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At Live Science: Why can’t we drink saltwater?


The Earth’s surface is 71% water, but just 3.5% of it is drinkable.

Water is essential for our survival, and yet more than 96% of the planet’s liquid water is ocean water — and it contains so much salt that it’s undrinkable by humans. 

Salty sea water won’t quench your thirst, and drinking too much can even lead to death by dehydration.

But if saltwater is still water, why can’t we drink it?

The answer to that question is actually pretty straightforward: Saltwater is simply too salty for our kidneys to manage.

Approximately 3.5% of seawater’s weight comes from dissolved salt, according to the National Oceanic and Atmospheric Administration(opens in new tab) (NOAA). If all the salt in the oceans were removed and spread over every land surface on Earth, the salty layer would tower more than 500 feet (166 meters) high — about as tall as a 40-story office building, NOAA says. The saltiness, or salinity, of seawater is too high for humans to safely process, as our cells require water “in a relatively pure form,” said Rob DeSalle, a curator in the Sackler Institute for Comparative Genomics at the American Museum of Natural History in New York City.

“For most animals, the kidneys filter impurities out of water,” DeSalle told Live Science, told Live Science. “What happens when you drink saltwater is you ingest a lot of salt that the body now needs to wash out [of the body].”

It does this in the form of urine, which the kidneys produce by dissolving impurities in excess water, which is then sent to the bladder to be eliminated. But the kidneys can only produce urine that is less salty than our blood, according to the National Oceanic and Atmospheric Administration(opens in new tab), and saltwater contains more than three times the amount of salt that is normally present in human blood. This means that for every cup of saltwater you drink, you’d need to drink at least the same volume of water in order for your kidneys to flush out all that salt.

Some animals can drink saltwater, so why can’t we?

Some animals, in ocean ecosystems, however, have adaptations that allow them to safely drink saltwater. Seabirds such as albatrosses, gulls and penguins, which might spend weeks on the open ocean with no freshwater in sight, have specialized salt glands and grooves in their bills for filtering and purging excess salt from ingested water before it hits their stomachs and is absorbed into their blood, according to the Audubon Society(opens in new tab). Marine mammals such as whales, dolphins and seals have also evolved adaptations to life in an environment where freshwater is scarce or absent.

“Marine mammals have adapted special enzymes and cellular structures that allow them to purge excess salt from their systems,” DeSalle said. “It’s like they have super kidneys.”

So why don’t we? Why did humans — and nearly all other land animals, for that matter —evolve to drink freshwater when saltwater is so much more plentiful? As animals emerged from the ancient seas hundreds of millions of years ago and began adapting to life on land, species moved away from coastal habitats where there was lots of saltwater. Many terrestrial species — including our primate ancestors — eventually came to inhabit inland ecosystems that had plenty of freshwater in lakes and rivers, but very few, if any, saltwater sources. This likely shaped biological adaptations for drinking water that wasn’t salty.

“Most of our ancestors were not exposed to saltwater, whether it’s animals in general, primates, or insectivores,” DeSalle said. “So natural selection honed in on processing unsalty water, and our physiology became so fine-tuned that disrupting it with saltwater down the line becomes very dangerous and damaging.”

Live Science

Give a salt-water organism fresh water and it will develop biological systems for drinking fresh water? This sounds like Lamarckianism (aka the magic wand of adaptation). Where’s the evidence for the natural mechanism that shows that new, complex biological systems can develop on cue to meet the needs of a species for survival?

