Archive for the 'Evolution'

My talk at Skeptech is now available on youtube. I am not kind to Transhumanism.

My students are also blogging here: My undergrad encounters Developmental Biology Miles’ Devo Blog Tavis Grorud’s Blog for Developmental Biology Thang’s Blog Heidi’s blog for Developmental Biology Chelsae blog Stacy’s Strange World of Developmental Biology Thoughts of Developmental Biology Biology~ I’m out of town! Class is canceled today! But still, my cold grip extends across the Cascades, over the Palouse, the Rockies, the Dakota badlands, the old homeland of the American bison, the the great farms of the midwestern heartland, to a small town in western Minnesota, where I crack the whip over a tiny group of hardworking students. They’ve been mastering the basics of timelapse video microscopy in the lab this week, I hope, and will be showing me the fruits of their labors on Monday. I’m also inflicting yet another exam on them over the weekend. Here are the questions they are expected to address. Developmental Biology Exam #2 This is a take-home exam. You are free and even encouraged to discuss these questions with your fellow students, but please write your answers independently — I want to hear your voice in your essays. Also note that you are UMM students, and so I have the highest expectations for the quality of your writing, and I will be grading you on grammar and spelling and clarity of expression as well as the content of your essays and your understanding of the concepts. Answer two of the following three questions, 500-1000 words each. Do not retype the questions into your essay; if I can’t tell which one you’re answering from the story you’re telling, you’re doing it wrong. Include a word count in the top right corner of each of the two essays, and your name in the top left corner of each page. This assignment is due in class on Monday, and there will be a penalty for late submissions. Question 1: One of the claims of evo devo is that...
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My students are also blogging here: My undergrad encounters Developmental Biology Miles’ Devo Blog Tavis Grorud’s Blog for Developmental Biology Thang’s Blog Heidi’s blog for Developmental Biology Chelsae blog Stacy’s Strange World of Developmental Biology Thoughts of Developmental Biology Biology~ We’ve been talking about flies nonstop for the last month — it’s been nothing but developmental genetics and epistasis and gene regulation in weird ol’ Drosophila — so I’m changing things up a bit, starting today. We talked about vertebrates in a general way, giving an overview of major landmarks in embryology, and a little historical perspective. We take a very bottom-up approach to studying fly development: typically, fly freaks start with genes, modifying and mutating them and then looking at phenotype. Historically, vertebrate embryology goes the other way, starting with variations in the phenotype and inferring mechanisms (this has been changing for the last decade or two; we often start with a gene, sometimes from a fly, and use that as a probe to hook into the genetic mechanisms driving developmental processes). What that means is the 19th and early 20th century literature on embryology is often comparative morphology, looking at different species or different stages and trying to extract the commonalities or differences, or it’s experimental morphology, making modifications (usually not genetic) to the embryo and asking what happens next. Genes were not hot topics of discussion until the last half of the 20th century, and even then it took a few decades for the tools to percolate into the developmental biologists’ armory. And much of 19th century embryology went lurching down a dead end. We talked about Haeckel, the grand sidetracker of the age. There was a deep desire to integrate development and evolution, but they lacked the necessary bridge of...
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In March 2005, after record rains but before devastating wildfires that destroyed wide swaths of the Mojave National Preserve, I did a little thinking in one of my favorite places about solitude, growing up silent, campfires, and Dear old Dad. Oh, and yucca moths. Fleshed out slightly more, this KCET piece will be a chapter in the long-overdue Joshua tree book.

Earlier this month, there was a flurry of headlines in the pop-sci press that exasperated me. “Have scientists discovered reversible evolution?” was one; “Evidence of Reverse Evolution Seen in Dust Mites” was another. They failed because they always tried to express a subtle idea in a fluffy way that screwed up a more fundamental concept in evolution — it was one step forward in trying to explain a legitimate science paper, and ten steps back in undermining understanding of evolution. This was just awful: Researchers who deny the idea that evolutionary traffic can only move forward saw their arguments bolstered this week with the publication of a study suggesting that house dust mites may have evolved from free-living creatures into full-time parasites, only to abandon that evolutionary track and go back the way they came, reverting to the free-living creatures that live invisibly in your carpet, bed, and other places in your home that it’s probably best not to think about them living. “Evolutionary traffic can only move forward”? Please, define “forward” in this context for me. Evolution doesn’t have a direction. You can talk about a temporal sequence of historical changes in a gene, for instance, but from the point of view of the process, there’s no “forward” or “backwards”, only change over time. Is a genetic deletion a backwards step? Is a duplication a forward step? If a mutation changes a cytosine to an adenine, is that going forward, and if there is a revertant, a mutation that changes that adenine back to a cytosine, is that going backwards? I keep hearing this talk about directions, and it doesn’t even fit into my understanding of the process of evolution. Direction is always something people infer retrospectively. The paper all this comes from, Is Permanent Parasitism Reversible?–Critical Evidence from Early Evolution of House Dust Mites, by...
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