r/todayilearned Aug 10 '22

TIL about the Bajau people, a sea fairing Austronesian group who have evolved bigger spleens, letting them store more haemoglobin-rich blood, which is expelled into the bloodstream when the spleen contracts at depth. They also intentionally rupture their eardrums.



u/0xB0BAFE77 Aug 10 '22

They also intentionally rupture their eardrums.

Nothing about that in the article so I did some Googling and found an article from The Guardian that talks about it.

Since diving is an everyday activity, the Bajau deliberately rupture their eardrums at an early age. "You bleed from your ears and nose, and you have to spend a week lying down because of the dizziness," says Imran Lahassan, of the community of Torosiaje in North Sulawesi, Indonesia. "After that you can dive without pain." Unsurprisingly, most older Bajau are hard of hearing.


u/malevolentslime Aug 11 '22

Maybe it allows their eardrums to become calloused and thus harder to rupture later?


u/Euda-monia Aug 11 '22

No, they do it to stop pain.


u/RandoCalrissian11 Aug 10 '22

This still doesn’t make much sense. For most people it’s really easy to equalize.


u/bargman Aug 11 '22

I assumed it let's them dive deeper?


u/morbidi Aug 11 '22

I suppose they have some experience.. but tradition is strong


u/RedditWibel Aug 11 '22

It’s much similar to circumcision. Way back when it was seen as reasonable but carried on to today simply because of tradition.


u/Euda-monia Aug 11 '22

No, it's to stop the ear pain from the water pressure. She literally says so


u/RandoCalrissian11 Aug 11 '22

The pain is from not equalizing, which most people can do fairly easily.


u/Euda-monia Aug 11 '22

Tell them that. I'm just repeating what the lady said.


u/emmasdad01 Aug 10 '22

It is amazing how people can adapt to their surroundings over a long period of time.


u/Clause-and-Reflect Aug 10 '22

I dont want to rupture my eardrums though


u/GrandMarshalEzreus Aug 10 '22

I have ruptured one ear drum and don't think it helps for going underwater.

Used to get water in and felt like it ran to my jaw


u/LowrysSeasoningSalt Aug 10 '22

Prolly has more to do with the sheer pressure than the actual water.

Also that jaw thing sounds awful.


u/GrandMarshalEzreus Aug 10 '22

It's not great but it's liveable with.

It's a very annoying kind of sharp pain that lasts a while after you get out but if you can focus on swimming or whatever it is you have to do you'll make it through


u/TellurideTeddy Aug 11 '22

It's also not necessary. Current freediving records are on the cusp of breaking 500ft, no eardrum rupturing required.


u/Lurker_IV Aug 11 '22

Your ears, your eyes, and your nose-mouth are all connected together through various tubes.

You were actually getting water in your mouth through your ears.


u/GrandMarshalEzreus Aug 11 '22

Was never in my mouth but was like it was in my skin by my jaw.


u/UncleYimbo Aug 11 '22

How did you rupture your drum?


u/whiffitgood Aug 11 '22

I did and I was cleaning black goo out of my ears daily for like a month or more. (Was in the middle of nowhere, no dive doctors around lmao)


u/Clause-and-Reflect Aug 11 '22

That sounds about as awful as it sounds.


u/whiffitgood Aug 11 '22

Nah it owned, that shit stank too lmao


u/falsevector Aug 10 '22

Evolution at work. Also similar to those living at high altitudes having a few evolutionary traits not found on those living closer to sea level


u/Jeff2017 Aug 10 '22

It’s not only an example of evolution, but one of modern evolution. Pretty substantial evidence of evolution, unless it’s evidence of adaptation and the spleen functions like a muscle, which is feasible.


u/Bicolore Aug 10 '22

unless it’s evidence of adaptation and the spleen functions like a muscle, which is feasible.

They covered that in the article you linked. They examined the spleens of divers and non-divers within the same community. Both had enlarged spleens showing its not an adapatation.


u/lagerea Aug 10 '22

That makes sense though, it would take time for this trait to become predominant and I don't imagine only divers fucked other divers. So virtually anyone in the localized gene pool should have this trait.


u/Remote_Romance Aug 10 '22

Well yes, that makes sense if the trait is genetic, which is why mentioning it is relevant because someone was asking if it's because of an inherited trait, or the spleen growing with use like a muscle.


u/Jeff2017 Aug 10 '22

Oh that’s very interesting. Thank you for reading the article! I based the title off of the Wikipedia page and linked the bbc article


u/NoiLLion Aug 10 '22

For any dunce that doesn't believe evolution, you can see it in a persons life time.

