[beanieb]

JustinW, on 16 January 2012 - 05:25 PM, said:

This is what we hit on a little earlier in the thread about sexual compatibility with the sugar gene that possibly seperated our evolvement from that of apes you see today. Certain changes of that nature can make the reproduction of one species incompatible with the reproduction of another even though the two may be very closely related. Lets say on the topic of the sugar production. Even though it was the same species, one or more had a defect that the ape's ancestor didn't posess the reproductive ability to cope with, therefore making the two reproductively incompatible. I think this is correct, but I'm not an expert so if I'm wrong feel free to correct me.

just a thought..
if the mutation rendered the "newer" offspring incompatible with the older one, how does the new offspring find another of its own kind to reproduce again to continue this new line? (enough to be of great size)
(i mean the theory did make it sound abit like it had to happen in 1 generation...)

[questionposter]

beanieb, on 16 January 2012 - 11:37 PM, said:

just a thought..
if the mutation rendered the "newer" offspring incompatible with the older one, how does the new offspring find another of its own kind to reproduce again to continue this new line? (enough to be of great size)
(i mean the theory did make it sound abit like it had to happen in 1 generation...)

That's a good point, but that almost never actually happens where something is directly mutated to the point where it can't reproduce with the same species that gave birth to it. It's more of "down the line" that things can't reproduce with. So something probably wouldn't reproduce with another thing that was like 10 major mutations away in the evolutionary line of that particular creature, but would be likely to be able to reproduce with something only 1-2 major mutations away in the evolutionary line because there wouldn't be too big of a difference.

[Ophiolite]

beanieb, on 16 January 2012 - 04:50 PM, said:

-> thus unless we have extreme isolation (and for at least a few hundreds of thousand years)... the scenario of a distinct-man creature (which is so contrasted in appearance to the other members of his ape family) appearing on earth is quite a questionable mystery isn't it?

No. You are mistaken.

You are under the false impression that isolation has to be geographic. It does not. It can be geographic, it is often goegraphic, but there are other options. I believe I already pointed these out, but you seemed to have missed them. The isolation may be behavioural. A mutation may lead to a creature spending more time on the forest floor than in the canopy, for example. Initially there will still be interbreeding between groups, but more inbreeding within groups. This will concentrate the different genes in their respective groups and increase the amount of separate behaviour. Or the isolation could be one of sexual selection.

There is no issue with some interbreeding occuring. It seems that at least some humans have Neanderthal DNA. The two species lived alonside each other for a time, interbred occassionally, yet still remained distinct species. I believe there has been a recent case of speciation of chiclids where the two groups are living in the same place, but have different behaviour patterns. I shall try to find you a reference for this instance.

[Arete]

Ophiolite, on 16 January 2012 - 11:48 PM, said:

No. You are mistaken.

The term you're looking for is "ecological speciation" - here's a review paper with a few examples.
http://www.sciencema...3/5915/737.full

[Sorcerer]

questionposter, on 10 January 2012 - 12:18 AM, said:

If there's some giant super-catastrophe like maybe yellow-stone erupting and people with lung problems die even though you can use gas masks and etc, then maybe there would be a slight chance "medicating ourselves right out of existence" but even at that point it wouldn't even be half the human race. If you look at how things are already, most people who have severe genetic health problems that don't benefit them don't live long or don't reproduce.

And that makes me wonder about IVF, if people with acess to IVF reproduce and pass on the genetic mutations that led to the need to use IVF, aren't they just making trouble for their offspring. I mean if their offspring are going to need IVF to reproduce too, wouldn't they be causing harm to them (although I guess it could be ethically argued that any existence is better than none).

Perhaps if we become too reliant on modern health care we may become less adaptable, however at present there are pockets of humanity still effectively living in the stone age, makes me think. Next time I assume how "we" are so much more culturally(technilogically) evolved than "them", I will remember evolutionary theory, and remember "our" cultures are just differently adapted for OUR environments.

[Ophiolite]

Arete, on 16 January 2012 - 11:51 PM, said:

The term you're looking for is "ecological speciation" - here's a review paper with a few examples.
http://www.sciencema...3/5915/737.full

Thank you Arete, unfortunately I do not have a subscription to Science.

