A New Twist on the Aquatic Ape Theory

[gwolf]

High in the mountain fastness of Uganda, so high that the tropics don't feel all that hot, one finds beautiful lakes of full of mineralized water that seem neither too cold nor too hot, and are choked with colorful fish. Surrounding the lakes are deep forests, full of heavy fruits, wild nuts and berries. The forests are a feast for the eye, with gigantic old-growth trees. It rains almost every day.

On the shores of the lakes lives a strange ape, one unlike every other type of ape one might find. It appears to be adapted for fishing. It can swim, unlike all other apes - even in deep water. It has a diving reflex, which by reducing the heart rate and changing the circulation makes it easier for the ape to hold its breath and conserve its heat. Its fingers are slightly webbed, an adaptation for more efficient swimming. It's body has subcutaneous fat to conserve heat. Unlike all other apes, it has a streamlined shape, improving its swimming efficiency. As part of the streamlining, it has little hair, mostly on the head where it acts as a sunscreen. The skin is tinted almost black, partly to avoid being damaged by ultraviolet radiation, but also to better camouflage the ape in the muddy water.

Its swimming talent is for transportation only, as like the crocodiles also found in these parts, it's an ambush predator. To fish, this ape stands quietly on two legs for many hours, totally immersed except for its head. This is not at all a difficult feat because it is adapted to standing on two legs and most of its weight is buoyed by the water. Fish are drawn by its smells; it is as though the ape's body serves as the bait. Unlike all other apes, it doesn't communicate with gestures. It can't, as that would scare away the fish. Instead, it uses its voice, much as dolphins do. When something wonders close enough, the ape grabs it with lightning-fast movements of its hands, then bites and twists the head to kill the catch.

It prefers not to eat in the water. Having caught its prey, it swims to shore. Then something peculiar happens. Surrounded by other members of the band giving it great approval, it weeps in happiness, which has a dual purpose; the salty tears get rid of just enough of the dissolved minerals in the water that this ape needs no fresher water to drink. Indeed, it prefers the taste of mineralized water to that of rainwater or fresh water from running streams.

In addition to fishing, this ape can also forage in the water. Its hands have an excellent sense of touch, much like swimming moles, and it can use this to find the hiding places of the many mollusks and shrimp that live on the bottom. It also forages in the bushes and trees near the lakes for fruits and nuts. And just as it will wait in ambush for fish, it will also wait in ambush for small mammals, sitting quietly until something suitable draws near. It can't chase the prey, for its legs are more adapted to standing or walking. Instead it hits or throws something at its prey, very much like chimpanzees.

It is good enough at doing this that it has little to fear from the crocodiles. Living in groups, it usually spots the reptiles with good vision long before they get close enough to attack - but they prefer not to. It is as easy for this ape to kill crocodiles with a well-aimed stave or heavy rock as it is for a porpoise to kill a shark with a good punch to the gut. Their aquatic habits and big groups also make them difficult prey for the big cats living in the woods. Here, the crocodiles actually offer protection, as the cats are at a disadvantage in the water. This ape actually fears hippos and elephants much more, another reason why it prefers the high lakes.

Its sexual habits are a little different than other apes, influenced by its strange aquatic existence. Both sexes appear to prefer slender streamlined shaped mates. Mating is done belly to belly rather than from behind, to the point that males are attracted by what look like a pair of artificial buttocks on the fronts of the females. Females in turn are attracted by penises that are noticeably larger than those of any other ape - and which also possess a streamlined shape. To show off their reflexes and coordination, both males and females will engage in elaborate dancing.

The young are born almost helpless, except for an ability to swim. Like other apes, they have the ability to grasp, but have weaker arms and hands that can only hold the young near the mother if she is immersed in water. Her "artificial buttocks" double as suckling teats that conveniently float. While she is suckling, she can't wade as deeply as the males can. Partly as a result, females tend to be shorter than males, although both sexes are taller than most other apes.

Also unlike all other apes except the bonobos, and very much like porpoises, sexual intercourse has little to do with estrous. Instead it appears to be used for social interactions. Unlike porpoises, intercourse appears to reinforce semi-permanent pair-bonds, that sometime last years.

These apes live in bands of twenty or thirty that protect a given territory. Quite often, most of the members of the bands are related to each other.

I'm sure you recognize Elaine Morgan's aquatic ape theory in the above. I've just explained why we find all of those hominid fossils in the Rift Lake regions of Africa, rather than on some sea shore. By the way, people in Africa still catch fish in the manner I describe. I just wish the rift valleys were still as pristine as I've described them.

George Wolf

[WordNerd]

Nice story.

[JeffLee]

I saw a whole lot of fantasy and not much twist, can we spare the theatrics?


Where along the time line of human evolution is your aquatic ape? do we have any fossils suggesting an aquatic lifestyle and/or diet related to this time line? what prompted these early apes to descend from the treetops and begin to fish? What prompted them to leave their aquatic habitat and high mountain regions for the savannah? what prompted the shift from a fish diet to larger game? I can't imagine the shift from a passive predator to open area hunter/scavenger to have been particular advantageous. do you suggest that the pressure could have been drops in lake levels? do we have corresponding evidence of these lake fluctuations? i imagine it would have to be on the extreme end as a simple retreat of the water line could be easily followed. how do chimps factor into all of this? would it not be more parsimonious to explain the evolution of bipedalism with the opening up of the African savannah as bipedalistic motion is more efficient then a knuckle walk on open terrain.

[gwolf]

I saw a whole lot of fantasy and not much twist, can we spare the theatrics?

