sino:
@tintingz

You cannot try to explain the origin of man with evolution, and then neglect the species in which man is said to have evolved from, more so, if the said ancestral Adam and Eve science is talking about are already fully formed, with reproductive organs, then it makes no sense arguing about having just one sex chromosome. The reason I had to ask whether humans had any record of reproducing asexually. I would love to ask you, how did the ancestral male, Y chromosomal Adam, and female, mitochondrial DNA Eve came into existence?! Who did science say were their ancestors?! Were they also distinguished as male and female?! If you want to talk evolution and science, you can’t cherry pick; you should be ready to follow through with scientists’ hypotheses.

Again the nomenclature of Y and X chromosomes, are just what they are, labels to identify each distinct chromosome. Mutation and recombination of the chromosomes, would not have happened in this ancestral Y chromosomal Adam, and ancestral Eve, we have already a fully formed distinguished male and female, in fact, it is said that there were other males and other females, are you trying to tell me that those males and females where carrying other forms of chromosomes and they are still humans?!

To your request for me to show you where science says the first man carried both X and Y chromosome, fortunately, your quote supports my arguments,

"One hundred and eighty million years ago, the Y chromosome of placental mammals was the same as our X chromosome, and sex was determined by other means, perhaps by environmental triggers such as temperature (as is the case in some turtles, lizards, and snakes today). These two proto-sex-chromosomes underwent recombination in the same way that our other chromosomes do. Then a male-determining gene originated on the would-be Y, and the two chromosomes started to diverge from one another. Once the Y started to become specialized for male genes, recombination between the X and Y became detrimental for individuals because the process sometimes mixed up the sex-determining genes."

If you read the bold above carefully, you would see that the Y chromosome was the same as our X chromosome, meaning the X and Y chromosome, at some point were the same, and sex was determined by other means, the word perhaps (in bold) suggest a speculation, unsubstantiated and unverified.

Now the TWO proto-sex-chromosomes (i.e Y and X, although similar), underwent recombination, just as other chromosomes do. Then the gene, which should not be confused with the Y chromosome, that determines male, was established on the Y chromosome, which eventually made recombination between the chromosomes problematic.

From the site you quoted from, it then continued:

"Ultimately, this process resulted in Y chromosomes that barely recombined with the Xs at all—just a little near the tips of the chromosomes, enough to keep cell division orderly, but not enough to move genes bits from one chromosome to the other. Of course, in females (bearers of two X chromosomes), the Xs could still recombine with another X. It was only in males that repressed recombination was advantageous. This innovation worked well for keeping sex determination straight, but it also had a detrimental side effect for the integrity of the Y chromosome."

Here it says how the Y and X chromosomes are associated in males, establishing order and restriction of gene transfer and continuous sex determination.

I hope you can see that there were two sex chromosomes 180 million years ago. This would also answer how the females were having two X chromosomes, that can exchange genes, only in the males that repressed the recombination between X and Y, due to that fact that the male-determining gene is present on it.

Again with this facts, then if the Ancestral Adam and Eve had just Y and X respectively, then their offspring would only be male. I didn't want to go back to discussing haploid and diploid, there are so many unsubstantiated hypotheses, there are large dark areas which science have not been able to answer and clarify.

This should put this argument to rest bro.

The theory I posted shows sex chromosome of our ancestors are different from ours today(modern human) am not arguing about diploid or haploid all am saying is there are evolutionary stages.

As you can see from what I posted says Y chromosome of mammals and X chromosome of humans are the same(a single cell functional) and sex was determine by environmental temperature which means baby gender was not a result of Y or X chromosome until mutation took place and chromosome recombined diverging X and Y(in offsprings) Evolution is evolution it took stages for humans to evolve to homo sapiens.

A little history of Science Adam.

The Book of Genesis puts Adam and Eve together in the Garden of Eden, but geneticists’ version of the duo — the ancestors to whom the Y chromosomes and mitochondrial DNA of today’s humans can be traced — were thought to have lived tens of thousands of years apart. Now, two major studies of modern humans’ Y chromosomes suggest that ‘Y-chromosome Adam’ and ‘mitochondrial Eve’ may have lived around the same time after all.

When the overall population size does not change (as is likely to have happened for long periods of human history), men have, on average, just one son. In this case, evolutionary theory predicts that for any given man there is a high probability that his paternal line will eventually come to an end. All of his male descendants will then have inherited Y chromosomes from other men. In fact, it is highly probable that at some point in the past, all men except one possessed Y chromosomes that by now are extinct. All men living now, then, would have a Y chromosome descended from that one man — identified as Y-chromosome Adam. (The biblical reference is a bit of a misnomer because this Adam was by no means the only man alive at his time.)

Similarly, the theory predicts that all mitochondrial genomes today should be traceable to a single woman, a 'mitochondrial Eve'. Whereas the Y chromosome is passed from father to son, mitochondrial DNA (mtDNA) is passed from mother to daughter and son.

http://www.nature.com/news/genetic-adam-and-eve-did-not-live-too-far-apart-in-time-1.13478?WT.mc_id=FBK_NatureNews
The above is what science believe in.

From the history it shows other men chromosome died out, one man chromosome can be traced to all living humans. There is no where it says science Adam had X chromosome from what I posted.

I have given different link talking about science Adam :

tintingz:
The theory I posted shows sex chromosome of our ancestors are different from ours today(modern human) am not arguing about diploid or haploid all am saying is there are evolutionary stages.

As you can see from what I posted says Y chromosome of mammals and X chromosome of humans are the same(a single cell functional) and sex was determine by environmental temperature which means baby gender was not a result of Y or X chromosome until mutation took place and chromosome recombined diverging X and Y(in offsprings) Evolution is evolution it took stages for humans to evolve to homo sapiens.