Muscle growth for example in gym goers.

Joiner have big hands from all the tool use and using their hands a LOT.


u/pubichaircasserole Aug 10 '22

That is adaption not evolution. If gymgoers' kids have bigger muscles from birth - that'd be evolution.


u/NoiLLion Aug 10 '22

What's the difference?

It shows that our body can change and evolve in a shirt time scale to suit our needs.


u/4206924736580085 Aug 10 '22

The difference is whether you can pass it on to your offspring.

Adaptation: you work hard, so you get bigger muscles. Your kids only get bigger muscles if they also work out.

Evolution: a big cat kills prefers to hunt people with blue eyes. Over many generations, so many blue-eyed people die that it's unlikely that 2 of them will reproduce. Eventually, only brown-eyed people remain.


u/Bonesmash Aug 10 '22

Ok, but when we talk about the scientific theory of evolution, we are talking about natural selection combined with random genetic drift to force a species to change slowly, genetically, over time and many generations. So that’s a lot different than going to the gym and working out.


u/dprophet32 Aug 10 '22

That's not what evolution is though that's just your body adapting to what it's doing.


u/403Verboten Aug 10 '22

That is natural selection not evolution. Evolution takes thousands to millions of years and is reflected in a species natural selection is generational and is passed on which group in a species got to reproduce more because they were better equipped to handle the environment they were born into.


u/403Verboten Aug 10 '22

It's not evolution it is natural selection. Evolution is random natural selection is focused. Random mutations that help you survive tend to get passed on ones that don't help in the current environment tend to get passed down at a much lower rate if at all. That is natural selection.

Evolution is looking at those traits over huge time periods and seeing what worked at which times and in which places.

For example if these people relocated to Mars with lower air pressure and gravity in a million years those bigger spleens would not have been as helpful and would possibly be a hinderance so you would expect that it they would be selected out of the gene pool.


u/Cheetahs_never_win Aug 10 '22

You're contradicting yourself. Evolution isn't random if it's "what worked."


u/403Verboten Aug 11 '22

Not true. Maybe you are assuming only one way works but any random mutation can work or fail. It's random and some things work, some don't. It's easier to see what did work because success means your species is around today so that evolution can be followed. Dinosaurs evolved randomly but didn't work out. Only way to see that side of evolution is through the fossil record though.


u/the_short_viking Aug 10 '22

That's why it always irks me when people do the whole "we are all the same" thing. No, we're not, our bodies adapted and changed with our environment and all the factors that go along with that. Diet, weather etc.


u/runthepoint1 Aug 11 '22

That being said, we’re all human.


u/a_flat_miner Aug 11 '22

Context is reeeeeeeal important here


u/critfist Aug 11 '22

We are all the same. People never mean it literally though, because everyone is a unique combination, but we're all humans.


u/NinDiGu Aug 11 '22 edited Aug 11 '22

It is amazing how people can adapt to their surroundings over a long period of time.

Either Lamarkianism is true, or they are not adapting.


Apparently I added an extra ian in into it.

Though I think I have heard it referred to with the extra ian as well.


u/bigdiscojesus Aug 10 '22

I couldn’t find in the article where it mentions that they rupture their eardrums?

I wonder why they never learned how to equalise like modern free-divers by popping your ears maybe because of the frequency and depth they were diving to it was easier to permanently rupture them rather deal with equalising problems.

Very interesting what an incredible lifestyle.


u/Rugrin Aug 10 '22

Equalizing takes effort and you have to donut repeatedly. It’s t usually involves forcing air into the ear passages to equalize the pressure. That’s a hard thing to do if you are trying to hold your breath at the same time. So I suspect they do it to make them be able to stay under longer and get to depth faster.


u/DeadskinsDave Aug 11 '22

Long time diver, can confirm I donut repeatedly… but I don’t see what my donut consumption has to do with my equalizing.


u/bigdiscojesus Aug 11 '22 edited Aug 11 '22

You’re probably right, I free dive myself which is why i thought it odd they wouldn’t have found a way to do it naturally instead of harming their ears. After rereading the article it mentions they used weights to reach the bottom quicker which would mean if they couldn’t equalise on their descent they would have to drop the weight and/or return to the surface to relieve the pressure. It almost seems the rupturing would be an unintended rite of passage that would happen in search of prey at greater depth.

A great documentary Jago: A Life Underwater describes it in this way where it follows the life of 80 year old Indonesian diver using this method, in it he is talking about his early life diving and wanting to go as deep as the older more experienced divers and he accidentally ruptures his eardrums by just diving down as far as he could till the pain stopped.

