Quickies

Skepchick Quickies 10.21

  • End of earth postponed – “t’s a good news/bad news situation for believers in the 2012 Mayan apocalypse. The good news is that the Mayan “Long Count” calendar may not end on Dec. 21, 2012.” From Nightfall.
  • Why women live longer – “With respect to that most essential proof of robustness—the power to stay alive—women are tougher than men from birth through to extreme old age.”
  • Do “medical miracles” really exist? – “What is troubling, however, is when the media – presumably secular institutions – report these “miracles” as credible, factual events, and when they buy into pseudo-scientific twaddle, consciously or otherwise.” From teragram42.
  • Hagfish analysis opens major gap in tree of life – ”
    Since the 1970s, many evolutionary biologists have considered an eel-like, deep-sea-dwelling creature called the hagfish to be the closest extant relative of a last common ancestor for all backboned creatures.” From Ryan.

Amanda

Amanda is a science grad student in Boston whose favorite pastimes are having friendly debates and running amok.

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9 Comments

  1. Knowing little of the biology involved, could some of it also be linked to having two X’s, rather than an X and a Y? If, as the author states, aging comes about from the gradual accumulation of errors in gene reproduction, wouldn’t it stand to reason that having two copies of a chromosome would insulate somewhat from mistakes that happen on that particular chromosome?

  2. @Rebel 16: True, but there’s also a fair amount duplication in the X, no matter which parent it comes from, yes? I know that it’s pretty frequent in X-linked (the new monthly from Marvel) syndromes for men to be more susceptible because they don’t have a “good” X to compare it to. I don’t see why reproductive degradation couldn’t play the same role as mutation in this scenario, rendering women slightly more resistant (and we’re talking less than 10% in the US).

  3. I have some research experience in evolutionary genetics, so I’ll throw in a few comments.

    Hagfish: The ‘family trees’ of species are known as phylogenies, and the generation of such trees if phylogenetics. This sort of rearrangement is not uncommon, caused by better methods and more data. However, it may be that the old view (hagfish are the basal vertebrate) is still correct – I predict that this new analysis will spawn papers defending the old view.
    As an example of such a rearrangement: traditionally, it was thought that sponges were monophyletic (i.e. there is a section of the evolutionary tree which includes all the sponges and nothing but sponges.) Then results from around a decade ago suggested that all the rest of the animals lay within the ‘sponge’ part of the tree (i.e. it was possible to find two sponges such that one of those sponges had a more recent common ancestor with us that it had with the other sponge.) A more recent paper from a few years ago has returned to the ‘monophyletic sponges’ view.
    The use of seasquirts as an example invertebrate was not accidental – they are the the closest related invertebrates, being in the same phylum as us (‘chordates’.)

    X chromosomes: My guess here is only slightly more educated than yours. I’d be surprised if the duplicate X could cause so much lifespan difference, and we have much more likely candidates for an explaination. However, I can’t reject the possibility.

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