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Human evolution: when male and female fully developed into separate and distinct ...?

by jackson6612
Tags: developed, distinct, evolution, female, fully, human, male, separate
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Jon Richfield
#73
Jul23-10, 01:36 PM
P: 258
Quote Quote by nismaratwork View Post
If it's so elementary, I'm sure you'll have no problem providing sources which confirm your statements; I look forward to seeing them.
Sources? Sources? Are you serious? Sources for what? Suppose you specify a few of the points that you find implausible and explain what you find difficulty with. I don't ask you to prove anything, just explain what you see as errors of fact or logic. (Facts, you know? Like the evolutionary level at which we find the most elementary examples of sexual (read genetic in this context) recombination, and in comparison the levels at which we find the most elementary examples of distinct gender? Or the levels of stromatolites at which we first find evidence for multicellular life? These connections are not too complicated for you I hope? And logic, you know? Like the connection between organisational level and derivation of evidence for phylogeny? And the connection between phylogenic history and adaptive selective pressures? Non-biologists often come up with some peculiar lines of discussion, but this one is a lulu.)
Sources for the likes of what I mentioned would include most of the introductory university texts I have seen so far for botany, cytology, or microbiology. You know? Or if those are too challenging, try Ken's
example: JMS & ES. Available from Amazon, most technical bookshops, and practically all university libraries (assuming they have biology faculties of course!) And those are excellently written by leading authorities (unless you happen to know better of course!) I suppose if I remarked on the catalytic effect of soluble iron salts on the corrosion of copper in the presence of air and water, you would ask for sources?
Well man, I really must admit you had me going there for a minute!

As for the ugly comment, it was a joke. You need to relax in the worst way. You've provided your view of when sexual division began, now you get to back it up with something solid, and if not, go home.
Oh, so you admit that they are real pretty huh? That's better. You got any sources? A joke hm? Did anyone laugh but you? Or grin?

Now, lets hear your sources for the origins of "sexual division" post chordate. I won't ask you to limit yourself to first-year references; post-graduate will do just fine, so just don't say I never do you any favours!
Jon Richfield
#74
Jul23-10, 02:36 PM
P: 258
Quote Quote by Ken Natton View Post
For certain, I agree with you that the male nipple thing is trivial, I only raised it because it has been a subject of discussion on this thread, and it does seem to be one that a lot of people latch on to as a mystery of evolution.
Ken, I am sorry if I gave you the impression that I thought that the nipple thing is in itself trivial. It is not. I just meant that in the perspective of the very large and fundamentally important subject you raised, it is just one small example of secondary sexual characteristic and of recent origin compared to primary mammalian sexual characters. I don't, by way of analogy, regard you personally as trivial, but I doubt that you would feel deeply offended if I overlooked you in juxtaposition with say, Grand Canyon... ;-)

You are right that many people do latch on to it as a mystery of evolution, but as I see it, they miss a lot of points dramatically. Your own discussion raised typical examples of such points very pertinently and correctly. Remember your discussion of intrauterine development and the point at which the secondary (and some primary) male sexual characteristics began to develop? You can carry this further; other secondary (and primary) characteristics don't complete their development till the end of puberty at least, some even later.


I’m surprised that you reject the idea of mammary glands as a defining mammalian feature. Apart from the obvious etymological connection, is not suckling the young the key defining feature of a mammal?
Please do not confuse "the idea of mammary glands as a defining mammalian feature" with "the idea of mammary glands as the defining mammalian feature". You did say: "Mammary glands are, after all, the very thing that define us as mammals," right? (My italics of course.) Let me give you an analogy to illustrate: a biologist for whose work I had respect for shocked me by insisting that the hook-lip of the black African rhino was "the most important" difference between the black and white rhinos. Biologically the statement was meaningless at best. What he really seems to have meant was that it was the most obvious (he was no mammalogist!). Actually there are no end of differences, and many of them are functionally more important, such as the differences in teeth and digestive systems (the two species have different diets.)
Now, I was not disputing that you could easily tell them apart by their upper lips, just that the lips, though sufficient as a diagnostic feature, were not necessary. Any mammalogist looking at a picture of an African rhino with the lip not visible could tell the species apart. (So could any layman familiar with the animals.) And the rhinos didn't develop their lips for the convenience of taxonomists; they have more important functions that represent adaptations to the animals' lives. Right?
Now, certainly, as I said, given the appropriate part of a mammal's anatomy, a mammalogist could identify the mammae, and tell you that they did not come from a bird. No argument. But would you like to sit down for a while and list major features of a mammal's anatomy that would not do just as well? How about the skin? Hair? Teeth? Eyes? Feet? External ears? Erythrocytes? Brain? Genitals? Adipose organ? Kidneys?

