When we have a sex with partner, we feel so tired that we don't have any power to do anything. Then it would be disadvantage to the animals, of course humans too, for they are exposed to danger. For example, the predator's atack. But you know, we cannot help having a sex. Then what is the advantage of being tired after having a sex?
11809
If a trait would be advantageous to an organism then why hasn't it evolved yet?  Conversely, if a trait is not advantageous or mildly disadvantageous, why does it exist?  In other words why does evolution not make the organism more "perfect"?    This is a general question that would be applicable for any kind of trait. Please keep the answers precise and scientific.   Read this meta post for more information:
84565
Plants and animals have the following distinct properties:    Plants live from solar energy by , they use solar energy to make sugar and oxygen out of carbon dioxide, which gives them energy. Animals live from the sugar and oxygen plants created and produce carbon dioxide for their energy. Animals can move across the planet while plants are tied to the ground.   Clearly, animals have a harder time to survive with no plants within their reach than plants have without animals coming close. This is logical because solar energy is always there while plants are not.  So my question is: Are there animals that can do photosynthesis? It's obvious that an animal with plant-like stateliness would be non-beneficial since it relies on eating other plants for it's energy and there may not always be plants within reach from it's spot.  But animals using the sun and carbon dioxide for energy production does not sound so stupid.   Night animals could also gather energy in their sleep. Much easier than plants, animals could make sure nothing blocks their sunlight. Many animals go through periods of hunger because food is scarce, for some of them this period is paired with high sunlight levels. (the dry season f.e.) (EDIT: This is just an idea, of course photosynthesis requires water, which is absent in the dry season. But still, in warm period with enough water, there's sometimes too much animals to feed from the available vegeation.)   Some things I already took into consideration:   I know that plants, because they are small in mass (compared to the area with which they can collect sunlight) and static, don't need nearly as much energy as animals do. Is this the main reason? I know that f.e. reptiles, but in fact all cold-blooded animals, already use the sun's energy. But they only use the heat from the sun to warm their bodies, they don't photosynthesize.
56186
My group have been playing various D&amp;D style games for a few years,  I have one player however that often will drift off and start playing on his phone  and several times has actually fallen asleep (with his character having to be "nudged" along by his fellow players).  He insists he's "just tired" and "isn't bored" — and besides, he keeps insisting we all get together for D&amp;D and wants to play.  Unfortunately we're all pretty busy, so if I'm to get the group together at all it's usually late on a Sunday. After talking to the player he insists it's not the game, or the story, he just happens to be tired. But, it's the same excuse every week, and the odd times we've played at different times or situations, the falling asleep has happened.  How do I cope with:   The morale destroying (for me) idea of your players falling asleep through a campaign and story you've put lots of work into. The general tone of the room when this player loses interest. (Occasionally a couple of others zone out into Facebook when they're not "active" because the players have split up / gone unconscious).   Given that it's an "all or nothing" situation with the group (there are only 3 players and they won't play unless all 3 are around), how do I best deal with it?
72403
First, if you are thinking that this question is a joke or troll, I'd like to welcome you to the 21st century when the mankind is discussing legality of gay marriages.  Now, if you look at the sexuality (I'll keep it clean) of all the Avengers minus Captain America:   Iron Man: Well, he is a billionaire playboy who can bring hot female journalists to bed with a snap of a finger (Iron Man movie). Otherwise, he has a girlfriend who is CEO of a multi-billion dollar company. Thor: He has a Nobel prize winning girlfriend who doesn't belong to his species. Hulk: Dr. Banner had a girlfriend, but then the gamma accident happened which could turn him into a green monster upon arousal (The Incredible Hulk movie). It's still unclear whether he can now have sex or not (after he controlled himself with meditation) and his girlfriend is still with him or not, but he isn't a virgin and nobody knows what happened after Age of Ultron. It's possible that Black Widow successfully seduced him after he was found again. Black Widow: Although, she is single and she has been sterilized, it's difficult to believe that she is a virgin and she doesn't have sex regularly because she is seen kissing around. And, she was trying to seduce Dr. Banner (Avengers: Age of Ultron movie). The point is: She is sexually active. Hawkeye: He is married (Avengers: Age of Ultron movie).   Now, look at Captain America:   When Peggy kissed him in Captain America movie, it was their first kiss and then he got iced. Fast forward to 21st century: Although his age is 80+, he is still young. Yet, he doesn't have a girlfriend and he doesn't show any interest in girls. Even when Black Widow kissed him, he didn't try to drag her to bed. Talking about low libido (a medical condition which arises due to stress and other factors), it's impossible because his super soldier serum should keep him healthy in all way. From the functional biology point of view, low libido is actually caused by imbalance of hormones. Stress suppresses rest-and-digest autonomous nervous system and activates fight-or-flight autonomous nervous system (that's why stress, depression etc damage health). In case of Captain America, yes, he got negative emotions after he was defrosted, but his super soldier serum should take care of his biological health. So, one of the other possibilities: He is gay (which has been proved to be a natural condition, not some kind of abnormality).   To prove that he is gay, let's look at his emotional responses: In 21st century, when he met Peggy, he didn't become emotional. But, when he saw Bucky, he became emotional.  I am a straight male and I am creative enough to emulate the situation well. If I had met my first love in such situation, I would have become emotional and it'd actually hurt to know that she is old and I am young. Talking about a dead best friend who is somehow alive and attacking me, my natural response would start with a slang. By no means, Captain America's emotional response looks straight man's response and it looks a gay's response.  Is Captain America really gay? Am I overthinking or producers are really hinting something to throw later? These days it's common in media for awareness. For example, Flash (2014) TV show has a gay police officer.  A more general question: Has sexual orientation of Captain America been disclosed? If he isn't gay, is he straight (there are lots of sexual orientations e.g. Bisexuality)? What about comics?
