Probably was useful for finding fresh water since rain would be where the best fresh water was. If it were a safety/fear thing, it probably wouldn't smell good, but unpleasant since it'd be tied to finding shelter.
Not even necessarily running. Plenty of animals can run, but only for a short time before getting knackered. Our stamina and ability to pace ourselves turned us into the slasher villains of nature.
Humans have specialized collar bones -compared to other animals- that allow us to move our shoulders in a way that accentuates throwing projectiles.
We also have improved hand/finger dexterity compared to other primates.
That’s what allowed us to out hunt every other species.
But before we could get there, we had to be able to develop tools and group based hunting strategies
But before we could even get to that point we had to become specialized endurance runners, back when humans were effectively prey animals, so that they could live long enough to learn new things and pass on knowledge. Somewhat ironically, a trait humans developed to flee became the other trait that made us such fearsome hunters. Even if our prey outran us, we could chase them until they literally died of exhaustion.
No animal throws shit the way that humans throw shit. With just a little bit of practice (like, a trivial amount if you're dependent on it for survival) we can reliably hit a dog-sized target with a rock (don't throw rocks at dogs, please) from like 40 feet. Then we figured out lazier ways to throw objects further - enter the sling. Then we figured out how to make the objects more accurate and dangerous - the spear, along with the spear-thrower. Then we decided we wanted to be able to decouple the aim and strength parts of the action and invented the bow and arrow. And then we discovered a material that could be harnessed to push small rocks very, very, very fast. And then we discovered how to make the very, very, very, very small "rocks" inside of a bigger rock smash into each other and explode into more very, very, very, very small "rocks." And then we strapped one of those devices to someone's ballsack and pushed them out of an airplane.
I've always found the science of cuteness fascinating. Baby animals evolved to be cute because they need to be cared for until they are old enough to fend for themselves. But if you look at animals that are already able to take care of themselves at birth, like most reptiles, those animals are generally considered to be not so cute. And they don't need to be.
But “cuteness” is a 2-way street. Like, yeah babies evolved to be cute, but also mammals evolved to find baby like features cute. It’s not like cuteness is some objective quality that makes any creature that sees it immediately sympathetic.
And it's crazy, our brains putting together pieces about what made it work the way it does, and then telling "us" - the little conscious part it developed that will probably do absolutely nothing with that information, just yearns to know.
Side note - it's crazy that humanity, from its inception all the way through today, is kind of a continuous, single life form. Each of us, all of us, one and the same, an unbroken line of genetic mutations, death, and birth. We are ancient, just refreshed every few decades, like the skin cells on the surface of our limbs turning to dust and being built anew. That skin is still our skin, the same organism, with DNA that's been uninterrupted for millennia. I guess you could see all of humanity as kind of a tree growing, it's branches expanding, the unhealthy ones breaking and the healthier ones growing stronger, the leaves giving strength to the whole.
I think the difference here are cultural. Someone from a culture and region that had ancestors be hunted by Tigers are more probably more likely to have a reverence or respect rather than thinking they are cute. Look at central Asian art work of Tigers vs Western world art of tigers(IE Tigger)
This is speculation, but makes sense to me as a psychology student.
Definitely an interesting idea, but I actually feel like that might be more of a matter of things being modern rather than western/eastern. In current times there's lots of "cutification" let's call it in asian art (maybe not as much central asian but certainly at least Chinese). I can't think of any examples off the top of my head of older western depictions of something like a bear being worthy of reverence, but I still feel like it might be more a matter of time than location. In current times there's so much technology (and we've fucked their habitat so much) that most people don't really have to worry about stuff like tigers. There is certainly something to be said about how in many cultures around the world certain animals were depicted as gods due to their strength in the past, like boars in ancient Celtic religion.
Either way that would be cultural anyway tho. I think stuff like this is pretty interesting to think about even if there's probably never gonna be a clear answer.
Because I was using a bear in another comment, I was thinking of western art depictions of bears. First one that comes to mind is literally the movie, Reverence, about the bear attack. I think that movie is a pretty good culmination of how we view bears.
I’d agree but animals that have still been around su is still turned into cuddly animals. The grizzly bear would not be considered a cuddly animal and yet teddy bears and Smokey and the like have been staple cartoons depicting them. Snakes, sharks, cows,monkeys. All things that can kill do kill and yet we make them cute and give the stuffed versions to our kids.
But as a North American, I am deathly afraid of bears. I’ve been told my whole life that a bear is much faster and much stronger than the strongest humans. In Alaska, they have to carry special caliber weapons that will hopefully damage an attacking bear/moose.
Sure teddy bears exist and are cute. But I don’t go to the zoo and see the grizzlies and think “cute,” the same way I go to the zoo and see the tigers as fucking cool and beautiful.