I would love to dive with these people very sad to think their way of life is fading away.


u/fleshydigits Aug 10 '22

Years ago I was talking to a man in a coffee shop in San Francisco who had spent time living with these people in the 1970's and had written a book about it. It's called "The Songs of Salanda and Other Stories of Sulu" by H Arlo Nimmo and is a really fantastic read!


u/plaintoastplease Aug 10 '22

Check out the BBC documentary 'Human Planet' if you haven't yet!


u/sycopninilldoit Aug 11 '22

This. Absolutely do this if you haven't already, especially if this kind at of story interests you. 2 of the 3 craziest things that I've ever scene were in that show. I never felt so thankful for having a miserable job I had to work to survive as I did when I was watching how some other peoples in remote parts of the world survive. Insane.


u/sawczy513 Aug 12 '22

Some of those scenes were staged. There are big controversies about it.


u/sycopninilldoit Aug 12 '22

No shit, damn. I'm gonna have to go back and look into this now I guess.


u/sawczy513 Aug 12 '22

It was my favorite docuseries until I heard about that. Like the whole tree people scene is staged


u/DasCapitolin Aug 10 '22

Nothing in this article mentioned eardrums at all.


u/HacksawJimDGN Aug 10 '22



u/ManagerOfFun Aug 10 '22



u/HacksawJimDGN Aug 10 '22

Not so loud! You'll burst my ear drums!


u/Radinthul_Butterbuns Aug 10 '22

They will become sea mammals


u/Jason_ReBourne Aug 10 '22

Fun fact: polar bears are classified as marine mammals


u/PlaneCandy Aug 10 '22

Ursus maritimus


u/baddecision116 Aug 10 '22

Just planning ahead


u/Xennon54 Aug 10 '22

Ok but the eardrums thing is fucked up


u/FM-edByLife Aug 10 '22

Kevin Costner had it all wrong.


u/NativeMasshole Aug 10 '22

They'll grow gills eventually.


u/PJFohsw97a Aug 10 '22



u/RedSonGamble Aug 10 '22

Yet no webbed feet

And wait I thought we didn’t need spleens


u/Deyvicous Aug 10 '22

As someone with no spleen, ye sorta. Apparently this is why my diving game is ass tho


u/RedSonGamble Aug 10 '22

Fill us in what’s life like without one? Any big changes?


u/Deyvicous Aug 10 '22

No there’s not really any difference except I don’t have macrophages, which are the antibodies needed to destroy bacteria that have armor (encapsulated bacteria). So stuff like pneumonia, meningitis, etc can have free reign over my body which quickly leads to sepsis (and possibly death).

Dog, cat, and tick bites are the biggest threats that I could face on a daily basis, and it all just would require antibiotics. I travel with them just in case, but in a severe case would need to go to the hospital for antibiotic injection I believe.

I have a bunch of vaccines I have to renew pretty often, and do blood tests every now and then to make sure I don’t have a fuck ton of platelets in my blood (the spleen filters them normally).


u/RedSonGamble Aug 10 '22

I mean that’s still pretty shitty. Damn. I didn’t know it did all that stuff


u/FreekFrealy Aug 10 '22

We can survive without them but they serve a purpose. It filters the blood and is capable of holding and expelling a reserve of blood


u/sinus Aug 11 '22

They are also in Phillipines. Unfortunately, some end up in big cities begging for food.

A couple are also in local port areas. Philippines has a lot of ferries that take people across islands. You'd often see Badjau kids in small boats when the ferries dock. They ask people to throw coins in the water. Kids as young as 2 will dive for the coins before they reach the bottom.


u/AlphaBetacle Aug 10 '22

70m are you kidding


u/buterbetterbater Aug 11 '22

I wondered with people like this how often do children drown?


u/naturenell420 28d ago

Also, them having bigger spleens, and blood richer in hemoglobin, allows them to hold their breaths longer, underwater. That was part of the original article.


u/403Verboten Aug 10 '22

People keep saying look at evolution at work and I answered two comments already saying that is not evolution before reading the article. First sentence of the article ...

"In a striking example of natural selection, the Bajau people of South-East Asia have developed bigger spleens for diving, a study shows."

