human sexual selection

[NullSpace]

See from 8:38 to 9:54 of http://www.youtube.com/watch?v=mISetzhs ... re=related

The guy posted a problem. Namely, why the human brain is so complex in contrast to brains of other non-humans when the only condition is being able to sustain oneself. The brain consume about 20% of the energy from a normal human. Non-human have brains that consume less energy. The solution comes from sexual selection of mates that are smart.

[Three Times Great]

There was an interesting documentary on Tv a while back regarding this issue of human brain size - one fascinating point was that human apes all share a certain genetic defect that is not shared by non-human apes/primates. This specific defect was found when comparing human to non-human primate DNA while they were working on sequencing the genome and trying to see where the differences lie between us and our other primate friends.

This specific genetic defect causes abnormally small size of the jaw muscle - so when the defect appeared those with it had much smaller and less powerful ability to chew. The surprising thing was when they found out that all modern humans have inherited this gene, that it has spread throughout the entire species.

The hypothesis is that with smaller jaw size, there is less stress on the skull to hold the muscle and counteract its amazing strength - in non-human primates the jaw muscle is immensely strong, and this requires a very thick skull in which the skull plates are "welded" together very strongly, with great rigidity so the jaw muscle has something to work against, to hold it securely while it is contracting its immense strength. This in turn prevents a great deal of growth in size of the brain during fetal development as well as after birth, because the skull plates come together faster and fuse more solidly; they do not expand and move as human skull plates do.

So, if this theory is correct we owe our capacity for the potential for larger brain development in part at least to a genetic error that shrunk the size and power of our jaw muscles, thus allowing the skull plates to stay loose and separate for longer, thus allowing for greater development of brain size.

Of course, sexual selection for brain size (as regards intelligence) is probably the case as well. This would simply be survivability expressed through whichever multitudes of behavioral, linguistic or otherwise cues that general intellectual ability would reveal itself through, and by virtue of the link between overall intellectual capacity and individual survivability thus becoming key differentiating criteria in mate selection.

[turtle]

There was an interesting documentary on Tv a while back regarding this issue of human brain size - one fascinating point was that human apes all share a certain genetic defect that is not shared by non-human apes/primates. This specific defect was found when comparing human to non-human primate DNA while they were working on sequencing the genome and trying to see where the differences lie between us and our other primate friends.

This specific genetic defect causes abnormally small size of the jaw muscle - so when the defect appeared those with it had much smaller and less powerful ability to chew. The surprising thing was when they found out that all modern humans have inherited this gene, that it has spread throughout the entire species.

The hypothesis is that with smaller jaw size, there is less stress on the skull to hold the muscle and counteract its amazing strength - in non-human primates the jaw muscle is immensely strong, and this requires a very thick skull in which the skull plates are "welded" together very strongly, with great rigidity so the jaw muscle has something to work against, to hold it securely while it is contracting its immense strength. This in turn prevents a great deal of growth in size of the brain during fetal development as well as after birth, because the skull plates come together faster and fuse more solidly; they do not expand and move as human skull plates do.

So, if this theory is correct we owe our capacity for the potential for larger brain development in part at least to a genetic error that shrunk the size and power of our jaw muscles, thus allowing the skull plates to stay loose and separate for longer, thus allowing for greater development of brain size.

Of course, sexual selection for brain size (as regards intelligence) is probably the case as well. This would simply be survivability expressed through whichever multitudes of behavioral, linguistic or otherwise cues that general intellectual ability would reveal itself through, and by virtue of the link between overall intellectual capacity and individual survivability thus becoming key differentiating criteria in mate selection.

very interesting. why do say it was an error.

[Three Times Great]

I believe it was no different than any regular genetic mutation, a common replication error that occurs for various reasons and which is the mechanism of genetic evolution itself - of course most of these "copy errors" phase out by causing the unsurvivability of the organism or not impacting its survivability one way or another. In this case, however, the random mutation gave rise to increased survivability and thus spread throughout the species, eventually contributing to drastic evolutionary change.

[turtle]

I believe it was no different than any regular genetic mutation, a common replication error that occurs for various reasons and which is the mechanism of genetic evolution itself - of course most of these "copy errors" phase out by causing the unsurvivability of the organism or not impacting its survivability one way or another. In this case, however, the random mutation gave rise to increased survivability and thus spread throughout the species, eventually contributing to drastic evolutionary change.

very good. thanks. you are an expert in evolution. i want to see more.

[Three Times Great]

I am not an expert, I only have a general or basic knowledge in this regard.

