Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
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05-08-2012, 08:55 AM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
I use stable isotopes on Permian(295-275Ma) bivalves. I have a colleague who uses them on Cenozoic whales. They survive as long as the specimens are well-preserved.

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05-08-2012, 09:10 AM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(05-08-2012 08:55 AM)TheBeardedDude Wrote:  I use stable isotopes on Permian(295-275Ma) bivalves. I have a colleague who uses them on Cenozoic whales. They survive as long as the specimens are well-preserved.

This is news to me. Am I understanding this correctly, this can determine the general diet in the life span of a specimen? And are you aware of any such studies on the Australo and Homo archive?

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05-08-2012, 09:20 AM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
I believe I have some of the articles somewhere for Australopithicenes so I know that their diet still appears to be more forest plants (carbon isotopes). I believe an entire issue of Nature was devoted to them a few years back.

As for homo, I don't think I have any articles local but if I remember correctly the carbon signature indicates a move towards plants from grasslands.

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05-08-2012, 11:31 AM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(04-08-2012 11:09 PM)CEngelbrecht Wrote:  
(04-08-2012 05:55 PM)fstratzero Wrote:  It was a fun idea, until the genetic, and fossil evidence pointed else where.

That's a little vague, 'cause to my knowledge nothing genetic or fossilic directly contradict the possibility of humans being a coastal ape in ancient times, rather than eg. an arboreal or grassland ape. What exactly do you mean?

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The aquatic ape hypothesis (AAH) is a hypothesis about human evolution, which posits that the ancestors of modern humans spent a period of time adapting to life in a wet environment.

After read the the whole theory, it posits that the majority of human adaptations come from a wet environment.

The problems come with looking at humans.

We perspire, leaking fluid from our skin for the air to dry and carry away heat.

In other aquatic species the fins, flippers, and the like are the source for heat exchange. Sweating under water doesn't make since.

The availability of omega 3's from fish doesn't necessitate brain growth. The majority of the other species who feed mostly on fish do not automatically grow larger brains.

The changing environment put a selection pressure on humans to find newer food sources. Omega 3's are available from fish, plants, and the bodies of other creatures. Being able to adapt to changing environments it where the selection pressure favored intelligence.

In other words the presence of nutrition does not automatically mean they'll use it a certain way.


Now don't get me wrong water did play a part, but wasn't the sole factor in the way humans gained their distinct features.

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10-08-2012, 04:35 PM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(05-08-2012 11:31 AM)fstratzero Wrote:  The problems come with looking at humans.

We perspire, leaking fluid from our skin for the air to dry and carry away heat.

I think human perspiration is still an enigma. The only other example I can think of of 'glissening' sweating to cool down is horses. That there is only this single phylogenic comparison (in a grassland taxa) increases the plausibility of at least human perspiration having developed in a grassland scenario. (Or though Philip Tobias and others have concluded, that the African savannah is much too young to have been the cause behind eg. human bipedalism.)
There is the key difference that horses sweat through apocrine sweat glands, which humans only have in the armpits and the anus, while human cooling sweat stems mostly from eccrine glands, which I think are unique to primates and covers the whole human body. But this difference may not have any practical impact on developing the shedding of skin water to cool off in both humans and horses.

(05-08-2012 11:31 AM)fstratzero Wrote:  In other aquatic species the fins, flippers, and the like are the source for heat exchange. Sweating under water doesn't make since.

I don't think it's being suggested, that we would ever have reached an aquatic level to have evolved features like fins and flippers. Whales and dolphins have had 50+ million years do develop such features, in such case humans would only have been semi-aquatic max 5-7 million years, perhaps less. I don't know if other semi-aquatic mammal taxa of a similar "young" age is available (otters? I don't know).
I believe human sport swimmers don't sweat in the same ammounts of eg. sport runners, even though they are at equal peak muscular performance. The odd thing is that swimmers instead increase in diuretics and need to urine more, which I have no explanation for.
Human perspiration seems to be primarily for dry conditions. If human ancestors have been semi-aquatic (at least for a period in African geological history), perspiration could've evolved in post-aquatic development, eg. in emerging drier eras (with the changes in the Saharan pump, etc.), and as a result of then human furlessness.
Either that, or humans have never been semi-aquatic, and perspiration developed for what ever reason we developed furlessness.

