There are several oddities about humans that seem to indicate that we were semi-aquatic at one time: webbed fingers and toes, hairlessness (compared to other primates and hominids, we are the "naked ape"), our big beak noses that help keep water out of our nasal passages (some people can voluntarily seal their nostrils), our babies float and instinctively hold their breath, the fine hairs on our backs are slanted towards our spine (rather than away like all other primates) improving flow, our fingerprints that swell and wrinkle when wet making it easier to grip things, our eyes have a special "underwater mode", etc.
Voluntarily sealing your nostrils is something I never knew about until I was complaining about some city odor to a girlfriend who said "Just plug your nose." I said I didn't just want to walk around pinching my nose, and she gave me the most incredulous look. She was like "No, just do it without touching your face..."
This definitely shocked me. May as well ask me to sprout wings and fly!
Me: I wonder why our son doesn’t like to get his head wet in the bath or the pool.
Her: I think he doesn’t like to get water in his nose, like me.
Me: uh... what?
Her: blah blah blah
Me: WHAT DO YOU MEAN YOU CANNOT CLOSE YOUR NOSTRILS FROM THE INSIDE?!
Or something like that. I guess I assumed that everyone could just block it off from the inside. It’s apparently not something that comes up very often?
Don’t we all naturally seal our nostrils from smell when we use non-nasal sounds? Think a nasal ahhhh sound versus a non-nasal ahhhh sound.
Although I am guessing sealing nostrils from water versus from smell is distinct: I feel you can seal at the front “inside” the nostrils (think blocked nose) versus sealing at the back (soft palate?). Edit: Also when you blow your nose, i think you partially use the muscles that close off the nasal passages?
Although quite possibly I am misunderstanding something - we often struggle to even realise what we naturally do (e.g. when swimming) or struggle to understand that others do things differently.
I tried to exhale through my nasal passage and then block it off with just the muscles in my nostrils, building pressure in the nasal cavity. I cannot do that.
I just looked it up and found this pdf[0] on some technique for divers I didn't bother to understand, but it contains an instruction (Step 3: Learn to control the soft palate) how to get a feel for this. It's not really nostrils, but I think this is what GP meant.
I'm no professional diver but thinking about it and reading that link, it's really a technique to maintain enough pressure inside the nasal cavity to prevent water from rushing in, achieved by closing the soft pallet then slowly moving air into the nasal cavity as needed to maintain that pressure. So not really closing nostrils (for me at least) just restricting them a bit I think... it still sucks to get water past the nostrils but that can be prevented and it's not something I've really had to think about before. When diving into water or changing depth I have to exhale hard through the nose to combat the surge of water pressure but after that it just happens.
I do it by pushing my top lip up against my nostrils. I look silly if there's someone with goggles on to see me underwater, though. Like an extreme duck face.
Also, it doesn't work well now that I have a mustache.
I don’t know about others but I don’t use my tongue. I can block my nasal passage and breathe through my mouth. I can have my mouth wide open and do this. It must be controlled by some muscle but I don’t know what.
I am pretty sure I am breathing through both right now (trying on purpose to do so). I can definitely feel the breath on my tongue and hold something to my nose and smell it.
Whether air from both places actually goes into my lungs? That, I don't know. So you may be right in that regard? I really don't know. :)
"No, just do it without touching your face..." -- doesn't that simply mean "stop breathing"? because that has the same effect. I do this all the time these days when I walk past people and not waring mask ;-)
I think that has a lot more to do with enabling us to walk, jog, and work long hours by sweating to keep cool. More water lost, but huge competitive advantage in endurance. Since we're literally oozing water, I'm guessing all those water-adaptive advantages start to make more sense for landlubbers.
Interesting. I happened to be one of those natural born swimmers (not as newborn) as an infant as I could float, move around by wiggling like a fish and close nasal passages instinctively (w/o exhaling) at 8 months. Always perplexed me that some people will hold their nose closed or have to exhale through it while under water.