[Sauwelios]

Of course, sexual selection for brain size (as regards intelligence) is probably the case as well. This would simply be survivability expressed through whichever multitudes of behavioral, linguistic or otherwise cues that general intellectual ability would reveal itself through, and by virtue of the link between overall intellectual capacity and individual survivability thus becoming key differentiating criteria in mate selection.

Well, not so much individual survivability as well as genotypic survivability. Evolution's not about the survival of organisms but of genes, and not of individual genes but of gene types (a reproduction of a gene is as good as the "original").

[Three Times Great]

Of course, sexual selection for brain size (as regards intelligence) is probably the case as well. This would simply be survivability expressed through whichever multitudes of behavioral, linguistic or otherwise cues that general intellectual ability would reveal itself through, and by virtue of the link between overall intellectual capacity and individual survivability thus becoming key differentiating criteria in mate selection.

Well, not so much individual survivability as well as genotypic survivability. Evolution's not about the survival of organisms but of genes, and not of individual genes but of gene types (a reproduction of a gene is as good as the "original").

Because genes reproduce generationally through the mechanism of the individual organism, it is pertinent to talk about the survivability of that individual organism, as well as of the species of which that individual is a part.

"Evolution" is just the name we have for this process of growth and change, it captures a process taking place on many levels, and if desired the genetic level may certainly be seen as the predominant one in this regard. But just as gene types (forms) evolve only through the likewise evolution of their individual genetic "parts" (individual genes), the genetic level itself evolves through and not without its higher counterpart, the organic level, because without successful survival behaviors on the organic level genes themselves, or the genotypical forms to which individual genes give rise, cannot and do not reproduce or evolve.

In effect, it is all one process with many involves pieces and parts; separating them out in any rigid or definitive manner can be helpful in conceptualizing what is going on, but it also tends to obfuscate the unity and interdependency of the process as a whole.

For clarity's sake, we could say that no part or level of the evolutionary process is ontologically "primary" or superior to any other part or level. That is really the main lesson we ought to draw from the notion of evolution: mutual interdependence, reciprocal causality and (the attempt at) an ontological objectivity.

[Sauwelios]

For clarity's sake, we could say that no part or level of the evolutionary process is ontologically "primary" or superior to any other part or level.

I disagree with this part. The gene is the unit of evolution. By "gene type", by the way, I just mean that a "copy" (reproduction) of a gene is as good as its "original". For instance, we have the code:

XBLA

This is the "original". We can reproduce it:

XBLA

These are twice the same "type" but not twice the same "individual" code (by definition).

[Three Times Great]

For clarity's sake, we could say that no part or level of the evolutionary process is ontologically "primary" or superior to any other part or level.

I disagree with this part. The gene is the unit of evolution. By "gene type", by the way, I just mean that a "copy" (reproduction) of a gene is as good as its "original". For instance, we have the code:

XBLA

This is the "original". We can reproduce it:

XBLA

These are twice the same "type" but not twice the same "individual" code (by definition).

Yes. The genotypical form would consist of the specific order-combination of individual genes, but we must remember too that a single gene is itself made of lesser combinations of parts, nucleotides, and that these nucleotides are themselves composed of smaller atomic components. Each part of this process has its own mechanics and depends on every other level of the process for its own function. And even what we call a "gene" is itself arbitrary, a chosen grouping of nucleotide base pairs that we believe relate, as a whole, to a certain phenotypical expression via protein synthesis. A gene is not a specific unit, and it certainly is not irreducible, so the stretch that it is the "primary" unit of evolution is dubious, at best.

As far as the "selection" element is concerned, this in fact only takes place, evolutionarily speaking, on the higher level of the organism and its behavior within its environment. Selection is the process defined by the relationship between an individual and its environment, regarding survivability (successful procreative ability) and thus has meaning only over a group of individuals, from one generation to the next (i.e. at least two individuals, the minimum being one parents and its offspring).

For instance, an organism reproduces a fertile offspring; thus we have selection of the genes of that particular organism which are transmitted to the offspring. This is the most basic selection component to evolution. Genes themselves, among themselves, are not "competing" except through the higher medium of survivability of the overall organism with respect to the needs of its environment.

[Pandora]

Wow! You guys are so smart!

That's hot!!!

[Sauwelios]

Again, I only disagree with a small part of what you're saying. In this case:

we must remember too that a single gene is itself made of lesser combinations of parts, nucleotides, and that these nucleotides are themselves composed of smaller atomic components. Each part of this process has its own mechanics and depends on every other level of the process for its own function. And even what we call a "gene" is itself arbitrary, a chosen grouping of nucleotide base pairs that we believe relate, as a whole, to a certain phenotypical expression via protein synthesis. A gene is not a specific unit, and it certainly is not irreducible, so the stretch that it is the "primary" unit of evolution is dubious, at best.

