The End of Men? Male Sex chromosome is slowly disappearing
This discussion thread was locked as off-topic by muriel_volestrangler (a host of the Latest Breaking News forum).
Source: Newsweek
The Y chromosome may be a symbol of masculinity, but it is becoming increasingly clear that it is anything but strong and enduring. Although it carries the master switch gene, SRY, that determines whether an embryo will develop as male (XY) or female (XX), it contains very few other genes and is the only chromosome not necessary for life. Women, after all, manage just fine without one.
Whats more, the Y chromosome has degenerated rapidly, leaving females with two perfectly normal X chromosomes, but males with an X and a shriveled Y. If the same rate of degeneration continues, the Y chromosome has just 4.6 million years left before it disappears completely. This may sound like a long time, but it isnt when you consider that life has existed on Earth for 3.5 billion years.
The Y chromosome hasnt always been like this. If we rewind the clock to 166 million years ago, to the very first mammals, the story was completely different. The early proto-Y chromosome was originally the same size as the X chromosome and contained all the same genes. However, Y chromosomes have a fundamental flaw. Unlike all other chromosomes, which we have two copies of in each of our cells, Y chromosomes are only ever present as a single copy, passed from fathers to their sons.
This means that genes on the Y chromosome cannot undergo genetic recombination, the shuffling of genes that occurs in each generation which helps to eliminate damaging gene mutations. Deprived of the benefits of recombination, Y chromosomal genes degenerate over time and are eventually lost from the genome.
Read more: http://www.newsweek.com/end-men-y-chromosome-slowly-disappearing-785043
Eliot Rosewater
(31,109 posts)demigoddess
(6,640 posts)ten thousand years. I think I believe him more than Newsweek's source.
Cary
(11,746 posts)Our species, homo sapiens sapiens, is 50,000 years old.
Kajun Gal
(1,907 posts)blue-wave
(4,352 posts)What a horribly sexist thing to say. Wasn't there a huge march across our nation this past weekend with lots of women and men in attendance? What the hell were they all marching for? So you can help divide, rather than heal any wounds between the sexes? I'm old enough to have witnessed good and bad in all races, ethnic groups and both sexes. Let's stop the divisive language and all seek a higher plain.
Skittles
(153,150 posts)MLAA
(17,282 posts)Unfortunately I expect we wont be around in 50 years, let alone thousands or millions of years.
StevieM
(10,500 posts)We are definitely in big trouble. It is going to take a massive change to our energy economy and a whole lot of geoengineering to save us.
Are just trying to make it until next Tuesday.
Every day I count my blessings- and hope that the Orange Orangutang doesnt blow up the planet.
democratisphere
(17,235 posts)BigmanPigman
(51,584 posts)unfortunately.
Xipe Totec
(43,890 posts)To be a male with a given last name, you have inherit your father's Y chromosome. So a frequency analysis of last names tells you which Y chromosomes are being successfully propagated, and which ones are failing to propagate. Fragile Y chromosome leads to progeny that are all, or mostly all, females.
So looking at the frequency of last names tells you which Y chromosome strains have been successful, and which are disappearing from the earth.
So, Y chromosomes do not have the advantage of recombination, but they are consequently subjected to more intense natural selection. The slightest defect in copying that affects reproduction leads to the extermination of that particular strain of Y chromosome.
Males are not disappearing.
But last names are.
Rollo
(2,559 posts)The disappearance of paternal last names - if it is happening - could easily be explained by several social factors that have nothing to do with biology or putative degradation of the Y chromosome:
1) More unmarried couples having kids, and the kids get to choose their last names
2) More single women having kids - but they still need that sperm to do it
3) Couples with kids splitting up, with the woman keeping the kids and giving them her last name
4) Unmarried new mother frequency rising
Probably more, but that's what comes to mind.
tymorial
(3,433 posts)Xipe Totec
(43,890 posts)At least in our societies last names are inherited from fathers who are the carriers of the Y chromosome. So last names are associated with chromosomes. One of them specifically; the Y chromosome. And although females inherit their last names from their fathers, they do not pass them on to their children who inherit their last names from their fathers in turn.
So, yea, although there is no 'last name' chromosome, last names are correlated to chromosomes.
Loki Liesmith
(4,602 posts)Ccarmona
(1,180 posts)A study published last week in Australia revealed that more than 99 percent of the juvenile and sub adult population on the northern part of the reef are female, and 69 percent are female on the southern reef. Their sex is determined when they are developing embryos based on the temperature of the sand they are incubating in. The two populations are genetically distinct.
jl_theprofessor
(95 posts)People should probably look up the original journal article (2012) and the subsequent articles that have been produced since then.
Honeycombe8
(37,648 posts)Stardust1
(123 posts)The environment being in tatters will kill us off first. Besides I'm pretty sure we have the medical knowledge to reproduce without men or modify embryos to get more males if it really did become a problem.
Laffy Kat
(16,377 posts)Of course, all offspring would be female.