Don't let me rush you.

And don't let me leave you thinking that I would exclude nipples from the list; I simply say that they are just one example among many. And what is more, if I gave you the nipples of a monotreme to identify, you might have a merry dance before you succeed!

And, connected with another one of my very favourite stories from the annals of human evolution, my understanding was that sweat glands, or at least a profusion of sweat glands, was very much a specifically human feature.
We all have our favourites, even I, and we all get led astray by them, even I. (NO!?! Oh yes! Really!) The profusion of sweat glands is by no means specifically human, and if it were, that would hardly be relevant. As things stand, there are several kinds of sweat glands, and most mammals have one or more. (I have seen claims that cetaceans lack them completely, but I have also seen it denied. It is hard to prove a negative.) The point is that finding even one undeniable sweat gland of any mammalian type is sufficient to tell you that you are not working with a fish or fowl.
Apes have plenty, though we are the sweatiest apes, I believe. Horses have more than we have.

The story, as I heard it, is closely connected with the reason why we became the naked ape. It’s all about our big, energy hungry, heat producing brains.
That story may have merit, but as it stands it is a classic example of a "Just-So" story. As a hypothesis it is not wildly unreasonable, but as commonly retailed, it is a bit holey. One of the holes is that the brain's heat production has been widely exaggerated. Another is that the range of heat shedding techniques among animals is quite wide enough to deal with the extra bit of cranial heat that we produce. And just in case you had not noticed, most of that mammary evidence for our mammalian nature, the more attractive, the more so, gets hidden from us behind... Artificial means of reducing heat loss!

I repeat: the whole theory (though personally I don't like it) is not to be rejected wholesale out of hand, but there is a heck of a lot ground to cover before it can be regarded as established.

Am I making the right points? Feel welcome to holler!

Cheers,

Jon
nismaratwork
#75
Jul23-10, 03:03 PM
P: 2,284
Quote Quote by Jon Richfield View Post
Sources? Sources? Are you serious? Sources for what? Suppose you specify a few of the points that you find implausible and explain what you find difficulty with. I don't ask you to prove anything, just explain what you see as errors of fact or logic. (Facts, you know? Like the evolutionary level at which we find the most elementary examples of sexual (read genetic in this context) recombination, and in comparison the levels at which we find the most elementary examples of distinct gender? Or the levels of stromatolites at which we first find evidence for multicellular life? These connections are not too complicated for you I hope? And logic, you know? Like the connection between organisational level and derivation of evidence for phylogeny? And the connection between phylogenic history and adaptive selective pressures? Non-biologists often come up with some peculiar lines of discussion, but this one is a lulu.)
Sources for the likes of what I mentioned would include most of the introductory university texts I have seen so far for botany, cytology, or microbiology. You know? Or if those are too challenging, try Ken's
example: JMS & ES. Available from Amazon, most technical bookshops, and practically all university libraries (assuming they have biology faculties of course!) And those are excellently written by leading authorities (unless you happen to know better of course!) I suppose if I remarked on the catalytic effect of soluble iron salts on the corrosion of copper in the presence of air and water, you would ask for sources?
Well man, I really must admit you had me going there for a minute!



