PDA

View Full Version : Genetic adaptations to diving discovered in humans for the first time



Jovialis
19-04-18, 22:55
Evidence that humans can genetically adapt to diving has been identified for the first time in a new study. The evidence suggests that the Bajau, a people group indigenous to parts of Indonesia, have genetically enlarged spleens which enable them to free dive to depths of up to 70m.

It has previously been hypothesised that the spleen plays an important role in enabling humans to free dive for prolonged periods but the relationship between spleen size and dive capacity has never before been examined in humans at the genetic level.

The findings, which are being published in the research journal Cell, could also have medical implications in relation to the condition known as Acute Hypoxia, which can cause complications in emergency medical care.

For over 1000 years the Bajau people, known as 'Sea Nomads', have travelled the Southeast Asian seas in houseboats and collected food by free diving with spears. Now settled around the islands of Indonesia, they are renowned throughout the region for their extraordinary breath-holding abilities. Members of the Bajau can dive up to 70m with nothing more than a set of weights and a pair of wooden goggles. As they never dive competitively it is uncertain exactly how long the Bajau can remain underwater, but one of them told researcher Melissa Ilardo that he had once dived for 13 minutes consecutively.

Ilardo, first author on the paper, suspected that the Bajau could have genetically adapted spleens as a result of their marine hunter-gatherer lifestyle, based on findings in other mammals. "There's not a lot of information out there about human spleens in terms of physiology and genetics," she said, "but we know that deep diving seals, like the Weddell seal, have disproportionately large spleens. I thought that if selection acted on the seals to give them larger spleens, it could potentially do the same in humans."

The spleen plays a central role in prolonging free diving time as it forms part of what is known as the human dive response. When the human body is submerged under cold water, even for brief amounts of time, this response is triggered as a method of assisting the body to survive in an oxygen-deprived environment. The heart rate slows down, blood vessels in the extremities shrink to preserve blood for vital organs, and the spleen contracts.

This contraction of the spleen creates an oxygen boost by ejecting oxygenated red blood cells into circulation and has been found to provide up to a 9% increase in oxygen, thereby prolonging dive time.
In order to gain evidence for this study, Melissa Ilardo spent several months in Jaya Bakti, Indonesia taking genetic samples and performing ultrasound scans of the spleens from both the Bajau and their land-dwelling neighbours, the Saluan. The results were sequenced at the University of Copenhagen and clearly showed the Bajau have a median spleen size 50% larger than the Saluan. Enlarged spleens were also visible in non-diving Bajau individuals as well as those who regularly free dive.

The international research team, led by academics from the Universities of Copenhagen, Cambridge and Berkeley, therefore eliminated the possibility that larger spleens were simply a plastic response to diving and began to investigate the Bajau's genetic data. They discovered that members of the Bajau have a gene called PDE10A which the Saluan do not. It is thought that the PDE10A gene controls the levels of thyroid hormone T4.

"We believe that in the Bajau they have an adaptation that increases Thyroid hormone levels and therefore increases their spleen size," said Melissa Ilardo. "It's been shown in mice that thyroid hormones and spleen size are connected. If you genetically alter mice to have an absence of the thyroid hormone T4, their spleen size is drastically reduced, but this effect is actually reversible with an injection of T4."

This is the first time a genetic adaptation to diving has been tracked in humans. Ilardo added, "until now it has been entirely unknown whether Sea Nomad populations genetically adapt to their extreme lifestyle. The only trait previously studied is the superior underwater vision of Thai Sea Nomad children, however this was shown to be a plastic response to training, and was replicable in a European cohort."

Ilardo was originally warned against undertaking this study for her PhD at the University of Copenhagen by her supervisors - Professor Eske Willerslev who holds dual positions at St John's College, Cambridge and the University of Copenhagen, and Professor Rasmus Nielsen who also holds dual positions, at the University of Copenhagen and the University of California, Berkeley. "We told Melissa that this was a very risky PhD and she needed to be aware that it was likely she would find nothing," said Professor Willerslev. "She said she wanted to do it anyway and that paid off. Melissa was right and our concerns were wrong."