(05-08-2012 11:31 AM)fstratzero Wrote:  The availability of omega 3's from fish doesn't necessitate brain growth. The majority of the other species who feed mostly on fish do not automatically grow larger brains.

I'm being told the exact opposite, that generally aquatic and semi-aquatic mammals do in fact grow larger brains, because the nutrition to sustain them is more readily available in seafood. Especially mammals adapting to grasslands from other habitats is said to reduce in brain size (I think comparitively though, species seem to grow in general size, but their brain doesn't grow at the same rate). The classic example is the difference between a grassland zebra and an aquatic dolphin of roughly the same body mass, a zebra having 350 grams of brain, while a dolphin has some 1800 grams.

(05-08-2012 11:31 AM)fstratzero Wrote:  The changing environment put a selection pressure on humans to find newer food sources. Omega 3's are available from fish, plants, and the bodies of other creatures. Being able to adapt to changing environments it where the selection pressure favored intelligence.

In other words the presence of nutrition does not automatically mean they'll use it a certain way.

It just seems parsimonous, if aquatic and semi-aquatic mammals do develop larger brains (compared to body mass). I don't know if it's a general rule (I think hippos have somewhat small brains, but then again I remember a reference labeling them somewhat smart for their brain's size, similar to elephants, also speculated to be possible past semi-aquatics), but either way, the human brain is aparently dependent not just on Omega 3, but also in particular Iodine. And both those exact nutrition elements are abundant in seafood, while quite difficult to acquire in adequate ammounts in a purely terrestrial diet. It is possible, but that's like a vegetarian having to apply its high intelligence to know exactly where to find adequate proteines in a purely floric diet. It doesn't parsimonously seem to have been the original human diet for a being like eg. Lucy with an intelligence like a 7 year old Homo sapiens.

On the flipside, primates and especially apes are said to generally have large brains, which I don't know how could've developed in the tree tops originally.

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10-08-2012, 04:48 PM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(10-08-2012 04:35 PM)CEngelbrecht Wrote:  On the flipside, primates and especially apes are said to generally have large brains, which I don't know how could've developed in the tree tops originally.

Really large brains didn't develop until we were already down from the treetops.

However, larger brain vs body size would be selected for because living in a 3-D world of the forest would reward it.

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10-08-2012, 05:34 PM
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(10-08-2012 04:48 PM)Chas Wrote:  Really large brains didn't develop until we were already down from the treetops.

However, larger brain vs body size would be selected for because living in a 3-D world of the forest would reward it.

Ok, but we're lacking in phylogenic examples of eg. forrest or grassland mammal taxa winding up with the same solution of growing its brain, while this seems to be, not universal, but common in aquatics and semi-aquatics. If growing the brain wasn't necessary for eg. chimps, gorillas, baboons, hyenas, lions, zebras, wildebeests or what ever, why was it for humans?
If the growth of the human brain developed in either dry scenario, it kinda demands that it would've spawned that development just totally random (eg. via genetic drift) and not by a phylogenic principle as such. Which is a distinct possibility, but it kinda defines the human brain as a peacock's tail. (Which would be the same for eg. bipedalism, furlessness, proto-blubber, speech, and the various other aquatic arguments.)

Don't get me wrong, it's a nice fantasy to think of one's own species as something that makes up its own biological rules down through the eons, but it's not that parsimonous I'd say.

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10-08-2012, 07:25 PM (This post was last modified: 10-08-2012 07:38 PM by fstratzero.)
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(10-08-2012 04:35 PM)CEngelbrecht Wrote:  I think human perspiration is still an enigma. The only other example I can think of of 'glissening' sweating to cool down is horses. That there is only this single phylogenic comparison (in a grassland taxa) increases the plausibility of at least human perspiration having developed in a grassland scenario. (Or though Philip Tobias and others have concluded, that the African savannah is much too young to have been the cause behind eg. human bipedalism.)
There is the key difference that horses sweat through apocrine sweat glands, which humans only have in the armpits and the anus, while human cooling sweat stems mostly from eccrine glands, which I think are unique to primates and covers the whole human body. But this difference may not have any practical impact on developing the shedding of skin water to cool off in both humans and horses.