Oh, so you admit that they are real pretty huh? That's better. You got any sources? A joke hm? Did anyone laugh but you? Or grin?

Now, lets hear your sources for the origins of "sexual division" post chordate. I won't ask you to limit yourself to first-year references; post-graduate will do just fine, so just don't say I never do you any favours!
The error that I think you've made is condemning one opinion in favor of your own, when you have no more ability to back that opinion than anyone else. Until you do, I'm not wasting my time with this. The title of the thread specifically referred to male and female differentiation, not simply the emergence of sexual reproduction. You're entitled to your opinions, but present them as such unless you're willing and able to back them up immediately.
Jon Richfield
#76
Jul24-10, 02:56 AM
P: 258
Quote Quote by nismaratwork View Post
The error that I think you've made is condemning one opinion in favor of your own, when you have no more ability to back that opinion than anyone else. Until you do, I'm not wasting my time with this. The title of the thread specifically referred to male and female differentiation, not simply the emergence of sexual reproduction.
Well NAW, you have a nice line in emotive nomenclature. When you present an opinion I assume you call it debate or something equally urbane. When anyone disagrees and points out holes in your assumptions or reasoning, that is condemnation. Yes?
Well, if that is the way you see it, here is another thought you may like to er... debate. What condemns an argument in science is not the antagonist, but its own weaknesses. Now, consider the argument that you apparently support (at least in opposition to mine, if I read you aright) that "male and female differentiation" began around or after the earliest emergence of the Chordata. Ask yourself how you would go about defending that in terms of comparative functional morphology or palaeontology. It was after all your idea, as far as I can tell, so don't bother to address my errr... opinions, just your own. But do try not to blush too deeply. After all, we all are entitled to our own pratfalls from time to time.

Next, ask yourself what reasonable arguments could be mustered to distinguish cleanly and usefully between sexual reproduction and gender differentiation, as you seem to demand. I accept that you are not going to waste your time with my views (and very wisely, if I may compliment you on your resolution in the light of the foregoing exchanges) but if you could present the forum with a cogent line of argument by which to demonstrate there could be no selection pressure for development of asymmetry in the size and mobility of gametes, and correspondingly, in the parents of the gametes, then please reveal your insights. I for one promise to receive them in a spirit of humility and praise, not to say astonishment.

You're entitled to your opinions, but present them as such unless you're willing and able to back them up immediately.
Gramercy and gramercy good sir, for the entitlement! This is no doubt the same entitlement by which you put forward your (ahem!) opinion about the squirts? And where, while we are on the subject, did you see my claiming literal and detailed special knowledge of the prehistory of the emergence of gender differentiation?

Frankly NAW, so far you are hardly presenting yourself in the best light in this exchange. Unless you shape up fast, ceasing to waste your time really seems your best option, and fast. Alternatively, if you have substantial arguments at your disposal, I'd be interested (and happy) to see them.

All the best,

Jon
nismaratwork
#77
Jul24-10, 10:18 AM
P: 2,284
Quote Quote by Jon Richfield View Post
Well NAW, you have a nice line in emotive nomenclature. When you present an opinion I assume you call it debate or something equally urbane. When anyone disagrees and points out holes in your assumptions or reasoning, that is condemnation. Yes?
Well, if that is the way you see it, here is another thought you may like to er... debate. What condemns an argument in science is not the antagonist, but its own weaknesses. Now, consider the argument that you apparently support (at least in opposition to mine, if I read you aright) that "male and female differentiation" began around or after the earliest emergence of the Chordata. Ask yourself how you would go about defending that in terms of comparative functional morphology or palaeontology. It was after all your idea, as far as I can tell, so don't bother to address my errr... opinions, just your own. But do try not to blush too deeply. After all, we all are entitled to our own pratfalls from time to time.

