Science desk
< May 12	<< Apr \| May \| Jun >>	May 14 >

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

May 13[edit]

Medicinal side effects[edit]

During a clinical trial for a new medicine, a significant number of patients report experiencing a certain unexpected effect that wasn't happening before the trial, and when they go off the medicine, they find that it stops. This is definitely going to be considered a side effect. But what if the unexpected effect only happens in certain situations, e.g. when the medicine's taken before bed but not when the patient will be standing for many hours, or when taken on an empty stomach but not when taken with food? Is such an effect still classified as a side effect, since it's a situation for which the medicine is a necessary cause (i.e. it won't happen without the medicine), or is it not so classified, because the medicine isn't a sufficient cause (i.e. the medicine by itself can't produce the effect)? Nyttend (talk) 04:06, 13 May 2017 (UTC)[reply]

Yes. It is a side effect as long as the medication is a cause, even if it is not by itself a sufficient cause. Side effects are often classed broadly with terms like "common", "uncommon", and "rare". A rare side effect may well have multiple preconditions (which may or may not be known). Dragons flight (talk) 06:29, 13 May 2017 (UTC)[reply]

It is improbable that all side effects would be discovered in the testing phase of a medicine. In the UK we have the Yellow card system to record any possible side effects after the issuing of the drug. Richard Avery (talk) 07:40, 13 May 2017 (UTC)[reply]

(aside): Is there an equivalent to the Yellow Card, for recording when a drug is 'too effective', such as for example what was sold as mild-pain relief, inducing total oblivion to pain, or would this just be recorded as a side effect, albeit one that's not necessarily harmful?ShakespeareFan00 (talk) 12:32, 13 May 2017 (UTC)[reply]

ShakespeareFan00, if the medicine deserves more than the yellow card, it gets a red card. Nyttend (talk) 00:17, 15 May 2017 (UTC)[reply]

A medication's strength is considered where a pharmaceutical regulator limits the size of the dose of the same medication sold both on prescription and non-prescription. Examples of two common pain relievers sold in prescription/non-prescription doses respectively ^{[do not assume these limits apply in all countries]} are Ibuprofen 600mg / 200mg and Diclofenac 100mg (as Voltaren) / 25mg (as Volterol). Blooteuth (talk) 18:08, 13 May 2017 (UTC)[reply]

After various reforms in the US during the 90's, (at the same time supplements were reclassified as food if they came from plant or animal sources) the FDA started requiring extensive lists of side effects noted during clinical trials, such as headache, upset stomach, etc., even if the drug was for headache or upset stomach in the first place, or which many people suffer daily, and which they reported during the trials, but which had nothing to do with their skin cream or contraceptives. (I laugh every time I hear that Cialis may cause "delayed back pain" and that "if you lose vision, cease taking your medicine, and call your doctor immediately").

Basically causation is ignored, @Nyttend: in the listing of side effects; they are reported based on patient surveys regardless of even the most trivial and obvious circumstances.

But it should be understood that clinical trials go through many stages; often in vitro, followed by tests on animals, then highly monitored 24 hour studies in a hospital setting with detailed monitoring of the liver, kidneys, circulatory system, etc. Then they get down to large scale trials to determine effective dosage. Even then, a drug can't just "work", it has to be shown to work better than its alternatives in at least certain contexts. For example, a certain drug might not be the best for cholesterol, but might be safer for liver patients. μηδείς (talk) 01:02, 17 May 2017 (UTC)[reply]

Evolution of sexual selection in humans[edit]

In most mammals, the very basics of reproduction starts with sexual selection. But why did humans evolve to select based on personality, love etc and become monogamous. What advantages does this bring in practice looking purely from a scientific point of view? 82.132.231.84 (talk) 13:11, 13 May 2017 (UTC)[reply]

Monogamy is in large part a cultural rather than a biological phenomenon. In practice humans (of both sexes) frequently ignore it – if they weren't inclined to, there would be no need for so many social customs and legal sanctions trying to enforce it. {The poster formerly known as 87.81.230.195} 2.122.60.183 (talk) 13:16, 13 May 2017 (UTC)[reply]

