June 22nd, 2014, 06:50 PM
Why do male Humans have nipples?
It seems other Great Ape's -like Gorilla- males have nipples,... Why?
Nipples -and more so breasts- are a pure mammal thing unlest I am mistaken,.... so.....
... are there other mammal species where the males have nipples or not functional breasts?
It is a known fact that some male humans can lactate.
May it be a still under-construction Darwinian Biology Great Ape strategy for feeding the kids?
Because everything's much the same at conception and for several weeks of gestation. The divergence only happens when male hormones take over at about 6 weeks in human male foetuses. Nipple - Wikipedia, the free encyclopedia
And yes, male non-primate animals also have nipples even though they are often much less developed. Just look at people trying to determine the sex of newborn puppies or kittens. Why do they look at the genitals? It would be much easier and quicker to see by the presence or absence of nipples if that was how it worked. But it doesn't. Both sexes have nipples.
even simpler... we all start out as woman. So, contrary to bible thumpers, Eve was made before Adam.
Ahahaha that's brilliant grmpysmrf
Evolutionary, all biological organisms of the Animal Kingdom come from primate monoecious ancestors. Dieciousim is only first seen in Cnetophores as stages of development (through the reproductive stage). Though later its seen entirely in an organismal life cycle in later phyla. Thus, our rudiments are originated from asexual organisms that had both ovarian and testicular systems, though a much more prominent feminine features inorder to support offsprings.
Interestingly, morphologically, many of our rudimentary characteristics are conserved throughout most of our embryonic stages. This also explains why embryos in different species and even between phyla look similar. Also, explains the "nipple" phenomena.
Last edited by AndresKiani; June 23rd, 2014 at 06:02 AM.
I've never really gotten the hang of the embryo/fetus's sex organ development, perhaps someone here can elaborate a little more if it isn't too off topic.Originally Posted by adelady
When you mentioned hormones, does the mother or the fetus itself determines which hormones to produce? To simplify, is the sex of the fetus determined upon gestation, or is there room for external "influence"?
The mother for given birth. But the fetus for development.
Its actually the few instances where positive feedback is implemented in hormonal regulation.
One of the reasons I'm asking is because I was under the impression that the sperm (either carrying the X or Y chromosome) upon fertilizing the egg (carrying only the X chromosome) determines the sex of the would-be fetus. If that is accurate, I'm just wondering why fetal development doesn't have distinct differences during sex organ development. I'm honestly curious as to why that is. Is it a more efficient template or something?
One of the reasons I'm asking is because I was under the impression that the sperm (either carrying the X or Y chromosome) upon fertilizing the egg (carrying only the X chromosome) determines the sex of the would-be fetus. If that is accurate, I'm just wondering why fetal development doesn't have distinct differences during sex organ development. I'm honestly curious as to why that is. Is it a more efficient template or something?
It actually does, for example, the DHT and Testosterone hormone regulate the development of the male sexual parts. Interestingly, the "female" related hormone estrogen develops the male brain.
In females estrogen is blocked and converted into another molecule before it reaches the brain, this allows the females brain to develop into a "feminine brain". On the other hand estrogen and progesterone regulate the female sexual parts.
All members of the Animal Kingdom come from primate ancestors? Even though mammals existed for millions of years before the first primates? Illogical, this is some really bizarre evolutionary anthropocentrism.
[/QUOTE]Dieciousim is only first seen in Cnetophores as stages of development (through the reproductive stage).[/QUOTE]
Most Cnetophores lack a larval stage, they progress from egg straight to a miniature form of their adult stage. Most Cnetophores are hermaphroditic immediately after the egg stage (though the eggs and sperm they produce are in very small quantities.)
[/QUOTE]Though later its seen entirely in an organismal life cycle in later phyla. [/QUOTE]
Asserting that in later phyla (I'm assuming that you mean bilaterians?) organisms change from hermaphroditic to dioecious throughout their life cycle? True, however, many of these animals are hermaphroditic ONLY prior to birth, and subsequently are dioecious throughout adolescence/adulthood.
[/QUOTE] Thus, our rudiments are originated from asexual organisms that had both ovarian and testicular systems, though a much more prominent feminine features inorder to support offsprings. [/QUOTE]
Cnetophores operate with external fertilization (with a few exceptions), external fertilization is not asexuality (though most would say it lacks intimacy).
[/QUOTE]Interestingly, morphologically, many of our rudimentary characteristics are conserved throughout most of our embryonic stages. This also explains why embryos in different species and even between phyla look similar. Also, explains the "nipple" phenomena. [/QUOTE]
Evolutionary recapitulation has been largely discredited. It's the biological equivalent of Freudian theory.
