Has humanity reached an evolutionary dead-end?

[John I Tzimisces]

I'd like to start with the disclaimer that I'm not starting this thread out of pessimism but out of musings I've had considering my understanding of the way evolution works.

My understanding is this: A mutation by whatever means occurs in a population. The mutation is beneficial to those effected by it. This beneficial mutation or other random genetic trait is passed onto the offspring of the effected individual. Over time, the entire population that has the trait becomes a new species because it has out-competed those without the trait or is geographically isolated from those without it.

Now, let's look at the current state of humanity.
The population is greater than it has ever been before. This means that evolution if it's still occurring with us would take much much longer.
Medical science has enabled those who would die normally or be out-competed by everyone else to survive.
Technology and, well, civilization also enables us to overcome any flaws we have or renders whatever traits that might have made us more likely to reproduce moot.
Those most differences we do have within a population tend to be more likely to certain choices or other environmental factors rather than something heritable. Consider that the american population wasn't always 25% obese: it was only after food became so cheap that virtually anyone could afford to have a diet rich in fat that this phenomenon began to occur.

So, does the way humanity is now, what with medical science, civilization, and the massive population = sustaining the status quo physiologically?

I'm still thinking about this, I'd like to hear your thoughts...

I suppose these musings were born out of how I've always seen the view that "in zee future, humans will have even smaller noses, giant craniums, big eyes, and very lean frames" was somehow stupid. What sense does that make when people with smaller skulls can pretty much survive just as well as people with bigger ones?

[Helm]

Conventional physical evolution won't affect us at this stage but technological evolution might, genetric engineering and such.

[sdomi_cabsav@Hotmail]

Evolution takes millions of years, its not a noticeable effect so of course it would seem like a dead end :p. Good mutations wont be all that noticeable unless something annihilates the population that doesn't happen to have the new trait even then there's only a small chance that the organism's offspring will obtain it. Im not a biological expert so maybe someone else could help you out with that.

[John I Tzimisces]

I suppose that's true sdomi, I admit one of the flaws in my thinking (at least in the title) is the presumption that A. the way we live will be unchanged for quite some time and B. the world misses the memo and goes ahead and changes around us.

[Helm]

Another possibility is that we become brains in jars living a form of cyber world or we gradually convert ourselves over thousands of years from being 100% organic to 100% synthetic.

[eisenkopf]

Another possibility is that we become brains in jars living a form of cyber world or we gradually convert ourselves over thousands of years from being 100% organic to 100% synthetic.

As much as I am a fan of science-fiction, this forum is about science, not fiction.

First of all, evolution will never stop, unless all life on Earth is dead. It is an ongoing process which has no end - and no aim. The concept that evolution leads to stronger and fitter specimen of a species is a misconception. Evolution leads to better adaptation to a certain environment (its "niche"). There are enough examples where evolution finally lead to the extinction of a species because it became so "evolutionary advanced" (note the ""), that it could not cope with minor changes to its environment. In addition, evolution can lead to major changes in a specie's physiognomy within a single generation, if the environment undergoes a drastic change and only certain members of a species with a certain phenotype can survive and reproduce.

Finally, the phenomena mentioned in the OP (obesity, bad sight, etc.) are an expression of evolution. In our case, we ourselves have changed our environment so much that certain characteristics have less influence on reproduction - less adaptation is needed. This is evolution, too.

So no, we have not reached an evolutionary dead-end. We continue to evolve right now.

[Helm]

As much as I am a fan of science-fiction, this forum is about science, not fiction.

If we're talking about a period of hundreds of thousands of years applied to the human technological time scale rather than the evolutionary time scale then I'm sure what would be considered science fiction now could quite easily become science fact. There was a time when walking on the moon would have been the stuff of science fiction, and it was.

[Manco]

A species that has evolved in such a way to adapt his surroundings to him instead of the reverse is quite a significant step in evolution. But it does not negate regular evolution, it's merely another variable.

I get the idea that the OP is equating a lack of bottle-neck events to a lack of evolution. In the current situation it would just mean evolution happens 'slower', or the beneficial traits spread more slowly through the population

[eisenkopf]

I get the idea that the OP is equating a lack of bottle-neck events to a lack of evolution. In the current situation it would just mean evolution happens 'slower', or the beneficial traits spread more slowly through the population

While there have been massive migrations in human history before, and thus the mixing of once geographically seperated gene-pools, this happens now more than ever. Therefore, I would argue that traits can spread more quickly than ever before.

[Helm]

For evolution to occur you require separated gene pools, that's how we ended up with thedifferent human races for instance. But since the coming of civilisation traditional evolution that effects animal populations will no longer apply to humans.

[Manco]

While there have been massive migrations in human history before, and thus the mixing of once geographically seperated gene-pools, this happens now more than ever. Therefore, I would argue that traits can spread more quickly than ever before.

Geographical spreading occurs more of course, but I meant substantial enough spreading to become a dominant trait in the entire population.

For evolution to occur you require separated gene pools, that's how we ended up with thedifferent human races for instance. But since the coming of civilisation traditional evolution that effects animal populations will no longer apply to humans.

That's just not true. Evolution happens regardless of isolated populations. With isolated populations you merely see two different strains of the same original population, without isolation the entire populations evolves roughly the same and there's only one strain.

[Helm]

That's just not true. Evolution happens regardless of isolated populations. With isolated populations you merely see two different strains of the same original population, without isolation the entire populations evolves roughly the same and there's only one strain.

It's not like our ancestors would have evolved into what we are today if they still regularly interbred with apes.

[Manco]

It's not like our ancestors would have evolved into what we are today if they still regularly interbred with apes.

No, we would have evolved into something different.

Your point?

[Helm]

No, we would have evolved into something different.

We wouldn't have evolved at all, unless there was a new selective pressure that happened to affect the entire ape population at the same time but that's unlikely.

[★Bandiera Rossa☭]

Geographical spreading occurs more of course, but I meant substantial enough spreading to become a dominant trait in the entire population.


That's just not true. Evolution happens regardless of isolated populations. With isolated populations you merely see two different strains of the same original population, without isolation the entire populations evolves roughly the same and there's only one strain.

So what you mean is something like http://en.wikipedia.org/wiki/Ostrich_people but on a huge scale?

[sdomi_cabsav@Hotmail]

If your living you evolve, nuff said.

[Helm]

If your living you evolve, nuff said.

Tell that to a horseshoe crab.

[chamaeleo]

Another thread on this?

If you're breeding you evolve, nuff said.

Fixed.

On a whole, we're simply at an equilibrium, waiting for the next bottleneck...altough current selection pressures do seem to favor Catholics, Hindus and other notoriously promiscuous / anti-birth control groups...

[Manco]

That's not true, evolution happens regardless of pressure. It might have been less noticeable, or the mutated traits might not have been so prevalent in the resulting population. But evolution would still have happened.
You're confusing bottle-neck events with evolution in general, bottle-neck events merely result in the population to change more drastically in a given time-frame

[Helm]

For evolution to occur there has to be some kind of selective pressure, even a mutation has to confer some kind of advantage in relation to a selective pressure else it will just die out.