Next, ask yourself what reasonable arguments could be mustered to distinguish cleanly and usefully between sexual reproduction and gender differentiation, as you seem to demand. I accept that you are not going to waste your time with my views (and very wisely, if I may compliment you on your resolution in the light of the foregoing exchanges) but if you could present the forum with a cogent line of argument by which to demonstrate there could be no selection pressure for development of asymmetry in the size and mobility of gametes, and correspondingly, in the parents of the gametes, then please reveal your insights. I for one promise to receive them in a spirit of humility and praise, not to say astonishment.


Gramercy and gramercy good sir, for the entitlement! This is no doubt the same entitlement by which you put forward your (ahem!) opinion about the squirts? And where, while we are on the subject, did you see my claiming literal and detailed special knowledge of the prehistory of the emergence of gender differentiation?

Frankly NAW, so far you are hardly presenting yourself in the best light in this exchange. Unless you shape up fast, ceasing to waste your time really seems your best option, and fast. Alternatively, if you have substantial arguments at your disposal, I'd be interested (and happy) to see them.

All the best,

Jon
I would say that the tone of your original post in response to mine and others appeared to be quite certain and, here I'll bow to your distaste for the verbosity you seem to enjoy, confrontational to the point of anger. Beyond that, the fact that you present your opinion in the form of multiple of paragraphs of polemic (ok, I do like debate) doesn't make them valid. If you can't provide some measure of substance beyond your own view and constant reference to their elementary nature, I'll say it again, this is not a worthwhile discussion. I do salute your posturing, which is done while accusing me of the same; it has an impressive timbre that really lets the reader know that you enjoy the 'sound of your own voice'. Perhaps if you want to have an actual discussion in the future you might want to adjust that to something more sotto voce.
Jon Richfield
#78
Jul24-10, 11:35 AM
P: 258
Quote Quote by nismaratwork View Post
I would say that the tone of your original post in response to mine and others appeared to be quite certain and, here I'll bow to your distaste for the verbosity you seem to enjoy, confrontational to the point of anger.
Whose anger NAW? Yours or mine? I wasn't angry. Mainly disapproving at first of your mockery in abuse of Tunicata. Confrontational? You must live in a position of considerable authority if you are so sensitive to disagreement that any propositions other than your own count as confrontation. Congratulations on your comfort zone. Bad luck when you are not at work though.

Beyond that, the fact that you present your opinion in the form of multiple of paragraphs of polemic (ok, I do like debate) doesn't make them valid. If you can't provide some measure of substance beyond your own view and constant reference to their elementary nature, I'll say it again, this is not a worthwhile discussion.
Denotional aren't we? Redundantly so? When it isn't confrontational, it is polemical, right? You do like debate? Not on the available evidence, you don't seem to; you haven't debated. Apart from some grizzling about (.... sources <siiigh!>...) you have not made a single substantive statement since I mentioned the reason to believe that there was not only sex, but gender long before there were chordates, and referred to multiple kingdoms as examples. Really polemical that was... I'm oh, so ashamed...!
You of course, in your far greater scientific dignity pointed out that... errr...
What was that again, apart from the sources bit?
So far that debate of yours seems to amount to JR two or three, NAW 0, right? Now tell me again about substance?

I do salute your posturing, which is done while accusing me of the same; it has an impressive timbre that really lets the reader know that you enjoy the 'sound of your own voice'. Perhaps if you want to have an actual discussion in the future you might want to adjust that to something more sotto voce.
Confrontation, polemics, now posturing, and audible timbre without audio... more and more. Just no substance. This from the guy who began with what was it again? Diatribe? What next? Invective? Billingsgate?

As a joker, you might like to know what is funniest? I really did hope for some substance from you. Not necessarily anything beyond rational opinion, but substance. I did ask remember? "Now, lets hear your sources for the origins of "sexual division" post chordate. I won't ask you to limit yourself to first-year references..."

So much for sources!

Oh well,

Go well,
Jon
jackson6612
#79
Jul24-10, 11:54 AM
P: 348
To Jon, Nismar

I request you both to end this. We are getting nothing out of it. You are both entitled to your opinions. There is no need for continuation of all this. Thanks for consideration.

