CharonY

If you heat the medium in which the bacterial are (e.g. yoghurt) sufficiently high, they will die. The intestine is physiologically outside of our bodies (our whole food intake and digestion tract is basically like a kind of hose that goes goes through our bodies. Interaction with the immune system only happens fairly close to the intestinal walls (with some exceptions).

Chylomicrons are lipoproteins and they are produced in enterocyte. So in terms of distribution of lipids, they are basically at the source of dietary lipids, which get mobilized to adipose and muscle tissue. Cholesterol seems to be directed to the liver. I assume that was a typo (as the next sentence says the opposite), but reducing SFA content increases expression of LDL receptors. The assumption here is that LDL receptors are involved in LDL-cholesterol clearance from blood. I.e. reducing SFA increases LDL-receptors, which in turn reduce circulating LDL-cholesterol.

Thread is closed pending review.

I think I mentioned it earlier, but sexual preference is likely not hard wired, but rather developed early on, which is similar but not exactly the same. The second thing is that having a sexual preference does not automatically result in disgust (or lack of disgust) of certain sexual acts or preferences. That simply does not follow. As others have mentioned, there are plenty of heterosexual acts that folks might be disgusted about, and conversely, there are identical acts and for some, only the knowledge whether the actors are of same sex would make it distasteful (or not). The flexibility in perception shows to me that the behaviour is and can easily be modulated by context and experience. And if we look at the reaction itself, the feeling of disgust is usually unconscious (or close to it), and there is little immediate conscious control over it. However, it is also well known that disgust of specific things has a learned component. I.e. it is heavily modulated by learning/experience. There is some deep-seated basis, not doubt but how we learn how something is disgusting or not, is highly flexible and as by far not as much ingrained as sexual preference. I.e. conflating these elements simply does not make a lot of sense to me. I will also add that studies also suggest that heterosexual men, on average, have a (much) more positive attitude towards lesbianism and, as also mentioned a couple of times, these negative attitudes kind of dissipate with direct experience. One think I am actually now curious about is how homosexuals perceive heterosexual advances or intimate situations between heterosexuals. If it is really ingrained, and if it was really tie to sexual preference, it should be a fairly equivalent situation. Not sure whether there are studies about that, as most studies have focused on heterosexuals and their attitudes (talking about research bias here). Also, I wanted to add a few related points here. The discussion of nurture vs nature has very deep roots, but research has shown that it mostly makes little sense in the vast majority of behaviours. The concept of instincts is not that much in use anymore, for example. The more we understand how neural correlates for certain types of behavior are formed, the clearer it becomes that these are developments that happen to complex interactions between the genetic material, developmental environment and associated factors. In the area of neuroethology the idea is therefore much more to figure out how these mechanisms create behaviour. The hope to uncover genetic basis of behavior often now hinge on either very simple systems (say fruit flies) or by trying to isolate rather inflexible behavioral patterns and even this tens to be rather complicated. As I mentioned before, even sexual preference might not be a perfect example of it. We still do not know everything that goes into it, except that there seems to be a genetic bias, but clearly it is not exclusively controlled by genes. So for the most part the nature or nurture discussion is really not useful at all. However, that makes OP a bit tricky, as it is placed in the ethics section. There is a kind of assumption that "natural" behavior are somehow ethical as one it is presumably something we cannot do anything about. But rather obviously that is not a good argument to make.

That would be my assumption, but obviously the science is not conclusive in that regard.

There was a bit with Stephen Colbert and Jon Stewart where they made fun of Super PACs how insane the 2010 Supreme Court decision was. But basically a Super Pac can spend whatever they want, with the only restriction (from what I understand) that they are not allowed to coordinate with the candidate directly. Colbert and Stewart specifically highlighted that by mock non-coordinating while having a Super PAC. I am not sure whether that is the only or even the most important difference, but it seemed to me the most ridiculous one.

The way I tend to think about food and health is that a) one should have limit of regular calorie intake. We do have too easy access to food and overeating clearly is associated with a wide range. From there b) the food should cover all the necessary nutrients (hence the common recommendation to have somewhat broad diet) within that rough calorie limit. So in this context the question would be whether you would just cut off excess olive oil and not replace it with anything else (i.e. reducing total calorie intake) which likely would have some net benefit. Conversely, if you would eat something else that contains e.g. saturated fats or instead increased carbohydrate intake, chances are that it would be more likely to be detrimental. In other words, I am skeptical of claims that adding something to the diet (on top) has benefits, I think it is more about the composition while eating a healthy amount.