The study also has implications for the world of medical research. The human dive response simulates the conditions of acute hypoxia in which body tissue experiences a rapid depletion of oxygen. It is a leading cause for complications in emergency care and as a result is already the subject of several genetics studies, specifically in relation to people groups who live at high altitudes.

Studying marine dwellers such as the Bajau has great potential for researching acute hypoxia in a new way. "This is the first time that we really have a system like that in humans to study," said Dr Rasmus Nielsen. "It will help us make the link between the genetics and the physiological response to acute hypoxia. It's a hypoxia experiment that nature has made for us and allows us to study humans in a way that we can't in a laboratory."

These findings open up the possibility of further research on other Sea Nomad populations such as the Thai Moken population and the Haenyeo diving women of Jeju in South Korea. Studying similar people groups could shed more light on the nature of the connection between human physiology and genetic adaptations to extreme lifestyles, and clarify whether these genetic adaptations have developed separately.

Taking the next steps in this area of research is a somewhat urgent task, as the traditional ways of life are under threat in a lot of communities. "This study is a wonderful example of the value of studying these small populations living under extreme conditions," said Professor Eske Willerslev. "A lot of them are threatened and this is not just a loss culturally and linguistically, but for genetics, medicine, and sciences in general. There's still a lot of information to be gathered from these understudied populations."

Read more at: https://phys.org/news/2018-04-genetic-humans.html#jCp


Physiological and Genetic Adaptations to Diving in Sea Nomads

Highlights:

•The Bajau, or “Sea Nomads,” have engaged in breath-hold diving for thousands of years
•Selection has increased Bajau spleen size, providing an oxygen reservoir for diving
•We find evidence of additional diving-related phenotypes under selection
•These findings have implications for hypoxia research, a pertinent medical issue

Understanding the physiology and genetics of human hypoxia tolerance has important medical implications, but this phenomenon has thus far only been investigated in high-altitude human populations. Another system, yet to be explored, is humans who engage in breath-hold diving. The indigenous Bajau people (“Sea Nomads”) of Southeast Asia live a subsistence lifestyle based on breath-hold diving and are renowned for their extraordinary breath-holding abilities. However, it is unknown whether this has a genetic basis. Using a comparative genomic study, we show that natural selection on genetic variants in the PDE10A gene have increased spleen size in the Bajau, providing them with a larger reservoir of oxygenated red blood cells. We also find evidence of strong selection specific to the Bajau on BDKRB2, a gene affecting the human diving reflex. Thus, the Bajau, and possibly other diving populations, provide a new opportunity to study human adaptation to hypoxia tolerance.



http://www.cell.com/cell/fulltext/S0092-8674(18)30386-6

Mark
19-04-18, 23:32
Dive or die selection.

Jovialis
20-04-18, 01:05
The average human can hold their breath for only 30 seconds, but this time can be extended when underwater due to a "diving reflex". This video says the record was 11 mins (at least in 2013). The guy in the study beats it at 13 minutes.

https://www.smithsonianmag.com/videos/category/ask-smithsonian/ask-smithsonian-how-long-can-a-person-hold-breath/

Mark
20-04-18, 01:21
“Race isn’t real.”
“You are like little baby, watch this,” proceeds to swim to the bottom of the ocean.

Jovialis
20-04-18, 01:27
“Race isn’t real.”
“You are like little baby, watch this,” proceeds to swim to the bottom of the ocean.

"Race" is a social construct that has changed very often throughout history, and is dependent on the location. However, there are certainly genetic differences between populations that have separated from one another for thousands of years which are not trivial. We're all amalgamations of various separated ancient populations at different percentages. You should check out this podcast:

https://www.eupedia.com/forum/threads/35925-Tech-Tonic-Podcast-with-David-Reich-What-we-can-learn-from-ancient-DNA

Jovialis
20-04-18, 01:57
Though I do believe that ethnicity is a reliable term, that's defined broadly by a gradient of specific admixtures, and shared culture.

Mark
20-04-18, 02:38
Sure and species is a social construct for polar bears and grizzly bears, doesn’t stop their hybridization.

