The news cycle on gun control issues seems to be slowing down a good bit this week. I both welcome and fear this. I welcome it because it means I have more breathing room as a blogger. I fear it because it could drive complacency. We’re not, by a long shot, out the woods. But in the mean time, I can spend time Wikiwandering like Tam. Today’s interesting fact:
Because of the early divergence from theÂ therian mammalsÂ and the low numbers of extant monotreme species, the platypus is a frequent subject of research in evolutionary biology. In 2004,Â researchersÂ at theÂ Australian National UniversityÂ discovered the platypus has tenÂ sex chromosomes, compared with two (XY) in most other mammals (for instance, a male platypus is always XYXYXYXYXY),Â although given the XY designation of mammals, the sex chromosomes of the platypus are more similar to theÂ ZZ/ZW sex chromosomesÂ found inÂ birds.Â The platypus genome also has both reptilian and mammalian genes associated with egg fertilisation.Â Since the platypus lacks the mammalian sex-determining geneÂ SRY, the mechanism of sex determination remains unknown.Â A draft version of the platypus genome sequence was published inÂ NatureÂ on 8 May, 2008, revealing both reptilian and mammalian elements, as well as two genes found previously only in birds, amphibians, and fish. More than 80% of the platypus’ genes are common to the other mammals whose genomes have been sequenced.
What’s interesting about the platypus having reptilian and avian DNA is that we (mammals) did not directly evolve from aves. Aves are actually surviving dinosaurs; both are theropods. Mammals diverged from a common synapsid ancestor sometimes in the Jurassic period, about 200 million years ago. Theropods diverged in the lateÂ Triassic.Â Monotremes would seem to have been an early mammal that just never felt the pressure to evolve much since it branched off early from a common ancestor at least 167 million years ago, and probably farther back that that. I think it’s fun that birds are actually dinosaurs. If you’ve ever observed them, wild turkeys seem to move like something out of Jurassic Park. Which begs the question: did dinosaurs taste like chicken? Did they have white and dark meat? Also, what does platypus taste like? Would platypus eggs make for a tasty omelet?
Maybe it’s better if I stick to thinking about gun policy.