I think it is actually fragmenting again. What for a while was considered bioinformatics have in part been reclaimed by biostatisticians, a part has peeled off to computational biology and yet another part falls under the broader umbrella of data sciences. And I think especially the latter is bound to specialize again (it seems to come and go in waves).

This is probably not quite what OP was thinking about, but in fast-moving sciences, often new terms are coined and changed in a relative fast manner. For example, the term "genomics" was coined in the 1980s and was used to describe the complete set of genes (genome) and later for the other biomolecules in a cell (e.g. proteome for proteins, transcriptome for RNA and so on). Then at some point folks like the term so much, that it started to be used in somewhat different contexts. For example, rather than using "proteome" to refer to a complete analysis of all proteins, it was eventually also used if one simply looked at more than one or two proteins. Another fancy term that has been circulating since the mid 2000s is "synthetic biology", which in many areas is now replacing the older term of molecular cloning (or molecular genetic) techniques. An interesting aspect of it, is that this rapid divergence of terminology actually seems to create a divide in literature. I found that many students only use the newer terms and thereby overlook older papers.

I thin it should be added that there is (AFAIK) no gold standard with regard to these tests. While NMR does work at least as well as the other methods, it is not clear which one is the best. And best is defined here as yielding a measurement that is clinically predictive. It is also important to note that there is more work looking into LDL subclasses as the category is rather overly broad and fluent. And there is at least some suggestion that certain smaller types of LDL might be more diagnostic, but the measurements are even trickier, as higher specificity is needed. That is actually also rather complicated. Early on, there were already suggestions that the link between saturated fat and LDL cholesterol (or specifically LDL/HDL cholesterol ratio) is not straightforward. Some studies for example suggest that reducing saturated fat in the diet hat less effect than exchanging saturated with unsaturated fat, especially cis-PUFA. There is certainly a connection somewhere but as metabolism goes, it is likely again indirect. Some data suggests that the issue with saturated fat is perhaps not really only in the realm of LDL/HDL cholesterol ratio, but perhaps by increasing the very small LDL cholesterol particles, which might be more likely to cause cardiovascular events. Edit: I have not read the paper referenced above, but the graph shows a slight increase in LDL-cholesterol but a shift of the most problematic (small) species from 45.2 nmol/dL to 39.6. It is unclear to me whether those changes are actually clinically relevant, but I suppose that would require a study on its own.

Nutritional guidelines are necessarily simplified and there will be a lot of individual variance. Generally speaking, once on is a healthy place, it is often helpful to check from deviations a given homeostatic situation, but even that is an imperfect approach. Sometimes recommendations are actually correct, but for incorrect reasons.

The details are actually quite complicated, but I can start simple (and my apologies if it is too trivial) and maybe start with comments on some of the trickier parts. As you mentioned, the terms LDL and HDL do not refer to the cholesterol itself. Rather, cholesterol is transported packaged by lipoproteins, the mentioned high-density lipoproteins (HDL) and low-density lipoproteins (LDL). In addition there are also very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL). The measurements therefore refer to the fraction of cholesterol associated with particles of specific density that circulate in the bloodstream. To complicate matters on this level a bit, there are slightly different assays that measure the fraction of LDL in different ways (often indirectly, e.g. using the Friedewald equation, whereas direct methods often also measured IDL and VLDL). There is some data suggesting that using ApoB (which only not associated with HDL) could be a better biomarker for cardiovascular health, but that is under discussion, too. But one way I think about VLDL- IDL-LDL is that they are different maturation steps where the very large VLDL are reduced in size and then can enter the intima. Now, originally it was believed that LDL is a transport vehicle to move cholesterol to peripheral tissue and organs and HDL moves surplus cholesterol back to the liver. In part, the idea is then that very high LDL-cholesterol leads to deposits that can cause arteriosclerosis, for example. However, when trying to look at associated mechanisms, things get complicated pretty fast. For example, it was found that the vast majority of cells actually have an active lipid metabolism and most cholesterol are produced where they are used and are not necessarily delivered via LDL. Then, there is the issue that a lot of LDL cholesterol is derived from HDL and a lot of them is taken up by LDL-receptors in the liver. I.e. of the LDL is actually directed to, not away from the liver, making it questionable whether delivery to the periphery is really the main function of LDL. Likewise, HDL has been known to be critical for cholesterol efflux capacity (removing cholesterol from macrophages and transport to liver), but now studies suggest that LDL amplifies these efforts by HDL pathways. So taken together, the classic dichotomy of LDL vs HDL (cholesterol) has become rather questionable but we do not have a fully articulated model yet that can be used for better health prediction. Edit: I should add that my expertise is mostly limited to biomarker analysis, and not the clinical aspects, so it is therefore biased a bit more on the molecular/analytical side and may not reflect clinical standards. Therefore none of it should be considered medical advice of any sorts.