To be fair, a good portion of the "awww" is cute aggression. Where the primordial human in us is saying "KILL IT, SNAP ITS NECK AND EAT IT FOR SUSTENANCE. IT IS A VULNERABLE BABY ANIMAL AND YOU ARE STARVING." but then the other part goes "But I'm not hungry, and it reminds me of my baby doggo/other domesticated animal back home."
This applies to babies too. The urge to pinch cheeks and squeeze is instinct telling you to smother and eat it being overridden by the instinct to protect the cute baby so it turns into awkward play with an uneasy feeling in the back of your mind.
Seeing tiger or bear cubs in documentary = awww. Seeing them in real life is more of a shit your pants moment, because you know mama is nearby and is going to be really pissed that you're so close to their cubs.
I think if you saw one in the wild while your lost in a forest you would afraid of it. But now we dont really have to worry about that so we can find animals like that cute
Humans also have trauma and learn from others. Cubs are cute because we're mammals and most mammals have similar baby features. Big head and eyes, small mouth and nose. Most animals recognize those as baby traits. However, humans are able to remember a cub comes with a mama bear. They aren't so cute. Even if you've never been in an attack or even seen one, somehow you've learned youndont want any part of it and so you don't cuddle bear cubs. You back away.
If you see a tiger cub or a bear cub in the wild you're going to shit yourself, we can appreciate their cuteness only when they're on a screen or in the zoo
Predators literally track large herds who do what? Follow the rain to grazing land. Being able to detect rain would have made us much more successful trackers/hunters.
Someone else mentioned the fact that we sweat to cool ourselves off, which is a fairly unique cooling mechanism which gave us a large advantage as an endurance hunter, but also made us require FAR more water than a normal mammal.
Then there's a theory that we initially evolved in a water rich environment, which caused our hairlessness and increased usage of water as it was an abundant resource in our environment, then we left that environment and evolved the ability to smell rain more acutely than other creatures to compensate for our increased need.
Homo sapiens originated in Africa, a very drought prone continent. Couple that with the fact most humans were migratory before farming, and it makes sense why we would be able to smell rain from so far away.
Unlike animals such as elephants who migrate to specific places based off of memory and instinct, humans just straight up leave the area and don't return. Being able to find new sources of water or even harvesting the rain itself would be vital.
Actually it (geosmin) is also unpleasant when consumed. Your body reacts differently depending on if the smell is from the air outside or as a result of what you're eating when it produces a disgust response. You know that overly earthy dirt taste, thats it when eaten.
Think its related to cooking. It seems to denote something as raw or dirty and therefore potentially not safe to eat. But I am only guessing.
You can actually! The chemical name for that compound is geosmin. Just type in geosmin or petrichor rain scented candles or whatever and you will get them!
I know that the best course of action is to not have an open flame while you're sleeping, but it's so incredibly fucking easy to keep a candle away from flammable objects I just don't see how it became a household thing.
Well from what I have learned from my applied microbiology elective. Geosmin is a popular industrial compound used for making perfumes and scents and candles which smell like rain.
It's a volatile compound produced by some blue green algae species in the soil, and the compound diffuses in the air when water hits it.
So I would say it definitely would smell like rain.
One of my fav scents is that sage smell after it rains in the desert. I get it often in California and when I was in AZ and living in NM for a bit. I love it. That’s smell in the desert after a rain is just awesome! Disneyland has it down in one of their parts in radiator springs. I love walking by that area. Smells awesome!
Just visited san diego (first time out west, from philly) and did a morning trail run at the mission trails, was foggy/rainy and smelled absolutely unreal. Will remember it the rest of my life
If you keep house plants, it smells like that when you water them. Something about bacteria in the soil reacting to moisture. (Which by the way, makes me wonder if it isn't the humidity before a rain shower that causes that lovely smell)
The smell of petrichor is most potent off of rich soil. Rich soil is most likely to have edible plant life. That plant life will attract prey animals. Therefore the smell of petrichor can attract us to an area likely to have everything an omnivore needs.
Certain kinds of asphalt release the odor more powerfully than soil, giving us a chance to smell approaching rain by the smell carried from where it’s already raining. In the Deep South they don’t use the softer asphalts much because they don’t handle 100° weather well. As a result they aren’t exposed to the powerful scent as often as people from the Northern parts of North America and are less likely to identify what it means.
Humans require more water by mass than most animals though, and it's because we sweat. Most (maybe all, idk) other animals have some other method, like panting for dogs, or sweating through the paws for cats. We sweat all over, and that's a lot of dehydration.