I'm describing people as they are now. My story is based on what I've heard from Ugandans. I take it as a compliment that you think of it as theatre. It certainly got your attention!

Where along the time line of human evolution is your aquatic ape?

This is homo sapiens without modification; as the species could easily exist today wherever it finds that habitat. I can only guess how far back it goes, perhaps as old as the oldest hominids in Olduvai Gorge and the other Central African rift valleys.

do we have any fossils suggesting an aquatic lifestyle and/or diet related to this time line?

In modern H.Sapiens, we know that most modern habitations are associated with water. In my old home in Central Pennsylvania, you always looked alongside the creeks and rivers for remains of Indian villages. In other human societies in Africa, ancient Switzerland and Indonesia, people actually build or built dwellings over water. Fish is repeatedly recommended by dietitians as a preferred meat, because human bodies don't seem to know what to do with the extra fat and cholesterol found in endothermic meats. As for fossils, it is noted that preserved hominid remains contrast with those of other apes in being plentiful as opposed to nearly nonexistent. Dating back to the first book I read on fossils (Dinosaurs by Edwin H. Colbert in 1960), the opinion seems to be that an aquatic or semi-aquatic environment seems to preserve more fossils than a jungle environment. Thus a plethora of hominid fossils indicates a semi-aquatic environment and a paucity of pongid fossils indicates a jungle habitat.

what prompted these early apes to descend from the treetops and begin to fish?

Here we get to speculation. I'm told that Africa went through a dry period in Miocene times, during which it is thought that many different primates became terrestrial rather than arboreal. I will speculate that at least one of these groups decided to hang out around permanent water holes so they wouldn't go thirsty.

What prompted them to leave their aquatic habitat and high mountain regions for the savannah?

I will speculate that they became a victim of their own success and overpopulated until the rift valleys could no longer support all of them. This forced them into other parts of Africa, and later the world.

what prompted the shift from a fish diet to larger game? I can't imagine the shift from a passive predator to open area hunter/scavenger to have been particular advantageous.

I think overpopulation explains it very well; they had no choice in the matter, but enough intelligence to adapt.

do you suggest that the pressure could have been drops in lake levels? do we have corresponding evidence of these lake fluctuations? i imagine it would have to be on the extreme end as a simple retreat of the water line could be easily followed.

My hypothesis doesn't require this, and I've seen no evidence to support it. Are you aware of any?

how do chimps factor into all of this?

I hypothesize that humans inhabited the uplands around the rift lakes and chimpanzees inhabited deeper rain forest. I presume they interacted at the peripheries but I don't know how.

would it not be more parsimonious to explain the evolution of bipedalism with the opening up of the African savannah as bipedalistic motion is more efficient then a knuckle walk on open terrain.

As bipedal locomotion goes, that of humans isn't all that efficient; most terrestrial mammals -- including chimps -- and all ratite birds (ostriches, emus etc.) can outrun h. Sapiens. Humans are also different bipedally than birds and dinosaurs; most member of the latter two groups appear to maintain their bodies as parallel to the ground as most mammals do. In contrast, humans (and interestingly, aquatic penguins) have a perpendicular posture, as though height was more important than speed (favorable muscle attachments are easier if the body is parallel rather than perpendicular). I look at this as evidence of hominids being ambush predators rather than chase predators. In fact on the savanna, humans are still ambush predators, using weapons (like spears, arrows and guns) to compensate for the lack of speed.

Thanks for your interest,

George Wolf

[JimC]

There are certainly some plausible elements to this hypothesis, but ideally it could make some testable predictions.

As bipedal locomotion goes, that of humans isn't all that efficient; most terrestrial mammals -- including chimps -- and all ratite birds (ostriches, emus etc.) can outrun h. Sapiens. Humans are also different bipedally than birds and dinosaurs; most member of the latter two groups appear to maintain their bodies as parallel to the ground as most mammals do. In contrast, humans (and interestingly, aquatic penguins) have a perpendicular posture, as though height was more important than speed (favorable muscle attachments are easier if the body is parallel rather than perpendicular). I look at this as evidence of hominids being ambush predators rather than chase predators. In fact on the savanna, humans are still ambush predators, using weapons (like spears, arrows and guns) to compensate for the lack of speed.

I am not sure that this is accurate, except for lack of sprinting. Many hunter-gatherer bands adopt a strategy similar to Cape Hunting Dogs, and wear down antelope etc. by remorseless, steady jogging. Few predators can last as long. The weapons are often used to kill an antelope that can run no more...
Also, humans have vastly better abilities at throwing than chimps, and I see nothing in the aquatic phase to select for such skills. If there was such an aquatic stage, the selective pressures of later life on the savanna were equally important in forging the phenotype, mental and physical, that we enjoy today.

[JeffLee]

I'm describing people as they are now. My story is based on what I've heard from Ugandans. I take it as a compliment that you think of it as theatre. It certainly got your attention!

yea, but thats mostly because the storyboard method always bugs me. ^^

This is homo sapiens without modification; as the species could easily exist today wherever it finds that habitat. I can only guess how far back it goes, perhaps as old as the oldest hominids in Olduvai Gorge and the other Central African rift valleys.

so... yea, I'm already confused. isn't the aquatic ape hypothesis about the formation of modern sapien traits based on a temporary aquatic lifestyle in our evolutionary past?

or are you suggesting a completely new species that diverged from "us" to form an aquatic ape?

In modern H.Sapiens, we know that most modern habitations are associated with water. In my old home in Central Pennsylvania, you always looked alongside the creeks and rivers for remains of Indian villages. In other human societies in Africa, ancient Switzerland and Indonesia, people actually build or built dwellings over water.

well yes, water is essential to all mammalian life so of course they are going to hang around constant sources. Deer will tend to in habitat territories with open access to water as well, but this does not make them aquatic animals like a beaver or a hippo.

