The End of Men? Male Sex chromosome is slowly disappearing

[Calista241]

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.

What’s 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 isn’t when you consider that life has existed on Earth for 3.5 billion years.

The Y chromosome hasn’t 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]

1. Evolution has it's reasons.

[demigoddess]

2. my son told me years ago that the Y chromosome would disappear in

ten thousand years. I think I believe him more than Newsweek's source.

[Cary]

3. Actually 4.6 million years is along time

Our species, homo sapiens sapiens, is 50,000 years old.

[Kajun Gal]

4. Thank God!

[blue-wave]

12. I just gotta say it

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]

23. wait, I thought you revered balls

[MLAA]

5. Weve screwed our planet.

Unfortunately I expect we won’t be around in 50 years, let alone thousands or millions of years.

[StevieM]

25. I think we'll be around in 50 years. 200 is another question.

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.

[James48]

29. Some of us

Are just trying to make it until next Tuesday.

Every day I count my blessings- and hope that the Orange Orangutang doesn’t blow up the planet.

[democratisphere]

6. Evolution will make sure the horrid human becomes extinct.

[BigmanPigman]

31. NOT before we've killed all animal and plant life first

unfortunately.

[Xipe Totec]

7. Just do a last name frequency analysis and you'll see the horrible truth

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]

21. Kind of silly...

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]

27. You do realize that last names have nothing to do with chromosomes correct?

[Xipe Totec]

39. On the contrary.

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]

8. Oh god not this crap again

[Ccarmona]

9. The Great Barrier Reef Sea Turtles are Beating Humans due to Climate Change

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]

10. This is based on really old research

People should probably look up the original journal article (2012) and the subsequent articles that have been produced since then.

[Honeycombe8]

11. Too much viagra? nt

[Stardust1]

13. Well...

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]

32. Two ova could fertilize each other in test tube.

Of course, all offspring would be female.

[Puzzledtraveller]

41. and clones of each other

[bucolic_frolic]

14. Federal Reserve Sperm Bank to the rescue

or test tube mixers

[Lokilooney]

15. And in other news...

I should probably add some non snark so:

https://www.scientificamerican.com/article/the-male-sex-chromosome-isn-t-shrinking/

[Stardust1]

17. Yup

1977... it amazes me how long we've had to fix it.

[Puzzledtraveller]

43. we over-corrected, Lol

[Stardust1]

46. Huh

How so?

[Puzzledtraveller]

42. Yes, I watched an In Search Of episode

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]

16. Nature will find a way.

[Stardust1]

19. Yes

Animals go extinct all the time, why should we be any different?

[Rollo]

18. This is much ado about nothing...

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.

[Stardust1]

20. Agreed

It sounds like sensationalist rubbish to me.

[Rollo]

22. As well as being really bad amateur science...

[burrowowl]

36. Love your end pics!

[jl_theprofessor]

26. It's outdated research

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]

44. This echoes my thought, which is that instead of a "shriveled Y" we could have a "dot"...

...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]

24. eh...

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]

28. Here's an academic paper

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]

45. The last sentence made me laugh. See my post above re phallic anxiety.

[Nitram]

30. Umm, I hope you all realize this is a ridiculous melodramatic sensationalist unscientific piece of

[shenmue]

35. No

[olddad56]

33. I'll bet I know of someone with a huuuuuuuuuggggggeee Y chromosome.

[DoctorJoJo]

38. I think the Y Chromosome Size Is Related To Finger Length! LOL

[Crash2Parties]

34. Just to clarify one point, pedantic as it may be?

"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]

37. Thanks for the clarification!

[briv1016]

40. We'll be lucky to last another 100 years, 200 tops. (at least as a technical society.)

[muriel_volestrangler]

47. Locking - the hosts feel this is a feature story, not news

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.