevolution. One of the biggest problem for me is Michael Behe's theory of irreducible complexity. If a fish managed to evolve lungs, it would drown. The only way to get from a fish to a land animal is to change at the very least the gills into lungs, the single circulation into double circulation and the 2 chambered heart into a 3 or 4 chambered heart all at the same time. It can't happen one small step at a time because the organism simply wouldn't survive. Bearing in mind that mutations don't really add new genetic information (the closest you're likely to get to that is gene duplication followed by point mutations), I find macroevolution rather difficult to believe.

Thanks! It took me a while to type out. I was worried I was being more confusing than anything else.

From what I understand, macroevolution is based on the compounded effects of microevolution. Macroevolution spans across the geological timescale while microevolution can be seen in the span of human generations. I've always viewed it as being more conceptual than anything else. And I believe gills to lungs could occur, albeit very gradually. An organism would need only develop the lung capacity to be able to leave the water for a small period of time, then a longer period of time, as it traveled farther out for newer resources. This would take place over entire eras of geologic time, however, so it's viewed as a macro change but comprised of thousands of micro changes.

I'm sorry if I'm a bit dull on this stuff. It's been ages since Paleo, and memories of that class still make me shudder a little.

 

[Midnight_Fairy]

Because evolution is a myth, thought of by someone with a great fantasy!

Seriously? I could easily say the bible was a fantasy but thats just disrespectful! I dont think your statement was fair (if serious).

Its a simple reason, the fish continued to live in water, no need to evolve any different. Take Crocodiles, they have not changed in hundred of years, they dont need to evolve, the way they are works!

 

[PeanutBean]

I think what you're really asking about is speciation rather than evolution, one doesn't necessarily lead to the other. For speciation to occur you need individuals to become isolated. This might be geographically, for example when the single continent split organisms were trapped on their own continent and couldn't therefore mate to share genes eventually reaching a point through gene mutation where they were no longer able to produce viable offspring (the definition of a species). Geographical separation can be on a smaller scale too, forest areas receding sufficiently that there is no migration between them to keep the gene pool shared.

Organisms can also be isolated by niche, like the rodent and nectar example. A trait making an individual better able to survive (disease resistance/exploiting new habitat etc) will reproduce more successfully, so this is kind of speciation directly through evolution.

I'm a bit confused about the issues of evolution from water to land given the existence of amphibians.

One of the things about evolution that people get stuck on is that they tend to think of it as organisms getting better and leaving behind their more humble ancestors but like mentioned above it's a tree not a chain and it is nature's way of exploiting every resource on the planet. The idea of evolution leading to better organisms dates back to the Christian idea that humans are better than other animals. It was pretty sinister when applied to humans. Like the progression of ape to man diagrams there are similaar for black to white people.

 

[tu123]

You also need to consider the environment with genetics when you discuss species becoming extinct.

Yes, our ancestors lived in the trees but that was because at that time most of north africa was tropical, then we had 20,000 years of more temperate climate that allowed grassy savannahs and more open land to develop. Some species entered this land and with genetics became better at walking on two feet. Other species didnt move and then died out or stayed relatively the same.

The same as some mammals re entered the sea after living on land for a few thousand years.

And as the continents moved together to create Eurasia our proto human ancestors moved across the continent adapting to the new ecology.

It is survival of the fittest. And that meas a genetic defect that allows you to survive an ecology that may have changed.

 

[tallybee]

Modern species have evolved from ancestral species; not from other modern species. We share a common ancestor with monkeys (as we do with all other organisms if we go back far enough; the less closely related the species, the more ancient the common ancestor). Our common ancestor with monkeys probably looked more like a monkey than a person, and gradual divergence caused by the buildup of many small changes over mind-bogglingly large numbers of generations eventually gave us different species. The lengths of time involved are so massive (current knowledge is that the first single-celled life existed sometime over 3 billion years ago) that tiny little changes, too small to be noticed on their own, can accrue to give the massively varied life we see today.

Organisms do all continue to evolve, different environmental conditions shape the pressures for survival in populations, and so determine which individuals reproduce more and so pass on genes into future generations. Fish and monkeys and everything else have been evolving for the same length of time as we have, just in different 'directions' to each other.

Hope this is helpful