Fish is repeatedly recommended by dietitians as a preferred meat, because human bodies don't seem to know what to do with the extra fat and cholesterol found in endothermic meats.

hmmmmmm. hate to tread on other peoples territory, I'm fairly ignorant as to the evolutionary effects of meat eating, and probably will be until my latest book order comes in...

but anyway, my curiosity has to ask a few questions, assuming of course, the statement is true.

is this a trait exclusive to humans or primates? if there was an aquatic meat eating ape in our past who later switched to terrestrial prey and acquired these difficulties, would we not see a higher tolerance to these cholesterol's in other apes/mammals who have begun to eat meat but most likely did not have an aquatic evolutionary past?

Chimps for example, eat meat now and again, and i believe they too share our cholesterol problems, if i recall correctly they may even be worse at t [eating meat] then we are.... but i could very well be wrong or failing to correctly recall the data.

As for fossils, it is noted that preserved hominid remains contrast with those of other apes in being plentiful as opposed to nearly nonexistent. Dating back to the first book I read on fossils (Dinosaurs by Edwin H. Colbert in 1960), the opinion seems to be that an aquatic or semi-aquatic environment seems to preserve more fossils than a jungle environment. Thus a plethora of hominid fossils indicates a semi-aquatic environment and a paucity of pongid fossils indicates a jungle habitat.

This is true, but could it not be equally explained with the opening up of the African savannah? leaving the jungle habitat behind, the apes should have clustered around waterways and lakes to keep themselves hydrated, much like modern savannah animals do today.

speaking of which, do you happen to know of any early hominid fossil sites containing fish fossils? i know of one [site 50somehting, it was an erectus 'camp'] that contained a single catfish skeleton... I imagine they wouldn't fossilize as easily though, so it wouldn't be surprising if the recod was silent on such a relationship.

Here we get to speculation. I'm told that Africa went through a dry period in Miocene times, during which it is thought that many different primates became terrestrial rather than arboreal. I will speculate that at least one of these groups decided to hang out around permanent water holes so they wouldn't go thirsty.

yep.

I will speculate that they became a victim of their own success and overpopulated until the rift valleys could no longer support all of them. This forced them into other parts of Africa, and later the world.

hmm. i'll wait to see what you said about the passive to active predator question before continuing on about this.

I think overpopulation explains it very well; they had no choice in the matter, but enough intelligence to adapt.

hmm.


what about the possibility that they were pursuing active game during your aquatic phase? IMO it makes more sense to me for fish to have been the supplementary diet[this could be due to me recently finishing 'at the water's edge', the transition to modern whales may be unconsciously biasing my train of thought towards aquatic apes becoming fully aquatic in their lifestyles], but as far as your hypothesis goes i don't see a problem with your aquatic apes taking down the odd antelope to supplement their fishing...

Perhaps population growth wasn't as much of an issue as sexual selection, with the females beginning to favour the now erect and toll capable apes who can take down an ungulate and feed the clan over a more traditional fisher who could feed one or two members with a single catch.

on the flip side, fishing seems more solitary work due do the limited amount of food per catch, i can more easily envision a complex social structure evolving from a group hunt effort then a clan of fishers feeding their mates and young. of course this could have occurred after the apes left the water and achieved your proposed morphological traits.

My hypothesis doesn't require this, and I've seen no evidence to support it. Are you aware of any?

Well, i know lake turkana tends to vary to some extremes.

I hypothesize that humans inhabited the uplands around the rift lakes and chimpanzees inhabited deeper rain forest. I presume they interacted at the peripheries but I don't know how.

alrighty then, maybe it's something i can look into when i get some free time...

As bipedal locomotion goes, that of humans isn't all that efficient; most terrestrial mammals -- including chimps -- and all ratite birds (ostriches, emus etc.) can outrun h. Sapiens.

hmm. it was my understanding that human bipedalism is more efficient then chimpanzee knuckle walking, now assuming that chimps did not separately evolve knuckle walking, then we most likely share a common ancestor who moved about in that manner. now, from the work of Peter Rodman and Henry Mchenry it was determined that there was no energy barrier for chimps [and presumably, our common ancestor with them] between quadrupedal and bipedal locomotion, but there was a distinct differences in efficiency between modern human bipedalism and ape quadrupedalism in favour of the human mode of transportation.

They suggest in Leakeys book 'origins reconsidered' that bipedalism arouse from the fragmentation of forest area in the rift valley. there was no drive... yet.... for humans or apes to be faster or slower [the fruit wasn't running away], but the fragmentation would have put a pressure on the efficiency of travel. With the evolution of more 'hunteresk' homo species arising later. [based on the anatomical work of Leslie Aiello]

Humans are also different bipedally than birds and dinosaurs; most member of the latter two groups appear to maintain their bodies as parallel to the ground as most mammals do. In contrast, humans (and interestingly, aquatic penguins) have a perpendicular posture, as though height was more important than speed (favorable muscle attachments are easier if the body is parallel rather than perpendicular).

why yes. but doesn't the corresponding lengthening of stride and the increased surface area to muscle mass suggest to you that there was selection for activity in a warm open area?

I look at this as evidence of hominids being ambush predators rather than chase predators. In fact on the savanna, humans are still ambush predators, using weapons (like spears, arrows and guns) to compensate for the lack of speed.

hmm. the water/land jump still seems abit unnecessary to me, so it's easier for me to guess and suggest that it wasn't as much about humans running and killing prey as it was about humans running the prey down, using their lack of fur and [maybe] sweating to keep themselves cool in the heat of the day while their prey overheats out in the sun.

hmm. i wonder how fast erectus and the like were... I have never seem much information on that.

