CharonY

It is funny, or rather sad that this keeps happening. Back when Harper led Canada, there were efforts to save Canadian environmental freshwater data (GEMS). Now Canada is part of a collaboration to duplicate US data (including from the NIH. It just shows how leadership can rapidly undo years of scientific progress rather rapidly.

Reading comprehension. I said I should have said "selective pressures in human evolution has stopped". You cannot find it because I wrote "human evolution". Hence the 'should have said'. That being said, as swansont pointed out, there was a bit of that sentiment throughout, which I honestly wasn't paying too much attention. Especially as attempts at explaining evolutionary basics kept being ignored. This is definitely true for evolution, but I am thinking that it also depends a lot on how we measure selective pressures. Traditionally that is expressed as a selection coefficient and the rate is kind of baked in as it is indicated as a reduction in fitness (i.e.. Darwinian fitness (W)= 1-s). When we use molecular markers often things like the rate between non-synonymous mutations to synonymous mutations. So essentially the selection is expressed as a ratio of what we expect to happen in the absence of selective pressure relative to what we see, which kind of eliminates the speed as an element. There are more sophisticated measures like molecular clocking, but I don't think that this within the scope of this discussion. Ignoring that part at the very onset of the discussion already pointed to a degree of learning resistance.

My bad, I should stated "selective pressures in human evolution has stopped". The examples later including analysis of the Framingham study were specifically regarding detecting signatures of natural selection in very recent times (which, again, is exceedingly difficult). So IOW there is evidence of NS in humans over the last thousands of years, and some data on very recent events. So far, I have not seen anything that convincingly suggests that they are now suddenly one except your repeated assertions. Combining it with the issue that the comparison that you are suggesting is largely impossible (at least the way as it is stated, and with the caveat that I am not well enough read in the modeling aspects to know whether there might be a theoretical way to do so), are you going now to reconsider your initial assumptions or are we stuck on repeat?

It goes even beyond that, in a "not even wrong" kind of situation. Natural selection is, by definition, a relative force acting on a gene pool (be it species of population). It causes certain genotype to be relatively more or less successful than others. However, if we compare species, we are looking at entirely different gene pools and the comparison makes absolutely no sense. Let's assume a population where there are literally no selection (or any stochastic parameters) except for one. Perhaps the ability to eat fast. In any other scenario it wouldn't be a meaningful fitness benefit, but in an otherwise entirely flat landscape, this would be the singular driver (imagine the only peak in an otherwise entirely flat landscape). If you investigate it, it will look like strong selective pressure as it seems that the gene pool single-mindedly drives towards that trait. Conversely, a different species might have a much more complex environment, so the same trait is also there, but kinds of drowns among all the other forcings. How would one compare this relative shifts to each other? At least AFAIK there is not simple calibrant that one can use to be able to compare that to each other.

This is a science forum, which requires some sort of supporting evidence for assertion. A single (scientific) publication that would outline or even hint at it would be a sufficient basis for discussion. Yet so far we only have your belief. Even worse, it is pretty clear that you fail to understand the basics of it, specifically why a) you cannot group all animals into one big category and b) you cannot compare selective pressures between species meaningfully. And by ignoring these issues you just revert to repeat your assertion. Even worse, the arguments you present are not even inherently consistent. You somehow want to link lack of natural selection to a certain genetic syndromes and disabilities. For that to even start to make sense you would need to provide some evidence that somehow those factors do not in fact affect reproductive success (and this is likely again down to the fact that you conflate the ability to survive with likelihood of producing fertile offspring). That being said, there are plenty of examples of human evolution over the last few thousand years and I have yet to see any evidence that this has somehow stopped. In contrast, there are studies using population data, such as the Framingham study (a long term cohort on cardiovascular health) which suggested that some folks had children earlier lower cholesterol and some other effects compared to models where selection was not a factor (Stearns was the lead author in PNAS, probably around 2010s). The issue I had with these and relates studies is that it struck me as a bit improbable to find these effects in such a relatively short time frame. But the paper exists. I believe there were more studies using another population coming to similar conclusions I believe. I am sure since then there is more out there. I remember that natural selection was considered to be factor of different variations of metabolic syndromes, for example, and potentially with increasing sequencing results folks are able to test it. What you are doing is to take assumptions and wildly extrapolate them. I see less disabled folks surviving, hence there is no natural selection anymore. This line of reasoning, is disconnected to the mechanisms of evolution (which I very superficially tried to introduce, and which is getting ignored). Also the fact that we have more data on animals vs humans is not evidence. It means a) there are more animal species than human species and thus more researchers in the field working on various aspects b) animal models are more accessible for experiments. c) it is just very tricky in humans (it is also tricky for broader analyses in animals, but often there is something specific that one can pick out).

