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Sentient, Intelligent, or Human?

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#151 Pess

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Posted 27 June 2013 - 08:20 AM

.... but many of them are simply invisible to selection.


Pesse (Until they get their turn at bat...) Mist

#152 shawnhar

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Posted 27 June 2013 - 11:46 AM

.... but many of them are simply invisible to selection.


Pesse (Until they get their turn at bat...) Mist

Or their turn at the teet!
I heard being able to digest cow's milk was extremely rare back in the day.

#153 scopethis

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Posted 27 June 2013 - 01:36 PM

evolution is caused by the environment

#154 EJN

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Posted 27 June 2013 - 03:55 PM

evolution is caused by the environment


Not necessarily. Mutations can be caused by substitution of different
tautomeric forms of the bases (purines & pyrimidines) in DNA when
replicating, as well as replication errors which involve the addition
or deletion of a base in the sequence.

#155 llanitedave

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Posted 27 June 2013 - 06:48 PM

evolution is caused by the environment


As EJN said, not necessarily. Evolution can occur in the absence of environmental change, via genetic drift. Further, even when a species is forced to adapt to a changing environment, it's not always predictable what direction that adaptation will take. For example, consider a mammal in a tropical environment that grows colder. To adapt to the cold, there are several solutions to the problem available. The population can grow longer warmer fur. It can grow fatter for insulation. It can grow physically larger. It can increase its metabolism to generate more body heat.

None of these potential solutions is exclusive to the others, and all of them are going to carry incidental consequences -- which adds to the unpredictability of the future.

So what IS the relationship between the environment and evolution? Exactly how do you define *cause* under such conditions? It's there, but it's not amenable to glib or simple statements.

#156 WaterMaster

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Posted 27 June 2013 - 07:49 PM

Well, to be precise, mutation and genetic drift are the grist upon which natural selection works, over generations via differential reproduction, to result in evolution. Certainly, neutral genes get carried along, but they, too, are grist - waiting for their turn at bat, as Pess put it (and with my apologies for mixing metaphors).

Earlier, when I spoke of evolution being directionless, I was referring to the evolutionary biology paradigm of n-dimensional ecological space. Since evolution is a destination, the 'direction' it has traveled can only be determined by looking backward. We can examine physiology and morphology and make hypotheses about why a particular adaptation might have resulted in differential reproduction (w, Haldane's quantification of 'fitness'). See this for a cool new example of this.

And, of course, evolution can occur without changes in environment (sexual selection is a good example of this). Actually, this can bring us back on topic - what might be the selective advantages of 'mind'?

#157 Otto Piechowski

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Posted 27 June 2013 - 09:11 PM

This is not a response to anyone in particular, thought the use of "quick reply" always seems to get attached to the last to post.

Anyway, you "pointy eared *BLEEP*" are so good at parse-ing words and focusing on the connotative and secondary words stated; let's try this one...are there any quantitative or qualitative changes in human-kind you would not expect to see from the parameters and limitations you are aware of in evolutionary biology.

Drawing, seriously now, on your scientific acumen, I would be very interested to hear if there are specific quantitative and qualitative changes to human-mind you would suspect are never possible; changes which others who haven't thought much about it, like myself, would be surprised to hear and then, once we get the gist of it, would say, "yah, that makes sense".

Otto

#158 WaterMaster

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Posted 27 June 2013 - 10:29 PM

Drawing, seriously now, on your scientific acumen, I would be very interested to hear if there are specific quantitative and qualitative changes to human-mind you would suspect are never possible...


Otto, you're asking us to speculate on the impossible. I don't think I can do that 'seriously'. :whistle:

#159 llanitedave

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Posted 27 June 2013 - 10:56 PM

This is not a response to anyone in particular, thought the use of "quick reply" always seems to get attached to the last to post.

Anyway, you "pointy eared *BLEEP*" are so good at parse-ing words and focusing on the connotative and secondary words stated; let's try this one...are there any quantitative or qualitative changes in human-kind you would not expect to see from the parameters and limitations you are aware of in evolutionary biology.