Thanks for your interest,
George Wolf

It's been fun so far, looking forward to your return. ^^

EDIT: yay! JimC managed to back my guess with some info. thanks.

[DavidMcC]

Where along the time line of human evolution is your aquatic ape? do we have any fossils suggesting an aquatic lifestyle and/or diet related to this time line? what prompted these early apes to descend from the treetops and begin to fish?

The hominins (as opposed to hominids) appeared about 6MY ago in NE Africa. At that time, the Afar depression was flooded due to sea level rise. Being a depression, it would presumably have flooded catastrophically, at least in part, suddenly bringing sea water, and fish into the forest. (I have mentioned this before in previous aquatic ape threads.)
When the flood waters divided NE Africa, creating the island of Afar for a million years or so, inevitably, ape populations became split up, some on the island, others on the other side of the new waterway. Thus new species are bound to have been created. One of them might have continued to find the fish that had been washed into their forests, even after a shoreline was formed by the saline water. As the sea retreated, the only option for some would have been fresh water.
EDIT:Old threads linked from here

[JeffLee]

The hominins (as opposed to hominids) appeared about 6MY ago in NE Africa. At that time, the Afar depression was flooded due to sea level rise. Being a depression, it would presumably have flooded catastrophically, at least in part, suddenly bringing sea water, and fish into the forest. (I have mentioned this before in previous aquatic ape threads.)

hmm.

do we have any specific dates as to the formation of the depression? i can't seem to pin it down, the date is floating around 20mya in the Miocene. As i understand it though, the late Miocene was a period of global cooling and the formation of the antarctic glacier. [as well as uplift in the mediterranean leading to a steep loss of rainfall in Africa and opening up grasslands]

your date of 6 mya also, interestingly enough, corresponds with the Messinian Event, it seems odd to me that a time highlighted with the complete drying up of the mediterranean sea could correspond with the high sea levels you are suggesting.

When the flood waters divided NE Africa, creating the island of Afar for a million years or so, inevitably, ape populations became split up, some on the island, others on the other side of the new waterway. Thus new species are bound to have been created. One of them might have continued to find the fish that had been washed into their forests, even after a shoreline was formed by the saline water. As the sea retreated, the only option for some would have been fresh water.
EDIT:Old threads linked from here

island of afar?
what island?

[gwolf]

isn't the aquatic ape hypothesis about the formation of modern sapien traits based on a temporary aquatic lifestyle in our evolutionary past?

or are you suggesting a completely new species that diverged from "us" to form an aquatic ape?

I think a lake-dwelling ape that's been exapted to other environments seems a more elegant and reasonable explanation of homo sapiens' current status than either the savanna ape or ocean coast aquatic ape. I should explain that "exaption" is Daniel Dennett's term for something evolved or designed for one use that turns out to be useful some other way. I don't propose any kind of separate aquatic ape to do this and it hardly seems necessary. Instead I'm suggesting that h. sapiens' hominid ancestors were evolving all of this time to fill the lake-dwelling ape niche. In classic evolutionary fashion, evolution favored those who happened to fit the niche the best.

well yes, water is essential to all mammalian life so of course they are going to hang around constant sources. Deer will tend to in habitat territories with open access to water as well, but this does not make them aquatic animals like a beaver or a hippo.

Deer don't make their living in the water! I propose that even more so than beavers or hippos, humans did.

[regarding fish-eating I] hate to tread on other peoples territory, I'm fairly ignorant as to the evolutionary effects of meat eating, and probably will be until my latest book order comes in...

but anyway, my curiosity has to ask a few questions, assuming of course, the statement is true.

is this a trait exclusive to humans or primates? if there was an aquatic meat eating ape in our past who later switched to terrestrial prey and acquired these difficulties, would we not see a higher tolerance to these cholesterol's in other apes/mammals who have begun to eat meat but most likely did not have an aquatic evolutionary past?
Chimps for example, eat meat now and again, and i believe they too share our cholesterol problems, if i recall correctly they may even be worse at [eating meat] then we are.... but i could very well be wrong or failing to correctly recall the data.

As far as I know, humans have more carnivorous tendencies than any of the other apes. Remember, it's only been in the last fifty years that we've become aware of any hunting behavior at all in chimpanzees.

[A greater chances of fossil preservation in aquatic environments] is true, but could it not be equally explained with the opening up of the African savannah? leaving the jungle habitat behind, the apes should have clustered around waterways and lakes to keep themselves hydrated, much like modern savannah animals do today.

As far as I know, places with shifting sediments capable of rapidly burying carcasses give the best chances of yielding fossils. Does that happen on the savannah? I can see how most likely to happen on muddy lake beds, plain old mud flats, tar pits, sand dunes and even volcanic ash. I get the idea that fossilized humans mostly come from mud flats -- but I claim no expertise here.

speaking of which, do you happen to know of any early hominid fossil sites containing fish fossils? i know of one [site 50somehting, it was an erectus 'camp'] that contained a single catfish skeleton... I imagine they wouldn't fossilize as easily though, so it wouldn't be surprising if the recod was silent on such a relationship.