Note that there is an evolutionary advantage to monogamy, in that it prevents the spread of venereal disease. AIDS, for example, would wipe out a larger portion of the population if we were completely polygamous and did not adjust our behavior to prevent the spread of the disease. The same is true for many other such diseases. StuRat (talk) 13:35, 13 May 2017 (UTC)[reply]

An interesting idea, but I'd need convincing. After all, a *lot* of people don't follow the model anyway. I'm not sure if preventing diseases in this way would have been relevant in an age of small independent tribes of people. After all, HIV seems to have smouldered on for at least a century before modern transportation, mobility, and convenience allowed it to hit the big time. Wnt (talk) 15:42, 13 May 2017 (UTC)[reply]

But AIDS is only one of many historically deadly or at least incapacitating venereal diseases. StuRat (talk) 19:14, 13 May 2017 (UTC)[reply]

True but what about selection by personality, love etc. 82.132.231.84 (talk) 13:25, 13 May 2017 (UTC)[reply]

Love or pair bonding, in scientific terms, is the mechanism by which monogamy is achieved. As for personality, it's important for survival to have complementary interests and skills. For example, if one partner likes to care for kids while the other looks for food, that works, but if both want to do the same thing, that won't work out as well. Of course, in modern society, all evolutionary rules are off, as kids can survive having bad parents now. StuRat (talk) 13:37, 13 May 2017 (UTC)[reply]

And we've also evolved beyond caring for kids and hunting food. So I wonder what the basis has become these days. 82.132.231.84 (talk) 13:47, 13 May 2017 (UTC)[reply]

Evolution is a very slow process, and our evolutionary pressures have only changed very recently, in terms of human history, so don't expect any changes soon. In a few decades we will take control of evolution by genetic engineering, so all bets are off then. StuRat (talk) 13:53, 13 May 2017 (UTC)[reply]

Intersting. Slightly different topic but there also seems to be a lot more singles in modern society and people seem to be settling down later. Could this be part of the evolution? 82.132.231.84 (talk) 14:29, 13 May 2017 (UTC)[reply]

I cannot see any evolutionary mechanism there, and, as StuRat writes above, the time scale is far too short, so I would put it down to social and financial pressures. Perhaps someone can point to some research? Dbfirs 15:13, 13 May 2017 (UTC)[reply]

Evolution can exhibit strong effects on a population in as few as 10-20 generations (see e.g. experimental evolution) given strong enough selection forces. That's too long to see an effect from "modern" society, but longer-term changes such as the rise of agriculture and cities probably have had an impact on the characteristics of the human population. Dragons flight (talk) 20:46, 13 May 2017 (UTC)[reply]

What do you mean by "we've evolved beyond caring for kids and hunting food"? Having children is a choice. Hunting food is not. No food, you die. And if you have kids, you care for them, assuming you're a civilized human being. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:16, 14 May 2017 (UTC)[reply]

See also here. Count Iblis (talk) 19:48, 13 May 2017 (UTC)[reply]

The term sexual selection is being used entirely incorrectly here. Sexual selection explains otherwise non-adaptive traits, such as bright colors and showy displays by male birds like the Northern cardinal or the Bower birds that otherwise put them at a survival disadvantage. Because females favor these traits, the males exhibit them, even though they are metabolically wasteful or put them at a greater risk of predation.

The relevant concept here is mate selection. In humans, large penises, permanent breasts, relatively hairless skin and manes are believed to be the products of sexual selection. Affection, and selection by smell (people prefer mates whose body odor does not match their own, as it is a sign of immunological diversity) have to do with mate selection. Mate selection can be considered a form of sexual selection, but it differs from traits which are showy, but otherwise put the individual at a survival disadvantage. μηδείς (talk) 22:19, 13 May 2017 (UTC)[reply]

Please provide a reference for "And we've also evolved beyond caring for kids...." I don't think that particular responsibility is fully resolved yet. Hayttom (talk) 18:52, 15 May 2017 (UTC)[reply]