Jovialis
20-04-18, 02:50
Sure and species is a social construct for polar bears and grizzly bears, doesn’t stop their hybridization.

A species (https://www.nature.com/scitable/definition/species-312) is not a social construct. Homo sapiens are all part of the same species with very minor admixture from other ancient hominids. I don't understand what kind of equivalency you're trying to make. At any rate, I'm not interested in dragging this thread any further off-topic.

If you're interested in educating yourself on these topics, I'd suggest using the search bar in the top right-hand corner.

LeBrok
20-04-18, 03:54
The max time for oxygen deprivation is about 15 minutes in humans. After that our brain cells die from lack of oxygen. So 13 min record makes sense.

Ygorcs
20-04-18, 04:55
Sure and species is a social construct for polar bears and grizzly bears, doesn’t stop their hybridization.

Whether a certain comparison means different races, different strutures of the same race or different is in fact just a matter of degree of genetic divergence, it's not a clear-cut process and in fact very gradual without clear distinctive limits between each of those "stages". What truly speciation means has actually been discussed by many scientists, in some cases species have been described for practical purposes as distinct based less on the inability to procreate and more on the fact that they could hybridize, but in real life will almost never do so because they occupy entirely different and distinct ecological zones. So, for all practical purposes, they live as different species that are getting increasingly divergent as time goes on, because there is absolutely no exchange of genetic influx between them.

In the case of the human species, we Modern Humans and Neanderthals could hybridize, so we could say they were in fact not different species or rather they were different races on the verge of becoming different species (again, this doesn't happen from day to night, it's a gradual process with a lot of grey zones between "race" and "species").

If even we and Neanderthals can roughly be described as distinct races, let alone the different genetic structures that exists in humankind now! They are extremely close to each other and have mixed extensively in the last 100,000 years avoiding further genetic differentiation, sharing now much, much more than they have diverged from each other. The differences are just enough enough to allow us to make clear-cut distinctions that will be considered unambiguous and consensual.

You can call those genetic clusters that are more distant from the others and closer to each other "races" in a very broad meaning, if you will, but you should keep in mind that THEY ARE ABSOLUTELY NOT comparable to grizzly and polar bears. The differences are on a much, much smaller scale and can only be really demonstrated in significant levels, allowing us to identify describe separate clusters, if we use a relatively big resolution in the analyses, because if you don't "zoom in" a lot all humans look so close to each other that you can't pinpoint the boundaries between any two groups, and the only really big boundary, in a scenario with low resolution, is Africans vs. non-Africans. The rest are just slightly different populations.

Ownstyler
20-04-18, 05:24
The 13 minute record was just one person claiming to have done it, it was not measured by the author. The record still stands. Still, it is fascinating to learn about this unique trait. There was a study on lizards in a Croatian island and the authors said that after 30 years in a new island, the lizards had developed much larger organs, I don't remember why, but it seems similar.

Mark, in addition to what everyone else said, also remember that you can't claim races just because of one trait. It would have to be a large number of unique genetic traits, all in common within one group and very rare or just not present in others. The people here just have large spleens and nothing else seems unique about them. Such unique traits are very, very rare in humans - Tibetans have one they got from Denisovans. Other than some special traits in isolated populations that you can count with one hand, most of the differentiation that is considered racial is just two groups with greatly overlapping traits but with slightly different averages. Meanwhile polar bears vs grizzlies - a whole list of characteristics that only one has and not the other.

Mark
20-04-18, 05:26
Sounds like tons of excuse making for legitimately definable genetic clustering.

Jovialis
20-04-18, 06:01
Sounds like tons of excuse making for legitimately definable genetic clustering.

We've already explained enough, I've even provided a link to the leading geneticist in the field's take on it. Guess what, he says the same thing I'm saying.

Start listening from 18:40, you think you know better than him?

https://www.ft.com/content/a3212710-736a-4327-b3d3-0d832e7958db

You're making excuses to define a simplistic unscientific outmoded term. There are substantial differences between human populations, but they don't coincide with the 19th or 20th century concept of race. Today, Europeans for example are composed of extremely divergent groups coming together to form the modern populations. The ancestral populations were genetically as different from one another as modern-day Europeans are from East Asians.