I don't know of any. Humans tend to break up fish as they eat them, so I'd be kind of surprised if we ever found recognizable articulated fish skeletons mixed in with humans.

hmm. i'll wait to see what you said about the passive to active predator question before continuing on about [overpopulation of the lake habitats]

I think that in the lakes we'd see the beginnings of both active and passive predation; passive predation would have begun with mollusk foraging in the shallows as an exaption of mollusk and insect foraging on land. Following this would be eating accidentally killed fish and finally predation of live fish. Stone tools would start out as a way of opening the mollusks, followed by rendering fish and later larger carcasses. Somebody would discover that digging sticks for roots also killed crocodiles quite nicely, though they may have started as a way to merely fend them off.

what about the possibility that they were pursuing active game during your aquatic phase? IMO it makes more sense to me for fish to have been the supplementary diet[this could be due to me recently finishing 'at the water's edge', the transition to modern whales may be unconsciously biasing my train of thought towards aquatic apes becoming fully aquatic in their lifestyles], but as far as your hypothesis goes i don't see a problem with your aquatic apes taking down the odd antelope to supplement their fishing...

It takes far less energy and resources to capture fish in a confined lake than to chase down terrestrial game. Why go to the trouble? Accidentally killed game would be another matter. Adding to this, as far as I know, H. Sapiens' ancestors were all of a smaller size. I think the game most likely to have been pursued would have been the crocs inhabiting the same lakes as the people. There'd be a positive reason for killing them off.

Perhaps population growth wasn't as much of an issue as sexual selection, with the females beginning to favour the now erect and toll capable apes who can take down an ungulate and feed the clan over a more traditional fisher who could feed one or two members with a single catch.

I think sexual selection favors trim "streamlined" people rather than big ones, whether fat or muscular. The easiest archetypes of sexual attraction that I can think of in the media seem to fit this description, whether male or female. Streamlining rather than overt muscularity would be an aquatic rather than terrestrial feature.

on the flip side, fishing seems more solitary work due do the limited amount of food per catch, i can more easily envision a complex social structure evolving from a group hunt effort then a clan of fishers feeding their mates and young. of course this could have occurred after the apes left the water and achieved your proposed morphological traits.

I think it involves much more effort and luck to bring down large prey than small prey or insects and plants. So on that basis it would be harder to make a living with it. The herds on the savanna migrated a lot, fish trapped in lakes couldn't.

Well, i know lake turkana tends to vary to some extremes.

Your tempting me to speculate that h. sapiens came upon a lake, killed and ate the crocs living in it, then proceeded eat all of the fish they found. When the lake was exhausted, they migrated to another and another. It would explain the great migrating stamina nicely.

hmm. it was my understanding that human bipedalism is more efficient then chimpanzee knuckle walking, now assuming that chimps did not separately evolve knuckle walking, then we most likely share a common ancestor who moved about in that manner. now, from the work of Peter Rodman and Henry Mchenry it was determined that there was no energy barrier for chimps [and presumably, our common ancestor with them] between quadrupedal and bipedal locomotion, but there was a distinct differences in efficiency between modern human bipedalism and ape quadrupedalism in favour of the human mode of transportation.

They suggest in Leakeys book 'origins reconsidered' that bipedalism arouse from the fragmentation of forest area in the rift valley. there was no drive... yet.... for humans or apes to be faster or slower [the fruit wasn't running away], but the fragmentation would have put a pressure on the efficiency of travel. With the evolution of more 'hunteresk' homo species arising later. [based on the anatomical work of Leslie Aiello]

Perhaps my answer about moving from one lake to the next provides still another reason why "efficient" bipedalism was adopted by humans. As I see it, an erect posture at first allowed human ancestors to wade into deeper water where there were bigger fish. Later it was exapted as a more efficient means of migration transportation.

doesn't the corresponding lengthening of stride and the increased surface area to muscle mass [associated with human bipedalism] suggest to you that there was selection for activity in a warm open area?

I think it was an exaption that could only work once a dangerous weakness was overcome; the use of sweat as a cooling mechanism. It works efficiently but requires great amounts of water. Until h. sapiens invented water carrying tools, the advantages of evaporant cooling were of much more limited use, or even none at all. Arid environment animals use alternate cooling means so as to conserve water; big ears, estivation, nocturnalism, metabolicaly derived water and so forth.

hmm. the water/land jump still seems abit unnecessary to me, so it's easier for me to guess and suggest that it wasn't as much about humans running and killing prey as it was about humans running the prey down, using their lack of fur and [maybe] sweating to keep themselves cool in the heat of the day while their prey overheats out in the sun.

Great stamina and evaporant cooling are indeed big advantages. However stamina depends on efficient cooling to work, and evaporant cooling requires a ready source of water. I discovered this the hard way.

hmm. i wonder how fast erectus and the like were... I have never seem much information on that.

I envision them as a slightly less specialized version of h. sapiens, perhaps the first people to have been evicted from the rift lake valleys.

It's been fun so far, looking forward to your return. ^^

I'm enjoying this too. Thanks for your replies.

George Wolf

[gwolf]

I am not sure that this is accurate, except for lack of sprinting. Many hunter-gatherer bands adopt a strategy similar to Cape Hunting Dogs, and wear down antelope etc. by remorseless, steady jogging. Few predators can last as long. The weapons are often used to kill an antelope that can run no more...
Also, humans have vastly better abilities at throwing than chimps, and I see nothing in the aquatic phase to select for such skills. If there was such an aquatic stage, the selective pressures of later life on the savanna were equally important in forging the phenotype, mental and physical, that we enjoy today.

I agree that an evaporant cooling system -- literally a heat pump -- is extremely efficient. It will keep muscles from overheating much better than passive cooling systems, such as insulating fur that reflects heat, flapping ears that radiate heat, or estivation in a nice cool burrow.