It is actually quite complicated. Originally there was the distinction between "bad" and "good" cholesterol (LDL vs HDL) and to some extent it still makes sense. Specifically LDL/HDL ratio seems to be somewhat diagnostic for cardiovascular risk, but there are quite a few caveats. There are some discussions on whether there is a functional role of LDL for e.g. atherosclerosis, or whether it is more of a side effect. Similarly, it was assumed that dietary intake of cholesterol would find its way into the bloodstream. However, newer findings suggest that dietary cholesterol has only an indirect impact. There is a ton of new findings, and robust discussion on that matter, but no simple answers yet. But for OP the studies suggest that cholesterol in eggs does not really have a direct impact on lipid profiles (i.e. it is not absorbed and released in the blood stream). However, high cholesterol food can apparently influence your own lipid homeostasis, but in many cases the effect was fairly moderate. I have not seen the video, but if the persons is arguing about absorption of dietary cholesterol, they are working on rather obsolete information.

Also it evaporates rather fast, making it rather useless (and dangerous) as a deterrent.

I think it is not only an issue of power (though it can be) but to a large extent it is exhaustion. The acts of what is now called microaggression often were normalized and even if pushback was successful, dealing with it on a regular basis, especially as it likely would not change anything, makes it easier to just ignore than to fight. I also suspect that this continues to be the modus operandi for most folks, but social media allows the voices that do object to be magnified (for better or worse). Context. Which is why it is mostly futile to try to come up with "objective" rules. Eh, I don't see how it has changed. Mostly about what folks get offended by, actually. Try to talk to folks about how stereotyping whole groups of people is harmful maybe one or two decades ago and see them implode because they feel that you accused them racism.

Much of it is due to the way hypotheses are set up and/or our tendency to create categories to make data and experiments easier to handle. The good news is that with better technology we also get more quantitative data. The downside is that new insights often have trouble penetrating public perception, which often prefers simple categories and narratives (for obvious reasons). I suspect it can also go the opposite way. I do not think that we can always expect that cultural norms necessarily follow the direction hinted at by biology.

I have not gone through all the posts, so I am sorry if I am being repetitive. However, it seems to me that there still quite a bit of back and forth on the nature vs nurture thing. And I think the evidence we have in general on that matter is that it is almost always not a "vs" but an "and" situation. Biological systems in general are highly dynamic and responsive to external and internal inputs and often do not behave in a strictly deterministic way (which is why I dislike the way "nature" as a term is used in this context). Even the behaviour of very simple systems, like cells can be difficult to predict unless you control virtually every environmental input. And even then we see differences within a clonal cell population. Development, especially of the brain, is highly interactive and even cues during fetal development can affect the outcome. As such, for virtually any trait we have a certain proportion of genetic vs developmental/environmental component. However, figuring the exact distribution is extremely difficult. It also does not help that there is a lot of assumptions regarding gender or sex preferences which often introduce bias in studies. Dissecting cultural effects (or impact by the test system, like the clever Hans effect) can further muddy the waters. The reproducibility crisis in psychology, which at least in part is related to a big narrative with little data issue and the fact that sometimes the studies are poorly standardized. Either way, as with most biological systems we are clearly looking at a continuum of behaviour that has to be explored quantitatively. Trying to force a clear binary system out of it tends to be problematic and is likely going to boil down into semantic exercises.

Developmental biology is not really my forte, but a lot of developmental timing is related to humoral control (which affects gene expression), which is also dependent on factors such as nutrition. So there is a bit of a complex interplay and I am actually not sure whether there is simple model explaining these differences somewhere.