I'm done with your sarcastic one-liners that are dragging this thread off topic. They don't even serve to make your point, you're just trying to antagonize, and that constitutes as t-rolling. If you do it again, I'm giving you an infraction for disruptive/provocative behavior.

Mark
20-04-18, 06:10
Race is just another word for subspecies. Different populations around the world have vastly different constituent ancestral components. Simply stating that populations across wide areas can share some traits yet not others does not negate some deeply divergent ancestry, including “denisovan,” “neanderthal” (all that entails as even neanderthals had divergent races), and various “unidentified hominids.” The truth is most people like to simplify humanity and say “one race the human race” to make themselves feel better and absolve themselves of any association with certain political entities... great for you, hope that works out, I don’t care about politics. Feel free to ban me for disagreeing with your contrived simplification of extremely complex histories we have only begun to understand.

Expredel
20-04-18, 06:11
There's also a link between the consumption of fish and IQ, though it's unclear if this is a recent adaptation. I haven't seen the invention of the boat being suggested as the definite advantage humans had over neanderthals. Aquaphobia might be more common among Africans than Eurasians. So there may be a whole slew of genetic adaptations to fishing related activities.

https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis

Jovialis
20-04-18, 06:14
Race is just another word for subspecies. Different populations around the world have vastly different constituent ancestral components. Simply stating that populations across wide areas can share some traits yet not others does not negate some deeply divergent ancestry, including “denisovan,” “neanderthal” (all that entails as even neanderthals had divergent races), and various “unidentified hominid.” The truth is most people like to simplify humanity and say “one race the human race” to make themselves feel better and absolve themselves of any association with certain political entities... great for you, hope that works out, I don’t care about politics. Feel free to ban me for disagreeing with your contrived simplification of extremely complex histories we have only begun to understand.

You are the one that is trying to simplify the complexity of human evolution and pre-history. Who calls race just another word for subspecies? Give me a legitimate human population geneticist today that does. Certainly not David Reich. Moreover, you're the one politicizing the issue, by assuming it has something to do with that. You sound pretty conspiratorial. I care only about speaking clearly, and in step with modern scientific terms. Not in the terminology of some moron on a YouTube video, or some 'edgy' puerile, low-brow t-roll community.

Also, if you were paying attention to what I was saying, I said there are in fact substantial differences between human populations, because they did separate from one another for thousands of years.

You're just hung up on unscientific semantics, and trying to politicize the issue.

If you want to discuss this any further, find some other thread that deals with this topic. Stop ruining this one, or I will certainly give you an infraction for non-respect for moderator's warning. For the last time, get back on topic.

Mark
20-04-18, 07:08
Subspecies are scientific and do not necessarily need to be defined by even genetical distinctiveness, re: speciation of red wolves and the threat to their survival by coyote hybridizations.

http://onlinelibrary.wiley.com/doi/10.1002/ece3.301/pdf

So even species can exist on a genetic and feature spectrum. I’m not politicizing anything.

Jovialis
20-04-18, 07:13
Well I am talking about genetics, which is what you tried to use to prove your point originally. Now you're changing the stipulations, because you've been checkmated.

The word race doesn't even come up in the entire study. This is absolutely pathetic.

https://i.imgur.com/Ev8izsG.png


I gave you fair warning, now you have an infraction. TAKE IT SOMEWHERE ELSE!



If you want to discuss this any further, find some other thread that deals with this topic. Stop ruining this one, or I will certainly give you an infraction for non-respect for moderator's warning. For the last time, get back on topic.

Salento
20-04-18, 07:28
I only last 1 minute or less under water.

bicicleur
20-04-18, 07:30
practice can do a lot too
when you do it regularly your capacity will increase very fast
I used to swim under water 50 meters easily
everybody can do that
many limits of the human body remain unexplored

of course there is no comparaison with what those Bajau do
it must have been a matter of life or dead

Mark
20-04-18, 07:34
Saying that perfect genetic distinctiveness is not required for speciation or subspeciation is not going back on anything I have said at all. You’re the one that tried to use non-perfect distinctiveness as proof that somehow race is merely a social construct but it does not. Non-perfect distinctiveness, hybridization and selection are bases for evolution and speciation.