A little history of Science Adam.

The Book of Genesis puts Adam and Eve together in the Garden of Eden, but geneticists’ version of the duo — the ancestors to whom the Y chromosomes and mitochondrial DNA of today’s humans can be traced — were thought to have lived tens of thousands of years apart. Now, two major studies of modern humans’ Y chromosomes suggest that ‘Y-chromosome Adam’ and ‘mitochondrial Eve’ may have lived around the same time after all.

When the overall population size does not change (as is likely to have happened for long periods of human history), men have, on average, just one son. In this case, evolutionary theory predicts that for any given man there is a high probability that his paternal line will eventually come to an end. All of his male descendants will then have inherited Y chromosomes from other men. In fact, it is highly probable that at some point in the past, all men except one possessed Y chromosomes that by now are extinct. All men living now, then, would have a Y chromosome descended from that one man — identified as Y-chromosome Adam. (The biblical reference is a bit of a misnomer because this Adam was by no means the only man alive at his time.)

Similarly, the theory predicts that all mitochondrial genomes today should be traceable to a single woman, a 'mitochondrial Eve'. Whereas the Y chromosome is passed from father to son, mitochondrial DNA (mtDNA) is passed from mother to daughter and son.

http://www.nature.com/news/genetic-adam-and-eve-did-not-live-too-far-apart-in-time-1.13478?WT.mc_id=FBK_NatureNews
The above is what science believe in.

From the history it shows other men chromosome died out, one man chromosome can be traced to all living humans. There is no where it says science Adam had X chromosome from what I posted.

I have given different link talking about science Adam, I think I will take a break.

There is no way you want to talk about human reproduction and evolution without discussing haploid and diploid, the fact remains that humans are diploid, and nowhere in the science world claim haploid for humans. All what you had presented only states how the Y chromosome can be traced back to the Y chromosomal Adam for the MALE. It did not state that this science Adam had only the Y chromosome. You are the one claiming so, which I had tried to explain how impossible that would be.

You amuse me when you say that the quote was talking about mammals and not humans, what are humans if not a subset of mammals?! It is either you state that the science Adam and Eve evolved from closely related mammal, or just came into existence by magic or chance! The evolution you are talking about did not happen within the science Adam and Eve (except for probably the shrinking of the Y chromosome), they were already having their X and Y chromosomes fully developed, which are in pairs of either XY or XX. As stated earlier, the mitochondrial DNA which can only be passed down from the mother is not the X chromosome, and it is not responsible for sex determination! So how did the X chromosome came into existence?! mutation and recombination of the Y chromosome which was said to be from the X chromosome (according to the evolutionary history of Y chromosome which you presented)?!

You should understand that, Y chromosome, which is said to be carrying the male gene, was as a result of a pre-existing chromosome, and this is said to be the X chromosome (this is the point were evolution occurred). In the process of favouring sexual reproduction, chromosomes, which are in pairs, aggregate and recombine in an orderly manner for proper gene transfer, as well as eventually undergo meiosis, which result in the donation of one chromosome from each partner to bring about a new offspring carrying pairs of chromosomes. I had brought evidences that suggests that meiosis and sex must have evolved together, because it is quite impossible to reproduce sexually, without meiosis. The reason I was asking if humans had a history of reproducing asexually.

The above quote of yours, especially the bold, only proposes that all men (during this Y chromosomal Adam) possessed the Y chromosome which are all extinct except one which the scientist can trace the male ancestry to. It does not suggest otherwise, and it does not negate that those men had X chromosome. The story of Adam and Eve would have been easily countered by scientists, if such men's Y chromosome still exists today.

To help put this my long story into proper perspective, read this:

"But in life forms that do set aside a pair of chromosomes to specify sex – from fruit flies to mammals and some plants – the two X chromosomes inherited by females look nearly identical to the other non-sex chromosomes, so-called autosomes, Bachtrog said. The Y chromosome, however, which is inherited by males in concert with one X chromosome, is a withered version of the X, having lost many genes since it stopped recombining with the X chromosome.

In mammals, that probably took place about 150 million years ago, while in the fruit fly Drosophila melanogaster, a laboratory favorite, the sex chromosomes arose independently about 100 million years ago. In both humans and fruit flies, the Y chromosome has dwindled from a few thousand genes to a few dozen."

https://www.sciencedaily.com/releases/2009/04/090416125209.htm

Personally, I do not believe anything about evolution, perhaps, maybe some aspects that can be verified, but all these speculations, and hypotheses are just imaginations of scientist with little known facts and evidences.

Many thanks for your time though...

@ Sino, all our argument falls under same scientific theories from evolution to genetic the only thing you fail to understand is the time and duration evolution took place.

• Before the first human(Lets say Neanderthal) evolve to homo sapiens, what were their genetic? It can never be both X and Y and if we agree to this, logically and scientifically the first man must have had a mother(parents) for him to inherit the X chromosome.

•There is no where scientist said the first man had X chromosome if not their will be a test using X chromosome to trace the male descendant patrilineally if we agree the first man had X chromosoe but the X can only be trace matrilineally which means the X chromosome didn't exist in the first man until mutation.

• Meiosis took place from haploid to diploid, the question is did all these cells cycle happen in one night? Because from science history It took years for humans to evolve completely.

• million years back Sex was determined by environmental triggered such as temperature not by X and Y chromosome because X and Y were the same( single cell and automatically the first man will be carrying Y) until mutation occur and chromosomes recombined separating X and Y( shrinking the Y). The question is did all these happened in the first man or offsprings because from the article the homo sapiens were already given birth to babies before mutation took place.

• The first man had two sons(first two children), most early men had sons. There were other early men with chromosomes but their linage can't be traced because it died out, only one man chromosome can be traced to all living humans.

I really enjoyed this discussion. Thanks bro.