1. frozenncyborg asked: Why are adults woken up automatically when they need to pee, while young children pee the bed?

It's both learned and related to development.

All mammals have the instinct not to "soil the nest". We mostly train our babies out of this instinct by putting them in diapers and being totally oblivious to their signals that they want to pee, but it's possible to keep it going - there is a thing called Elimination Communication which is one of those "parenting movements" with an awful name but effectively, it's a googleable phrase which means you can find information about how to watch your infant for signs they are about to pee or poop and "catch" it in a little pot instead of using a diaper. This is also common practice in some non-Western cultures. Of course, if you want to do it at night you have to sleep in very close proximity to the infant. But doing this even very young babies will wake at night to pee and then go back to sleep.

So partly we train them out of it and then have to train them back into it again when we potty train. What happens when potty training is that toddlers are learning to associate the feelings of a full bladder/bowel with the imminent arrival of pee, and control the muscles around the urethra to hold it long enough to get to a toilet first. Children sleep much more deeply than adults - they tend to sleep through noise, for example, much more easily - and it's common that for some time during and after potty training they are either not aware enough of the nerve endings around the bladder to pay attention to them even during sleep or they are just too deeply asleep to notice these sensations. Once they become more accustomed to paying attention to these signals, they'll be more likely to wake up, assuming they are not too deeply asleep.

Secondly, the hormone part somebody mentioned below is also true but it's not strictly related to why we wake up, more the amount of pee created. The adult body produces a hormone called ADH (antidiuretic hormone) during sleep which tells the body to produce less urine during this time, meaning that adults rarely produce enough urine at night to get into a desperate enough state to wake us up. When we do, it's likely unusual enough that this is a significant factor as well. For children who haven't started producing this hormone yet (the exact age varies, but girls tend to develop it a couple of years earlier than boys, which is why boys are more likely to suffer from bedwetting for longer), the feeling of having a full bladder at night wouldn't necessarily be unusual meaning it's less likely to wake the child up.

Lastly there is the simple fact that adults tend not to be afraid of the dark and additionally are much more aware of where their limit for actually peeing themselves is, whereas children might delay getting out of bed because they are cold, scared, or just sleepy and they don't have as good of a handle on that tipping point yet because they don't have as much experience. (This is the same reasoning for why young children sometimes hold on so long that they just pee themselves because they were too busy playing or didn't know that they didn't have enough time to get to the toilet, whereas this rarely happens to adults without incontinence issues.) But again, this isn't strictly the same situation since you mentioned waking.

Submitted by caffeine_lights

2. BenRayfield asked: How did ancient people figure out that sex leads to kids, since the effects are so delayed?

They observed animals. They noted that women who did not have sex did not get pregnant. Some Neolithic art can be interpreted as actually showing Some Neolithic art can be interpreted as actually showing that they were aware of the relationship. But we can never know for sure.

Submitted by Rhynchelma

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3. Polish_William asked: How come when you're sick you can blow your nose and they'll be completely empty and 5 minutes later they're full and dripping. How does mucus generate so quickly and where is it even made?

The mucus comes directly from the surface of your nose, called a mucous membrane because it produces mucus to protect itself and as lubrication. This mucus is a combination of long, stringy proteins and water, which allows it to stick to most surfaces.

We produce a ton of it while we have upper respiratory tract infections like the common cold because our immune systems are trying to isolate the virus causing the infection and prevent more from getting in. This measure isn't actually that effective, as it only slows down viruses and bacteria can swim right through it, but we do it anyway. Allergies do the same thing because they are an attempt by the immune system to attack something that isn't actually a disease, like pollen. We are less clear on why allergies happen, but some hypothesize that they occur due to infants and children living in environments that are far too clean. Their immune systems don't have anything to fight, so they start fighting random things instead.

Submitted by Frommerman

4. Hrothgarex asked: If you did a ton of sprints, going farther and building endurance, could you eventually full sprint a mile? Is there a limit we can push ourselves?

Professional sprinters can only hold their top speed for about 10 strides. Usain Bolt achieved and maintained his top speed for 8 strides during his 9.58s record 100m run.

Slow twitch muscles, where endurance is built in, are required even for 100m. The opposite is true for fast twitch muscles, one needs a speed to run a marathon. There is no clear physical boundary between a sprint and endurance runs. The difference between a sprint and endurance runs is in contribution of each muscle type. Sprint events "end" at 400m, and endurance events "begin" at 1500m, 800m is a like a 50-50 combo of the two, meaning 50% of work(=power*time) comes from each muscle type.

You can try to "sprint" a mile mentally, like go a full force from the start and try to hold for as long as possible. But physically it would be something like 95% of power by the fast muscles and 5% of power by the slow muscles from the start. Then the ratio changes as the run progresses, and in the end your power ratio is something like 20% and 80%. I'm making these numbers up, but you get the point.

