The trashcan categorial 20 Nov 2008 I’m introducing a new category – the Trashcan. This is a term used in systematics to identify a group that comprises “everything else” once you have done the identification of the real groups of some taxonomic grouping. I will be using the Trashcan to group together all and only those links that have one common property – that they caught my eye. No other property is necessary or sufficient for inclusion. It has no rank, either.* Under the fold is the Inaugural Trashcan. Some work on the simplest vision system, of a marine worm, suggests how complex vision got started. Just two cells – a light sensitive cell, and a pigment cell above it. Courtesy of the inestimable but all-too-infrequent Small Things Considered blog, a paper in Annual Reviews of Genetics that reviews the origins of multicellularity. I can’t access it easily today, as I’m officially on leave and at home (huh, like that’s making any difference). Nature also has a summary of recent work that supports the idea that trace fossil tracks in the Precambrian might have been made by large single celled protists, not eukaryotes. I expect Chris Nedin to blog this in detail. Chris? Finally, Siris has a quote that claims that the so-called “Modern” philosophers are squarely in the medieval tradition. I reckon this is true as late as Mill, Peirce and Jevons in the 19th century. The notion that critical thought began sometime in the 17th or 18th centuries is just revisionist. We owe so much to the revolution that began in the 10th century. * Because ranks are purely arbitrary, unlike a trashcan… nevermind. Evolution Species and systematics trashcan categorial
Epistemology The evolution of common sense on Scientific American 25 May 201125 May 2011 No, I do not mean that SciAm has finally evolved common sense, which would be an insult for the magazine that I grew up with. Instead quite the opposite: they have published a piece of mine on their Guest Blog on this topic. This indicates a growing lack of common… Read More
Evolution An essay on the evolution of human evolution 12 Aug 2007 Laelaps has a very nice essay that ranges from the number of ribs humans have, the book of Genesis, creationism, and the variety of stories told about human evolution from the nineteenth century to now. Go read it. It’s one of the few blog posts in which you’ll read of… Read More
Academe More deaths 18 Oct 2010 Two researchers have recently died who are relevant to evolutionary biology. Leigh Van Valen, the originator of the “Red Queen Hypothesis” and a proponent of the Ecological Species Concept, died yesterday, John Hawks is reporting. I had some correspondence with him, which makes me glad that I did before he… Read More
so this is going to be kind of like Colubridae or Insectivora in that whatever you can’t fit elsewhere will be dumped here based upon some arbitrary characteristic of your choosing? (like in the case of Colubridae, I still don’t know what they use in this one; in the case of Insectivora, I hope people can figure that one out)
so this is going to be kind of like Colubridae or Insectivora in that whatever you can’t fit elsewhere will be dumped here based upon some arbitrary characteristic of your choosing? (like in the case of Colubridae, I still don’t know what they use in this one; in the case of Insectivora, I hope people can figure that one out)
On the simplest vision system, I think they missed Euglena, a protist. Euglena has chloroplasts and thus is interested in where the light comes from. At the anterior of the cell is the stigma, a red dot structure. Associated with the stigma is a light sensitive area of protoplasm. As the eugelena swims along, it rotates and can thus tell which way the light is by the stigma blocking, or not, the incoming light to the light sensitive area. The invisible man is blind because light comes into his eyes from all directions.
On the simplest vision system, I think they missed Euglena, a protist. Euglena has chloroplasts and thus is interested in where the light comes from. At the anterior of the cell is the stigma, a red dot structure. Associated with the stigma is a light sensitive area of protoplasm. As the eugelena swims along, it rotates and can thus tell which way the light is by the stigma blocking, or not, the incoming light to the light sensitive area. The invisible man is blind because light comes into his eyes from all directions.