This is again shows a focus on the wrong elements. You should instead ask, do folks with blindness and deafness have higher or lower reproductive success than those without. This is the actual basis on how fitness is being calculated (the relative ability of a genotype compared to another). Surviving is not the key part of the equation. And again, you can only compare reproductive success within species not between. IOW, what you are interested in engaging with is more like a narrative discussion (similarly like would Godzilla win against King Kong) but it is not based on evolutionary science.

That is an interesting point. Generally speaking, specialist species tend to do develop within stable environments. The reason is that under unchanging conditions, there are certain optimizations (e.g. resource use) that provide relative fitness benefits (e.g. moving towards a set of fixed maxima in a fitness landscape). Generalists are more commonly found in changing environments, as optimizations do not provide the same fitness benefits. Humans are a bit different as they extend their generalist ability by being able to create fairly static habitats. I.e. they are not necessarily genetically as generalist as other species, but I would argue that their optimization of traits related to higher brain functions allowed them to expand the concept adaptability. Some other species do similar things, but not at that scale.

Except, of course animals that produce dozens or hundreds of offspring each season, of course. Again, this comparison makes no sense.

This is again conflating survival with reproductive success. Again, you still misunderstand the basic premise of evolution, in which fitness is not indicated by individual health or survival. Just the reproductive success over generations. This is a very basic mistake and keeps leading the discussion astray, as it is still based on erroneous assumption about what evolution and the role of natural selections (as well as repeatedly ignore, but equally important other factors ) are. Natural selection is not a magical element that purifies the gene pool, nor is it a singular shaping force. Rather, think of it as one of many factor that create a fitness landscape of a population. If we look at the gene pool, different genotypes are associated with distinct reproductive success rates (think of it as the height in the landscape). The landscape is highly dependent on the environment interaction with the genotype. For example in an area where Malaria is highly present, alleles associated with sickle cell disease are going to create hill (higher reproductive success) whereas in areas without, it might create a valley (lower success). The idea of that is that we don't look at singular observations and try to derive a story regarding fitness in population, that fitness is relative, not absolute measure, and it also has other implications (e.g. that gene pools could be shaped by local maxima, but not reaching another higher theoretical peak). Importantly, fitness landscapes are dynamic, that is the relative contribution of a genotype to fitness can change depending on the situation, even the frequency of a given genotype. So one aspect of the model you are proposing is that in humans the fitness landscape is fully flat or at least flatter than any animal on earth. The latter, as mentioned can of course never be validated as we do not have the means to fully reconstruct this model for all animals, and it therefore remains an assertion that cannot really be discussed (it is equally informative to speculate which favorite superhero would be the other one up). However, what we can address is to assess whether the human fitness landscape is indeed flat. If that is the case, one would assume that the human gene pool is exclusively formed random effects (i.e. there is not fixation). That, of course is not true. Studies in current humans have shown significant selective pressures to make us who we are over the thousands of years or so. The challenge is now that we cannot obviously find any evolutionary signatures for changes in the last 100 years or so. However, we can go beyond mere assumptions and actually look at the literature. There is a large body on mate selection among humans which includes certain cues (such as the major histocompatibility complex) that affect this rather complex behaviour, which, without doubt continues to happen. If that wasn't the case your are basically stating that humans engage in random mating, which is clearly not the case. Likewise, reproductive success is not equal in all humans, though there are complex factors pertaining to it. As mentioned, but not fully connected, humans engage in deliberate limitation of reproduction. Here, we have to ask ourselves, a) are all humans doing that at the same rate b) if not are there genetic differences between the groups (at scale). In case of b) and assuming there some populations are more fecund in but not connected genetically, we would still see shifts in the fitness landscape, but they are more likely stochastic. I have to stop here but both, population limitation amplify even weak selective forces due to bottleneck effects and there are selective forces which, while lessened in absolute terms, will still relatively form our gene pool. But the bottom line is a) trying to do a superficial comparison between vastly different populations is going to be exclusively speculative and just-so stories and b) human evolution continues to be shaped by the an environment where cultural aspects have a strong impact but we we there is no evidence that somehow we have approached anything like a W-H equilibrium (or a flat and static fitness landscape).