Please ban me for disagreeing with you.

Jovialis
20-04-18, 07:40
It’s not unusual to Declare your Race/Ethnicity when filling up some Government Forms, and others in the US.
Supposedly is a self declaration of what race/ethnicity you belong to.
But that’s not always the case, I’ve been told multiple time in person by Officers and Officials to check the dot for “Caucasian”, or “White”.
We are still Classified by Race.
We can argue what Race is, or is not, Science and Politics don’t matter much for the Government and private entities.

This thread is about the Bajau peoples' genetic ability to breath underwater for an extended period of time. It has nothing to do with the definition of race. The very next person to go off topic about this issue is getting an infraction for it.

Jovialis
20-04-18, 07:43
Saying that perfect genetic distinctiveness is not required for speciation or subspeciation is not going back on anything I have said at all. You’re the one that tried to use non-perfect distinctiveness as proof that somehow race is merely a social construct but it does not. Non-perfect distinctiveness, hybridization and selection are bases for evolution and speciation.

Please ban me for disagreeing with you.

I've already proved you're a liar. BTW you're getting infractions because you're continuously going off topic, after I told you like 5 times not to do that. Not because of our disagreement.


Well I am talking about genetics, which is what you tried to use to prove your point originally. Now you're changing the stipulations, because you've been checkmated.


The word race doesn't even come up in the entire study. This is absolutely pathetic.

https://i.imgur.com/Ev8izsG.png


I gave you fair warning, now you have an infraction. TAKE IT SOMEWHERE ELSE!

Ygorcs
20-04-18, 07:47
It’s not unusual to Declare your Race/Ethnicity when filling up some Government Forms, and others in the US.
Supposedly is a self declaration of what race/ethnicity you belong to.
But that’s not always the case, I’ve been told multiple time in person by Officers and Officials to check the dot for “Caucasian”, or “White”.
We are still Classified by Race.
We can argue what Race is, or is not, Science and Politics don’t matter much for the Government and private entities.
For them Race is real, and at times is taken in consideration, an an example “Affirmative Action”.

To say that race (race as is it is understood by most people who don't know anything about population genetics, i.e. they don't think of it as just distinct genetic structures that interact with each other without clear boundaries) is a social construct DOES NOT MEAN that it isn't "real". It's real as a social and cultural phenomenon, that's why it is called "social CONSTRUCT", it is a combination of some ideas, concepts and classifications that were culturally developed along the time AND EFFECTIVELY influence people's lives, relations and identities. It is just as real as a "country" is real, an "ethnic group" is real - it's not a god-given piece of nature, but a social fact. You should never think that those who say races are social constructs are stating simply that just don't exist at all and everybody is the same. There are some nutcases who think so, but not those who propose that as an intellectual statement. They are saying that whether there is a "white race" or "black race" was determined by historical and social dynamics, not just by the observation of genetic differences allowing us to group separate genetic clusters.

Mark
20-04-18, 07:49
To say that race (race as is it is understood by most people who don't know anything about population genetics, i.e. they don't think of it as just distinct genetic structures that interact with each other without clear boundaries) is a social construct DOES NOT MEAN that it isn't "real". It's real as a social and cultural phenomenon, that's why it is called "social CONSTRUCT", it is a combination of some ideas, concepts and classifications that were culturally developed along the time AND EFFECTIVELY influence people's lives, relations and identities. You should never think that those who say races are social constructs are stating simply that just don't exist at all and everybody is the same. There are some nutcases who think so, but not those who propose that as an intellectual statement. They are saying that whether there is a "white race" or "black race" was determined by historical and social dynamics, not just by the observation of genetic differences allowing us to group separate genetic clusters.

So I’ll say subspecies from now on so you know what I’m talking about.