Lol.. I meant NOT "PRIMATE" *typo, I was writing response on phone and my phone likes to fill in the words for me before I even finish typing. I meant "PRIMATIVE".
Also Cnidarians and Ctenophores where just a quick example of "primitive" dieocious organisms. Another one could have been Rotifers. I was not referring to their secondary sexual system as they do not possess one, only the fact that their dieocious at some point in their development.
Yeah, I read somewhere that recapitulation is no longer a popular idea. Though, I figured that embryogenesis is a good example of conserved features between different embryonic taxa and gets the point across.
Last edited by AndresKiani; June 23rd, 2014 at 11:54 AM.
Outdated science is outdated science. "Primitive" makes most of my quibbles irrelevant, Cnetophores are also hermaphroditic throughout more-or-less the entirety of their life cycle. As I am unaware of any macro-surgeons who would surgically make said Cnetophores dioecious.
P.S: I LOATHE discussing biology because (A) Out of my "jurisdiction", so to speak. (B) Filled with sesquipedalian terms, therefore any discussing of it using said terms causes the typer to appear a bit, er... continental philsophy-y (not a true adjective).
What is your argument? Lol. We all are well aware that for the most part Ctenophores do not perform sexual reproduction but some species of Ctenophores experience dimorphism at one point as your pointing out. Even though recapulation is an out dated idea, the conservation seen in embryology is a good example of decent with common ancestor.Outdated science is outdated science. "Primitive" makes most of my quibbles irrelevant, Cnetophores are also hermaphroditic throughout more-or-less the entirety of their life cycle. As I am unaware of any macro-surgeons who would surgically make said Cnetophores dioecious.
P.S: I LOATHE discussing biology because (A) Out of my "jurisdiction", so to speak. (B) Filled with sesquipedalian terms, therefore any discussing of it using said terms causes the typer to appear a bit, er... continental philsophy-y (not a true adjective).
I'm not a Biologists either, and I don't really like Biology. I'm more of Chemistry, Biophysics, and Neuroscience interest.
External fertilization is not asexual. It is a form of sexual reproduction. I'm making no argument, only finding/pointing out/fixing inaccuracies.What is your argument? Lol. We all are well aware that for the most part Ctenophores do not perform sexual reproduction but some species of Ctenophores experience dimorphism at one point as your pointing out. Even though recapulation is an out dated idea, the conservation seen in embryology is a good example of decent with common ancestor.Outdated science is outdated science. "Primitive" makes most of my quibbles irrelevant, Cnetophores are also hermaphroditic throughout more-or-less the entirety of their life cycle. As I am unaware of any macro-surgeons who would surgically make said Cnetophores dioecious.
P.S: I LOATHE discussing biology because (A) Out of my "jurisdiction", so to speak. (B) Filled with sesquipedalian terms, therefore any discussing of it using said terms causes the typer to appear a bit, er... continental philsophy-y (not a true adjective).
I'm not a Biologists either, and I don't really like Biology. I'm more of Chemistry, Biophysics, and Neuroscience interest.
I don't think you read my comments very well, I said "not sexual reproduction". Though are dioecious species and that's the whole point of the argument. That biological organisms where originally monoecious up to the point of the Radiates and the other primitive organisms that started expressing dioeciousim, even if it was for a short time in their life cycle.External fertilization is not asexual. It is a form of sexual reproduction. I'm making no argument, only finding/pointing out/fixing inaccuracies.What is your argument? Lol. We all are well aware that for the most part Ctenophores do not perform sexual reproduction but some species of Ctenophores experience dimorphism at one point as your pointing out. Even though recapulation is an out dated idea, the conservation seen in embryology is a good example of decent with common ancestor.Outdated science is outdated science. "Primitive" makes most of my quibbles irrelevant, Cnetophores are also hermaphroditic throughout more-or-less the entirety of their life cycle. As I am unaware of any macro-surgeons who would surgically make said Cnetophores dioecious.
P.S: I LOATHE discussing biology because (A) Out of my "jurisdiction", so to speak. (B) Filled with sesquipedalian terms, therefore any discussing of it using said terms causes the typer to appear a bit, er... continental philsophy-y (not a true adjective).
I'm not a Biologists either, and I don't really like Biology. I'm more of Chemistry, Biophysics, and Neuroscience interest.
True hermaphroditism, is actually a form of sexual reproduction and may or may not be sexual in some instances.
the father determines the sex of the child based on what the sperm designates once it's in the egg.
When you mentioned hormones, does the mother or the fetus itself determines which hormones to produce? To simplify, is the sex of the fetus determined upon gestation, or is there room for external "influence"?