However, evaporant cooling requires large amounts of water, which aren't normally available in arid locations. So pursuit to heat exhaustion as you describe it would have been impossible before the invention of highly portable water-carrying tools. For this reason, I suggest that evaporant cooling could never have evolved in an arid climate. Otherwise, other creatures besides h. sapiens would probably have discovered it first.

As for human throwing skills, the lake environment would have been perfect. What better way to deliver mollusks or small fish foraged in deep water to your kin on the shore? Why else would there be any ability for people to catch with their hands as well as throw? Better yet, wouldn't the safest way to kill crocodiles be with projectiles rather than knives or spears?

Thanks for your reply,

George Wolf

[gwolf]

DavidcC, thanks for your links.

George Wolf

[Largenton]

Well after being dragged onto this subject by JeffLee I've got a few points to make. Firstly, a few references to make on this particular subject. I've done some research into the subject which does suggest that fish are extremely influential in the development of the brain (Crawford MA, Bloom M, Leigh Broadhurst C, Schmidt WF, Cunnane S.C, Galli C, Ghebremeskel K, Linseisen F., Lloyd-Smith J and Parkington J, (2000), Evidence for the Unique Function of Docosahexaenoic Acid (DHA) During the Evolution of the Modern Hominid Brain, Lipids, 34: S39-S47) and Bailey's novel idea that the Homo Sapiens used their evolutionary advantages to use the lava flows in the area for protection (Bailey, G., King, G., and Manighetti, I., (2000) Tectonics, Volcanism, Landscape Structure and Human Evolution in the African Rift, Oxford, Oxbow). Both are available by googling as well, look for the pdf files.

Whilst I agree that a fish diet had a significant advantage for humans, the idea of us being aquatic is problematic.

The main problem I have is from my experiences as a swimming teacher. From teaching classes on personal survival I know that the human body is ill adapted for staying in water for a long time, it damages the skin cells and also is extremely susceptible to getting cold very quickly, especially in water where the heat drains out in an effort to warm the surrounding area.

I also think that the use of our legs is perhaps due to efficiency and our stamina (as demonstrated by the H/G example given) which suggests the movement over long distances, perhaps for the purpose of hunting and gathering.

Better yet, wouldn't the safest way to kill crocodiles be with projectiles rather than knives or spears?

Forgive me for stating this but aren't crocodile skins too thick for projectiles to slice through? After all, doesn't it form a type of armour to protect the crocs?

I would also suggest that the primary food from the lakes would be the fresh-water molluscs. My knowledge on H/G (standing for Hunter-gatherer which I'll continue to use) society (lectures from Bailey who I mentioned earlier) suggests that they were used as dependable food sources since they are always there, a good example of a band-like society is some North American Indians that stay in one place due to the fertile area around them. Therefore, it would be likely that even if any risky hunting activities didn't pay off, the gathering of molluscs would suffice, especially since they are not seasonal resources.

I think overpopulation explains it very well; they had no choice in the matter, but enough intelligence to adapt.

I would like to also add to this that overpopulation is rarely a problem in H/G societies, due to the mobility of the people restricting the amount of babies that a woman can have. Please consider that childbirth for humans, due to our narrow pelvises and strange upright positions, makes it harder for us to give birth, essentially meaning that there was a natural birth control in place. This is further shown by the fact that when the Neolithic Revolution takes place, there is a huge population boom with this natural birth control mechanism being removed.

Thanks for the interesting and enlightening discussion on this, I rarely get a good debate on these ideas apart from with JeffLee.

[gwolf]

The main problem I have is from my experiences as a swimming teacher. From teaching classes on personal survival I know that the human body is ill adapted for staying in water for a long time, it damages the skin cells and also is extremely susceptible to getting cold very quickly, especially in water where the heat drains out in an effort to warm the surrounding area.

I don't posit a completely aquatic existence, but rather an amphibious one. So the people would spend foraging time or retreat from predator time in the water and be "beached" or doing terrestrial foraging the rest of the time.

The heat loss to water varies with exposure and water temperature; the water in the lakes we're talking about approaches normal human skin temperature, so it would serve as a temperature stabilizing mechanism rather than a source of either overheating or "overcooling." Individual reaction to cold varies; Darwin watched in amazement as the native inhabitants of Tierra del Fuego walked around almost naked in falling snow -- indeed he watched the snow melt on their bare backs! For heat, they carried torches about with them wherever the went, hence the name which means "Land of Fire." I assume this means that the subcutaneous fat layer grows or wilts as needed. I'm reminded of the story of a movie company that did a shoot in Alaska. They used a trained, zoo-raised polar bear in some scenes -- or tried to. The animal had never experienced arctic cold before and refused to leave its heated cage!

Forgive me for stating this but aren't crocodile skins too thick for projectiles to slice through? After all, doesn't it form a type of armour to protect the crocs?

I can provide a simple answer; if penetrating projectiles don't work you can always use crushing ones! However I doubt they needed to. There are places where crocs have less armor, and there are places where their armor has chinks. Richard Leakey has written about hunter-gatherers eating crocodiles.

Could it be that your comments on freshwater mollusks provide some further proof of the rift lake hypothesis?

I would like to also add to this that overpopulation is rarely a problem in H/G societies, due to the mobility of the people restricting the amount of babies that a woman can have. Please consider that childbirth for humans, due to our narrow pelvises and strange upright positions, makes it harder for us to give birth, essentially meaning that there was a natural birth control in place. This is further shown by the fact that when the Neolithic Revolution takes place, there is a huge population boom with this natural birth control mechanism being removed.