No. Maybe you should make it clear you are asking someone who posted ten posts back to do that by naming him explicitly. μηδείς (talk) 19:45, 15 May 2017 (UTC)[reply]

In many developed nations, if you have no food, it will be provided for you, whether by individuals, charities, or the government. Similarly, if you don't properly care for your kids, the government will take them and provide the basics (food, clothing, shelter), but perhaps not affection. So, your likelihood to pass down your genes isn't much affected by your ability to find food and care for your kids. StuRat (talk) 20:28, 16 May 2017 (UTC)[reply]

See also Idiocracy. But don't be overly convinced by such claims, as there are a wide range of expressions of intelligence. Wnt (talk) 23:37, 16 May 2017 (UTC)[reply]

Don't assume that social leeches are representative of the population as a whole. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:54, 17 May 2017 (UTC)[reply]

Lactose gene[edit]

Why exactly LCT gene for lactose digestion turns off by itself in mammals after weaning causing lactose intolerance? There doesn't seem any strong evolutionary pressure against it. Besides, given our long sequence of evolution from previous mammals, one might assume that the gene should have firmly rooted itself in the genome without turning off later. Yet it turns off in other mammals too after some time. Brandmeister^talk 18:51, 13 May 2017 (UTC)[reply]

Just a thought, but could this have helped to wean the young ? After all, until this happened, if the mother couldn't have another litter, it would be important to move them along to solid foods. Also, milk is somewhat incomplete, nutritionally, so solid foods would also be important for the survival of the first litter. StuRat (talk) 19:09, 13 May 2017 (UTC)[reply]

Lactase has an evolutionary history in bacteria and humans alike of being "inducible". It is a fairly rare energy source, so the gene is usually around somewhere, but usually off. Such is the case in humans -- I looked into this a while back and it is very common for lactose intake to increase lactase production; I think I personally have experienced lactose intolerance after going a long time without milk products, and then induced it back up to the point where I could consume inadvisably large amounts of ice cream and/or cheese without intestinal issues. (True, some of that is doubtless a function of intestinal bacteria; and I can't swear it wasn't all that). It is common to portray "lactose intolerance" as an all-or-nothing phenomenon, but I think there are many shades of gray like this.

Note that "firmly rooting itself in the genome" actually is something of a thing (transgenes notoriously can lose activity in a mouse strain over time, as genomic 'spam filters' hone in on it by gene silencing or heterochromatin formation perhaps, so a history of a few generations for a gene actually is somewhat relevant. But on the evolutionary time scale we can assume all genes are stable. But one sign of an old gene is a complex pattern of regulation, which often means developing more reliable ways to turn it off! And lactase is a very old gene indeed. Over very long evolutionary time scales - and sometimes, even in a long term microbe culture in a very careful laboratory - the reduction in optimal growth and evolutionary fitness caused by supporting a single unnecessary gene can actually be measured. Wnt (talk) 20:13, 13 May 2017 (UTC)[reply]

Lactase is a protein, and protein synthesis is one of the major metabolic costs of life. There is no good reason for organisms not getting lactose to produce lactase, for the exact same reason cave fish don't waste energy to grow eyes. μηδείς (talk) 03:09, 14 May 2017 (UTC)[reply]
We have a whole Lactase persistence article that addresses the history and possible evolutionary advantages. DMacks (talk) 04:30, 14 May 2017 (UTC)[reply]

…one might assume that the gene should have firmly rooted itself in the genome without turning off later. You seem to be implying that if a gene is required at some point in an organism's life, its expression wouldn't ever be switched off, but that's not true. Just because a gene is highly conserved doesn't mean it won't be subject to regulation. The obvious example: all of your somatic cells with nuclei contain the exact same DNA (with minor exceptions). Genes that a particular cell type doesn't need are silenced as part of cellular differentiation. Your nerve cells don't produce hemoglobin, and your bone marrow cells don't produce myelin, even though they have the genes for those proteins. Some genes are normally never expressed after early life, like fetal hemoglobin. Regulation of gene expression is complex and there's still a lot we don't know about it. --47.138.161.183 (talk) 09:43, 14 May 2017 (UTC)[reply]