Men! Y u so SRY? There was a time when our gender was determined by environmental cues such as temperature, rather than our genes. Then, about 200-300 million years ago, the SRY gene evolved from the related SOX gene, and thus was born the Y chromosome. While all the other chromosome pairs swapped genetic material (thus repairing damaged genes), the Y chromosome began to lose its genes at an alarming rate, eventually only swapping with the X at its very tips.

Nearly Gone: Over time, the Y lost 1,393 of its 1,438 original genes:that’s a rate of 4.6 genes per million years! Today, only 19 genes are shared between X and Y.

Bombshell: In a 2002 Nature paper, Australian scientists dropped a bombshell, predicting that the Y may be lost altogether in about 10 million years! After all, spiny rats and male voles have already lost their Y, resorting to sex determining genes on other chromosomes.

Enter monkey business: A new report shows that the rhesus macaque’s Y has 20 genes shared with its X, of which 19 are shared with the human Y. This suggests that the human Y chromosome has lost only one gene since humans and macaques last shared a common ancestor 25million years ago. So the linear extrapolation model is flawed . It is likely that the genes remaining have an essential function in fertility and are not going to be shed any time soon.

Sneaky Backups: David Page of MIT found that the Y chromosome has a sneaky way of making backups: the most important genes are stored in the DNA as mirror images, or palindromes — which read the same way forwards and backwards. (It’s the Y’s way of saying “Madam, I’m Adam”.) This means that Y genes can repair themselves when they get damaged. But Jennifer Graves, the Australian scientist who published the 2002 story considers these duplications to be the chromosome’s dying gasps. “The Y could disappear tomorrow if another sex-determining gene were to arise on an autosome,” she says.

Fun reads:

Serious stuff: Hughes, J. F. et al. Nature (2012).

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30 Responses to Men!

  1. Very cool and informative.

  2. Ethical issues aside, can science now splice/insert a sex-determining gene onto an autosome to create a viable human based lifeform?

  3. Rajini Rao says:

    I heard David Page speak at a conference a few years ago, Shaker Cherukuri . He was hilarious. The subject of the Y chromosome is truly fascinating. 🙂

  4. Jaz Emminger says:

    Does God know about this?

  5. Rajini Rao says:

    Richard Healy , technically not there yet. If we could, I’m guessing there are some nasty genetic defects that would take precedence before we indulged in monkey business 😉

  6. Rajini Rao says:

    If she does, Jaz Emminger , she must be toying with the Y 🙂

  7. Jaz Emminger says:

    Boy, the poop is getting deep in here…better pull up my SOX.

  8. John Midkiff says:

    Rajini Rao Always such awesome posts! Not currently in the news but I find the finding that the origin of placental mammals came from an insertion of a virus gene into the genome fascinating!

  9. Rajini Rao says:

    Really, John Midkiff , I had no idea! I’ll be sure to google that little morsel, thanks.

  10. Chad Haney says:

    Another interesting post. Kudos Rajini Rao. I’m afraid my White SOX are going to by SRY this seasone :-(.

  11. Rajini Rao says:

    LOL, keep those puns coming 🙂

  12. Ernest Rider says:

    Thats easy problem. Men don’t need all the baby construction genes.

  13. Rajini Rao says:

    “Men don’t need the baby construction genes” but that very simplicity of construction could put them in danger of being rendered superfluous 🙂

  14. Chad Haney says:

    Martin Sacha, do you mean de-bug as in remove the genes from our bacterial ancestors? Clever!

  15. Rajini Rao says:

    Chad Haney , that depends on who/what Martin Sacha considers buggy. Surely not women? 🙂

  16. Heh Martin Sacha: mother@nature:~$ strip /earth/human/male

  17. J Huntemann says:

    Do not believe everything you read! Some People still believe the the world is flat. That does not make it so. Take it from an OLD scientist I have seen more things go than you are old! BTW I love your blog! and most of what you write is solid, for now! Wait another fifty years and reread and laugh; how could I have written that! Keep climbing! Just be very careful what you take for a fact. From an OLD man……..

  18. J Huntemann says:

    Men! Y u so SRY! YES Lordy YES!

  19. J Huntemann says:

    We men are all alike. You just have to find one Ladies you can live with!

  20. Ernest Rider says:

    I was thinking we must be pretty close to doing a virtual model of DNA synthesis. i.e. PetaBytes per second supercomputers. We could virtually grow a person. I wonder what the moral guidelines for that would be. The kW/hr consumption of such a virtual object. If we put all the analytics into a virtualization of the process it could tell us the story of how we have come to be.


  22. TDF is located in SRY gene and hence sex determining chromosome, and also few traits such as pattern baldness and hypertrichosis is due to holandric inheritance,

  23. Great post. Once again. Hides behind sofa till the Ysome apocalypse is over

  24. Tom Lee says:

    Rajini Rao Humans are generally sneaky because of the built in chromosome?:)

  25. Rajini Rao says:

    No, Tom Lee , just guys 😉

  26. Tom Lee says:

    I didn’t know there are male and female chromosome Rajini Rao LOL

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