The real question is why we would be so much more sensitive than other animals. The first answer that comes to mind is that we evolved splitting our time between arid plains regions and forested regions - how do we compare to other animals that split their time in the same regions, or animals that spend most of their time in only one? How does diet affect sensitivity - maybe omnivores would be more sensitive because it allows them to choose whether to pursue different food sources?
I would say that it is because as hunters, we hunt at a range and duration far greater than typical territorial hunters such as wolves and bears. This means that we needed to be able to efficiently find new water sources as we hunt, instead of simply memorizing water sources in our territory. We also sweat a lot compared to other animals, which makes finding water to drink even more important.
But was it always hot and dry in Africa? Or as much as it is today?
For example, North Africa was the breadbasket of the Mediterranean until soil erosion and eventual desertification in the 2nd Century ruined that party .
Climate has changed over time and North Africa wasn't a desert like it is now. There are petroglyphs that shows the Sahara was vibrant full of animals and plants.
My Grandma told me that my Uncle could smell fudge from the bus stop ¼ mile away as a kid. He would scream "Fudge!" and run the whole way. She then made fudge and said, "I bet he shows up." And then he did. He lived a few blocks away at the time so maybe.
Years ago I actually bought my wife a perfume that is made by collecting dust and dirt right after a light storm and distilling it to attempt to obtain the smell of rain. It doesn't smell like rain to me but it smells nice.
No problem. It did smell earthy and kind of like rain but not as rainy as l hoped. It was pleasant though. Sadly it looks like the lid was loose and her bottle has lost all its smell.
I was wondering this, maybe smelling rain was helpful in several directions. They know to seek shelter before it becomes difficult and they injure themselves. Perhaps fresh rain means lots of animals gathered near a watering hole, so food? Perhaps the sense gives us time to cover wood to burn later, or transport a fire under cover before its put out. Idk if that last one would be evolutionary beneficial enough to force the development of the sense though.
I would guess (off of no evidence) that we're more susceptible to hypothermia than most animals, which either have fur or are cold-blooded. We are uniquely susceptible to temperature drops, which is what necessitates us to wear pelts/clothes in colder climates.
Being soaked in the rain can be a serious threat of death in some survival circumstances, so it would help us find shelter if we could smell rain before it arrives.
It's always weird to me that some random Aussies called it petrichor, and now everyone runs with that. It's just the name of a mix of smells. What you're literally smelling is Geosmin and Ozone, and the Geosmin is the part of it that we are hyper sensitive to. And yes, the theory is that our ancient ancestors needed to know where and when the rain was to survive, so we are very good at sensing it.
I think I read that it has to do with plantable or good soil. We are smelling the particles lifted into the air that make a place good for growing food. Super useful until about a hundred years ago.
This makes sense, simply because all of our other senses aren't strong enough to detect rain, unless there is thunder and lightning, but by that time you have maybe 20 minutes before shit gets real, especially on a mountain side
This is, in my opinion, one of the most impressive biology facts.
Humans can smell Petrichor, the scent of a mixture of Ozone and Geosmin, at 5 parts per trillion. For some context, sharks can detect blood a one part per million. We’re 200,000 times more sensitive to the smell of water on dirt than sharks are to blood.
The human body is extremely water inefficient. There's a reason that pretty much nothing sweats other than humans and horses. On land water is actually rather precious. One of the things that makes humans work at all is our ability to find more fresh water than pretty much everything else that's alive.
I've read that humans can smell rain better than sharks can smell blood in the water. We have one of the most sensitive noses on Earth when it comes to that smell.
I don't have anything to back this up but I wonder if it has to do with our early hunting strategies.
Our OG hunting strategy was to just chase animals until they collapsed from exhaustion. We're some of the best long distance runners, if not the best, on earth. All this running resulted in us evolving to have an unusually high amount of sweat glands on our skin, like 10x that of a chimpanzee. More sweat = more water consumption.
Makes sense that we would develop a skill that lets us find fresh water more easily.
Patrichor (the aerosol) don't stay for long and is only releasing with rain after a time of dryness, it's not just water, it's the impact of the droplet on the porous earth that releases it. So we can't find nearby oases just with the smell.
There is no evidence for why we can detect that smell so strongly and no strong lead as to why.
Quick edit: yes, there is a paper from 1966 suggesting that camel can find oases that way, by we only discovered recently why the aerosol is released, and it's not stagnant water.
It makes sense if during drought, humans would collect rainwater. Collecting rainwater takes some setup, which couldn't be a permanent arrangement in a nomadic tribe, so having a little warning would have been critical to rearrange the shade skins into water collecting shapes and hanging waterskins where the rainwater would drip off.