Fred Hickson:
Science is an ongoing project.
Your posts demonstrate that you don't understand science.
Ideas have to be modified or discarded in the light of new data.
The only data that supports evolution by means of blind and mindless processes involve genetic diseases and deformities.
Molecular phylogenetics is a powerful new tool that continues to add to our knowledge of how organisms (and molecules such as aaRSs) are related.
Related via a common design. Molecular phylogenetics doesn't support universal common descent. There aren't any known naturalistic mechanisms capable of universal common descent. You need to start there. ET
Molecular phylogenetics is a powerful new tool that continues to add to our knowledge of how organisms (and molecules such as aaRSs) are related.
i am not sure you did get the point ... from the paper i cited above, did you get this ? A Darwinist said:
It means that convergent evolution has been fooling us – even the cleverest evolutionary biologists and anatomists – for over 100 years!"
Your Darwinian scientists had to invent a new term "convergent evolution". But do you realize, that the term "convergent evolution" are only words ? ... Only words ... nothing more ... we can also call it "common design" ... so when species 'evolved' the same features by 'convergent evolution', in other words, INDEPENDENTLY, where is your 'relatedness' ? How do you know, that the same mutations (proving relatedness and common ancestor) did not mutate independently the same way by 'convergent evolution' in unrelated species (created from scratch) ? martin_r
Fred your response just shows that there is design in nature not how it got there , men can design computer programmes to react to different input and change where necessary , and just because the programme changes are we to believe it does it itself or was designed by a designer to do so. Marfin
More and more mainstream papers show up claiming that ‘tree of relatedness’ might be wrong …
Science is an ongoing project. Ideas have to be modified or discarded in the light of new data. Molecular phylogenetics is a powerful new tool that continues to add to our knowledge of how organisms (and molecules such as aaRSs) are related. Fred Hickson
Hickson ...
The above paper compares genetic sequences in primates to produce a tree of relatedness.
to produce a tree of relatedness. More and more mainstream papers show up claiming that 'tree of relatedness' might be wrong ...
It turns out that we’ve got lots of our evolutionary trees wrong. For over a hundred years, we’ve been classifying organisms according to how they look and are put together anatomically, but molecular data often tells us a rather different story. ... But now with molecular data, we can see that convergent (repeated) evolution happens all the time – things we thought were closely related often turn out to be far apart on the tree of life. It means that convergent evolution has been fooling us – even the cleverest evolutionary biologists and anatomists – for over 100 years!
https://www.bath.ac.uk/announcements/study-suggests-that-most-of-our-evolutionary-trees-could-be-wrong/ or this one:
DO SCIENTISTS BUILD ‘TREES OF LIFE’ WITH FAULTY METHODS? Our finding casts serious doubts over literally thousands of studies that use phylogenetic trees of extant data to reconstruct the diversification history of taxa, especially for those taxa where fossils are rare, or that found correlations between environmental factors such as changing global temperatures and species extinction rates
The main issue is that Fred thinks that the environment selects. It doesn't. The environment eliminates. And yes, there is a huge difference between a process of selection and a process of elimination. As Ernst Mayr wrote:
Do selection and elimination differ in their evolutionary consequences? This question never seems to have been raised in the evolutionary literature. A process of selection would have a concrete objective, the determination of the “best” or “fittest” phenotype. Only a relatively few individuals in a given generation would qualify and survive the selection procedure. That small sample would be only to be able to preserve only a small amount of the whole variance of the parent population. Such survival selection would be highly restrained. By contrast, mere elimination of the less fit might permit the survival of a rather large number of individuals because they have no obvious deficiencies in fitness. Such a large sample would provide, for instance, the needed material for the exercise of sexual selection. This also explains why survival is so uneven from season to season. The percentage of the less fit would depend on the severity of each year’s environmental conditions.
Fred will still conflate the 2 processes. People who argue without evidentiary support always do. ET
Fred Hickson:
think the environment designs.
Good for you. We are still waiting for the science to support that claim. Continuing to make the claim is not evidence.
I have a candidate for my designer, the environment.
That dog doesn't hunt. You can keep repeating yourself. That doesn't help. Each environment contains several different biological designs. So, clearly you are just spewing untestable nonsense. The ONLY way the environment can design- biological design- is if organisms have built-in responses to environmental cues. So, if organisms were intelligently designed with built-in responses to environmental cues, Fred has a point. The environment directs the design. ET
Fred Hickson:
The above paper compares genetic sequences in primates to produce a tree of relatedness.
Related via a common design, yeah. Seeing that genetics doesn't determine the type of organism, it can't be a tree of common descent. The problem that Fred refuses to deal with is that there isn't any naturalistic mechanism capable of producing eukaryotes from the given starting populations of prokaryotes. Endosymbiosis just puts one prokaryote inside of another. There isn't any evidence that blind and mindless processes can change the inner prok. into mitochondria. Fred is putting the cart before the horse. And he is too dim to understand that. ET