I have a "weaker" and a "stronger" response to this. The "weaker" one is that Jane Goodall found that chimpanzee bands would split up because of internal politics, regardless of population. I'm sure we all know of human organizations that have mimicked them! Thus there would be an incentive despite static population for aquatic hominids to seek new habitats. The "stronger" response is that I don't know how successful these people would have been in their lake habitat. If they were somewhat isolated from predators and diseases, there might very well have been a population boom. This might be one way to falsify the argument.

Thanks very much for your response, Largenton. This is stimulating.

George Wolf

[JeffLee]

Well after being dragged onto this subject by JeffLee I've got a few points to make.

i did not drag you into this! i merely asked you if you knew anything about the dating of the afar depression!

i in know way asked you to come over mr. fish fetish, i implied it, but i didn't ask. XD

Thanks for the interesting and enlightening discussion on this, I rarely get a good debate on these ideas apart from with JeffLee.

*thwaps you with homo florensis*
couldn't have alittle higher cc to fall on the line... nooooo... that would be too easy. :P

I think a lake-dwelling ape that's been exapted to other environments seems a more elegant and reasonable explanation of homo sapiens' current status than either the savanna ape or ocean coast aquatic ape. I should explain that "exaption" is Daniel Dennett's term for something evolved or designed for one use that turns out to be useful some other way. I don't propose any kind of separate aquatic ape to do this and it hardly seems necessary. Instead I'm suggesting that h. sapiens' hominid ancestors were evolving all of this time to fill the lake-dwelling ape niche. In classic evolutionary fashion, evolution favored those who happened to fit the niche the best.

Exaptation is actually Goulds term. ^^

So, your suggesting that this kicked off in roughly 6mya and continued into the known hominin fossil record, ergo: lucy, java, turkana, etc. were actually lake dwellers?

i have trouble accepting that, a 6mya [assuming the dating stuff I'm looking for pans out] to Lucy era ape, i could see that. a 6mya ape to erectus being primarily fishers and water dwellers.... can't see it.

Deer don't make their living in the water! I propose that even more so than beavers or hippos, humans did.

thats my point, deer and antelope fossils are found in abundance, but we don't take that as a sign that antelope ancestors were water dwellers. they were perfectly talented land dwellers, but like all animals they lived and died around water sources. my point is that we can't take the prevalance of homo fossils over pongo fossils as evidence of water dwelling lifestyles.

As far as I know, humans have more carnivorous tendencies than any of the other apes. Remember, it's only been in the last fifty years that we've become aware of any hunting behavior at all in chimpanzees.

okay then, if we have more carniviourious tendancies then apes, then shouldn't we likewise see a higher tolerance of meat eating in chimps since there ancestors did not share this 'healthy' aquatic stage for such a huge segment of their evolution?

As far as I know, places with shifting sediments capable of rapidly burying carcasses give the best chances of yielding fossils. Does that happen on the savannah? I can see how most likely to happen on muddy lake beds, plain old mud flats, tar pits, sand dunes and even volcanic ash. I get the idea that fossilized humans mostly come from mud flats -- but I claim no expertise here.

*points up to stuff on deer*

I don't know of any. Humans tend to break up fish as they eat them, so I'd be kind of surprised if we ever found recognizable articulated fish skeletons mixed in with humans.

yep.

I think that in the lakes we'd see the beginnings of both active and passive predation; passive predation would have begun with mollusk foraging in the shallows as an exaption of mollusk and insect foraging on land. Following this would be eating accidentally killed fish and finally predation of live fish. Stone tools would start out as a way of opening the mollusks, followed by rendering fish and later larger carcasses. Somebody would discover that digging sticks for roots also killed crocodiles quite nicely, though they may have started as a way to merely fend them off.

wait... a minute ago you had them staying completely still in the water waiting for the fish to swim by, and compared it to some modern fishing practices. now we have them actively pursuing fish? in open water? upright? that's not happening. When i was young it took me an entire day to catch a single small trout in a 2x2m pool at the base of a stream running by my house. and i had the benefit of being out of the water!

we just don't move that well in water, frankly, we'd have to revert to quadrupedal movement. as for the mollusk thing, sure if it's paste you want. ^^ the ones we got down east could be opened reasonably well without inventing tools. if you needed a rock youd hit one in the ground, there is little call for specialization. unlike, say, breaking the bones and slicing the hid eof a prey animal. ^^

It takes far less energy and resources to capture fish in a confined lake than to chase down terrestrial game. Why go to the trouble?

my initial thought response was "hell no it doesn't", but I'm going to back off of this until one of us finds a source on the claim.

Accidentally killed game would be another matter. Adding to this, as far as I know, H. Sapiens' ancestors were all of a smaller size. I think the game most likely to have been pursued would have been the crocs inhabiting the same lakes as the people. There'd be a positive reason for killing them off.

...

I think you watch alittle bit to much discovery channel[not being insulting, incase you take it that way!], crocs are not as obvious in the wild as a camera pointed directly at a resting croc may imply. ^^

in a slow aquatic environment, nothing our ancestors could do would beta off a croc, heck, modern humans with knives and stones on shore can rarely save a victim once struck. much like sharks, you don't see them coming until it is too late, you can't scare them off with loud noises as a majourity of attacks along the Nile occur when groups of people are bathing or washing clothing.

they'd be better off on land doing what modern chimps do today, acting aggressively and scaring the big cats away.

