Dear Researchers,
I wish to know who the first in life.. whether male or female ?
I feel that males are adaptive form of females, where the males possess some of the female characters like chest and nipples. But how extend it can be evident that the males are adoptive form of females or vise-versa.
There is a very simple answer to that: all embryos will develop into females - however - if TDF1 is expressed from the Y-chromosome, then a female embry will become a male embryo. There is plenty knowledge about this. TDF1 is "testicle determining factor 1". This transcription factor is driving all the male embryogenesis. Genetic males with defects in TDF1 will end with a complete female phenotype. Thus, man is not the adaptive form of woman, but a derivative.
with kind regards
Rolf
you mean adaptive? I think It is hard to say that. It seems that male does not show great advantage than female, however, the opposite is true sometimes. For example, the lifespan of female is longer than male.
I would strongly say that man are from the women.. Similarities of female characters in male are chest-nipples, they develop from the fetus that develop testosterone, excess of testosterone turns the females into males.
30,000 genes to built a human, one SRY to built a man.
Its like a Switching on and off of the SRY chromosome. Switching ON of the Male and Switching OFF Female.
I think, an observation in a certain species of reptiles can help by comparison.
The females of the species can / are known to reproduce offspring without the aid of male members but through the 'aid' of another female member. Can a male produce offspring in the same manner? Not known.
Female is the inherent nature; male characteristics are 'add-ups'. An embryo, without the presence of male hormones, develops female organs and characteristics by default.
Maybe you are right in that men are from women, or we say, males have more characteristics on the basis of females. However, even if this is true, it doesn't mean male is more adaptive. I think in evolutionary biology, 'adaptive' means that the organisms show greater advantage fitting the environment.
There is a very simple answer to that: all embryos will develop into females - however - if TDF1 is expressed from the Y-chromosome, then a female embry will become a male embryo. There is plenty knowledge about this. TDF1 is "testicle determining factor 1". This transcription factor is driving all the male embryogenesis. Genetic males with defects in TDF1 will end with a complete female phenotype. Thus, man is not the adaptive form of woman, but a derivative.
with kind regards
Rolf
Agree with Rolf's comments! 'derivative' is more accurate than 'adaptive'.
derivate is more appropriate to the fact you asked about. Mirgendra A. is talking about parthenogenesis: animals who can clone themselfs as in the outcome of offspring, this species populations consists only out of female subjects, best example: gecko: lepidodactylus lugubris.
evolutionary sexual reproduction is believed to be the most adaptive reprod.-strategy to answer and adapt to envrionmental change. therefore the merge of two stranger genetic strings posseses a higher variability and especially a flexibility because the storage of traits is within the individuals of one population and not only one individual.
A sexual dimorphismus which is most highlighted in vertebrats devides the strategy of pre and post investigation in offspring and population fitness as a solution in the size and noumerous in gamete production. There are evidences that small eukaryonts devide in different reproduction strategies within one species without any gender devision in dimorphism or genetic identity.
Why man have chest nippels without any function as female have our Prof in ecology once introduced us a Theory about selction pressure: Men have nippels because there is no selection pressure on having non. Beside that it is a trait of the spezies, as for example other mamels have more then a pair. Female mouse have additional axillary nippels. In a way male mouse undergo a seleciton pressure about their fitness having no axillary nippels ;-)
Your question askes for who was fist? Considering the facts you should ask which reproduction-strategy was first. For that you have to go back to eukaryots.
Dear Aksay you said excess of testoterone converts female to male, vice versa less of testesterone converts male to female. The incorporation of Y gene makes the difference..
Life is a mix, Male has female characters, and female has male characters. one is not derived from the other, nor is one totally dependent on the other. there is existance and sustenance, reproduction is a part to extend your progeny,
If hormones were to decide then the world would have had only males and fewfemales.
What about birds who have a completely different chromosomal sex-determination system? There it is obviously not known what is the inherent gender.
From an embryological point of view I agree with Rolf male is derivative from female but actually a fetus is potentially both, the mullerian duct is in both male and female fetuses. Testosterone drive testicles to produce and secrete anti-mullerian protein and this results in self-destruction of the mullerian duct cells, the duct breaks down and we have a male. AMH is really important in the process and I was quite surprised to know that there is correlation between AMH and perception of sexual identity in some inividuals so it is not just an hormones story.....
Hello guys. If still interested keep an eye on this interesting review
http://www.ncbi.nlm.nih.gov/pubmed/23450642
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