Hickson @ 6 When water first condensed on the Earth’s surface over four billion years ago, it would have contained no salt. Sure, minerals must then have dissolved in the seas but it would have taken time. Careful, if you start making calculations around those assumptions you might just get answers you don't like. Very Little Salt in the Sea Latemarch
At 24 FH appeals to genetic evidence to claim that, "evidence from biology screams silently and consiliently. (sic)" Let's just say that the genetic evidence is screaming alright. But it is NOT screaming what Fred imagines it to be screaming. Instead it is screaming, 'COMMON DESCENT IS FALSE!"
The evidence from genetics, directly contrary to what Darwinists claim, simply does not support the Darwinian ‘narrative’. https://uncommondescent.com/intelligent-design/evangelical-scientists-getting-it-wrong/#comment-740245 Darwinists simply have no evidence that morphology, and/or biological form, is reducible to mutations to DNA. https://uncommondescent.com/intelligent-design/evangelical-scientists-getting-it-wrong/#comment-740247 Population Genetics falsifies, instead of confirms, Darwinian claims for human evolution https://uncommondescent.com/intelligent-design/christian-darwinists-must-now-backtrack-re-adam-and-eve/#comment-741335
The Catholic Church has stated that God works infallibly in Creation, not blind luck or chance.
Never said anything to contradict this. But, from Wikipedia:
Early contributions to biology were made by Catholic scientists such as the Augustinian friar Gregor Mendel. Since the publication of Charles Darwin's On the Origin of Species in 1859, the attitude of the Catholic Church on the theory of evolution has slowly been refined. For nearly a century, the papacy offered no authoritative pronouncement on Darwin's theories. In the 1950 encyclical Humani generis, Pope Pius XII confirmed that there is no intrinsic conflict between Christianity and the theory of evolution, provided that Christians believe that God created all things and that the individual soul is a direct creation by God and not the product of purely material forces. Today, the Church supports theistic evolution, also known as evolutionary creation, although Catholics are free not to believe in any part of evolutionary theory. Catholic schools in the United States and other countries teach evolution as part of their science curriculum. They teach the fact that evolution occurs and the modern evolutionary synthesis, which is the scientific theory that explains how evolution proceeds.
https://en.wikipedia.org/wiki/Evolution_and_the_Catholic_Church There have been long discussions on this site about the Catholic Church and Evolution. Several ID people are Catholic, for example Denyse. What I said above is not inconsistent with the Catholic Church position. I, personally, have debated with many Catholics on other sites who are emphatically anti ID and defend Darwinian processes as obviously the source of Evolution. The excerpt emphasizes that point as the Catholic Church supports theistic evolution. As I said, this has been discussed numerous times on this site. Everything seems to repeat itself here. There are at least four tags for Catholic in the archives and over 150 references to theistic evolution. Some discussions go back to the beginning of the site in 2005. For example, https://uncommondescent.com/evolution/pope-benedict-xvis-inaugural-mass/#comments Essentially Catholic scientists have fallen for the genetic evidence as supporting Evolution. This of course is a non-sequitur but is taught in textbooks used in Catholic schools and has led to the nonsense called theistic evolution which the Catholic Church endorses. jerry
Jerry at 21, You were vague about which religions accepted what. The Catholic Church has stated that God works infallibly in Creation, not blind luck or chance. relatd
https://journals.plos.org/plosgenetics/article?id=10.1371%2Fjournal.pgen.1001342 The above paper compares genetic sequences in primates to produce a tree of relatedness. Everywhere you look, evidence from biology screams silently and consiliently. Fred Hickson
Enjoy your life
Thank you for your advice, i enjoy things like these: https://www.youtube.com/watch?v=k0kk37iFgWk martin_r
Here’s an interesting mental exercise. What would it have taken to convince Darwin that his idea of natural selection never amounted to anything major given the knowledge of his time. That knowledge included the effects of breeding to bring about substantial change in a species such as faster race horses, stronger beast of burden, fancier birds etc. But what would have convinced him (assuming he was reasonable) that his ideas while true in terms that these small changes (something that’s obvious to everyone) could not be the explanation for Evolution? My example is with humans themselves, that strength is inherited and strength of the average human never evolved even though this was an extremely desirable characteristic for survival and leaving more children. The evolution of strength obviously could not produce a new species. But it does show that given millions of years, such a desirable change never happened even though extremely advantageous. jerry
The evidence is all around you
All the evidence around precludes Evolution by Darwinian processes. Not only is there no positive evidence for Darwinian processes changes anything other than in genetics but logic and the environment/ecology itself eliminates It as a potential explanation for Evolution. The reasoning is irrefutable. Aside: in the old days, we would get the evidence is overwhelming. The defenders of Darwinian Evolution would say there was so much of it, they didn’t know where to begin. Aside2: this has nothing to do with atheism. Most of the religions espouse Darwinian processes as the way God works in His creation. They have bought the explanation by religious scientists that small changes add up to big changes. The religious scientists have been intimidated to this position by the scientific establishment. Solely based on genetics. jerry