Drawing, seriously now, on your scientific acumen, I would be very interested to hear if there are specific quantitative and qualitative changes to human-mind you would suspect are never possible; changes which others who haven't thought much about it, like myself, would be surprised to hear and then, once we get the gist of it, would say, "yah, that makes sense".

Otto


As for natural-type impossible changes, I'd say there are quite a few. One would be for feathers to sprout from our limbs. Remember, evolution can only work with the genes it already has, and it doesn't go back to start with a state that has been long left behind.

I would also expect that our broken vitamin C gene will never mutate back into a functional state. At least not a state of producing vitamin C.

#160 Otto Piechowski

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Posted 27 June 2013 - 11:14 PM

Now that's cool. The human genome once made it possible for the human being to produce its own Vitamin C?

#161 llanitedave

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Posted 28 June 2013 - 12:58 AM

The mammal genome has the vitamin C gene, but in higher primates, the gene is broken.

The Genetics of Vitamin C Loss in Vertebrates

#162 Pess

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Posted 28 June 2013 - 10:31 AM

evolution is caused by the environment


As EJN said, not necessarily. Evolution can occur in the absence of environmental change, via genetic drift. Further, even when a species is forced to adapt to a changing environment, it's not always predictable what direction that adaptation will take. For example, consider a mammal in a tropical environment that grows colder. To adapt to the cold, there are several solutions to the problem available. The population can grow longer warmer fur. It can grow fatter for insulation. It can grow physically larger. It can increase its metabolism to generate more body heat.

None of these potential solutions is exclusive to the others, and all of them are going to carry incidental consequences -- which adds to the unpredictability of the future.

So what IS the relationship between the environment and evolution? Exactly how do you define *cause* under such conditions? It's there, but it's not amenable to glib or simple statements.


I'm not sure I get this line of thought.

If you have a religiously static environment you still get evolution. That environment will select what gene expressions work best to date, not necessarily what work best out of all possible combinations.

So despite a never changing environment some mutations will occur at random that work 'better' than what has worked for eons and thus the new characteristic will allow that species to out compete its brethren which may have dominated for eons.

Changing environmental conditions only select for genes that may have previously had no particular competitive value before the change or may have been detrimental before the change.

A prime example comes to mind. Moths in an industrialized city were light colored and almost invisible to see against the light colored bark of trees and thus hard for predators to see. Occasionally a mutation for dark coloration in the moths was expressed but these expressions were 'eaten' and removed from the gene pool rather quickly because they were silhouetted against the light tree bark.

With industrialization 'soot' began accumulating on the tree bark and the trees turned dark brown/black. The drak moths now were very well camouflaged while the white, dominate moth, was silhouetted.


In a very short time the dark mutation became the dominant moth species.

Pesse (There is no good or bad, there only is what is.) Mist

#163 Otto Piechowski

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Posted 28 June 2013 - 11:23 AM

One day, as I was walking into the school where I had taught, I saw a moth on the exterior brick wall; about the size of a deck of playing cards. I was stunned by what I saw. So stunned I took it to the biology teacher for display to students if he so chose.

The moth had exactly the same appearance as a tree leaf; of light green color, but the same delicate and complex appearance of veins on a leaf. Had this moth decided to be in the respective tree, I could have touched it with my nose and not seen it.

#164 Ravenous

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Posted 28 June 2013 - 11:35 AM

If you have a religiously static environment you still get evolution.

Think of sexual selection. Male peacocks have elaborately oversized tail feathers, which are probably quite dangerous to own in the wild; their ladies are drab brown, but have a liking for overly decorated males.

I'm not sure how a cycle like that starts, but once it does, selection occurs even if the environment is unchanging and the original creatures are well adapted to it. The male gets to father more chicks if he has the right plumage; the female's male chicks are more likely to be successful if she selects the right male herself.

#165 Pess

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Posted 28 June 2013 - 01:46 PM

Think of sexual selection. Male peacocks have elaborately oversized tail feathers, which are probably quite dangerous to own in the wild; their ladies are drab brown, but have a liking for overly decorated males.