[Sorcerer]

Ophiolite I think ur talking about sympatric and allopatric speciation.

http://en.wikipedia....tric_speciation
http://en.wikipedia....tric_speciation

This post has been edited by Sorcerer: 17 January 2012 - 09:37 AM

[Ophiolite]

Sorcerer, on 17 January 2012 - 09:36 AM, said:

Ophiolite I think ur talking about sympatric and allopatric speciation.

http://en.wikipedia....tric_speciation
http://en.wikipedia....tric_speciation

Exactly. Beanieb has reached the faulty conclusion that only allopatric speciation can occur and only when there is total, extended isolation. Cichlids in the East African lakes have been shown to speciate in 10,000 years or less, despite still being in the same lake as their parent species. I think his difficulty may be is that he is thinking that speciation is something that happens to an individual rather than a population.

[Sorcerer]

yes cichlids are a good example of sympatric speciation.

This post has been edited by Sorcerer: 17 January 2012 - 12:09 PM

[questionposter]

Sorcerer, on 17 January 2012 - 09:17 AM, said:

And that makes me wonder about IVF, if people with acess to IVF reproduce and pass on the genetic mutations that led to the need to use IVF, aren't they just making trouble for their offspring. I mean if their offspring are going to need IVF to reproduce too, wouldn't they be causing harm to them (although I guess it could be ethically argued that any existence is better than none).

Perhaps if we become too reliant on modern health care we may become less adaptable, however at present there are pockets of humanity still effectively living in the stone age, makes me think. Next time I assume how "we" are so much more culturally(technilogically) evolved than "them", I will remember evolutionary theory, and remember "our" cultures are just differently adapted for OUR environments.

I'm sure that for every person with IVF there's a pretty healthy person, and if something is really that bad to have then you just die from it and you can't pass it on or there's some law. Besides, you can't determine how all of the mutations would play out. A lot of things like asthma wouldn't necessarily be a problem in the stone age where the longest your likely to live is like 30 years anyway.

[beanieb]

okies..
must admit i haven't heard about sympatric speciation before and was thinking along allopatric only....
some thoughts after reading about sympatric speciation..

Is sympatric speciation more possible for simpler organisms (eg flies, fishes) but less likely for more complex organisms (eg mammals)?
this is taking into consideration the life cycle.. the ease of change to the organism's DNA makeup and behavioral patterns of the organism..

then considering extreme isolation and extreme environments again...for a complex organism like man.. say if some of us chose to go back to water to live..
and we decide by sheer will to mate only amongst the new waterbound-clan and isolate ourselves from the outside world..
though theoretically plausible, would we see a new aqua-humanoid being arising some 100,000 yrs later?
(consider the people who lived in harsh conditions like the artic.. after many thousands of years separated from people of the man-friendlier environments. though they have developed adaptions to their environment.. they are still "man"..just like any of us)

[Moontanman]

beanieb, on 17 January 2012 - 05:13 PM, said:

okies..
must admit i haven't heard about sympatric speciation before and was thinking along allopatric only....
some thoughts after reading about sympatric speciation..

Is sympatric speciation more possible for simpler organisms (eg flies, fishes) but less likely for more complex organisms (eg mammals)?
this is taking into consideration the life cycle.. the ease of change to the organism's DNA makeup and behavioral patterns of the organism..

then considering extreme isolation and extreme environments again...for a complex organism like man.. say if some of us chose to go back to water to live..
and we decide by sheer will to mate only amongst the new waterbound-clan and isolate ourselves from the outside world..
though theoretically plausible, would we see a new aqua-humanoid being arising some 100,000 yrs later?
(consider the people who lived in harsh conditions like the artic.. after many thousands of years separated from people of the man-friendlier environments. though they have developed adaptions to their environment.. they are still "man"..just like any of us)

Actually, there is such a population of humans, a small group of islanders who spend most of their lives on boats and dive for fish have developed the ability to focus their eyes underwater. They are just as human as we are but they do have these small adaptations...

[JustinW]

Quote

Actually, there is such a population of humans, a small group of islanders who spend most of their lives on boats and dive for fish have developed the ability to focus their eyes underwater. They are just as human as we are but they do have these small adaptations...

I do believe they also have a stronger lung capacity on average also.