Well, that explains it. It is all a liberal conspiracy. Obviously the way to maintain pristine water is not to figure out what is inside in the first place.

Also to add to that, natural selection as doesn't necessarily affect evolutionary rates as such. One huge challenge in determining rate on the molecular side is that certain parameters are invisible and we cannot really quantify them well. For example, mutation rate have a huge impact on the rate of evolution, as they determine overall timing. But quantifying that is difficult, because what we see in the DNA is an interplay between purely stochastic mutational events and cellular mechanisms that affect them (e.g. DNA repair, metabolic rates, reproductive speed etc.). On a higher level, population size further skews results, making it very difficult to accurately determine germline mutation rates. I.e. comparing the impact of selection between populations only make sense if we assume same mutational rates, and the hypothesis here is that stronger selective factors will increase fixation rates. However, even that can be complicated by the fact that we also have to contend with recombination. Here, some models have shown that if recombination (i.e., sexual reproduction or horizontal gene transfer) are the major sources of diversity over mutation (which is the case for species with sexual reproduction and low mutation rates), then natural selection actually slows down evolution. That is all to say, that any discussion on evolutionary rates or selection has to look through a population lens. Even among mammalian species evolutionary rates vary significantly and there is ongoing discussion about the determinants for that.

I would be careful with that. For starters that really only relates to allergies, not the immune system wit large. We had a bit of a discussion those interactions here https://www.scienceforums.net/topic/140127-the-rise-of-allergies/#comment-1303884 Though I am a bit skeptical regarding the explanatory power of microbe-host interaction alone, as our immune systems interact with a host of other antigens, too. There is also a bit of a misconception that the immune system can be trained like a muscle. It is a fair bit weirder, and certainly your immune system doesn't get better the more often you are sick. Not saying that is your claim, but that is something I keep hearing from some folks and now also students, which is a bit worrisome. And this is called an assertion, but as mentioned before, it is not one that can be verified. As I mentioned there is no way to quantify that across species. Moreover, such generalizations are almost always wrong (heh). In very small populations, regardless of species stochastic effects are quite a bit more likelier to impact evolution rather than selective sweeps. Moreover, you haven't even begun to figure out what kind of selective forces might be present in humans or animals. It goes way beyond just prey interactions, for example. Take sexual selection for starters. Do you think in human populations there are no preferences? In many animals this likely contributed to hugely ineffective and even potentially harmful phenotypes (e.g. excessive plumage). Or weird adaptations including loss of the ability to live independently from each other. How would you even begin to try to quantify your claim?

I think it was a common occurrence as seen here. https://www.politico.com/gallery/algae-in-the-reflecting-pool?slide=0 It is just a big thing because this administration has an uniquely unfavourable boast to competence ratio.