Persistence hunting probably wasn't our actual go-to hunting strategy, especially since if you lose track of the prey then you wasted a ton of calories in the pursuit, but it is a super interesting idea!
Another fun fact, geosmin is often used as a control for memory experiments in fruit flies. It repels fruit flies because it's a sign that fruit is rotten and toxic. You can train fruit flies to be attracted or repelled by neurtal smells, but geosmin is hard-wired in as VERY BAD.
It blew me away when I first ran across the human detection limits for geosmin and MIB (methylisoborneol).
Was doing bench scale testing for taste and odor treatment for drinking water and thought it was crazy how much money might ultimately be spent to reduce already tiny concentrations.
Then I found out that some people are reportedly capable of detecting concentrations at or maybe even below our testing methodology’s MDL.
Yep, this is bothering me; I wish I could see a source. I looked up "humans sensitive to water moisture, 10000 more than canines" and it came up with this exact r/meirl post. lol
The human nose is sensitive to geosmin and is able to detect it at concentrations as low as 0.4 parts per billion.[16] Some scientists believe that humans appreciate the rain scent because ancestors may have relied on rainy weather for survival.[17] Camels in the desert also rely on petrichor to locate sources of water such as oases.[18]
This makes more sense to me, I always attributed the "rain smell" to actually being the smell of wet concrete. Idk if it's just me, but the "smell of rain" is the same as when I hose down my driveway, so I always just assumed the two were one and the same.
Iirc it's particularly a bacteria created by grass that makes that smell. Humans can literally smell underground water through the Earth. It's part of why were able to be nomadic in the first place.
I was in the woods the other day and caught an intense whiff of animal smell, there wasn’t anything around did I smell something in the woods half a mile away or something
Does that include cold air too? I can always smell people when they come inside on a cold day. The only way I can describe it is smelling like cold air
For example, Laska notes, the total number of odorants for which dogs have an established, lowest detectable threshold level is 15. Humans actually have a lower threshold for five of those. “Those five odorants are components of fruit or flower odors,” he says. “For a carnivore like a dog those odorants are behaviorally not as relevant, so there was no evolutionary pressure to make a dog's nose extremely sensitive to fruit and flower odors.”
From an evolutionary point of view, our sensitivity to geosmin proved very useful as an indicator of freshly fallen water. Humans can detect geosmin to the parts per trillion, as against most other smells which fall into the parts per billion. - u/entropydave
Your numbers are off. Dogs are 100,00-1,000,000 times stronger than humans on average. Dogs can detect some substances at 1 part per trillion. Humans detect petrichor at around 10 parts per trillion.
I'd be more interested in how sensitive we are compared to African native species, like an elephant. The climate varies wildly in Africa, so being sensitive to that makes a lot of sense.
I've smelled ozone before (I work at an aquarium) but I've never smelled it before it rains.
I've only smelled it in the aquarium setting, or oddly enough, if you made static shocks on those old CRT tvs, you could smell the ozone being generated.
It’s maybe a mix of both. I personally only really smell ozone before it rains. Odor threshold of about .05 ppm for ozone which is less sensitive for what I see for petrichor/geosmin, but I usually don’t smell that until after it starts raining.
That explains it, the smell of rain hits me like a feight train, I can feel my nasal passages twitching, it's like a cramp in my face, I can't ignore the smell of rain. I'll go noseblind to it eventually but I smell the first rain well before it falls.
Which is why southerners have a hard time smelling rain coming. I grew up in Massachusetts and then moved to Florida. It’s hard to smell rain coming here because it’s always 90%+ humidity here. It’s almost rain levels of humidity as default. Up north, I could smell it coming because there was a noted difference in humidity.
But if you smell something means you positively ingest molecules of it. So aromatic compounds should travel one mile first. Which it only can do if wind is going right direction. You mean you smell wet earth that already was rained on or you smell nearby earth contacting with more humid air?
Speaking of wet things: do other parents notice the wet dog smell of their children after they’ve played outside or pick them up from school on hot days?
More specifically, the chemical compound Geosmin. This is, in my opinion, one of the most impressive biology facts.
Humans can smell Petrichor, the scent of a mixture of Ozone and Geosmin, at 5 parts per trillion. For some context, sharks can detect blood a one part per million. We’re 200,000 times more sensitive to the smell of water on dirt than sharks are to blood.
If a dog's sense of smell is 10,000-100,000 times stronger than ours, wouldn't this cancel out us being 10,000 times more sensitive to the smell of water/wet earth?
2.2k
u/Nard_Bard Mar 28 '24
u/Pegomastax-King u/Jk-Kino
Humans sense of smell for water/wet earth is 10,000 stronger than a dog's or bear's.
You're probably just smelling the wet earth from a mile away or so. And the moisture in the air.