Such attempted "sprint" would be extremely exhausting and maybe dangerous. I don't think even animals running for their lives from a predator can pull this off. They still tactically pace themselves and conserve strength even when a certain death is right behind them.

Submitted by iiRunner

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5. pmmecoolpianopics asked: What causes some people to be more "addiction prone" than others?

There are several factors at play, and it seems to vary from individual to individual. The problem of addiction and alcoholism has been around for millennia, and we still don't have something we can point to, and say, "There it is. There's the problem, right there."

Genetics seem to have an influence. It can cause a tendency to be prone to addiction, but is not the causative factor. There are studies of identical twins, where one is addicted, and the other, not. There are also "black sheep" that come from a long and wide genetic history of normal intoxicant use, but these "black sheep" become addicts.

Dr. Gabor Mate, in his book "In The Realm of Hungry Ghosts" postulates that it is a combination of a genetic predisposition to addiction, triggered by environmental conditions, which may include trauma, such as sexual molestation as a child.

As time continues, and the consumption of intoxicants continues, it messes with the normal distribution of certain neurotransmitters, such as serotonin and dopamine. It is speculated that genetic vulnerabilities make this rewiring of the brain easier, and this is why some people are more prone to addiction.

As the addiction takes hold over time, its effects begin to manifest in the environment of the addict. They spend time with other addicts, and tend to damage their relationships with the non-addicted. If you become drunk and aggressive, you don't get invited to too many parties...unless everyone else at the party tends to get drunk, too.

At this point, the genetic tendency has been fully triggered, and the environment becomes one that fosters the consumption of intoxicants. The brain has become rewired so that pleasure by normal means is elusive, but can be had in an instant with another helping of the drug of choice.

Now the spectre of withdrawal sets in....and to break the cycle requires a complete overhaul of one's life, as well as suffering the physical symptoms of withdrawal. At this point the addict feels trapped, hopeless, and alone. Feelings of shame, remorse and self-loathing are common...and again, the only escape from them is another dose.

But there is some hope. It has been proven that participating in a community of recovery is beneficial to many addicts...indeed, most recovered addicts claim that the loss of a sense of isolation, the feeling of belonging to a fellowship, and the advice and support of other recovering addicts was instrumental in their recovery.

I am an alcoholic in recovery. My brain is wired in such a manner that the consumption of the smallest amount of alcohol creates a powerful, and virtually irresistible, craving for more. I can't open a bottle of rum, have 2 drinks, and put the bottle on the shelf. I just can't. I will drink until that bottle is empty.

Through my work in AA I have learned better patterns of behaviour. If I am feeling unsettled...lonely, stressed, anxious...I no longer reach for a glass, or a joint, or a line, or a pill to make me feel better. I have slowly brought the wiring in my brain to a more normal state.

But I don't fool myself. The changes made to my brain are permanent, and if I have one drink, I risk falling back into state of addiction. This is why so many people fall "off the wagon". They believe that a period of sobriety has provided a measure of control, and that they now possess the ability to moderate their consumption. In my personal experience, i have never met an addict or alcoholic that could PERMANENTLY moderate. Some manage to, for a time, but gradually slip back into a state where the neurotransmitters are only experienced with intoxication.

So, I guess the short answer to your question is, "Nobody knows. It's different for each addict." Personally, I find my life without intoxicants to be vastly more rewarding, and I am much happier.

And maybe that's the root of it. People take drugs because they are unhappy, and want to change the way they feel. The genetically predisposed quickly find themselves in a position where the brain has rewired itself to the point where happiness is difficult to achieve without the drugs.

Submitted by PJMurphy

6. PM_UR_PICS_asked: Why is cannibalism detrimental to the body? What makes eating your own species's meat different than eating other species's?

Your own species meat is infected with diseases that can also infect you, by definition. (Conversely with other animals, some but not all diseases can be spread by under-cooked meat.) There are also some degenerative diseases that are spread by mis-shaped proteins, which you can generally only get by eating a human brain.

Submitted by simpleclear

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7. Elocmada asked: Why does adrenaline in certain circumstances give people super human strength? (Being able to lift extremely heavy things off of people, etc.)

First its important to note that so called feats of "hysterical strength" are not scientifically recognized, although they are well documented. They clearly happen, but science has a hard time testing them, because its obviously very hard to reproduce in a lab.

However, they have given small tests, like testing grip strength, and then electrically stimulated the muscles and tested again, and found that people exhibit about 25% more strength under electroshock, which definitely verifies people are in general stronger than they're normally able to access. Additionally, you may have heard of people being flung across an entire room after being electrocuted. This isn't because of the electricity - electricity doesn't move things like that - its because the shock caused massive muscle contraction, and the people flung themselves across the room, jumping far further than they would have believed possible under normal circumstances.