95787
I don't know about all the mankind, but I know enough people, who becomes sleepy after their meals. Also, I'm not sure, what kind of food do they consume, but I personally get sleepy almost from any food: sweet, fat, spicy, salty, liquid, tasty, not tasty, etc.  Is this phenomenon well known? And, if yes, how does it occur?
7992
Question  Quite a few plant species can be used for medicinal purposes . As an example, Filipendula ulmaria is rich in acetylsalicylic acid (aspirin).  An allele that produces a substance which is beneficial for a predator should not get fixed in the population! Why are there so many drug-like plants?    Thoughts  Here are some (intuitive, unclear or far-fetched, non-exhaustive and non-exclusive) hypotheses I can think of:   Because plants want their seeds to get ingested in order to propagate Is it because there are so many substances that affect our homeostasy that many plants are toxic and many are healthy just by chance. Containing healthy substances are not adaptations but by-product of evolution. The substances that are beneficial for us actually evolved to repulse predators. These substances are toxic at high dosage and therefore are efficient against predators that are small or eat a lot of plants (herbivorous). These substances at low dosage might actually have a benefical effect. For example a substance that make blood thicker is very toxic except if you eat just a bit of it while bleeding. We (primate or whatever taxon you want to consider) evolved in order to get advantage of the surrounding envirronment. Sbstances that were neutral became beneficial. The advantage of being sensitive to various products cause that, by chosing our food source, we can heal. Therefore, by evolving sentivity to various substances, our behaviour can act as a reinforcement to immunity (and other anti-illness system). If this is true, we might expect that the frequency of presence of a plant species affect the probability that out homeostasy get affected when eating it. Lineage selection. Lineages that produce substances that are active in predators body in a way or another are undergoing many various selection forces because of these substances. Therefore they get a higher speciation rate than other lineages. Keeping some non-herbivorous species in large population size (by helping them) is the best way to keep herbivorous species in small population (because of territory competition, predators relationships, etc... )
121022
I'm reading an article about two pets rescuing their owners. After the cat managed to wake up the mother, she tried to wake up other members but they wouldn't wake up.     Cathy tried to tell her husband and son to leave the house, but they wouldn't wake up.   Why wouldn't and not didn't?   (I checked possible duplicates but they weren't convincing at all. Besides, none of the answers were confirmed. One said would is used for permission and another said it's for emphasis!)
24711
When we push the wall, no work is being done. But we feel tired after some time. Since energy cannot be destroyed , the question is where does all the energy get transferred in this scenario. Note : It cannot be all heat as we feel more tired than standing still and if it is being transferred in heat then why it is faster than standing still if no work is being done?
23493
For the last 1.5 years I've tended to put my laptop in sleep mode rather than turn it off. Recently I started to feel it's not as fast as it was when I bought it, even if I restore a fresh Windows 7 image (I made it 1 week after installing the system for the first time).  Maybe it's just an impression, I'm not sure...   Can it be a result of putting my laptop in sleep mode? What computer parts get worn down over time? Is there software to test if these parts are worn?