I'm not sure how a cycle like that starts, but once it does, selection occurs even if the environment is unchanging and the original creatures are well adapted to it. The male gets to father more chicks if he has the right plumage; the female's male chicks are more likely to be successful if she selects the right male herself.


Good thing human men wear clothes.

Pesse (Otherwise, I shudder to think what selection pressures might be brought to bare.....) Mist

#166 scopethis

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Posted 28 June 2013 - 02:45 PM

yep, god made people naked and then covered them up..decisions, decisions, decisions....

#167 shawnhar

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Posted 28 June 2013 - 03:44 PM

Well, I guess if you believe in that silly sort of thing...
We aint got no fur man, had to do something...
REAl people almost never wear clothes.

#168 WaterMaster

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Posted 28 June 2013 - 06:52 PM

Evolution is the result of differential reproduction. That is, the genotype that produces the most viable offspring has a higher relative fitness. The 'reason' for this differential can be, literally, anything.

Even in a 'static' environment (there's not really such a thing, but we can make the assumption for illustrative purposes), competition for resources (food, light, water, mates, refugia, etc.) is a constant selective pressure. Any competitive advantage (conferred by difference in genotype) will result in differential reproduction. The moth example mentioned above is the 'textbook' illustration of natural selection (and in this case, differential predation resulted in differential reproduction). Competition can also result in radiative speciation, as in Darwin's finches, where competition for food was the primary selective force. Peacocks, or any 'showy' bird is a great example of yet another selective pressure (and evolutionary biology is rife with stories of 'runaway' sexual selection).

Natural selection works on individuals, evolution occurs on the population level. As I used to tell my second year ecology students, "It's all about your baby's babies, baby". :ubetcha:

And, we're getting way off topic.

But now that we've discussed selective pressure a little, I'll ask my question again: What might be the selective pressures that result in the appearance of 'mind'?

#169 llanitedave

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Posted 28 June 2013 - 07:53 PM

I'm not sure I get this line of thought.

If you have a religiously static environment you still get evolution. That environment will select what gene expressions work best to date, not necessarily what work best out of all possible combinations.

So despite a never changing environment some mutations will occur at random that work 'better' than what has worked for eons and thus the new characteristic will allow that species to out compete its brethren which may have dominated for eons.

While this is true, it's not the whole story. A genetic variation can fix within a population even in the absence of selection. That's the basis of genetic drift. Mutations come and go. Some increase in the population merely due to the chances inherent in reproduction, and some decrease. Occasionally a variation will increase to the point where it achieves critical mass, and finds itself monopolizing its particular gene, for no apparent reason. This happens most often in small, genetically isolated populations that are more sensitive to random changes. It would be like a mutation for a front-tooth gap occurring in an individual member of population that until then had all gapless front teeth. If, for reasons totally unrelated to the gap, that mutation succeeds in replicating for a few generations and becomes established, it's possible that eventually ALL the members of that population will have the gap, and the hapless gapless gene would have simply been snuffed out.

That's evolution, but it's not selection. It's actually pretty common.

#170 Otto Piechowski

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Posted 28 June 2013 - 10:01 PM

The very pronounced gap between my two front teeth is genetic?

#171 llanitedave

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Posted 28 June 2013 - 10:14 PM

That depends on whether you got them for Christmas.

#172 Mister T

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Posted 29 June 2013 - 06:25 AM

or from Hockey!!

#173 scopethis

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Posted 29 June 2013 - 02:49 PM

if all this mutation/evolution stuff is true, how much longer do we have to wait before our ape cousins start acting like us??

#174 llanitedave

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Posted 29 June 2013 - 11:02 PM

There's no reason why they ever should. Three million years ago "humanity" was an empty niche. Now it's filled.

#175 shawnhar

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Posted 30 June 2013 - 11:43 AM

It is also possible 3 million years could produce another sentient hominid branch (kind of like us). Current "human" progress will destroy the current ape habitat. They already have serious enviornmental pressure, they may get smart or die off.






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