{
  "export": {
    "source": "https://urth.darkrealm.vip/thread/urth/5941",
    "note": "Exported from an unofficial mirror of a public mailing list. Copyright in each message remains with the person who wrote it.  Email addresses are obscured as `user at host`, the form the original archive published. This file was rebuilt from parsed fields rather than retained headers, so it is faithful in content but not byte-exact.",
    "addresses": "obscured as 'user at host'"
  },
  "archive": "urth",
  "thread": {
    "id": 5941,
    "subject": "What Dollo's Law means and what it doesn't",
    "messages": 2,
    "voices": 2,
    "first": "2011-01-25T22:12:52+00:00",
    "last": "2011-01-26T00:27:07+00:00"
  },
  "messages": [
    {
      "message_id": "<AANLkTin4Rje=7WB_51vm1JHRFtPqMLgP_jHyVk6hDG+o@mail.gmail.com>",
      "from": {
        "name": "Dan'l Danehy-Oakes",
        "address": "danldo at gmail.com"
      },
      "date": "2011-01-25T22:12:52+00:00",
      "subject": "(urth) What Dollo's Law means and what it doesn't",
      "in_reply_to": null,
      "reply_link": null,
      "blocks": [
        {
          "kind": "text",
          "depth": 0,
          "text": "Let's look at the cetacea for an illustration.\n\nLong, long ago, their ancestors left the ocean, fish becoming\namphibians and, ultimately, mammals. They lost the shape of fish, and\nthey lost the ability to \"breathe\" water (i.e., gills).\n\nMillions of years later, their more recent (but still rather distant)\nancestors _returned_ to the ocean, becoming first kind of crocodilian\nthings and finally the sleek dolphins, orcas, and whales we know\ntoday.\n\nNote that they have regained the rough shape of fish.\n\nNote also that they have _not_ regained gills.\n\nDollo's Law applies to the gills, but not the shape. Organisms can\nadapt to a new environment, even one that resembles an older\nenvironment. In so doing, they may develop characteristics that\n_resemble_ the characteristics their ancestors lost; but they do not\nregain those precise characteristics.\n\nAnd so whales must still return to the surface to breathe."
        },
        {
          "kind": "sig",
          "depth": 0,
          "text": "Dan'l Danehy-Oakes"
        }
      ]
    },
    {
      "message_id": "<SNT123-W65469E680961228424AEB0CFFF0@phx.gbl>",
      "from": {
        "name": "Lee Berman",
        "address": "severiansola at hotmail.com"
      },
      "date": "2011-01-26T00:27:07+00:00",
      "subject": "(urth) What Dollo's Law means and what it doesn't",
      "in_reply_to": "<AANLkTin4Rje=7WB_51vm1JHRFtPqMLgP_jHyVk6hDG+o@mail.gmail.com>",
      "reply_link": "subject",
      "blocks": [
        {
          "kind": "quote",
          "depth": 1,
          "text": "Dan'l Danehy-Oakes: Let's look at the cetacea for an illustration."
        },
        {
          "kind": "text",
          "depth": 0,
          "text": " \n \nActually whale vs. fish fins are one of those classic examples of convergent \nevolution. Fish (ancient and modern) mostly have fins built on a fan-shaped\npattern of spiny rays. Whales have built their fins on the mammalian bone pattern\nand humerus, radius and ulna structures can be found.\n \nBeing warm-blooded probably locked whales into being air-breathers. Water has much\nless dissolved oxygen than can be found in air.  All gill-breathing creatures are \ncold blooded (though certain shark species eat so much and swim so fast that they\ncan raise their body temperature for a short time).\n \nThe interesting question to me is...say Earth had a 100 year long flood that killed \noff all land dwelling animals. After the flood receded, could certain whales colonize\nthe land, their parts reverting back to a land mammal form?\n \nLess interesting is my discussion with Gerry on whether the darker grey humpback whale population\nof the arctic ocean could ever end up looking like the lighter grey humpback population of the \nindian ocean. \t\t \t   \t\t  "
        }
      ]
    }
  ]
}