> our babies float and instinctively hold their breath
This is just partly true, however, and I assume you don't mean that babies are natural born swimmers. :) Ref. Wikipedia; "Babies are not old enough to hold their breath intentionally or strong enough to keep their head above water, and cannot swim unassisted. Most infants, though not all, will reflexively hold their breath when submerged to protect their airway and are able to survive immersion in water for short periods of time." [0]
We put all 3 of our kids through ISR (Infant Swim Resource). they started at 9 months (based on summer relative to their birthdays). Its pretty incredible to see a 6-9 month old baby float indefinitely. At a year, they teach them to "swim, float, swim". The swim phase is targeted to 5-7 sec of holding their breath while swimming.
Yes. Also, most every mammals other than whales _still_ have fur (seals, sea lions, otters, etc), so it's not clear that hairlessness has strong selection pressure.
> Worse, if we drink too much water too fast, we can throw off our electrolyte balance and develop hyponatremia—abnormally low levels of sodium in the blood—which is just as deadly if not more so than dehydration.
I remember reading a news article about the tragic death of a young girl from this. It was at her birthday party. Her friends got her some MDMA, which she had never tried before, and she freaked out, locked herself in the bathroom, and drank an unbelievable amount of water. Her sodium levels tanked, her brain swelled, and she died.
As a tangent, the news article was titled something like "MDMA kills teen", as if the drug had poisoned her, rather than blaming ignorance and sodium depletion from drinking too much water.
One of the many sources of hysteria around drugs in that period of time, and from the wikipedia it looks like it wasn't just anti-drugs campainers who exploited the situation; alcohol companies fearing competition had a go too...
I mean, if she had taken PCP and jumped off a bridge while trying to fly, I think it's it would be fair to blame PCP and not ignorance about gravity. I think it's pretty fair to blame deaths based on bizarre behavior while on drugs, on the drugs.
But in this case the idea "drink lots of water" was directly from hysteria about the dangers of that drug at the time, not just random bizarre behavior.
I have wondered why humans don't really have much of a water buffering capacity, mostly prompted by a line in Dune about "water-fat" Atreides. Would be great to be able to chug like two liters of water and go about your day reasonably hydrated.
Actually this very practice is described in the book "The Old Way". The natives in a dry region in Africa would drink massive amounts at a watering hole before setting off for a journey. It was probably more than 2 liters.
I try to take a similar approach when hiking of drinking as much water as I can before starting a hike. In a hot and dry climate you don't end up urinating out as much as you might think.
Exposure to this practice over time in a particular environment might be able to alter gene expression to better support the practice much like the hunter reflex develops with cold exposure. People often make the mistake of thinking their personal modern experience is close to some human limit.
"The Old Way" also points out that persistence hunting (mentioned in this article) could only be used under particular environmental conditions (mud after rain that slows down animals) with a particular animal that overheats more than others so it didn't seem a reliable hunting method.
To others reading this there needs to be a big bold WARNING: Do not drink liters of water as people have died doing just that. Google it and you’ll find horror stories of people in competition to chug tons of water only to make an ER trip and die on the way.
There is a myth on the internet that drinking shitload of water beyond comfort is acceptable and has zero risks because hey it’s just water right?
To be more precise: do not chug liters of water without supplemental electrolytes. What kills people is the fact that salts are water-soluble and are flushed out as you drink water. It's not the volume of water that's inherently dangerous. It's that it flushes out water-soluble electrolytes that are necessary to muscle function.
I can't edit my comment anymore but did upvote yours. I agree with those warnings about imitating this practice. My "drinking as much water as I can" is perhaps 1 liter, much less than what seemed to be described in "The Old Way".
In the article you point to the main issue seems to come from inhibition of urination. I think native people knew their bodies extremely well and could avoid any problem here whereas in modern times we have been training ourselves since being a small child to ignore or hold back urination. Combining that with other suppressors mentioned in that article can end in tragedy.
Water is pretty heavy (eg, denser than wood, denser than oil, denser than fat, etc).
Weight is costly (eg, mv^2 energy to accelerate). I guess human bodies have spent a lot of time trying to find the minimum amount of water necessary rather than trying to build up a reserve.