I disagree with that statement, at least the way it can be interpreted. In evolutionary sciences it makes zero sense to try to rank selective forces. Those are relative quantities. Assume for example a population where predation is the strongest shaping force. Now, suddenly all predators are gone. What happens is not that suddenly evolution stops, but instead the other evolutionary elements contribute more to the changes in the gene pool. Extremely strong selective sweeps can keep the gene pool a bit more narrower, as for example a particular trait might become essential for survival. But once that is gone, other traits may rise, which could open up the pool more and give rise to other positive traits that otherwise may not have appeared in the first place. Both are are evolutionary processes which cannot be ranked as OP desires to. Moreover, "wild animals" covers a huge range of very disparate population with wildly different conditions that shape their evolution. Stating that humans are categorically different is, in my mind, a very anthropocentric claim. The mechanisms may be different, but tool use and tech just creates a different environment where other forces (selective or not) impact our evolution. Similarly to how other organisms impacted our world. Things like oxygen production has massively changed the world in the past and way more profound to what tech is doing to us, for now at least. The fact that humans practice birth control, also has impact on the evolution, in multiple ways. On the one hand, one can thing about it as creating bottleneck structures in the gene flow, as only a small subset (below replacement level, for instance) of folks reproduce. But then in recent times, economic stability seems to be associated with reproduction. And while wealth is not associated with genes as such, generational wealth runs in families. So one can speculate about how that impacts our gene pool (with emphasis on speculate). In terms of rapidity, human evolution seems to have accelerated and this is documented both, on the fossil as well as the genetic level. Changes in skull shapes and brain development seemed to have happened faster than in our cousins. There are multiple hypotheses, including the ability to learn better use of resources, with allowed dispersion of human population followed by massive shifts in selective forces. Some of the most obvious genetic examples we find in text book are changes associated with diet, as well as climate adaptation, which happened very fast. But with urbanization we also see a lot adpatation related to pathogen exposure. One of the challenges of modern life is that we are connected (in case folks forgot about the annual influenza pandemic or COVID-19). All those are selective forces that OP neglects. Likewise, because of our changes in diet, certain populations are now at higher risk of metabolic syndromes, severely impacting reproductive success. And yes, those with more resources might have a better chance to address some of them, which has its own accelerating impact, as I mentioned earlier. Also, the examples of OP have given earlier, such as Klinefelter, Angelman, Downs etc are under negative selection, so it doesn't really add to the their argument. My bigger point is that the idea of comparing wild vs human is not really feasible as selection is a relative force action on the gene pool under a given environment. If humans change the environment, they change selective forces, but again, unless they are able to create conditions approaching the Hardy-Weinberg scenario, the pool will shift and functionally there is little difference if the environment is caused by technology, or a beaver dam or biochemically (e.g. oxygen production). Now the respective consequences are different, of course, but for that you would need to compare specific populations rather making a wide claim. And perhaps rather symptomatic, when folks talk about natural selection for some reason they do think about sweeps of disorders, and assume that strong selective forces somehow keep the gene healthier (in a eugenic sense) but forget that what it also means is that the gene pool is likely narrower. As such, when talking biology, rather than social sciences, it makes little sense to frame it around the concept of disorders, but one has to take a view on the shape of the gene pool as a whole. After all, we do not really categorize alleles as unequivocally good or bad, nor does it really make biological sense. A gene might reduce your performance is some way, but provide resilience to a certain pathogen. Is that good or bad? In the absence of the pathogen, it might show up as a negative, in the presence it is a positive.

