From which gene does intelligence come from--the X or the Y?

Question

And is the male's Y gene dissolving? I know the answer--just want to see if you know the answer--I was surprised by the what I discovered!

Answer 1

G'day Tampagirl1015,

Thanks for your question.

Considering the way some men have behaved, many have said it must be the X chromosome that has the intelligence genes. :>) This seems to have been borne out by research.

Due to problems with the Y chromosome, men rely more on their X chromosome. Accordingly, they have more genetic problems such as retardation. However, there are also more male geniuses as they may have a genetic predisposition to high intelligence on their X.

The Y chromosome has slowly degraded over time.

Many ectothermic vertebrates have no sex chromosomes. If they have different sexes, sex is determined environmentally rather than genetically. For some of them, especially reptiles, sex depends on the incubation temperature, others are hermaphroditic.

The X and Y chromosomes diverged around 300 million years ago when some reptile, the distant ancestor of all mammals, developed a so-called 'male gene' - simply possessing this gene caused the organism to be male. The chromosome with this gene became the Y chromosome, and a similar chromosome without it became the X chromosome. So initially, X and Y chromosomes were nearly identical. Over time, genes which were beneficial for males and harmful to (or had no effect on) females either moved to or developed on the Y chromosome.

Recombination between the X and Y chromosomes proved harmful - it resulted in males without necessary genes formerly found on the X chromosome, and females with unnecessary or even harmful genes previously only found on the Y chromosome. As a result, genes beneficial to males assembled near the sex-determining genes in order to make this less probable. Eventually, the Y chromosome changed in such a way as to inhibit the areas around the sex determining genes from recombining at all with the X chromosome.

With time, larger and larger areas became unable to recombine with the X chromosome. This caused its own problems: without recombination, the removal of harmful mutations from chromosomes becomes increasingly difficult. These harmful mutations continued to damaged Y-unique genes until several finally stopped functioning and became genetic junk; this eventually being removed from the Y chromosome.

As a result of this process 95% of the human Y chromosome is unable to recombine, the chromosome itself contains only 78 working genes; compare this to close to 1000 working genes on the X chromosome. In some animals, Y degradation is even more severe. For example, the kangaroo Y chromosome contains only the SRY gene.

After only an SRY (or other sex-determining) gene remains from the whole Y chromosome, there are the following possibilities:

* The gene is connected to X chromosome or some autosome, making it the new Y chromosome. The whole process starts again. This has happened with two species of mole vole (Ellobius tancrei and E. lutescens). In one species, both sexes have unpaired X chromosomes; in the other, both females and males have XX.
* Part of some autosome is connected to both the X and Y chromosomes. This happened with one species of Drosophila.

The Y chromosome has the ability to regenerate and will be around for a while yet.

I attach some sources for your reference.

Regards

Answer 2

Intelligence comes from the brain. Genes to make the brain are likely present on just about all the chromosomes except the Y. LOL.

The Y chromosome is not dissolving,. It's still the "sex determiner" chromosome. In time, through genetic drift, it may lose some of its genes to the other chromosomes -- but enough will remain so that its presence will determine maleness.

Answer 3

You see the thing about genetics is that it is science and the thing about science is that you need to do experiments. Now to do the experiment to test if there is a genetic basis to intelligence (let alone what gene is responsible lol) we would need to do unbiased crosses. In placental mammals this is simply imposable because we cannot have two genetically identical individuals placed in different environments. You might think of identical twins separated at birth but they have still shared a virtually identical environment in the womb. On top of that adoption agencies try to place children with families similar to that of their biological presence. These two factors make it imposable to deduce if intelligence has a genetic or environmental basis (or of course a combination of the two)

The next point is that intelligence is a very complex thing and if we assume a genetic basis, at least in part, there will undoubtable be many genes involved. Simply put it is ludicrous to assume that one gene and consequently one single protein be responsible. You could argue that this gene might in fact turn on other genes to give the 'indigence' phenotype however this is again unlikely.

Answer 4

Intelligence comes from the X chromosome. Smart son is most likely because of mom's Mother passing on the gene.

Answer 5

it is not on either gene. it is on a seperate cromosome altogether