Ygorcs
20-04-18, 07:53
Sounds like tons of excuse making for legitimately definable genetic clustering.

Of course it sounds like that to you. You want simple, either-this-or-that, black-or-white answers, so it will all sound like very suspicious excuses to obfuscate the "simple truth". But well, it should all become very easy for you if you can prove that the traditional definitions of races with clear-cut boundaries are perfectly demonstrated by genetic clusters, and not the much more complex and diverse reality of clusters structured in clines and with several processes of past and present admixture linking distant groups and blurring the exact boundaries between them. Or you can just go back to the "knowledge" of your great-grandparents and use a clear and unambiguous - and, precisely because of that, false - racial classification, dividing the entire humankind into 4 or 5 races and completely ignoring the fine-grained nuances, e.g. that the genetic diversity and inter-group divergence of Africa alone - to which a generic "black race" will be assigned - surpasses that of all non-Africans. In any case, good luck, but don't complain if people here and elsewhere don't take your word too seriously because of such choices.

Mark
20-04-18, 07:54
Good luck with the gangsaying, ad hom and automatic politicization of any discussion of the topic.

Mark
20-04-18, 07:55
practice can do a lot too
when you do it regularly your capacity will increase very fast
I used to swim under water 50 meters easily
everybody can do that
many limits of the human body remain unexplored

of course there is no comparaison with what those Bajau do
it must have been a matter of life or dead

I don’t think that practice enlarges the size of your spleen though.

Salento
20-04-18, 08:00
practice can do a lot too
when you do it regularly your capacity will increase very fast
I used to swim under water 50 meters easily
everybody can do that
many limits of the human body remain unexplored

of course there is no comparaison with what those Bajau do
it must have been a matter of life or dead
My Eardrums might explode without protection by 17-20 meters.

Ygorcs
20-04-18, 08:01
Good luck with the gangsaying, ad hom and automatic politicization of any discussion of the topic.
Oh, dear, who do you think you can deceive with all this nonsense self-victimizing? You were the one who brought this issue under discussion, saying in ironic tone: "“Race isn’t real.”“You are like little baby, watch this,” proceeds to swim to the bottom of the ocean. You can't simply state a controversial and obviously "politicizing" opinion - and stating it with irony - and then whine because people simply didn't agree with you and presented a lot of reasons to explain why they disagree with that. If everybody had agreed with you and talked about the horrible and silly leftists who think race is just a social construct and so on, you'd be very glad about the "automatic politicization" of this thread. You sound like you're offended and were attacked because people think you're wrong. Come on, that's childish behavior. Learn to accept that people may disagree with you, strongly even. As long as they don't offend you on a personal level, it's all fine.

Ygorcs
20-04-18, 08:02
So I’ll say subspecies from now on so you know what I’m talking about.

That would be nice, indeed. I need some good laugh now and then. ;-)

Mark
20-04-18, 08:05
Nope I simply got threatened with infractions for joking about race denial, which, as you say, is political. The existence of subspecies is not political but denying them is so we finally agree.

Jovialis
20-04-18, 08:10
Nope I simply got threatened with infractions for joking about race denial, which, as you say, is political. The existence of subspecies is not political but denying them is so we finally agree.

You were given infractions for going off topic after repeatably being told to stop; not for disagreement. There's threads already dedicated to this topic. Stop it or I will give you yet another one.

Mark
20-04-18, 08:19
Cool, I could use another. Delete my account while you’re at it, don’t need to be a part of a forum with such reactionary and easily riled up moderators. Talk about childish, can’t even take a joke, have to expound on it and turn it into something else entirely. Maybe all of you should take a step back, reexamine your lives that you’d take such things so personally.

Jovialis
20-04-18, 08:25
Cool, I could use another. Delete my account while you’re at it, don’t need to be a part of a forum with such reactionary and easily riled up moderators. Talk about childish, can’t even take a joke, have to expound on it and turn it into something else entirely. Maybe all of you should take a step back, reexamine your lives that you’d take such things so personally.