Puzzledtraveller
(5,937 posts)bucolic_frolic
(43,128 posts)or test tube mixers
Lokilooney
(322 posts)I should probably add some non snark so:
https://www.scientificamerican.com/article/the-male-sex-chromosome-isn-t-shrinking/
1977... it amazes me how long we've had to fix it.
Puzzledtraveller
(5,937 posts)Stardust1
(123 posts)How so?
Puzzledtraveller
(5,937 posts)about the coming ice age, it's quite entertaining, not because the real deadliness of such an event and they examples used in the episode but the freaky 70's music used to accent the episode. Leonard Nimoy ads to creep effect. I did watch these as a kid and love seeing them again on Youtube.
snort
(2,334 posts)Animals go extinct all the time, why should we be any different?
Rollo
(2,559 posts)The main purpose of the Y chromosome is to signal the embryo to develop as a male. It really is not needed for anything else. It's like a light switch, which used to be burdened with extraneous wiring but that has gradually gone away since it's not needed.
Will males themselves disappear? Quite unlikely - they are still needed to provide sexual recombination for all the non-Y chromosomal information. If parthenogenesis was such a great adaptation we'd see a lot more of it in the animal world. Instead it's rare and limited to relatively primitive life forms.
It sounds like sensationalist rubbish to me.
Rollo
(2,559 posts)burrowowl
(17,638 posts)jl_theprofessor
(95 posts)From more than five years ago. They won't let you cite that in a dissertation but we'll just make new articles about it in 2018 and spread sensationalist garbage throughout the internet.
Hekate
(90,645 posts)...with all the necessary information: XDot -- Y Not? Calling it a "shriveled Y" sounds like phallic anxiety rather than scientific description.
We're a young species, and thanks largely to our own foolishness, such as breeding like crazed rabbits and destroying the Earth, we are not likely to last another 10,000 years, much less 4 1/2 million.
jmo
dweller
(23,628 posts)humans as a species are quite resilient, so much so as to be as mysterious and magical as most of Nature surrounding us
not going to fret this 🙏🏻
canetoad
(17,152 posts)That argues both for and against. I'll post the abstract, the whole article is free and available online.
https://link.springer.com/article/10.1007%2Fs10577-011-9252-1
Is the Y chromosome disappearing?Both sides of the argument
Abstract
On August 31, 2011 at the 18th International Chromosome Conference in Manchester, Jenny Graves took on Jenn Hughes to debate the demise (or otherwise) of the mammalian Y chromosome. Sex chromosome evolution is an example of convergence; there are numerous examples of XY and ZW systems with varying degrees of differentiation and isolated examples of the Y disappearing in some lineages. It is agreed that the Y was once genetically identical to its partner and that the present-day human sex chromosomes retain only traces of their shared ancestry. The euchromatic portion of the male-specific region of the Y is ~1/6 of the size of the X and has only ~1/12 the number of genes. The big question however is whether this degradation will continue or whether it has reached a point of equilibrium. Jenny Graves argued that the Y chromosome is subject to higher rates of variation and inefficient selection and that Ys (and Ws) degrade inexorably. She argued that there is evidence that the Y in other mammals has undergone lineage-specific degradation and already disappeared in some rodent lineages. She also pointed out that there is practically nothing left of the original human Y and the added part of the human Y is degrading rapidly. Jenn Hughes on the other hand argued that the Y has not disappeared yet and it has been around for hundreds of millions of years. She stated that it has shown that it can outsmart genetic decay in the absence of normal recombination and that most of its genes on the human Y exhibit signs of purifying selection. She noted that it has added at least eight different genes, many of which have subsequently expanded in copy number, and that it has not lost any genes since the human and chimpanzee diverged ~6 million years ago. The issue was put to the vote with an exact 50/50 split among the opinion of the audience; an interesting (though perhaps not entirely unexpected) skew however was noted in the sex ratio of those for and against the notion.
Hekate
(90,645 posts)Nitram
(22,791 posts)olddad56
(5,732 posts)DoctorJoJo
(1,134 posts)Crash2Parties
(6,017 posts)"Although it carries the master switch gene, SRY, that determines whether an embryo will develop as male (XY) or female (XX),"
The SRY gene merely triggers certain specific sex dimorphic sites (ranging from reproductive to skeletal to neural to endocrine) to begin to develop as typical for a male. Then an inhibitor gene has to kick in, and a second inhibitor must be expressed to stop the first. The entire chain must occur for that given body site to develop as what is typically categorized as "male" (because most people labelled as such have that particular configuration).
SRY can and does transpose onto other genes, sometimes resulting in men with SRY and male sex dimorphic body sites that are XX, btw. So, technically that Y really is not needed so long as another mechanism is worked out by nature to ensure genetic mixing within the species.
burrowowl
(17,638 posts)briv1016
(1,570 posts)muriel_volestrangler
(101,306 posts)As some replies point out, this has been discussed for some time - the link Newsweek gives to say "opinion is currently divided" goes to an article from 6 years ago. There is no new development in this article, so we don't think it's 'breaking news'.
Please repost in GD, or the Science group. Thanks.