Dawkins’s answer to the Edge question: the genome as palimpsest

Jan 2, 2017

By Jerry Coyne

As I posted yesterday, a lot of contributors gave their answers to the 2017 annual Edge Question, “What scientific term or concept ought to be more widely known.” (See all responses here.) In the last 24 hours Richard Dawkins has weighed in with his answer, “The genetic book of the dead,” which involves reverse-engineering our DNA sequences to reconstruct the ancestral environments of living species. While Dawkins has discussed this before, most notably in The Ancestor’s Tale, not everyone’s read that book. It’s worth considering that an organism’s genome may be a palimpsest of its ancestry, which in turn reflects in part the environments to which those ancestors are adapted.

You can read Richard’s piece for yourself; I’ll give one brief excerpt:

Given a key, you can reconstruct the lock that it fits. Given an animal, you should be able to reconstruct the environments in which its ancestors survived. A knowledgeable zoologist, handed a previously unknown animal, can reconstruct some of the locks that its keys are equipped to open. Many of these are obvious. Webbed feet indicate an aquatic way of life. Camouflaged animals literally carry on their backs a picture of the environments in which their ancestors evaded predation.

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One comment on “Dawkins’s answer to the Edge question: the genome as palimpsest”

  • Dawkins’s answer to the Edge question: the genome as palimpsest

    It seems other historical information is also being recovered from hidden records!

    Ancient Parchments Reveal Old Texts Concealed by Newer Ones
    In a sixth-century Egyptian monastery’s library, high-tech imaging of parchments reveals thousands of pages of hidden text.

    Built in the sixth century at the foot of Mount Sinai in Egypt, St. Catherine’s Monastery is the world’s oldest such institution in continuous use. Its library preserves hundreds of manuscripts collected during medieval times—classical texts, scriptures, and other documents of interest to the monks. But it turns out that people recycled the pages of some of those manuscripts, erasing texts they no longer needed. Since 2011 the monastery has been working to recover some of those long-lost erasures using modern digital technology.

    About half of the library’s manuscripts were written on parchment, the specially prepared skin of a calf, goat, or sheep. Parchment can be recycled by scraping off any ink and writing on the fresh surface. The old text isn’t entirely gone, though. It remains embedded in the page as a ghostly shadow, which can be resurrected with a technique called multispectral imaging, designed to peer into both visible and invisible wavelengths of light.

    So far the imaging has revealed some 6,800 hidden pages in 74 of the monastery’s 163 recycled parchments, called palimpsests. “We have identified erased texts in 10 languages that date from the fifth to the 12th centuries,” says Michael Phelps, the director of the recovery effort. In the example above, a text in Syriac overlays a ninth-century translation of a page from a medical treatise by the ancient Greco-Roman physician known as Galen.

    With dozens of palimpsests yet to be scanned, Phelps believes there are still treasures to come: “It’s not unlikely that St. Catherine’s holds many more pages of previously unidentified and unstudied texts from antiquity.”

    They may even turn up evidence of antiquated fakery of religious documents if dates of earlier and later overlaid documents don’t match! 🙂

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