The little micro-optimisations add up over time. The penalty for excess weight doesn't have to be large before evolution tries to get rid of it. Historically, fat people are an anomaly.
> Would be great to be able to chug like two liters of water and go about your day reasonably hydrated.
During Ramadan (not Eid as someone pointed out!), most Muslims refrain from eating or drinking during the day, and Muslims are highly overrepresented in warmer countries, so it's definitely possible, though maybe not comfortable.
During the lunar month of Ramadan. Eid is the first day of the following month when Muslims celebrate the end of Ramadan. (There is an unrelated separate Eid at a different point in the year).
When I lived with Saudis during Ramadan in college, their fasting strategy was mostly to just sleep all day and wake up a little before sundown. I ate some really delicious food during that month!
I have often visited Morocco and lived in Malaysia for some time.
Sort of, yes. During noon and afternoon most shops, restaurants, and other places were closed. Certain essential things were open. There was also a divide between rural vs urban, with urban have more open stores.
Especially in Morocco this didn't seem too uncommon even outside of Ramadan though as its often simply too hot to really work during the day.
Depends on the country. When we lived in Saudi, during Ramadan most stores took the morning off and were open well into the night (like midnight). Many businesses (banks etc) did a morning shift (9-1) and then an evening shift (6-10).
No. Rather productivity is down 50% or more for the entire month.
Imagine two civilizations otherwise equal. One works 12/12=100% of the year, and the other 11.5/12=96% of the years. Then compound the gains over 14 centuries!
Not just uncomfortable. I remember reading that women who are in early stage of pregnancy during that time are more likely to have disabled kids. (Women who know about pregnancy dont have to fast, so it affects early stages the most).
In the outdoors community, there is an emerging breed of ultralight backpacker that wants to shed carried weight so much that they refuse to carry water. Instead, they chug as much as they need when they reach a water source, and continue on the trail without any reserve in water bottles.
So it’s in their bodies instead of carried on their bodies? Maybe the few grams of plastic for the container means that much to them?
It’s seems like this is kind of related to where bikers (cyclists) pay double for a component to save 100 grams instead of losing a bit of body weight.
> It’s seems like this is kind of related to where bikers (cyclists) pay double for a component to save 100 grams instead of losing a bit of body weight.
Is kind of dumb argument. There is no tradeoff between the two. You can do both of these or neither. The additional weight in equipment will be there regardless of what happens to your bodyweight.
Which is why when I went hiking, I attached a couple of home-made carriers to the front straps of my rucksack. One to carry a water bottle, and the other to carry a camera. Having some of the weight on the front (rather than all of it on the back) helps. There's (quite old now) research that shows that people in Africa who carry immense loads on their heads actually have a more efficient walking gait than people who carry loads on their backs.
I suspect the amount you can "carry" in your body (ie. not including the amount you'll urinate 1 hour later) is in the order of 1-2kg tops, so ease of carrying isn't noticeable.
1-2kg can be a big fraction of the total weight an ultralight backbacker packs. I'm by no means an ultralight backpacker and my backpacks are usually around 10-15kg. A 10% saving is definitely noticable on longer hikes.
I think this is extremely dangerous because of what happens when you don't find water.
Getting lost on the trail, somebody getting injured, relying on water along the trail, just being sweatier than you expected, all of these end with somebody being very uncomfortable or worse.
OK - show me someone who's done a thruhike with just a Lifestraw.
Sorry, but not bringing a bottle or a flask because of weight is known as Stupid Light. Yeah, you could probably do it, but it's stupid to do. Another example is using a keychain light as your only light. You could do it, but it's stupid to do, and if you end up in an emergency situation, you're going to get little sympathy for the team of rescuers that save your stupid light butt. These ideas are what happens when you are sitting and looking at a spreadsheet of gear weights in a far larger proportion then actually being out and seeing what actually works.
I can't imagine doing any multi day hiking without carrying water, unless you are ABSOLUTELY SURE that water is available on the trail in regular intervals.
We probably could if we didn't sweat. Sweating (combined with hairless-ness) is a competitive advantage in thermal regulation, that enables long, long runs during hunting (or maybe foraging too, I don't know). But, you lose a lot of water.