Only for more than 100 years or so.
you don't need to drag ancient theories out of the dusty library to get points across with embrogenesis. Do it with modern developmental biology.
Anything else is just sloppy thinking.
If its such "crappy thinking", why is Ontogeny with special emphasis on embryogenesis still a widely studied focus in developmental biology and evolutionary biology. Even though recapitulation is not expected anymore.. Embryogenesis is still a good example of "decent with common ancestor", and is still studied.Only for more than 100 years or so.
you don't need to drag ancient theories out of the dusty library to get points across with embrogenesis. Do it with modern developmental biology.
Anything else is just sloppy thinking.
You guys kill me with this pseudoscience, crappy thinking, and complete woo, accusations. The last time I checked embryogenesis was still a valid argument for decent with common ancestor against creationists. Somehow here it becomes crappy thinking. Keep in mind I didn't even bring up the "idea" of recapitulation until shlunka brought it up, otherwise I was specifically pointing out decent with common ancestor and how most organisms start off as females. You can't tell me that embryogenesis in variety of taxa, is not studied in 2014, and if you want I will bring up specific papers on it in 2014.
Last edited by AndresKiani; June 24th, 2014 at 10:19 AM.
But there's a failsafe mechanism built in.the father determines the sex of the child based on what the sperm designates once it's in the egg.
There's no difference between zygotes and early foetuses before about six weeks gestation. At that point, a potentially male foetus starts on the hormonal, developmental path towards full development as a male. If anything goes wrong with that, but not so wrong as to result in miscarriage, the foetus can continue development as partly, mostly or entirely female.
This also not a universal concept in biology, there is plenty of other exceptions to this rule.
Like what?
The only reason I even know the male is responsible for the sex of the child is because the irony of King Henry III. He killed all his wives for not bearing him a son when in reality it was his fault he had no son.
So the limit of my bio education is based on ironic history.
Exceptions to this rule are:Like what?
The only reason I even know the male is responsible for the sex of the child is because the irony of King Henry III. He killed all his wives for not bearing him a son when in reality it was his fault he had no son.
So the limit of my bio education is based on ironic history.
Asexual Organism obviously don't use the male Y chromosome to determine sex.
Then we have examples of sexual organisms who also don't rely on the Y chromosome to determine sex.
1. Sequential Hermaphrodites - these are fishes and insects, where they are born female but will eventually transform into males. Male Y chromosome does not determine sex here.
2. Other Hermaphorodites - unlike what Shlunka was saying, "hermaphroditism" can be sexual. When it is the Y chromosome is not used to determine sex.
3. Parthenogenesis - activation of zygote with no meiosis state. This is seen in insects, rotifers, flatworms, crustaceans. Y chromosome does not determine sex.
4. Gynogenesis - in these animals sperm is used only to initiate fertilization of zygote, but the male chromosomes are not passed to the offspring.
5. Haplodiploidy - seen in Bees and Wasps, the male chromosomes do not influence the outcome of the offspring's gender. The Queen Bee or Wasp, will take in and store the males sperm, however she may or may not use it. This will determine whether or not her eggs will be female or male bees, fertilized eggs become female offspring and unfertilized eggs become male offspring. Y chromosome is not a determining factor.
Other examples..
- In birds, the DMRT1 gene functions as a gender determining gene, rather than the traditional SRY gene on male Y chromosome.
- Also, in some cases the X chromosome is the sex determining gene, specifically the WNT4 and DAX1 genes on the X chromosome.
- More so, in some fishes and reptiles, gender is determined by temperature fluctuations, and even behavioral rituals. In crocodilians, many turtles, and some lizards, the incubation temperature of the nest determines the sex of the offspring.
Last edited by AndresKiani; June 25th, 2014 at 10:42 AM.
Most (if not all) mammalians however, rely on the Y chromosome SRY gene to determine sex of offsprings.
Is that why mammals are such sorry creatures?
The real question is why should they not have nipples? For a characteristic to be eliminated by the evolutionary process it needs to have a negative impact on its bearer's ablity to reproduce or survive to reprodutive age. If a characteristic is neutral or has only a slight positive impact on reproduction it is very likely to be retained. Contrast this with flight. The ablity to fly is very energy intensive and limits the physical size of an organism. Birds that for some reason no longer need to fly very rapidly lose the ablity. Domesticated fowl, lose the ablity to fly in a few generations. Large sized males have a reproductive advantage and if they don't need to be able to fly to escape preadetors and find food then the largest males will reproduce with geater success than the smaller but more areodynamic competitors.
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