With regard to differences we should differentiate aspects related to development/maturation, which does seem to have measurable sexual dimorphism, to structural aspects. The knowledge on the latter and especially the question whether sex dimorphism in human brains actually exists is an everchanging discussion, which is highly dependent on our technology to measure these differences. In mature humans, the effect size seems to diminish, the more we measure. A fairly recent meta-analysis argues that most differences described are related to brain size rather than any functional differences, for example. This is, of course, not the question in OP, but I thought it might be worthwhile to mention, in case the discussion drifts into that area.

Well, there is a bit of nuance, as mentioned earlier, one of the question in some of the standard surveys specifically asked whether folks would be uncomfortable with and showing that the comfort is highly contextual. And this is really the issue when trying to frame it as an innate response. The distaste for being approached is not only dependent on the suitor, but highly dependent on context. I would bet that in a highly professional environment most folks would feel uncomfortable when approached overtly sexually, regardless of ones sexual orientation, for example. Moreover, I think I may mentioned that folks might be put off by by sexual advances of any folks they are not interested in. While this mechanism might have some innate components, it is clear that it is not specifically targeted at homosexuality. I.e. there are many cues at play that can trigger the distaste reaction. We learn, for example, that this behaviour has no place at work. We might be more receptive in other social settings. So in short, the feeling of distaste might only be partially learned, but the cues triggering those are social and hence, learned (and therefore also malleable). This is what I tried to address with my comment about hardwired before.

To your first point, I think it the term hardwired or innate does obscure some of the mechanisms surrounding sexual orientation. Most likely it is a developmental mechanism where genetic factors contribute, but not necessarily determine sexual orientation. What we do know is that typically it is fixed at an early age. However, one should contrast them to sexual preference, which might be finer grained. I.e. the attraction among the perceived sexually compatible partners. These are much clearer to be learned, but are likely also heavily influenced by child-hood learning. There are several mechanisms described in psychology in that regard where childhood might influence partner selection. There is for example a hypothesis in psychology, called the Westermarck effect which assumes a form of inprinting in which folks tend not to be attracted to siblings, if they have lived together at a young age. It is an attractive hypothesis as in contrast to what is under discussion here, there is a path to selective advantages (i.e. avoiding incest). The problem though is if experimental data does not really support such a mechanism. What has been found is that e.g. disgust with incest is more related to social and cultural cues, though the debate is not fully settled yet. So even from a perspective where at least theoretically there could be strong selective factors and which appear to be a automatism, the underlying mechanisms are apparently far more complex. And obviously there is not really a good argument to made for strong selection on mutable traits. As with many things, I think the somewhat unsatisfactory answer is that most behaviour, even many unconscious ones are learned on one level or another. Our brain requires constant feedback to develop and some behavioural traits (such as sexual orientation) can be fixed very strongly, whereas others remain malleable. The OP was talking about selection and as such the traits that are malleable are not under selection. However, the basis for such traits (e.g. the mechanisms which influence how we develop sexual preferences) might be. And I think in the discussion so far, both factors have been mixed up.

It falls roughly under the same umbrella. There is a host of data, starting from the one I mentioned above where it shows that folks are far less uncomfortable (including sexual advances from individuals from the same sex). I think it is fairly clear that this is not true for sexual orientation. I.e. it only seems similar if you use the terms of like and dislike. But I think you will agree that sexual orientation is far more hardwired (though part is likely learned early on), whereas the other "dislike" is far more malleable.

The logic is that sexual orientation basically does not change through life, making it either genetic or at least strongly imprinted early in life and in a mostly unchangeable way. By the same token, homophobic sentiments can change quickly as noted earlier. Thus, using the same reasoning, it is much less likely to be innate.

I just want to add that group selection has been in discussion for a long time and despite some resurgences, most evolutionary scientists find it problematic, as other than just-so stories, it has not been useful in explaining persistence of traits. Moreover, many social traits can and have been explained in the context of "regular" selection more efficiently. The whole idea kind of nosedived together with the sociobiology and evolutionary psychology.

Considering how much a person has learned by that age, including one or more languages, and many other unnatural things (wearing clothes, hygiene, culture-specific mannerisms). Moreover, "natural" reactions can also have learned components. Imprinting is such an example, for example (though perhaps less well studied in humans compared to other animals).