I wonder if our closest living relatives have lesser or greater water capacities? You'd think persistence hunting in the savannah would select pretty hard for such an advantage, but perhaps that particular need was already offset by early tool-use? (portable water containers, wet furs)
Sure. Also you hydrate your whole body so all the processes that need water have water. And then you can last some time without water(without perceived negative effect), but I do prefer to always have water around.
half a liter and I'm going to the WC in 15 minutes. But then I weigh little. If you drink 2 liters and don't need to check the toilette for several hours, I'd visit a doctor.
Whats wrong with going to the toilet? Thats part of the body process to flush out unwanted substances. So if you drink enough, you flush out enough - and then you do not need so much water anymore. So you can drink lots of water and then not needing more water. So the storage of water you have when you are hydrated, lasts some time. That was my point.
But you are correct, that when you drink more and more, despite your body being already hydrated - then it pretty much comes out like it is soon after.
": Our findings agree with the long held notion that each gram of glycogen is stored in human muscle with at least 3 g of water. Higher ratios are possible (e.g., during REHFULL) likely due to water storage not bound to glycogen. "
If you want to store extra water for short periods drink/eat carbs
starch can also stimulate the uptake of water in your small intestine. Oral Rehydration Salts combine some dextrose and salts to mix into a liter of water. When properly mixed the salts are in a homeostatic quantity and won’t affect the salt balance of existing tissue. So you can drink them to recover from severe dehydration without risking hyponatremia.
You need to replace the salts in your body if you're drinking large amounts of water. Sodium and potassium are what signal muscles to fire. If you drink excessive amounts of water without supplementing electrolytes, you end up with water toxicity, which can be fatal.
Sports drinks are generally water with sodium chloride and potassium chloride added, often with sugar as well. Trust me, if you're sweating a lot and drinking a lot of water, you need a source of the appropriate salts.
We do store water in our fat. Dry fasting will cause your body to more aggressively break down the fat to get this water. Unfortunately, your body won't/can't always break down fat.
In Russia there are dry fasting resorts that allow people to fast without drinking water for 7-11 days under medical supervision. Most people do it for medical conditions, but some indeed as a way to quickly drop weight. Note that such fasting does not avoid all contacts with water. People still bath and brush teeth.
Because we have skills to maintain ourselves in advanced ways, the optimal answer was apparently to give us more problems to solve while liberating us from the drawbacks of built-in solutions.
generating electricity will also create waste products. i'm not sure that part can actually be avoided. biological systems can repair themselves (within limits) and make use of a wide range of energy sources. silicon based life certainly sounds interesting, but it would probably end up being a lot more biological than you're expecting.
well, solar power is abundant both on Earth and in the vicinity space. The waste product just happen to accumulate at Sun's core where there are enough space for 5 more billion years.
depending on how you capture that energy there will be waste of some kind that is created either in the manufacturing/growing process for the capture system or as a byproduct of converting solar energy to another form that is more easily stored. one of the advantages of diverse biological systems is that you can have cycles of organisms that process waste back into energy sources using solar energy + reactants as input. a self-sustaining silicon-based life-system would probably end up following a similar pattern to process waste back into useful resources, because waste products probably cannot be avoided.
You're absolutely right. Silicon based 'life' system does have the advantage that it would not be restricted to Earth environment - it can probably also adjust itself in way that biological beings here on Earth cannot easily achieve (genetic engineering are almost always generational, software engineering is the complete opposite).
Yeah, and pottery is great for stationary storage of water but poor for portable water storage… the pot can weigh almost as much empty as the water it contains!
What fascinates me are sea mammals. I can’t get my head around how whales and dolphins survive. Their daily fresh water consists of seafood, not to mention having to deal with all of the saltwater that accidentally goes down.
Cells contain less salt than sea water, and cell membranes are semi-permeable. That leads to osmosis drawing water out of the cells, drying out the fish.
Sea-dwelling creatures have different ways to deal with this. Most fish can "pump" salt from their blood into the water in their gills, in addition to their kidneys filtering salt.