Regards
Jack
Jon Richfield
#80
Jul24-10, 12:10 PM
P: 258
Quote Quote by jackson6612 View Post
To Jon, Nismar

I request you both to end this. We are getting nothing out of it. You are both entitled to your opinions. There is no need for continuation of all this. Thanks for consideration.

Regards
Jack
No problem. I have made my points and am not angry. I hope that Nismar feels the same way. Let's hope that future exchanges are amiable.

Cheers,

Jon
jackson6612
#81
Jul24-10, 12:30 PM
P: 348
Thank you, Jon.
nismaratwork
#82
Jul24-10, 06:47 PM
P: 2,284
Quote Quote by jackson6612 View Post
To Jon, Nismar

I request you both to end this. We are getting nothing out of it. You are both entitled to your opinions. There is no need for continuation of all this. Thanks for consideration.

Regards
Jack
I'm not going to go forward to the detriment of others in this thread, and you have my apology if this has been disruptive already.
nismaratwork
#83
Jul24-10, 06:58 PM
P: 2,284
To the point at hand, the thread specifically asks, "when male and female fully developed into seperate and distinct...:, not "when did asexual forms of reproduction lose dominance. Some believe that early plants take that cake, http://www.msnbc.msn.com/id/27927661/

and others believe that this occurred long before plants developed. I believe that Jon and I can agree that pinpointing this kind of thing with current technology is just not possible unless, as he says, pinpointing means hundreds of millions of years. Did this occur to resist parasitism and disease in general, or was it advantageous in providing a higher rate of mutation? These remain serious unknowns. The issue of swapping genes, and gender is very different.
jackson6612
#84
Jul31-10, 03:53 PM
P: 348
Main question:
http://www.physicsforums.com/showpos...1&postcount=55

Quote Quote by AlexB2010 View Post
The "furnace" is still working, the selection enviroment changed.
Best,
Alex
As we know, the life started from the non-living molecules which somehow, no one knows how, banded together to form simple proteins etc. That was the initial stage of all the life on primordial earth. I believe that initial is no longer active. The reason is the environment has changed. All that happened in primordial earth. So, I think saying that the furnace is still working is not actually correct. Mutations are taking place all the time and this gives rise to new varieties of life but the furnace which was really responsible for the life is not there now. Do I make any sense? Please guide me.

I'm not a biology student, so I request you to be plain and explain things in layman terms. Thanks.
nismaratwork
#85
Jul31-10, 06:17 PM
P: 2,284
Quote Quote by jackson6612 View Post
Main question:
http://www.physicsforums.com/showpos...1&postcount=55



As we know, the life started from the non-living molecules which somehow, no one knows how, banded together to form simple proteins etc. That was the initial stage of all the life on primordial earth. I believe that initial is no longer active. The reason is the environment has changed. All that happened in primordial earth. So, I think saying that the furnace is still working is not actually correct. Mutations are taking place all the time and this gives rise to new varieties of life but the furnace which was really responsible for the life is not there now. Do I make any sense? Please guide me.

I'm not a biology student, so I request you to be plain and explain things in layman terms. Thanks.
It's still there, although it's true that there is no longer a literal primordial ooze (well, there is some in the seabed and in labs), but that's not what evolution is all about. Evolution is an ongoing process and I'm not sure that it's possible to be alive and "turn off the furnace". Your question is phrased in such a way that to answer without refuting your premise is impossible; evolutionary pressures change, and mutations constantly occur. This has not changed from ooze, to people. As Jon Richfield has said, it's sometimes in spurts of rapid change, and as I pointed out it can be incremental and even useless! Still, one way or the other you have the furnace alive and well as long as there is life... or maybe even simple organic molecules.
jackson6612
#86
Aug1-10, 12:56 AM
P: 348
Quote Quote by nismaratwork View Post
It's still there, although it's true that there is no longer a literal primordial ooze (well, there is some in the seabed and in labs), but that's not what evolution is all about. Evolution is an ongoing process and I'm not sure that it's possible to be alive and "turn off the furnace". Your question is phrased in such a way that to answer without refuting your premise is impossible; evolutionary pressures change, and mutations constantly occur. This has not changed from ooze, to people. As Jon Richfield has said, it's sometimes in spurts of rapid change, and as I pointed out it can be incremental and even useless! Still, one way or the other you have the furnace alive and well as long as there is life... or maybe even simple organic molecules.
Hi Nismar

I have some questions. Please help me with them and also please also remember I'm a layman.