You have, likely unknowingly, shifted the question you are asking throughout the discussion and this is likely caused by conflating multiple concepts. Your original question was regarding the drivers of evolution. However, you mostly ignored the various drivers and exclusively focused on natural selection. IOW in most of your arguments you are not discussing the drivers of evolution, but rather ask the question whether natural selection still occurs in human population. Within this context you are using a concept that is not really accurate by distinguishing "good" and "bad" traits. In the context of evolution, a bad trait suggests a trait that is negatively selected, whereas a good train would undergo positive selection. However, you define good or bad in context that goes outside of evolution and is more a social darwinistic view of good and bad (or survival of the strongest), that really is not an evolutionary concept. The reason is simple, and it is in fact the basis of your own argument. If a trait does not cause negative selection, because any negative reproductive effects are eliminated, then by definition it is not a "bad" trait in the context of evolution. And it matters not if that was caused by technology or anything else. For example, animals that do not rely on eyesight have no positive selection for maintaining eyesight. The consequence could be reduction of this ability without it having (by definition) any impact on reproductive success. The same goes for correcting eye issues, even if they are genetic. They are not negative traits, in an evolutionary context. It all relates to the common misconception that somehow evolution makes us stronger, yet in nature there is no such concept. Also disabilities are a bit of a value judgement, though it might feel counterintuitive. The reason is that because in order to define them, we define a baseline which we consider to be "able". But the issue is that this is a value judgement. In biology there are just different phenotypes.

You should check at the basics of evolution. Much of your speculation can be addressed with minimal reading. To make things easier for your here is a link: https://en.wikipedia.org/wiki/Hardy%E2%80%93Weinberg_principle. So to address your question You should first look at the list of parameters. Just very quickly, depending on the granularity you want the key parameters would include: infinite population size (eliminating drift), random mating, no gene flow, lack of mutations, and finally no natural selection. Now you can think what still exist. You have a very narrow view of natural selection, but at minimum think about conditions that renders folks sterile and/or less likely to procreate. There quite a few conditions that fall into that category. Likewise some negative traits can also be positive or are co-located at the same region with positive ones. Protection against malaria via alleles associated with sickle cell are a classic example of the former. There are many other examples for selection that are frequently discussed in class, including lactase persistence, amylase production, skin pigmentation etc. It is true that these are partially lessened in modern societies, but often they are not eliminated fully. You kinda, sorta dismiss mutations, but of course they also play a role. Then look into population size. Human populations are large, but they are also geographically distributed. Do you think that there are large enough that the gene pools of all human populations are resilient to random effect? Especially consider that only part of the population procreates (considering that many countries are below replacement levels). Now within population, to humans randomly mate? Have you considered cultural and religious barriers for starters? Ultimately I think the issue is that you focus on dying as somehow it being a key element of evolution, and it really isn't. It is one possible parameter, if it occurs before procreation, but it is just one of many. And again, it is not unique to humans. In nature procreation is not solely dependent on survival. Random mating is rather rare (look up sexual selection, for example).

What is the difference? Evolution is an universal descriptor and there is not difference how it works mechanistically. This is demonstrably false, bottleneck effects had huge impact on human population we see today, especially related to reduced genetic diversity outside Africa.

That is wrong. Evolution is the change of the gene pool over time. Natural selection is part of it, but mutation, drift, sexual selection etc. all play a role. You should read up on the Hardy-Weinberg equilibrium, which outlines the conditions where evolution doesn't occur. IOW, if Hardy-Weinberg is not satisfied evolution occurs, which makes the rest of your argument moot. I will just add that evolution is not about survival of the fittest, it is about reproductive success and associated changes in the gene pool. But individual survival matters little, as long as there is reproduction.

Yersinia is also often found in soil, so it sticks around and there is a chance for sporadic outbreaks. Though for big spreads sustained human-to-human connections is important.