I don't think it's being suggested, that we would ever have reached an aquatic level to have evolved features like fins and flippers. Whales and dolphins have had 50+ million years do develop such features, in such case humans would only have been semi-aquatic max 5-7 million years, perhaps less. I don't know if other semi-aquatic mammal taxa of a similar "young" age is available (otters? I don't know).
I believe human sport swimmers don't sweat in the same ammounts of eg. sport runners, even though they are at equal peak muscular performance. The odd thing is that swimmers instead increase in diuretics and need to urine more, which I have no explanation for.
Human perspiration seems to be primarily for dry conditions. If human ancestors have been semi-aquatic (at least for a period in African geological history), perspiration could've evolved in post-aquatic development, eg. in emerging drier eras (with the changes in the Saharan pump, etc.), and as a result of then human furlessness.
Either that, or humans have never been semi-aquatic, and perspiration developed for what ever reason we developed furlessness.

Simply put, no fur, better air flow, better air flow, faster evaporation, cooler humans. Cool
en.wikipedia.org/wiki/Perspiration

our study showed that swimmers do sweat, although at rates that are lower than land-trained athletes. And we showed that swimmers are able to replace their fluid losses during the session by drinking from water bottles kept at the end of the pool.

http://www.swim-city.com/library.php3?id=34

Quote:I'm being told the exact opposite, that generally aquatic and semi-aquatic mammals do in fact grow larger brains, because the nutrition to sustain them is more readily available in seafood. Especially mammals adapting to grasslands from other habitats is said to reduce in brain size (I think comparitively though, species seem to grow in general size, but their brain doesn't grow at the same rate). The classic example is the difference between a grassland zebra and an aquatic dolphin of roughly the same body mass, a zebra having 350 grams of brain, while a dolphin has some 1800 grams.

Drinking Beverage Bad argument. For example 5.4kg Elephant brain(veggie eater) vs White Shark brain (fish eater)35g

Crocodiles, birds, snakes, eels, rays, sharks, aquatic turtles, lobsters, crayfish, crabs, and other fish eating species haven't enjoyed large brain growth.

And if you want to go the brain to body mass route, the largest brain to body mass ratio is the ground shrew. Not exactly exciting.

Quote:It just seems parsimonous, if aquatic and semi-aquatic mammals do develop larger brains (compared to body mass). I don't know if it's a general rule (I think hippos have somewhat small brains, but then again I remember a reference labeling them somewhat smart for their brain's size, similar to elephants, also speculated to be possible past semi-aquatics), but either way, the human brain is aparently dependent not just on Omega 3, but also in particular Iodine. And both those exact nutrition elements are abundant in seafood, while quite difficult to acquire in adequate ammounts in a purely terrestrial diet. It is possible, but that's like a vegetarian having to apply its high intelligence to know exactly where to find adequate proteines in a purely floric diet. It doesn't parsimonously seem to have been the original human diet for a being like eg. Lucy with an intelligence like a 7 year old Homo sapiens.

Insects, grazing animals(in their fat),mammalian brains and eyes, and green vegetables all contain omega-3's

Iodine is a component of almost every living plant and animal. No standard measurements of iodine in food exist because iodine concentrations vary across the world.

Quote:On the flipside, primates and especially apes are said to generally have large brains, which I don't know how could've developed in the tree tops originally.

They aren't always in the tree tops........ And assuming they eat insects, and greens they should be good.

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11-08-2012, 11:29 AM (This post was last modified: 11-08-2012 11:39 AM by fstratzero.)
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
α-linolenic acid (ala) which is a common omega 3 in plants gets converted into dha or docosahexaenoic acid.
DHA is essential for brain growth, some gets converted from ala to dha, from plants.
http://www.dhaomega3.org/Overview/Conver...-in-Humans

Eating animal brains is a good direct source of dha, their fat, and insects.

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14-08-2012, 05:29 PM (This post was last modified: 14-08-2012 05:35 PM by CEngelbrecht.)
RE: Dear sciencey people: what are your opinions on the Aquatic Ape Hypothesis?
(10-08-2012 07:25 PM)fstratzero Wrote:  
Quote:I'm being told the exact opposite, that generally aquatic and semi-aquatic mammals do in fact grow larger brains, because the nutrition to sustain them is more readily available in seafood. Especially mammals adapting to grasslands from other habitats is said to reduce in brain size (I think comparitively though, species seem to grow in general size, but their brain doesn't grow at the same rate). The classic example is the difference between a grassland zebra and an aquatic dolphin of roughly the same body mass, a zebra having 350 grams of brain, while a dolphin has some 1800 grams.

