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.
"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?
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!
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.
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.
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)
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.
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?
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.
Readit News
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?
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.
That's the coolest thing since a friend showed me he could move his ears.
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]
[0] https://en.wikipedia.org/wiki/Infant_swimming
https://www.youtube.com/watch?v=jeY9zYkNf7M
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...
"If Leah had taken the drug alone, she might well have survived. If she had drunk the amount of water alone, she would have survived."
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.
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?
Here is some literature: https://www.scientificamerican.com/article/strange-but-true-...
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.
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).
https://en.wikipedia.org/wiki/Expensive_tissue_hypothesis
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.
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.
Deleted Comment
Deleted Comment
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.
What's up with needing water sugar and air, while creating waste product? Just use electricity.
Why is saltwater such a hypothetical problem for them? How are ocean-going fish and shrimp "fresh water"? Those are going to be saltwater too.
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).
If X has something generally harmful to animals, Y has likely evolved some mechanism to filter it or neutralize it.
Meat is impedance matching for the food chain.
It doesn’t sound very pleasant though…
As discussed a few months ago: https://news.ycombinator.com/item?id=26232597
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?
There’s also the water heater if it has a tank - it can be drained from the bottom (you’ll want to shut it off if it’s not refilling).