I think some specifics have shifted, especially related to COVID-19 but there are some general themes that come up. One is often economic concerns, often rather diffuse, and also globalism. But these tend to be soft arguments and some studies looking at more solid aspects have a few common elements. One is simply the fear of status loss. It is a diffuse, emotional angst that interestingly is independent of their actual economic situation. I.e. folks with high socioeconomic status react similar to the same cues as folks who are at a lower status. This fear is strongly connected to another aspects, the appearance of the "the others". That is often seen in a racial light (sometimes hard, sometimes soft) but increasingly plays out on the ideological range, too (e.g. left vs right; dems vs reps etc.). The idea here is that if the other is more visible, it will diminish my status. And I think this is the real threat. If all had a rational basis, such as measurable economic situation, conventional wisdom would tell you that addressing the economy would tangibly shift perception. That happened in the Weimar Republic. Following the treaty of Versailles, the extreme right and left made rapid gains, but by 1928 the centrist and the SPD made promises for more welfare spending and brought the hyperinflation you mentioned under control. But then in 1929 the Wall street crash happened and we all know what happened afterwards. The issue now is that the perception has increasingly decoupled from facts, and this is something that is happening across virtually all sectors (heck, even things like the evaluation of Musk's company could fall under that). US economy stabilized under Biden, but the perception was that somehow it was worse. It worsened under Trump, but some folks feel that they are on the winning side (despite losing out on cash). We are increasingly going into a "feel" society, which I think is largely driven by tech-created disruption of information streams. We do not have a diversity of opinions anymore, but a diversity of realities. In think that part is a grand challenge for the coming generation, and we are only vaguely aware of it and certainly not equipped to deal with it. Moreover, with AI taking over the internet, the reality distortion will ramp up to massive levels in the next few years. I do not think anyone living now will have a strategy to deal with that.

Interesting study documenting plague outbreak in hunter-gatherer communities over 5000 years ago. While the sequence Yersinia pestis strain lacked certain pathogenicity factors compared to those found later in the bubonic plague. it appeared to be lethal especially to children. In the past, it was often assumed that urbanization and rats were key factors in the spread of the bubonic plague. However, lately studies challenged the relevance of rats and this one here challenges the need for urbanization for such outbreaks. Macleod, R., Seersholm, F.V., De Sanctis, B. et al. Lethal plague outbreaks in Lake Baikal hunter-gatherers 5,500 years ago. Nature 654, 697–705 (2026) DOI 10.1038/s41586-026-10540-5

The big issue is that what happened doesn't even have to be true. You just have to make feel true. As Swansont mentioned, it is easy to do by scapegoating someone and it is a well honed tradition to do so. It also comes naturally to folks like Trump who really do not have understanding or expertise in doing policies that actually make things better.

Well, and the electorate. Regardless how silly a government has become, the ultimate check should be the voters. Of course, Gerrymandering and similar mechanisms make it so much harder, but it is not that folks look at that mess and universally rejected it. Far from it, there are even for example conservative, typically religious white women who are seemingly OK with having their right to vote stripped from them. Also, it is not just America. Looking at Alberta right now, and the number of MAGA hats is worrisome.

I would argue that even simple biological system vastly outstrip the complexity of current most advanced tech. The reason being that we are able to create that advanced tech from scratch, but we don't have the tech to create simple life forms.

Unless there is some new technology coming in, the footprint for a robotic creation system seems to be quite a bit more complicated and inefficient. Where it seems superior appears to be scaling. Every step of the supply chain, from extraction, refining, production of parts and assembly requires large footprints to establish. Producing an biological individual is far more efficient than producing one robot, for example. I would also disagree with the clunkiness of metabolic pathways. It is supremely flexible, allowing survival and efficient energy and biomass conversion under extremely variable conditions. Currently robots require external systems to do that, using systems that are much less flexible overall. Of course future tech might catch up but giving what we have now biology does have an edge, with the exception of immediate scaling (if we disregard microbes). I think of it that way: robotic systems seem to require a highly complex supply where external systems (e.g., mining operations, refineries, energy production facilities, fabrication etc.) have to work together to produce new units. In contrast, even simple biological system incorporate core elements, such as energy conversion, biomass production, in an extremely small, efficient package.