Well, that merits another one. I guess we can finally get back to how the Bajau people have genetically advantageous spleens.


https://www.youtube.com/watch?v=MgRpwESWPLM

Ownstyler
20-04-18, 12:40
Race is just another word for subspecies. Different populations around the world have vastly different constituent ancestral components. Simply stating that populations across wide areas can share some traits yet not others does not negate some deeply divergent ancestry, including “denisovan,” “neanderthal” (all that entails as even neanderthals had divergent races), and various “unidentified hominids.” The truth is most people like to simplify humanity and say “one race the human race” to make themselves feel better and absolve themselves of any association with certain political entities... great for you, hope that works out, I don’t care about politics. Feel free to ban me for disagreeing with your contrived simplification of extremely complex histories we have only begun to understand.

If there ever was a human subspecies it was the neanderthals and denisovans. Today's populations are much, much more similar to each-other than sapiens were to neandethals, so the term subspecies just proves you completely wrong.

Ownstyler
20-04-18, 12:47
I wonder why they are already claiming it's an adaptation and not introgression from another hominid as in Tibetans.

Expredel
20-04-18, 14:18
of course there is no comparaison with what those Bajau do
it must have been a matter of life or dead
Bajau who could dive deeper and longer likely brought home more food, then eventually being able to survive and thrive where those without the genetic adaptations couldn't.

Angela
20-04-18, 16:41
Evidence that humans can genetically adapt to diving has been identified for the first time in a new study. The evidence suggests that the Bajau, a people group indigenous to parts of Indonesia, have genetically enlarged spleens which enable them to free dive to depths of up to 70m.

It has previously been hypothesised that the spleen plays an important role in enabling humans to free dive for prolonged periods but the relationship between spleen size and dive capacity has never before been examined in humans at the genetic level.

The findings, which are being published in the research journal Cell, could also have medical implications in relation to the condition known as Acute Hypoxia, which can cause complications in emergency medical care.

For over 1000 years the Bajau people, known as 'Sea Nomads', have travelled the Southeast Asian seas in houseboats and collected food by free diving with spears. Now settled around the islands of Indonesia, they are renowned throughout the region for their extraordinary breath-holding abilities. Members of the Bajau can dive up to 70m with nothing more than a set of weights and a pair of wooden goggles. As they never dive competitively it is uncertain exactly how long the Bajau can remain underwater, but one of them told researcher Melissa Ilardo that he had once dived for 13 minutes consecutively.

Ilardo, first author on the paper, suspected that the Bajau could have genetically adapted spleens as a result of their marine hunter-gatherer lifestyle, based on findings in other mammals. "There's not a lot of information out there about human spleens in terms of physiology and genetics," she said, "but we know that deep diving seals, like the Weddell seal, have disproportionately large spleens. I thought that if selection acted on the seals to give them larger spleens, it could potentially do the same in humans."

The spleen plays a central role in prolonging free diving time as it forms part of what is known as the human dive response. When the human body is submerged under cold water, even for brief amounts of time, this response is triggered as a method of assisting the body to survive in an oxygen-deprived environment. The heart rate slows down, blood vessels in the extremities shrink to preserve blood for vital organs, and the spleen contracts.

This contraction of the spleen creates an oxygen boost by ejecting oxygenated red blood cells into circulation and has been found to provide up to a 9% increase in oxygen, thereby prolonging dive time.
In order to gain evidence for this study, Melissa Ilardo spent several months in Jaya Bakti, Indonesia taking genetic samples and performing ultrasound scans of the spleens from both the Bajau and their land-dwelling neighbours, the Saluan. The results were sequenced at the University of Copenhagen and clearly showed the Bajau have a median spleen size 50% larger than the Saluan. Enlarged spleens were also visible in non-diving Bajau individuals as well as those who regularly free dive.

The international research team, led by academics from the Universities of Copenhagen, Cambridge and Berkeley, therefore eliminated the possibility that larger spleens were simply a plastic response to diving and began to investigate the Bajau's genetic data. They discovered that members of the Bajau have a gene called PDE10A which the Saluan do not. It is thought that the PDE10A gene controls the levels of thyroid hormone T4.