Bad argument. For example 5.4kg Elephant brain(veggie eater) vs White Shark brain (fish eater) 35g

Crocodiles, birds, snakes, eels, rays, sharks, aquatic turtles, lobsters, crayfish, crabs, and other fish eating species haven't enjoyed large brain growth.

A white shark is a fish, not a mammal. Large brain development seems to be occuring specifically in at least some aquatic/semi-aquatic/marine mammals, for which ever reason, diet, etc. (Or though I'm not too familiar with if the same applies for aquatic birds and reptiles, eg. penguins and turtles.)

(10-08-2012 07:25 PM)fstratzero Wrote:  And if you want to go the brain to body mass route, the largest brain to body mass ratio is the ground shrew. Not exactly exciting.

With the danger of venturing into confirmation bias, I would then suggest considering if shrews originate from semi-aquatic forms in their evolution, this then being the source of their growing brain. There are already considerations about semi-aquatic stage(s) in the evolution of (AFAIK) elephants, rhinos, tapirs and suids (not that all those necessarily developed large brains, though).
The best info I could find about shrews at a flash is this work: "It is concluded that the evolution of shrews is stimulated by humid paleoclimates." But I'm not sure what exactly that means, I haven't had access to the work in full, the writers don't necessarily mean that shrews were semi-aquatic.
[Image: Watershrewskeleton.jpg]

(10-08-2012 07:25 PM)fstratzero Wrote:  Iodine is a component of almost every living plant and animal. No standard measurements of iodine in food exist because iodine concentrations vary across the world.

Again, I'm being told otherwise. As I recall, it will take many kilograms of assorted terrestrial meats and vegetables to acquire the daily recommended 150 µg of Iodine ions, while it would take some 150 grams of fish or shellfish. However, I do think that chicken eggs are high on the Iodine list as well (something like 200 grams of eggs daily), which opens the possibility that proto-humans were egg eaters for Iodine (not necessarily eggs from the originally SE Asian chickens, but from other African birds). Or though one downside to the egg argument is that at least chicken eggs present us with cardiovascular problems, eg. through cholesterol.

(11-08-2012 11:29 AM)fstratzero Wrote:  α-linolenic acid (ala) which is a common omega 3 in plants gets converted into dha or docosahexaenoic acid.
DHA is essential for brain growth, some gets converted from ala to dha, from plants.
http://www.dhaomega3.org/Overview/Conver...-in-Humans

Eating animal brains is a good direct source of dha, their fat, and insects.

The problem is not as much acquiring DHA beyond the water, because that is indeed possible through a (somewhat specific) terrestrial diet, The issue is again more with Iodine, which practicality has shown to be near impossible to garner in adequate quantities via terrestrial foods. WHO today observes that somewheres between 1 and 2 billion (billion!) Homo sapienses suffer from Iodine deficiency, causing endemic goiter many places (goiter being a traditional sign of Iodine deficiency, which is why industrialized regions add Iodine to commercial salt and other products). I know of studies on islands in Indonesia and the Philippines, where inland villages suffer greatly from goiter, while on the same island fishing villages have virtually no problems.

So upwards of two sevenths of the entire human population, this increasingly agricultural ape for the last 10.000 years, are nowhere near the correct intake of Iodine, vital for our brain. Most likely because today, most of us do eat mostly terrestrial foods and not aquatic as we may have been adapted to originally through up to as much as 5-7 million years of evolution (this because agriculture makes it a lot easier to produce large quantities of carbohydrates and animal fats and proteines, obviously).

Insects as sources for DHA is indeed possible, but the argument of proto-humans eating animal brains for eg. DHA and perhaps even Iodine has the shortcoming, that it's extremely difficult to get into the skulls of eg. carcasses, even with lithic tools (or even modern power tools), before the brain tissue is spoiled and uneatable for an ape. I don't think it's very likely that our ancestors ate carcass or even freshly killed brains to grow its own brain, at least not to the point of having an evolutionary impact. Also, we don't see a modern human behavioral tendency to wanting to eat animal brains (and to a point neither insects, or though that does vary). For all I know we all find the mere thought of eathing ox brain disgusting. Whereas a tendency for seafood which gets the job done easily seems to be universal.

It's not completely impossible that the human brain did start to grow on a purely/largely terrestrial diet, but seafood as a source of both DHA and Iodine (vital for the human brain) demands the fewest assumptions and would therefore still be the parsimonous conclusion. Especially when coupled with the already long list of other phylogenic indications for something wet in human evolution.

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