41681
Researchers suspect that early exposure to pets carrying bacteria on their fur may encourage the proper functioning of the immune system, helping it to attack only harmful things.  I'm really confused about these.  What is the subject of &quot;helping&quot;? If one thing is right, why are the others not? I cannot refute the ideas myself. a) early exposure to pets carrying bacteria on their fur b) early exposure to pets carrying bacteria on their fur may encourage the proper functioning of the immune system(the whole of the previous clause, if this is the subject we can rephrase the sentence as follows: &quot;~ immune system, and this(or it) helps it to attack only harmful things&quot;) c) the proper functioning of the immune system  What does &quot;it&quot; after &quot;helping&quot; indicate? Is it &quot;the immune system&quot;? Am I right?
45947
Many articles on the internet write about melatonin and its effects, making you tired. A lot of articles also point out how the use of devices before going to bed in modern days likely decrease melatonin production. Therefore, making it harder to fall asleep. But this information is only about the process of getting to sleep, before we are actually sleeping.  A recent Harvard Medical article 1 states:     High exposure to bright, artificial outdoor lights during the night may result in sleepless nights for older adults.   Referring to a publication on Nov. 15, 2018, in the Journal of Clinical Sleep Medicine.  Considering that:    many people nowadays, use their mobile devices in bed prior to going to sleep; modern cities or houses have (street) lights that are always enabled at night; ignoring the phase of falling sleep; focusing only on the time we are asleep already, so during the actual sleep cycles.   Does a darker room with less or no (artificial) light pollution improve sleep quality, with all associated health benefits as a result? In other words: Does light pollution, while asleep decrease the sleep quality or does light pollution only negatively affect the phase of “falling asleep”?  I wasn't able to find any studies or information regarding sleep quality in relation to light pollution during sleep. Were such studies performed? Are there specific moments when light pollution affects sleep quality the most, for example during REM-sleep or in a specific sleeping phase?    1
82938
I'm sure that everyone is familiar with the sensation commonly known as "butterflies in the stomach".  It is commonly experienced during periods of anxiety or stress (e.g. before high stakes job interviews or roller coaster rides) and apparently (after my web research) often felt in new romances without an obvious cause of tension.    However, whilst my googling did turn up an inordinate amount of rubbish regarding love-sicknesnes, I have been unable to find even a suggestion as to a mechanism as to the physiology behind this feeling.  Is it a sensation of physical change in the stomach (some sites vaguely mentioned the restriction of blood flow to critical organs but it was entirely unsupported) or is it neurological in nature?
99107
In D&amp;D,  is an extremely powerfull spell, but it also comes with its risks:     The stress of casting this spell to produce any effect other than duplicating another spell weakens you. After enduring that stress, each time you cast a spell until you finish a long rest, you take 1d10 necrotic damage per level of that spell. This damage can't be reduced or prevented in any way. In addition, your Strength drops to 3, if it isn't 3 or lower already, for 2d4 days. For each of those days that you spend resting and doing nothing more than light activity, your remaining recovery time decreases by 2 days. Finally, there is a 33 percent chance that you are unable to cast wish ever again if you suffer this stress.   This consequence ensures that the players can't exploit this spell, at least, not too much. But, since the spell wish basically allows us to do almost anything, is there any reason that prevents a player from doing something like this:      I wish to be able to cast wish, without ever suffering stress from it.   Now, apart from rule 0, is there any written rule preventing this? Or is it technically allowed?
55228
So, it is established that using the bodily fluids of a zombie hides you from zombies. The characters know this. (They also may know that keeping semi-disabled zombies also works).  Why don't they just keep the innards around to keep themselves safe?
42264
Some animals like tigers, lions, cats, etc do this action before attacking their prey suddenly and unexpectedly. In fact they seem waiting insidiously (?) until the appropriate moment for attacking and (usually) the poor prey is not aware of their presence.  What is the verb, phrase, or idiom for describing this action/ state?  I have found  but I don't know wether it can be used for animals or not.
89347
I have yet to understand why so many viruses or bacteria haven't evolved to be harmless (specifically, I don't know of any harmless virus). I think it would be greatly beneficial for a virus to control his population and use natural transfer channels that dont cause discomfort(like feces), since it would be allowed to stay in an organism indefinitely and would have a lifetime channel for transmission, hopefully getting to be the most common strain.  So, why have viruses not evolved to be harmless to their hosts?
79751
I am inquisitive to know about how a person contracts AIDS. Among the common masses it's still the belief that having sex with multiple partners causes the disease but that is not the case when read online that it can come only from persons carrying the virus.  So, if a person (male or female) is carrying the virus (HIV positive) does it mean that he/she is suffering from the disease or the person may be carrying the HIV disease and still be free from AIDS. If so how did this chain reaction of spreading the virus start?  Also is it true that immune systems of some rare people in this world can fight with this disease.