My point is that it's the gene which is "selfish", not its components or that of which it is a component. The gene does not "care" about its components or about that of which it is a component for their own sakes, but only for the sake of itself.

[jonquil]

My point is that it's the gene which is "selfish", not its components or that of which it is a component. The gene does not "care" about its components or about that of which it is a component for their own sakes, but only for the sake of itself.

Your point.. or Dawkins'?

[Sauwelios]

My point is that it's the gene which is "selfish", not its components or that of which it is a component. The gene does not "care" about its components or about that of which it is a component for their own sakes, but only for the sake of itself.

Your point.. or Dawkins'?

Ah, jonquil, the self-proclaimed Enneagram type 4, meaning she's sooo concerned with originality. Why, one may ask? What does the need for originality imply?...

[Three Times Great]

Again, I only disagree with a small part of what you're saying. In this case:

we must remember too that a single gene is itself made of lesser combinations of parts, nucleotides, and that these nucleotides are themselves composed of smaller atomic components. Each part of this process has its own mechanics and depends on every other level of the process for its own function. And even what we call a "gene" is itself arbitrary, a chosen grouping of nucleotide base pairs that we believe relate, as a whole, to a certain phenotypical expression via protein synthesis. A gene is not a specific unit, and it certainly is not irreducible, so the stretch that it is the "primary" unit of evolution is dubious, at best.

My point is that it's the gene which is "selfish", not its components or that of which it is a component. The gene does not "care" about its components or about that of which it is a component for their own sakes, but only for the sake of itself.

Um.

A gene doesn't "care" about anything..

[Three Times Great]

What does the need for originality imply?...

Consciousness..

[Sauwelios]

A gene doesn't "care" about anything..

It does inasmuch as it's "selfish".

[jonquil]

My point is that it's the gene which is "selfish", not its components or that of which it is a component. The gene does not "care" about its components or about that of which it is a component for their own sakes, but only for the sake of itself.

Your point.. or Dawkins'?

Ah, jonquil, the self-proclaimed Enneagram type 4, meaning she's sooo concerned with originality. Why, one may ask? What does the need for originality imply?...

If you are taking your view of the "selfish gene" from Dawkins, then why not say so? I like the Enneagram, and I am a type four, and originality is important to me... that is true.

[jonquil]

A gene doesn't "care" about anything..

It does inasmuch as it's "selfish".

Ermm.. Sauwelios. Do you realize what is implied in this view?

[Sauwelios]

My point is that it's the gene which is "selfish", not its components or that of which it is a component. The gene does not "care" about its components or about that of which it is a component for their own sakes, but only for the sake of itself.

Your point.. or Dawkins'?

Ah, jonquil, the self-proclaimed Enneagram type 4, meaning she's sooo concerned with originality. Why, one may ask? What does the need for originality imply?...

If you are taking your view of the "selfish gene" from Dawkins, then why not say so?

If you're trying to accuse me of plagiarism, you're being ridiculous: it's common knowledge that the term "selfish gene" refers to Dawkins.

[Sauwelios]

A gene doesn't "care" about anything..

It does inasmuch as it's "selfish".

Ermm.. Sauwelios. Do you realize what is implied in this view?

That either a gene "cares" or it's not "selfish"?

[jonquil]

If you are taking your view of the "selfish gene" from Dawkins, then why not say so?

If you're trying to accuse me of plagiarism, you're being ridiculous: it's common knowledge that the term "selfish gene" refers to Dawkins.

No problem then.. if it's comon knowledge . . . .

[jonquil]

A gene doesn't "care" about anything..

It does inasmuch as it's "selfish".

Ermm.. Sauwelios. Do you realize what is implied in this view?

That either a gene "cares" or it's not "selfish"?

It would have to be the former since you operate on the premise that it IS selfish. If a gene "cares," then . . . .

[Sauwelios]

A gene doesn't "care" about anything..

It does inasmuch as it's "selfish".

Ermm.. Sauwelios. Do you realize what is implied in this view?

That either a gene "cares" or it's not "selfish"?

It would have to be the former since you operate on the premise that it IS selfish.

To be precise, I operate on the premise that it is "selfish".

If a gene "cares," then . . . .

Yes, then?

[MagsJ]

Genes r us, as in they are reflective of our sociotel standing...