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Arthur Smith

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Everything posted by Arthur Smith

  1. https://sandwalk.blogspot.com/2014/05/answering-creationist-questions-about.html Ten years ago. Some good comments, including Joe Felsenstein.
  2. A skeleton found in Gough's Cave, Cheddar (of the cheese), UK recently had remnants of DNA extracted and sequenced. According to press reports, this fully modern human, when living around 10,000 years ago, had dark skin and blue eyes. Fixation by drift? Sexual selection? Niche change and population explosion from neolithic to now? ETA: and there's no reason to suppose "either or" here. Ah, missed that. There was a discussion on Larry Moran's blog a while ago that might be of interest.
  3. Sure. But I would find it difficult to remain optimistic, even though it is the outcome I expect. Where are they? Anyway, the hiatus between yule and New Year will soon be over so much less time for me to comment. Happy New Year everyone.
  4. Sorry, I corrected the link. Extrapolation may be justified, I suggest. What if the mission brings back evidence of micro-organisms fundamentally unlike that found on Earth? On that basis, separate abiogenesis events on two adjacent planets in one solar system, abiogenesis seems inevitable given the right range of conditions.
  5. It refers to the ongoing Mars Perseverance mission, of which one objective is to return physical samples to Earth. The article discusses possible results from examining those samples and the implications.
  6. Not sure if this blog post from 2021 is still valid or if budget cuts will cause the venture to be cancelled.
  7. I wonder if the claimed positive effect of random genetic drift could be (or has been) measured. The hypothesis I imagine would be something like "Under the effect of selective pressure on a population of sexually reproducing organisms, a locus with fewer alleles lost to drift will move to fixation in fewer generations than a locus with more variants". Consider population 1. A gene is fixed in the population of 100 and 1 beneficial allele enters the gene pool. Consider then population 2 (also 100). A locus has 10 neutral alleles at 10% frequency and 1 beneficial allele enters the gene pool. Is the rate of selection of the beneficial allele going to be different between population 1 and population 2, all else being equal? You, me and Sir Arthur Eddington. 😉
  8. It wouldn't surprise me that evolvability would be a trait subject to selection. Yes, it is my view that drift is not an adaptive process but becomes insignificant in large populations. I'm not quite sure what you mean about energy and entropy in this context. Certainly one attribute of known living entities is that they maintain themselves out of thermal equilibrium with their immediate environment by using an available energy source
  9. Indeed. Drift is the process by which an allele (a variant of a gene) will fix in a sexually reproducing population in the absence of selective pressure. The effect is noticeable, particularly in small populations lacking genetic diversity, and often results (or contributes to) in loss of a species by extinction. Perhaps it would be an idea for commenters to identify what sort of evolution is being referred to. Biological evolution seems to be the subject of the thread, but there is also cultural evolution and using evolutionary algorithms to solve problems such as the evolved antenna. 1. Why not list them, then, for clarity? 2. Disagree. But I am open to correction by an example. 3. There's nothing complicated about the idea of selection in biological evolution. Darwin categorized three sorts of selection: artificial, natural, sexual. The process is change in allele frequency in all those cases. 4. Not really. I would use the word "niche". 5. Allele variation and fixation can be a slow process where generation times are long, but evolution can be fast enough to be observable. Here is a classic. 6. Yes, biological evolution can be outstripped. Rapid climate change is a disaster for many species. Mass extinction events are unfortunate for those caught up in them, but the subsequent opportunities for survivors got us here.
  10. Well, I don't dispute that random genetic drift happens (or at least convincing models exist in the sphere of population genetics). But the clue is in the "random" bit. In small populations, genes may fix randomly which leads to loss of diversity and extinction. Resulting empty niches may be opportunities for other populations (the Chicxulub bolide did that for mammals around 65 million years ago) but without selection change does not produce the fit of species to niche. You need that feedback for change to be adaptive. I'm curious to learn of other ways that feedback can lead to an evolutionary process. Goodness me. All life on Earth, ALL life, is on the same branching tree. Admittedly the roots are a little tangled but the evidence is overwhelming. Perhaps I should make a distinction between shovels and entities such as biological organisms that reproduce. Tool use (not restricted to humans) evolves adaptively. If you want to access tubers, a stick is handy. A stick that doesn't break is better, a hardened point more so. Observing and learning from others even better. The bias is stronger when the learning is retained over generations. Human cultural evolution has swamped human biological evolution.
