Evolution

ChrisJSY said:
I sort of understand what he means, at what point did the chameleon start to adapt to have the ability it does
Click to expand...

Contrary to popular opinion, the primary purpose of colour change in chameleons is actually social signalling. When you understand this it becomes much more obvious out it evolves. The animals that really do impressively match themselves to their surroundings are cuttlefish but, again, it appears to have first evolved as social signalling and only later been exapted for disguise.

To change into something visually it would have to have been observed, no? Then passed down, over many, many, many unfathomable generations until it was good enough to be of any use.
Click to expand...

There's actually been quite a lot of work in this area. Remember that predators are generally not closely studying the moths they're flying around looking for food, only a small difference in visibility may mean the difference between getting spotted and not. In studies things that look very unlike their surroundings to our eyes have proven effective.
 
we're not really evolving anymore, more 'flat lining' now and have been for a long long time because our environment is more stable
 
cm1179 said:
we're not really evolving anymore, more 'flat lining' now and have been for a long long time because our environment is more stable
Click to expand...

In the 'viability' sense, sure. But what about the sexual sense? Why do women find taller men more attractive? Why, generally speaking, do men not want women to be flat chested? There is plenty of 'evolution' going on in the human race, although it is not necessarily obvious. Furthermore, evolution is just an ongoing progress. Even if there are no selective pressures present, there will still be changes in gene allele frequencies across generations. So in that sense, a population can never stop evolving.

Sorry, I'm not trying to be pedantic, it's just that evolution is typically described in a sort of 'levelling-up' fashion whereby organisms get 'bigger' or 'better'. In reality that's far from the truth.
 
cm1179 said:
we're not really evolving anymore, more 'flat lining' now and have been for a long long time because our environment is more stable
Click to expand...

I think that's a massive misconception people have. Remember, evolution takes a very long time through very, very small incremental changes and the Holocene is at best 10,000 years old. No society lasts long enough to effect natural selection holistically. The only thing that could truly be said to be effecting our evolution at present is contemporary sexual-selection which is largely guided and influenced by modern culture (fashion, celebrity, etc.).
 
cm1179 said:
we're not really evolving anymore, more 'flat lining' now and have been for a long long time because our environment is more stable
Click to expand...

Our environment stable? :eek: Are you living in the same country? In the last hundred years our diet has altered radically, modern medicine has revolutionised the survivability of many diseases and conditions and fertility treatment has altered the fitness effect of many reproductive defects.
 
I think he's coming at it from the Boserup angle Mr Jack, in that as technology increases, life becomes 'easier' and more stable. Less nastiness basically.
 
Nix said:
I think he's coming at it from the Boserup angle Mr Jack, in that as technology increases, life becomes 'easier' and more stable. Less nastiness basically.
Click to expand...

Aye, but from an evolutionary point of view that's a big shift in environment.
 
I know, but I'm assuming he's talking about the potential stability post environmental shift.

Just to throw this out there: with anthropogenic influence altering habitats, is it not possible that flora will adapt their phenology over time (as we have actually seen) and therefore influence postive-feedback across the board?

Again, evolution is far from 'done'. It never stops.
 
Mr Jack said:
Our environment stable? :eek: Are you living in the same country? In the last hundred years our diet has altered radically, modern medicine has revolutionised the survivability of many diseases and conditions and fertility treatment has altered the fitness effect of many reproductive defects.
Click to expand...

that's pushing science, not human evolution. our bodies may be slightly bigger than they were 100 years ago but the basics are still the same.

i often look to sports for evolution ie the 100 m, will it ever get to sub 8 seconds? i'm not sure we'll ever see it in our lifetime but then i remember reading about some very old aboriginal fossiled footprints of a runner that had been found on an australian beach that were at such lengths apart that he/she would have left usain bolt for dust
 
cm1179 said:
that's pushing science, not human evolution. our bodies may be slightly bigger than they were 100 years ago but the basics are still the same.

i often look to sports for evolution ie the 100 m, will it ever get to sub 8 seconds? i'm not sure we'll ever see it in our lifetime but then i remember reading about some very old aboriginal fossiled footprints of a runner that had been found on an australian beach that were at such lengths apart that he/she would have left usain bolt for dust
Click to expand...

For a modern human, what possible benefit is there to running 100m in 8 seconds?
There is nothing I can think of that means those individuals that can run fast are able to produce descendants better that those that can't.

We're not predisposed to becoming faster, bigger, more intelligent or anything really.
 
cm1179 said:
that's pushing science, not human evolution. our bodies may be slightly bigger than they were 100 years ago but the basics are still the same.
Click to expand...

No, it's pushing evolution.

For example, whereas 100 years ago being born prematurely by more than a couple of weeks was a virtual death sentence now those children are more likely to survive than not. That means that any genetic influence controlling the chance of premature birth is no longer being selected against.

Conditions that would have been fatal 100 years ago can now be treated medically and so homozygous carriers of those conditions can pass on their genes. Again a massive change in selective pressure.

Similarly, whereas genetic differences in immune function that helped someone survive childhood diseases such as measles or mumps used to have a big selective advantage but do so no longer.

Any change to the environment that influence the fitness of any gene has an evolutionary effect.
 
Mr Jack said:
No, it's pushing evolution.

For example, whereas 100 years ago being born prematurely by more than a couple of weeks was a virtual death sentence now those children are more likely to survive than not. That means that any genetic influence controlling the chance of premature birth is no longer being selected against.

Conditions that would have been fatal 100 years ago can now be treated medically and so homozygous carriers of those conditions can pass on their genes. Again a massive change in selective pressure.
Click to expand...

Surely this is actually having a detrimental effect on our health as a whole (genetically speaking)..

As you've said, people who are born with these diseases are now passing on these genes when they reproduce, where as previously the genes would have left the gene pool.

Similarly (sweeping generalisation alert!!) the more stupid people are now those who breed the most, while the more intelligent choose not to, due to various "sensible" factors - e.g. stable relationships, financial situation etc.

In essence we're heading towards being an extremely weak, disease-ridden, stupid species, who's only chance of survival is based on scientific "crutches" (I realise this has always been the case with our reliance on tools etc, but is heading towards much more of an extreme!)

Of course, I guess this will reach a point of equilibrium at some point, where everyone will be so stupid that there wont be anyone smart enough to invent these crutches...

I'm just musing here really =P
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom