Science desk
< April 18	<< Mar \| April \| May >>	April 20 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

April 19

The definition of evolution in relation to humans

Evolution is simply whenever the genetic makeup of a particular population changes as a result of reproduction and, of course, the older generations gradually passing away, correct? The same also applies to human evolution, correct? As in, if a particular human group has its smart members reproduce much more than its not-so-smart members, then this group's genetic makeup is going to change over the generations (and it would also "help" with this that the older generations are gradually going to pass away) and thus this group is going to evolve to become smarter on average, correct? This would be an example of human evolution in action, correct?

All of this seems so obvious but I just want to make sure about all of this considering that I get the impression that some people even nowadays are oblivious as to the fact that humans are not immune from evolution even nowadays and that depending on which members of society reproduce more, humans even nowadays are capable of evolving in all sorts of different ways--whether becoming smarter, becoming duller, becoming thinner, becoming fatter, becoming stronger, becoming weaker, becoming taller, becoming shorter, becoming more liberal, becoming more conservative, et cetera. Of course, at least some of these factors could also be influenced by the environment, but nevertheless my point here is that even nowadays the genetic makeup of a particular human group/population could change through reproduction. thus causing this specific human group/population to evolve in some way. Futurist110 (talk) 06:58, 19 April 2020 (UTC)[reply]

See sickle cell trait and lactase persistence for examples of evolution in action in human populations in relatively recent times (last 10,000 years or so). Mikenorton (talk) 08:39, 19 April 2020 (UTC)[reply]

Yep, and another, much more controversial hypothesis is that Ashkenazi Jews evolved a higher average IQ over the last 1,200 years or so. If you'll take a look at this article, a 2005 paper actually proposed this as a hypothesis--as in, that there was selection for intelligence among Ashkenazi Jews during the Middle Ages and that smarter Ashkenazi Jews consistently out-reproduced duller Ashkenazi Jews for centuries during this time--thus causing the Ashkenazi Jewish average IQ to increase by ten or more IQ points from 800 AD to, say, 1800 AD or so. Futurist110 (talk) 18:32, 19 April 2020 (UTC)[reply]

Isolation of population groups is a factor in evolution. You can observe this in group traits and also in languages. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:47, 19 April 2020 (UTC)[reply]

Much of the change in the genetic make-up of Homo sapiens is due to random genetic drift, which is as often detrimental as it is beneficial, the separate minute changes being too small to result in an appreciable selective advantage. Natural selection operates as well, but its "natural" (often cruel) ways are nowadays often mitigated by medical intervention. Featuring a prediction of the long-term evolution of humankind used to be a staple item in pop-science magazines. Usually focussing on the phenotype, they described a future of hairless eggheads with formidable domes to accommodate their phenomenally large brains. For now, a breeding couple's being more educated tends to give more moderately sized litters, so I do not expect being smart to give much advantage until everyone can enjoy a good education. (Frankly speaking, I don't expect it will confer much of an advantage then either.) It only becomes really interesting if we have speciation, like the split into the Eloi and the Morlocks from The Time Machine. In other science fiction stories, space-faring humans have been depicted as having evolved to adapt to the weightless environment. If at some time genetic engineering applied to human embryos becomes socially acceptable (as it is in Brave New World), all bets are off. --Lambiam 16:49, 19 April 2020 (UTC)[reply]

Human intelligence is a hugely polygenic trait which is also massively influenced by environment (nature versus nurture). You seem to be implying "smart parents have smart children", which is not really accurate. --47.146.63.87 (talk) 22:53, 19 April 2020 (UTC)[reply]

I tend to believe that the ability to score high on intelligence tests is not 100% an environmental matter, but that there is also a genetic component. I expect that children of very smart parents are, on average, at least a bit smarter than children of very not-smart parents. For evolution to work over very long periods, event slight heritable advantages suffice. --Lambiam 00:37, 20 April 2020 (UTC)[reply]

There is also regression toward the mean to consider. This should also apply to IQ. So, on average, the children of extremely smart parents should be a bit duller than these parents themselves are. I've heard that regression occurs towards the family mean, but when we don't know what the family mean is, we should use the racial mean or ethnic mean instead assuming largely endogamous mating within this specific racial or ethnic group. For the children of mixed-race couples, of course, the regression should be towards the midway point between the means of the races of these children's parents. Futurist110 (talk) 00:57, 20 April 2020 (UTC)[reply]

Eugenics had been considered a legitimate scientific subject, but has become a taboo subject for scientists (for the obvious reason). There is, however, something known as New eugenics. 2606:A000:1126:28D:38A7:2D25:F9F0:4858 (talk) 19:05, 19 April 2020 (UTC)[reply]

I am actually personally a huge fan of (non-coercive) "new eugenics" just so long as everyone actually manages to have access to this technology--if necessary, through state/government subsidies for those people who cannot afford to use such technology out of their own pockets/checkbooks. Futurist110 (talk) 20:45, 19 April 2020 (UTC)[reply]

Do you consider elective abortion to be "non-coercive"? ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:43, 19 April 2020 (UTC)[reply]

Yes, I do. Why? Futurist110 (talk) 00:47, 20 April 2020 (UTC)[reply]

Yes, biological evolution is just change over time in a population. Unless a species goes extinct, it's always evolving. There are lots of widespread misconceptions about evolution, often because it's not taught very well, and also in some cases due to misinformation spread by creationists. A lot of people wrongly conceptualize evolution as a process that has some kind of "final result" it's trying to achieve. And because we humans tend to think rather highly of ourselves, many assume humans are the "pinnacle" of evolution and humans are "done evolving"; this can be seen in the outmoded idea of a "great chain of being", which is often still implicitly popularized by the common visual metaphor of a linear progression of human ancestors leading up to modern humans. I like this Rationalwiki page which explores some of these misconceptions. --47.146.63.87 (talk) 22:53, 19 April 2020 (UTC)[reply]

I haven't looked at that RationalWiki page specifically and thus won't comment on it, but it's quite interesting how RationalWiki is attempting to smear anyone (such as Richard Haier, Noah Carl, Bo Winegard, and Nathan Cofnas) who argues in favor of an evolutionary explanation to observed human group differences on various important traits (such as intelligence)--or who is at least open to this possibility. RationalWiki denounces such views as "racist pseudoscience" yet it's fairly clear that with different selection pressures, different groups of humans could have indeed evolved differently on various important traits--including within relatively short time periods (such as centuries, in the possible case of Ashkenazi Jews) if the selection pressures on these traits were sufficiently strong. The SPLC is also guilty of being a bit too eager to dismiss such hypotheses (and, of course, to label such hypotheses "racist pseudoscience" or whatever--as if it's actually going to be the end of the world if these hypotheses will actually be proven to be true/correct!), in my honest opinion. In comparison to RationalWiki and the SPLC, people such as Steve Sailer really do appear to be voices, beacons, and paragons of reason in regards to this specific issue. Seriously. Futurist110 (talk) 00:50, 20 April 2020 (UTC)[reply]

Nah, the denunciation makes perfect sense. The type of people you're referring to aren't being flagged as racists for having controversial hypotheses - they're being flagged as racists for using uncertain science to argue for racist policies, and/or palling around with nazis (at least when the flagging is being done by those who have actually looked into the issue). The "I'm being persecuted for believing in SCIENCE" line is often a deflection from the real issue. Now, there is definitely a fear of stigmatization and knee-jerk reactions in this field, but that's due to how freaking many of the people publishing in it really are demonstrably racist.

Also, best to avoid ever saying you support eugenics. Simply because of who uses the term, it will for the foreseeable future be assumed to mean, "the coercive or forceful use of government power to prevent reproduction by individuals subjectively considered by those in power to be undesirable, usually on the basis of race, religion or national origin, but ostensibly in the interest of improving the average human condition." For comparison, even the most hardcore supporter of the death penalty would do well not to say something like, "let's do the holocaust, but for criminals."

I, for one, support the availability of genetic counseling and family planning, including voluntary abortion, provided on an individual level by one's own healthcare providers. I think parents should have the freedom to make decisions on the basis of genetics and the best science if so desired. I would never in a million years call this eugenics, because that word is used for racist ideas. Though if someone's idea of family planning is encouraging latinos not to procreate, it's not the word that's the problem. Someguy1221 (talk) 06:20, 20 April 2020 (UTC)[reply]

This is why there's a distinction between "positive eugenics" and "negative eugenics". I obviously support the former but not the latter. If terminology is a problem, though, then how about someone comes up with some better terminology for this? For instance, "population genetic improvement" or something even better? Personally, I like the term "positive eugenics", but if there's a better term for this, by all means, please present it!

As for advocating for racist policies, exactly which racist policies did people such as Richard Haier, Noah Carl, Bo Winegard, and Nathan Cofnas actually advocate? The only "racist policy" that I can think of in regards to Bo Winegard is that he apparently supports policies to slow down the rate of racial and ethnic demographic change in the US--or at the very least views the support of such policies (such as immigration restrictionism of some sort) as being a perfectly legitimate political position. (I deduced this information from looking at his Twitter feed.) Which other racist policies are any of these people advocating? By all means, please do tell!

As for palling around with undesirable people, this appears to be a guilt by association fallacy. The fact that someone pals around with, say, Communists does not in itself actually make this person a Communist. By this logic, maybe we should criticize, say, W. Kamau Bell for making conscious efforts to interact with the alt-right for his TV show, eh? Futurist110 (talk) 22:05, 20 April 2020 (UTC)[reply]

A new phase of human evolution may have started about 10,000 years ago due to invention of agriculture and the changes in the diet. Human remains from just after this transition show evidence of malnutrition due to eating one-sided diets. The original diet was a primarily whole food plant-based type supplemented by small amounts of meat and fish. So, we got all our protein from the plant-based sources and the small amounts of meat and fish made up for the compounds like vitamin B12 that are absent in the plant-based foods. After the invention of agriculture, we could get all our calories from more refined carbs and fats which are depleted n nutrients, particularly protein. We then had to get our protein from animal products, so we needed to eat much more meat and dairy. This was also necessary due to the lack of minerals like zinc and calcium from the new refined agricultural products.

Lactose intolerance which was the norm before agriculture, vanished in Northern Europe around this time. The driving force behind this was the high mortality of malnourished children due to diarrhea. If children could drink more milk, they would have a better chance to survive.

Polar bears are a good example of this, see here:

"But they are descended from terrestrial bears that, before colonising the frozen Arctic, ate a very different diet. “Their ancestors will have eaten healthy food like tubers and berries, and all of a sudden there they were eating almost exclusively fat and blubber from seals,” says Rasmus Nielsen of the University of California at Berkeley. “So the fast-food experiment has already been done by nature.”

To find out how the first polar bears coped with this dramatic shift in diet, Nielsen and his colleagues sequenced the genomes of 89 polar bears and 10 brown bears, their closest relative. Out of 20,000 genes, they found 20 gene variants that were most distinct in polar bears, and which evolution has evidently favoured."

The list of genes was dominated by metabolism, heart function and coat colour. “Usually, the genes that evolve most radically in species are immune and defence genes,” says Nielsen. “What’s surprising was the focus on cardiovascular function.”

Of the top 20 genes, nine relate to heart function or development in humans. One variant that scored especially highly was the APOB gene. This makes Apolipoprotein B (ApoB), the protein component of “bad cholesterol”, otherwise known as low-density lipoprotein (LDL). ApoB normally removes artery-clogging LDL from the bloodstream, dumping it out of harm’s way in fat cells or elsewhere." Count Iblis (talk) 01:43, 20 April 2020 (UTC)[reply]

I'd say you're right that nothing stops evolving, but it would be a mistake to assume that the existence of a selective pressure implies the population is evolving in the direction of that pressure. Not only are we often considering complicated and poorly understood genetic phenomena that are strongly influenced by environment (and that includes the behavior of other humans), we're talking about a population under many simultaneous pressures. It is my impression that "humans stopped evolving" is mostly an inaccurate executive summary of the vast selective pressures that have been minimized by modern medicine and other technology. Someguy1221 (talk) 06:26, 20 April 2020 (UTC)[reply]

I think the 47's point about creationists and misunderstandings of evolution is also important here. Some creationists like to spread nonsense like we've observed microevolution, but no macroevolution which they then argue doesn't exist which leads to the mistaken belief that evolution must mean radical changes. And outside of humans, there is also a lot of similar confusion, e.g. the belief that living fossils 'stopped evolving'. (When you combine the 2, you get a lot of weird confusion as the 47 sort of mentioned. E.g. questions over why monkeys or other primates "stopped evolving" or didn't evolve into humans.) Nil Einne (talk) 06:59, 20 April 2020 (UTC)[reply]

Virus Movie #2

Virology

@Alansplodge:, @Lambian:, @Graeme Bartlett:, @DroneB:, @Graham Beards:

I have re-recorded the video on the basis of your critique. I would appreciate if you can take 6 minutes time to view and add a brief evaluation. Thank you for your review.
--Cookatoo.ergo.ZooM (talk) 17:37, 19 April 2020 (UTC)[reply]

after watching, it is now much less cluttered. Though you could popup some text when you mention a technical term, so that people know how the word is spelled. As regards accuracy I don't think is is quite correct to say that chains of amino acids polymerise into proteins. I should probably listen again to the exact wording, but amino acids polymerise into proteins (which are chains of amino acids). PS I am more into the chemistry side of Wikipedia. Graeme Bartlett (talk) 00:40, 21 April 2020 (UTC)[reply]

Thanks, Graeme, for taking your time. I am planning better written textual information to improve didactics. I am currently using a standard video editor which is free as part of the OS but lacking in some useful advanced / professional / flexible tools.
Good Day to Down Under. --Cookatoo.ergo.ZooM (talk) 20:16, 21 April 2020 (UTC)[reply]

Car air conditioning

Does the A/C in a 2017 Subaru Crosstrek draw in air from outside of the car? 67.253.78.55 (talk) 20:09, 19 April 2020 (UTC)[reply]

On page 250 of your owner's manual, the 'Air inlet selection' section explains that "On" position recirculates cabin air and "Off" draws outside air. 2606:A000:1126:28D:38A7:2D25:F9F0:4858 (talk) 20:28, 19 April 2020 (UTC)[reply]

High consequence infectious diseases (HCID) definition

According to the UK government, Covid 19 is not a "High Consequence Infectious Diseases" [[1]].

The government website, and every other site I can find discussing or defining this only gives a qualatative definition:

acute infectious disease
typically has a high case-fatality rate
may not have effective prophylaxis or treatment
often difficult to recognise and detect rapidly
ability to spread in the community and within healthcare settings
requires an enhanced individual, population and system response to ensure it is managed effectively, efficiently and safely

Does anyone know (or know where to find) the quantitative definition of a HCID? (In particular, what fatality rate counts as "a high case-fatality rate"?) Iapetus (talk) 20:49, 19 April 2020 (UTC)[reply]

Googling the subject, it kind of seems like a judgment call. For example, Ebola virus disease has a high death rate, so presumably it would qualify. The UK originally labeled COVID-19 as HCID because they didn't know what the death rate was. It turns out to be relatively low, at least compared with Ebola. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:41, 19 April 2020 (UTC)[reply]

That's what I assumed was the reasoning, given that most of the listed examples seemed to be "any contact with an infected person and you will probably die" types of diseases. But it would be nice to have a harder definition - especially as I've seen people making various assumptions about the reason for the downgrade that either border on conspiracy theories ("the government is trying to cover up that it didn't take this seriously") or are out-right conspiracy theories ("Covid 19 isn't dangerous, the government is just using it as an excuse to impose a lockdown, for reasons").

Someone explained this to me a while back. HCID means that it is treated in special HCID centres. There are nowhere near enough of those to treat Covid 19 patients, so it is being treated in regular hospitals instead, out of necessity. Yes HCID is an escalated response, but what's happened with Covid19 is even more escalated, enough that HCID designation is wimpy by comparison. 2601:648:8202:96B0:E0CB:579B:1F5:84ED (talk) 02:34, 23 April 2020 (UTC)[reply]