  11. Not sure how much broader the idea could get. Selective bias on populations of reproducing individuals leads to change in time over those populations. Works with shovels, Covid virus, Great Auks, computer memory.
  12. Yes. Evolution requires a selective bias for adaptive change to take place. Drift does not introduce selective bias. Your demand for a definition of "agency" may be perhaps answered by a selection process.
  13. In small populations, random genetic drift results in loss of allelic variation, which in turn can lead to extinction. I guess the empty niche left is an opportunity for another species. I'm yet to be convinced of how else drift contributes to adaptive evolution. Would that not be artificial selection?
  14. Asking as a dyed-in-the-wool adaptationist, what other mechanisms can be substituted for selection that produce change over time?
  15. Any explanation for the site being off-line? ETA: never mind. Failed to scroll.
  16. My house is 42° N, with (maybe too) many sunny days. Plus the grant, zero interest loan and buyback scheme means there is no downside. Unless the plug gets pulled on the buyback scheme. No. Ring mains! I'd forgotten about those. In France domestic sockets are fused at 16A (no ring mains) but single spurs can be 20A. When I lived in UK, the main fuse was rated at 100A. Here, my contract limits me to 9KVA, exceeding that for any length of time causes the system to trip. Just checking my app, I see my average consumption so far today is less than 1KVA. I haven't checked but I've heard one can installa 70KVA home charging point. There's a buyback scheme. Excess electricity is money in his pocket and avoids having a battery storage system. OK, so charging cables and home charging points are a bit of a minefield. EVs have a maximum charge rate (single phase) that maxes at 7KW for top of the range. A 32A point also gives 7KW. Charging cables vary in carrying capacity, with type 1 capable of handling up to 7KW.
  17. My runabout is a twenty-two-year-old golf 1.6 (naturally aspirated) and I have the same plan: hang on to it until something major breaks while watching developments in electric cars. There is currently also a scheme to subsidize photovoltaic installation, with the ability to sell excess back to the grid. My neighbour already has a roof installation that delivers 9KVA in good daylight. The idea of charging my car with free electricity appeals very much.
  18. Z There is indeed a typo in my comment. I meant "cubic millimetres" where I wrote "cubic millilitres". I believe the arithmetic is correct, though. And to clarify, I think representing fuel consumption as an area is trivial and unhelpful. I'd be much more interested in how to compare holding on to a reasonably economic, well maintained IC car or swapping for an all-electric, taking into account all the relevant factors, including the overall carbon footprint. Eta including the carbon cost of manufacturing an electric car and its batteries.
  19. Integration, not differentiation, for the area under a curve. Sorry to have misled you.
  20. Ah but am I not simulating total drag force by using the output from my "instantaneous" fuel consumption gauge on the dash to set the power equivalence to that necessary to drive the car at 100 kph (and speedo to 100 kph) as I already know the car consumes an average of 5L/100 kph? If the rolling road is set to simulate that, surely it simulates total drag, including air resistance.
  21. An ad on Spotify telling me if I swap to Spotify premium I can avoid listening to ads.
  22. Having come across the "problem" elsewhere, I asked to confirm my take that it is a pointless exercise. Thanks for confirming I chose "brainteasers" presuming it to be not for serious issues. The question is the same for any fuel. I have a car that I run on petrol/gasoline with 10% "bio" ethanol added. I get, on average, about 5 litres burnt for 100 km of travel. My larger-engined turbo diesel also returns around 5L per 100km. Of course the calorific content of fuel and the thermal efficiency of internal combustion engines is a whole subject (as is carbon emissions)in itself. The more interesting question is overall fuel economy, thermal efficiency, and carbon footprint. I can bypass all of that in buying an electric vehicle. But factor in the construction of a new vehicle when comparing carbon footprints and the comparison is not so easy. But I'm derailing my own thread... If I wanted to measure the actual thermal efficiency of an IC vehicle moving at a reasonable constant speed (say 100 kph) and I had access to a rolling road, and able to apply a variable braking load (that I could measure as a drag force) that I could regulate so that the "instantaneous" fuel consumption settles at 5l/100km, do I then have enough information to calculate the torque at the driving wheel, the net power output of the engine and, hence the thermal efficiency of the vehicle and fuel?
  23. One bonus of moving to France. Crystalline oxalic acid, copper sulphate as Bordeaux mixture, and sulphuric acid of sufficient strength for most purposes
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