"We believe that in the Bajau they have an adaptation that increases Thyroid hormone levels and therefore increases their spleen size," said Melissa Ilardo. "It's been shown in mice that thyroid hormones and spleen size are connected. If you genetically alter mice to have an absence of the thyroid hormone T4, their spleen size is drastically reduced, but this effect is actually reversible with an injection of T4."

This is the first time a genetic adaptation to diving has been tracked in humans. Ilardo added, "until now it has been entirely unknown whether Sea Nomad populations genetically adapt to their extreme lifestyle. The only trait previously studied is the superior underwater vision of Thai Sea Nomad children, however this was shown to be a plastic response to training, and was replicable in a European cohort."

Ilardo was originally warned against undertaking this study for her PhD at the University of Copenhagen by her supervisors - Professor Eske Willerslev who holds dual positions at St John's College, Cambridge and the University of Copenhagen, and Professor Rasmus Nielsen who also holds dual positions, at the University of Copenhagen and the University of California, Berkeley. "We told Melissa that this was a very risky PhD and she needed to be aware that it was likely she would find nothing," said Professor Willerslev. "She said she wanted to do it anyway and that paid off. Melissa was right and our concerns were wrong."

The study also has implications for the world of medical research. The human dive response simulates the conditions of acute hypoxia in which body tissue experiences a rapid depletion of oxygen. It is a leading cause for complications in emergency care and as a result is already the subject of several genetics studies, specifically in relation to people groups who live at high altitudes.

Studying marine dwellers such as the Bajau has great potential for researching acute hypoxia in a new way. "This is the first time that we really have a system like that in humans to study," said Dr Rasmus Nielsen. "It will help us make the link between the genetics and the physiological response to acute hypoxia. It's a hypoxia experiment that nature has made for us and allows us to study humans in a way that we can't in a laboratory."

These findings open up the possibility of further research on other Sea Nomad populations such as the Thai Moken population and the Haenyeo diving women of Jeju in South Korea. Studying similar people groups could shed more light on the nature of the connection between human physiology and genetic adaptations to extreme lifestyles, and clarify whether these genetic adaptations have developed separately.

Taking the next steps in this area of research is a somewhat urgent task, as the traditional ways of life are under threat in a lot of communities. "This study is a wonderful example of the value of studying these small populations living under extreme conditions," said Professor Eske Willerslev. "A lot of them are threatened and this is not just a loss culturally and linguistically, but for genetics, medicine, and sciences in general. There's still a lot of information to be gathered from these understudied populations."

Read more at: https://phys.org/news/2018-04-genetic-humans.html#jCp



We have adaptation to high mountain and deep sea environments. I wonder if someday we'll have adaptations to breathing different air, the type of atmospheres we might find on other planets. Or maybe I've read too much science fiction! :)

Ed. Razib Khan has some commentary on the paper:
https://www.gnxp.com/WordPress/2018/04/20/so-merfolk-are-a-real-thing-now/?utm_source=dlvr.it&utm_medium=twitter

Jovialis
20-04-18, 18:21
We have adaptation to high mountain and deep sea environments. I wonder if someday we'll have adaptations to breathing different air, the type of atmospheres we might find on other planets. Or maybe I've read too much science fiction! :)

Ed. Razib Khan has some commentary on the paper:
https://www.gnxp.com/WordPress/2018/04/20/so-merfolk-are-a-real-thing-now/?utm_source=dlvr.it&utm_medium=twitter

I think your right about new adaptations on different planets. Especially with gene editing emerging. Which will help us along with that process. We will probably need to tailor our bodies to become accustomed to different environments outside of earth. Overtime, humans will become more acclimated to it , even more so naturally.

Much like the wooden googles the Bajua people use which enabled them to see underwater, which in turn helped lead them to this lifestyle that lead to this adaptation; our technology will help us drive our evolution.

Expredel
20-04-18, 23:59
Much like the wooden googles the Bajua people use which enabled them to see underwater, which in turn helped lead them to this lifestyle that lead to this adaptation; our technology will help us drive our evolution.

10035

Looks like the 'wooden googles' are a very recent development?