So, because they can't test hysterical strength, we can only hypothesize why adrenaline causes it. More than likely it is because your muscles are under several inhibitory systems, including pain as well as the neurological restriction of simply having not enough signalling at any given time to activate all the muscle fibres in a group. Strength isn't just about raw strength, its about timing; you need one perfectly timed electrical burst to signal all fibres to work in concert when exerting force. The more fibres activated simultaneously, the more strength you'll have.

Adrenaline most likely acts to remove several different limiter systems. Your pain sensation is dulled or removed entirely, your blood vessels are dilated and your muscles are more heavily oxygenated, and your neural activity increases; more brain activity = increased signalling, which means you're better able to activate more muscle fibres at once.

The reason we can't do this all the time is fairly obvious - it puts much more strain on the body and consumes far more energy. Since our bodies evolved in times of scarcity, our bodies evolved a logical mechanism for limiting the bodies ability to use its full strength and energy; only when the brain sensed certain stimuli (a tiger, a child in trouble), would it release its natural chemicals that overrode its own internal limiters, allowing for a brief state of higher muscle performance.

Answered by ninemiletree

8. Consinneration asked: Why is it that when you get hit (I.e. bang your head on a corner) you instinctively apply pressure with your hands? Why does that seem to help?

Your body can only process so much sensation at once. By touching the place that you've hurt, you're basically distracting your brain from the sensation of pain by introducing pressure.

It's another reason why ice packs can help with pain - not only do they reduce swelling, they introduce the cold sensation and give your brain something else to think about other than the pain.

Edit: what I've described above is apparently known as Gate Control Theory. I didn't know this, all I've done is transcribed the explanation that I was given when I was little, because my dad is a very knowledgeable man and I used to ask a lot of questions!

I think it's worth noting some of the other theories given below that may have been buried: you instinctively check the damage to see if you are bleeding or missing anything; you place pressure on the area to stem the bleeding.

I'd imagine it's a combination of the three, and probably more! Thanks for your input everyone. I've learned a lot today.

Submitted by BindweedHawkmoth

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9. MaxwellVador asked: Where does our head voice come from if it doesn't sound like our actual voice?

The psychological theory of bicameralism [a hypothesis in psychology that argues that the human mind once assumed a state in which cognitive functions were divided between one part of the brain which appears to be "speaking", and a second part which listens and obeysa bicameral mind] is controversial, but interesting nonetheless.

It basically states that humans developed consciousness with an intermediary step -- bicameralism. This involved two parts of the brain communicating, one is talking to the other and telling it what to do. The author states that this is where the concept of "god" came from, as early humans were literally hearing another voice giving them commands. Over time this evolved into true consciousness with an internal dialogue.

Some of these themes are being addressed (via artificially-intelligent androids) in HBO's new series Westworld.

Answered by TheLorenzo

10. AmericanPixel asked: Why do men appear to have a "stitch line" or "scar line" at the base of their ballsac?

Saying it "started out as a vagina" is an overstatement, but it's grounded in truth.

When we're forming in the womb, we start with a shallow slit between our legs. For women, that slit deepens while in men it stitches together.

The left side is grown, the right side is grown, and then they fuse together. Later, the testes descend into them.

Calling it a vagina at that stage in development isn't really accurate; a vagina is more than just a gap in skin, it's a structurally complex organ with a dozen different unique cells and its own intricate biology. The prenatal gap superficially, however, is closer in appearance to a vulva than to testicles, hence the common narrative that we all start as women.

Submitted by ManualNarwhal & Notmiefault

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11. LebumGermsJr asked: Why does a hangover get worse as we age?

Alcohol is metabolized by liver enzymes and first broken down into acetaldehyde - which is our hangover culprit. After that, it is broken down by an enzyme into acetate which eventually turns into carbon dioxide and water. All are then washed out along with sins from the night before...

The number of enzymes used in this two step metabolism process slowly dwindles as we age, making us less and less efficient at processing the toxins. This means that the asshole acetaldehyde hangs around longer in our aged bodies that it did before, making us feel like we're slowly dying.

Submitted by marriedtodata

12. MisterE_MD asked: Why do animals (including humans), in general, become less playful as they grow older?

Play is all about exercise and learning. Part of it is simply about increasing strength and coordination. A lot of it is about learning valuable physical skills like stalking, fighting, chasing, catching etc. And a lot of it is about learning non physical skills. For instance a lot of young animals (including humans) do mischief because it teaches them about social boundaries.

Young animals go too far in their play because they only learn about social boundaries when an adult puts them in their place. Along the same lines, they learn about appropriate consequences by watching adults interact with other adults.

And finally play teaches young animals about their personal limitations. Theyll teach it to climb fearlessly because it knows what it can and cant do. Itll know how fast it can run, how far it can jump and so on. Itll help them learn that their abilities increase as they grow because they run faster and jump farther than they could last week during the same game.

Play tends to be unique to animals whose abilities change and grow with them. You wont see much play among insects, arachnids and most reptiles for instance. Theyre born fully capable (even though practice and learning can improve their capabilities).

Submitted by TheSecretMe