Fred H , Seriously thats your position , the evidence is all around , I must get you to defend me if I ever end up in court , your honour of course my client is innocent , sure the evidence is all around us , and what is that evidence ? don`t worry about that just accept that I say its all around us. Marfin
The evidence is all around you. Fred Hickson
Fred H , Instead of just making a statement " the environment is the designer " please provide some evidence to support that position ,statements are not evidence . So starting from rocks just how did the environment design everything. Marfin
Jerry at 14, You can't write that! You can't write things like: OK, I've got four early multicellular forms of life living in a body of water. One gets an upgrade. It has lots of offspring who start eating everything in sight. Soon, the other three organisms die of starvation, shortly followed by the improved organism. Their dead remains float to the surface of the body of water, rot and sink to the bottom. Nothing lives there now. relatd
FH at 13, You're still pushing the narrative? Evolution is fast, except when it's slow. Life forms change, except when they don't. A particular fish, for example, can remain unchanged for an alleged millions of years. No superhero has this power. Evolution only works as a storytelling device. relatd
:lol: The environment doesn't know how to produce a single gene so environment creates nothing . A greenhouse do not creates tomatoes . Lieutenant Commander Data
but change can be slow enough that populations can adapt.
Wrong! This assumes that millions of entities will have built in the means to also produce superior versions of itself. Just so to counteract the improvements in another. This would require impossible built in capabilities all acting in consort. Populations can adapt but change unless extremely small will overrun the other members of the ecology because by definition it is superior, leaving more offspring. If the change is significant, it will then destroy itself. So change by Darwinian processes is always very small and essentially never changes the balance of forces in the ecology. That’s what we observe. This means Darwinian processes are limited to genetics. They cannot go beyond simple changes in the genome. It’s also consistent with known biological processes that limit what can happen to an organism. There is zero evidence that anything else ever happened. Again the challenge is, show evidence of this happening. It’s never done except by assertions because the evidence doesn’t exist. But the more interesting thing is that it can’t exist. Why? It would destroy the ecology. Again, I point to humans. Weakness prevented more food gathering and thus limited offspring but yet stronger individuals are possible. So why no stronger humans - or faster ones or better eyes or more agile ones? Answer, the limitations to change were built in. Then there is the other limitation on change, that is biological. While there are probably over 50 sources to variation in a new offspring, these changes are very limited. None will change an offspring much. For example, it can make the skin lighter to be more accessible to vitamin D in northern climates but it will never eliminate the need for vitamin D. jerry
Wrong, Jerry. Change can outrun evolution resulting in extinction, yes, but change can be slow enough that populations can adapt. Fred Hickson
a candidate for my designer, the environment
But it can’t. Environments/ecologies limit change. So it cannot be the source especially since the change would destroy the environment. And there is zero evidence for it, if it did happen this way. So one will have to look elsewhere. jerry
-R I agree life is designed. I have a candidate for my designer, the environment. Who is yours? Is it (your particular personal) God? Fred Hickson
Hickson, yes, the reality is, that you Darwinists mislead lay uneducated people. Good for you, that cell biology and biology overall is so extremely complex (which only makes sense, because why should a fully autonomous self-navigating flying system or a human be something simple, or made of something simple) Biologists with their unqualified misleading fraudulent claims gave common people a hope, that life could have emerged just so. What worse, you people still doing it, despite in 21st century it is more than clear, then life was created/designed. The only scientific question is who did it and how it was done. Everything else you Darwinists say is a fraud, hoax, conspiracy ... So once again, the scientific consensus on the origin of life should be: LIFE WAS CREATED/DESIGNED and then let's wait till your Darwinian scientists can prove the contrary - which they never will ... martin_r
Reality - the fine tuning of the universe, the earth, the ecologies are a very real reality. All this fine tuning has implications. One is that Darwinian processes are extremely limited in what can change. Something that is observed by the data. Ecologies are the interaction of biological and the physical/chemical world and stasis is fragile. Changing too much causes it to become unstable unless it is fine tuned to resist too much change. Thus because it is blind and extremely limited by definition, Darwinian processes can have almost zero to do with Evolution. Ecologies would prevent it. jerry
Calm down, -R. Reality is what it is. You can probe it, find out about it or shake your first at it. Reality doesn't care; it just is. Fred Hickson
The default in science should be “we don’t know” rather than an explanation unsupported by evidence.
yes, Hickson, do your science, but till then, the scientific consensus should be: Life on Earth was designed BECAUSE IT MAKES WAY MORE SENSE (WHEN YOU ARE A HONEST SCIENTIST) and, if one day, you Darwinists can show how life can emerge just so (which you never will), then, you Darwinists may rethink that scientific consensus above. martin_r

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