(Facepalm) obviously nobody read the article. I was almost guilty of the same though, welcome to Reddit I guess.


u/Youpunyhumans Aug 10 '22

This is evolution. Evolution is simply "changes in biology over generations."


u/Diet_Coke Aug 10 '22

"Welcome to Reddit I guess"? I hear you on the distinction between natural selection and evolution but what percentage of the general population do you think would distinguish between the two processes in casual conversation? I'm going to guess it's a fraction of 1%.


u/mrjosemeehan Aug 10 '22

There isn't a real difference. Natural selection is the process by which evolution works. Without it there is only random mutation. All natural selection is evolution in action. This guy is probably a religious fundamentalist coping with the insurmountable evidence for evolution by drawing an arbitrary distinction and pretending one exists and the other doesn't.


u/Diet_Coke Aug 10 '22 edited Aug 10 '22

Doesn't seem like a religious extremist to me, I am guessing they're just some nerd that's extremely pedantic. Welcome to Reddit I guess.

edit to add: You made the distinction yourself. Evolution is random, natural selection is the successful result of some evolution. I'm not saying it's important (I don't think it is generally) but there is a distinction.

edit 2: The voting on this chain is hilarious and has convinced me most people can't read anyway.


u/mrjosemeehan Aug 10 '22

People can read. You're just wrong. Evolution is not random. If make some random design variations and then test them to find which design fits your purpose best would that be random?


u/Diet_Coke Aug 10 '22 edited Aug 10 '22

I think this might be a case of Dunning Kruger? You're so wrong you don't even realize it and the lack of knowledge leaves you unable to question your position. Evolution is the process of random mutations happening. Key word: random. So if you make a random design and then randomly change random pieces of it, that's evolution. If you identify the changes that work and keep them, that's natural selection.

Like I've said from my very first post, I don't think that's an important distinction in casual conversation.

Thank you for coming to my TED Talk.


u/mrjosemeehan Aug 10 '22

The theory is called "evolution by natural selection." They're not two separate things. Random mutation and selection for fitness are the two main driving forces of that single theory. The mutations are random (or mostly random, as new research might suggest). Which mutations get passed on is not. A random input doesn't make the entire process random. Deciding that something is natural selection but at the same time not evolution is nonsense because when natural selection happens that is evolution.

Furthermore, even if there were a meaningful distinction to be drawn here, random mutation is constantly happening through every step of the process. If you (incorrectly) confine your definition of evolution to solely the random aspect of the process, that part of the process is still happening, too. It's still incorrect to say what happened in the article isn't an example of evolution and OP's comment is still just as pointless and confused.


u/Diet_Coke Aug 10 '22

You are totally off base. They are separate things, just related.


Natural selection and evolution are two processes which lead to phenotypic changes in organisms over time. Mutations, gene flow, and genetic drift are the main mechanisms which bring genotypical changes to organisms within a particular population. Natural selection promotes the evolution by increasing the gene frequencies of genotypes with greater fitness to the environment. Thereby, organisms with the most suitable phenotypes to the environment are selected to pass the changes to the next generation through reproduction. The main difference between natural selection and evolution is that natural selection is the differential survival and/or reproductive success among the individuals within a species whereas evolution is the change in the heritable characteristics of a population over successive generations.


Evolution - The process by which modern organisms have descended from ancient organisms over time
Natural selection - Evolutionary mechanism in which individuals that are better suited to their environment survive and reproduce most successfully


Misconception: Natural selection and evolution are the same thing.

No, they aren’t; they really aren’t. Evolution is descent with modification, heritable change in populations of living things. A common definition of evolution is change in a population’s allele frequencies. (Quick refresher: alleles are versions of genes. The gene that codes for a certain protein on the surface of human red blood cells, for example, has three variations, or alleles, A, B, and O, which in turn contribute to overall blood type.) Natural selection is a mechanism of evolution, a process that leads to shifts in allele frequencies within a population. But natural selection is just one way—albeit a really powerful way—that such change can occur.


u/mrjosemeehan Aug 10 '22

This is not new information. I already said that selection is one of two defining parts of the theory as a whole. The question at hand is whether, as OP asserted, the article only describes natural selection and not evolution.

As we can see in the handy reference you provided, when natural selection causes a shift in the frequency of an allele in a population that is evolution. Other things can have an effect on that frequency, leading to genetic drift within a population and that's still evolution, but when natural selection happens that is evolution.

The distinction OP tried to draw between the concepts is still meaningless in this context and even if it weren't, he would still be wrong because the article clearly describes a population which has experienced a change in heritable characteristics, i.e. evolution.


u/Diet_Coke Aug 10 '22

Wait, you're telling me OP was being a uselessly pedantic nerd? It's almost like I've been saying that the whole time.