The other strategy is to eat fish that have already done all that work, after all most animals are mostly water of compatible salt content.
(Freshwater fish have the opposite problem, without active salt management they would explode from osmosis drawing water into their cells).
Basically the same reason it is for humans – it puts a lot of strain on their kidneys. I believe that cetaceans are thought to be able to drink seawater as a last resort, but get most of their water from eating fish. The fish don't have the same salt content as the water that they swim in.
Humans can't survive on salt water, your kidneys need like 1.6 liters of water to remove salt contained in 1 liter of sea water.
If the reverse were true we wouldnt have hundreds of people a year dying on dingies trying to cross Mediterranean. Do you think they never tried drinking water around them?
Thank you for posting a relevant poem! I realize my day would be improved if that occurred more frequently. It's a good way to stretch the mind in a sea of artless information.
I am particularly conscious of this dependency due to a family history of kidney stones and a personal terror towards the thought of getting them myself. I aim to drink 2L of water/day minimum, and usually aim for 3-4L per day. It's not really that hard as I just drink when I'm thirsty, but I did eventually realize it would make going on a long wilderness excursion rather inconvenient.
I remember a similar rationale for why Neanderthals died it. Their larger size meant they needed to stay closer to sources of fresh water which prevented them from traveling to the most favorable environments.
I always thought that humans are more resistant to dehydration than all other mammals except camels. That (plus the fact that we do not have fur) is what gives us an advantage used in persistence hunting https://en.wikipedia.org/wiki/Persistence_hunting
But of course once you're dehydrated you need to replenish your water reserves.
Bighorn sheep can go 3 days between drinking water in 100-degree weather.
The article mentions persistence hunting but says the efficiency of our sweat system is part of what made it work — something that makes us need more water.
It's actually a crazy feeling to go 24 hours without water and then take a drink of water when it's warm. I've felt the crossover where my body decided that is safe to ramp up sweat production.
Persistence hunting requires good thermoregulation. Sweating (loosing heat fast) makes persistence hunting possible and keeps body temperature down. Animals human hunt will get overheated. They have to stop to cool down.
ps. Endurance running helps with scavenging too, not just hunting.
> Animal metabolism produces about 110 grams of water per 100 grams of fat, 42 grams of water per 100 g of protein and 60 grams of water per 100 g of carbohydrate.
The amounts listed is a bit puzzling. For every gram of glycogen stored (stored carbohydrates) 2-3 grams of water is needed, so naively one would thing the number should be much higher for carbohydrate.
Don't quote me but what I remember is that water is roughly stored with "sugar" in short term storage (liver, muscles) at a 3:1 ratio and in long term storage (fat cells) at a 1:1 ratio.
My guess is that while it may sound good in theory it would in fact be counterproductive, especially considering that we evolved as a tropical animal: need more water -> burn more fat –> generate more heat -> need to cool down -> sweat more -> need more water...
Of course, but metabolism also generates heat, and heat needs to be dealt with by evaporating water. Consider that the only human tissue that increases its metabolic rate just for the sake of it is brown adipose tissue[0], and its purpose is to generate body heat. On the other hand, compounds that can significantly increase base metabolism (and thus generate more water) such as 2,4-dinitrophenol[1] are dangerous because they can easily result in lethally high body temperature. That's why increasing metabolism with the sole purpose of generating water would be self-defeating.
On a high fat ketogenic diet, my thirst is satisfied on ~500ml of water a day. I drink much more when running on glucose, if it's really hot or I exercise intensely.
Just curious, really. I'm not aware of any serious downsides to ketogenic diets, except I suppose for the smell, but it doesn't take much glucose or starch at all before ketone bodies are no longer needed.
It still amazes me that most animals can hydrate themselves from the water content of what they eat. I was thinking either there’s something wrong with what we eat (not much water content), or we really just require more water than animals.
It’s amazing how much water you can drink when you’re exerting yourself. When I’m hiking uphill in the white mountains and it’s hot outside I’ll go through about a liter of water for every 1200 feet of elevation gain. (About an hour)