My question was more centered on the origin of life. I understand evolution is not about just the origins but still the origin is an important part.

I'm an English learner therefore I couldn't understand the part "turn off the furnace". Please help with it.

Would you mind telling me what was my premise?

In sum, are you saying that somewhere on earth chemicals are still combining to form living chemical beings?

Thanks for the guidance.
Jon Richfield
#87
Aug1-10, 04:00 AM
P: 258
Quote Quote by jackson6612 View Post

My question was more centered on the origin of life. I understand evolution is not about just the origins but still the origin is an important part.

I couldn't understand the part "turn off the furnace". Please help with it.
I assume that Nismar will not mind my contributing part of a reply?

Hm? I thought you, Jack, asked about the furnace?

Would you mind telling me what was my premise?
Well Jack, that was part of my problem as well. I (and I think Nismar) were having difficulty understanding your intention. It can be very difficult to answer a question when one does not understand what the question was intended to mean. Sometimes it turns out not to mean what the questioner thought it meant, and that leads to real difficulty.

In sum, are you saying that somewhere on earth chemicals are still combining to form living chemical beings?
I think what he meant (and certainly what I meant) was not necessarily that new living things are being formed from non-living chemicals. For one thing, it is possible that the conditions under which they formed on the ancient Earth are now too rare for life to be re-created, but if they are (it is quite possible in theory) then there are so many bacteria nowadays that any suitable new life molecules probably would get eaten up long before they got combined into new living things. Just think what happens to a new piece meat dropped into a pond! And that meat is far closer to life than any random molecules joining together.

But certainly some molecules that could be parts of living things if they got the chance, are being formed all the time, sometimes inorganically, sometimes as waste from living things.
nismaratwork
#88
Aug2-10, 09:52 AM
P: 2,284
Quote Quote by Jon Richfield View Post
I assume that Nismar will not mind my contributing part of a reply?

Hm? I thought you, Jack, asked about the furnace?



Well Jack, that was part of my problem as well. I (and I think Nismar) were having difficulty understanding your intention. It can be very difficult to answer a question when one does not understand what the question was intended to mean. Sometimes it turns out not to mean what the questioner thought it meant, and that leads to real difficulty.


I think what he meant (and certainly what I meant) was not necessarily that new living things are being formed from non-living chemicals. For one thing, it is possible that the conditions under which they formed on the ancient Earth are now too rare for life to be re-created, but if they are (it is quite possible in theory) then there are so many bacteria nowadays that any suitable new life molecules probably would get eaten up long before they got combined into new living things. Just think what happens to a new piece meat dropped into a pond! And that meat is far closer to life than any random molecules joining together.

But certainly some molecules that could be parts of living things if they got the chance, are being formed all the time, sometimes inorganically, sometimes as waste from living things.
I don't mind the assist at all, and you've said everything that I would have. Jackson, if you need any help, I think it's safe to say that Jon and I can probably cover it. I might add, that for someone learning English, you sound like a native speaker; well done!

Jon, well said.
Jon Richfield
#89
Aug2-10, 10:05 AM
P: 258
Quote Quote by nismaratwork View Post
Jackson, if you need any help, I think it's safe to say that Jon and I can probably cover it. I might add, that for someone learning English, you sound like a native speaker; well done!
Yes, I must say that I too have been wondering about that. Without wishing to pry, Jack, if you don't mind telling us what languages you are master of, I for one would love to know. But if you would rather not say, please don't bother.

Jon, well said.
Thanks mate! You too.

Cheers,

Jon


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