I think sexual selection favors trim "streamlined" people rather than big ones, whether fat or muscular. The easiest archetypes of sexual attraction that I can think of in the media seem to fit this description, whether male or female. Streamlining rather than overt muscularity would be an aquatic rather than terrestrial feature.

streamlined works both ways, unless your a grazer. I think it's the lose of fur without any complementary intake of blubber that is most telling of a Savannah, rather then aquatic lifestyle. we just don't see any comparable examples of a thin naked mammal spending large amounts of time in the water. they usually either get big like seals/whales or they get extra furry to trap air bubbles like otters, beavers, platypus and for a good reason, heat lose will always be a problem when your spending large amounts of time in water.

I think it involves much more effort and luck to bring down large prey than small prey or insects and plants. So on that basis it would be harder to make a living with it. The herds on the savanna migrated a lot, fish trapped in lakes couldn't.

fish have the advantage of being well adapted to water and lakes are most certainly big enough. Savannah herds migrated alot, but they could be easily followed once we started going the way of meat eating. [unlike lucy, or example who had relatively unspecialized teeth]

oh, another thought on lucy. she was still capable of climbing extremely well and provides a rather nice illustration of the 'descent' from the tree tops, now, if lucy was very capable of climbing trees to escape predators why would they rush to the water and risk crocs if they could be perfectly safe up the nearest tree?

Your tempting me to speculate that h. sapiens came upon a lake, killed and ate the crocs living in it, then proceeded eat all of the fish they found. When the lake was exhausted, they migrated to another and another. It would explain the great migrating stamina nicely.

I am? i just said that lake levels varied...

as for h. sapiens doing it, largy has managed to convince me to some extent that archaic sapiens were on a fishy diet, but i wouldn't go as far as to suggest that they[and especially their ancestors] were prolific water dwellers, it goes against what i know of aquatic mammals and the homo lineage. pre-homo maybe, i don't know as much about that group.

Perhaps my answer about moving from one lake to the next provides still another reason why "efficient" bipedalism was adopted by humans. As I see it, an erect posture at first allowed human ancestors to wade into deeper water where there were bigger fish. Later it was exapted as a more efficient means of migration transportation.

i doubt that overfishing was much of a problem and i have yet to form a worthwhile opinion on over-population, so for now I'll nod that your exadaptation model is plausible and defer to largy as a source for criticism.

I think it was an exaption that could only work once a dangerous weakness was overcome; the use of sweat as a cooling mechanism. It works efficiently but requires great amounts of water. Until h. sapiens invented water carrying tools, the advantages of evaporant cooling were of much more limited use, or even none at all. Arid environment animals use alternate cooling means so as to conserve water; big ears, estivation, nocturnalism, metabolically derived water and so forth.

we aren't talking about arid environment animals though. africa was drying out, yes, but it didn't come close to being a deathtrap until recently in geologic terms, roughly around the time of the archaic sapiens/cro-magnon. (400,00-100,00 ya) at which point, evidenced by you and me, they developed said tools (apparently*) and/or left Africa.


* potentially false, source is episode 4 of the BBC documentary 'walking with cavemen', as a t.v. show i don't consider it to be that authoritative.

Great stamina and evaporant cooling are indeed big advantages. However stamina depends on efficient cooling to work, and evaporant cooling requires a ready source of water. I discovered this the hard way.

Yes.

no one is suggesting a desert ape hypothesis as a counter to AAH.

I envision them as a slightly less specialized version of h. sapiens, perhaps the first people to have been evicted from the rift lake valleys.

so your saying that the ancestors of modern humans were leaving the lakes around the time of homo erectus and were more specialized to an aquatic lifestyle then modern humans are to a terrestrial lifestyle? If so it'll help me narrow down my searchlight. ^^


golly this is getting fun. :D no creationists to get in the way.

[Largenton]

hmmm, I'm going to let the other things slide for a moment, especially when Jeff answered the crocodile question well. However, this caught my eye:

I have a "weaker" and a "stronger" response to this. The "weaker" one is that Jane Goodall found that chimpanzee bands would split up because of internal politics, regardless of population. I'm sure we all know of human organizations that have mimicked them! Thus there would be an incentive despite static population for aquatic hominids to seek new habitats. The "stronger" response is that I don't know how successful these people would have been in their lake habitat. If they were somewhat isolated from predators and diseases, there might very well have been a population boom. This might be one way to falsify the argument.

For the first argument I can say this is a mere hypothesis. One interesting point that Lewin makes in his Human Evolution book is that primate societies are completely different to each other. So to be honest, comparing humans to chimpanzees isn't necessarily fool-proof.

As for the second argument I propose you read my second article that I mentioned which gives an opinion on the geography of the region providing safe havens for the humans. However, the movement that would be required is still an effect birth control.

[wintermute115]

You say that you are describing H. sapiens, but several things jump out at me as not being true about this species...

It has a diving reflex, which by reducing the heart rate and changing the circulation makes it easier for the ape to hold its breath and conserve its heat.

It is certainly possible for humans to train themselves to do this (pearl divers of South-East Asia are the classic example), but it is certainly not reflexive behaviour. Humans are generally very inefficient divers.

Its fingers are slightly webbed, an adaptation for more efficient swimming.

The webbing of human fingers is neither greater than that seen in other apes, nor significant enough to be of any benefit while swimming.

this ape needs no fresher water to drink. Indeed, it prefers the taste of mineralized water to that of rainwater or fresh water from running streams.

Anything more than trace amounts of minerals (say, the amount found in rainwater, or fresh running streams) tends to make water very unpalatable to humans, and at a fraction of the salinity of sea water it becomes impossible to sustain yourself on. Yes, humans prefer the taste of mineral water to pure, distilled water, but the mineral water you see on the supermarket shelves is far purer than the lake water you're talking about.

it has little to fear from the crocodiles. Living in groups, it usually spots the reptiles with good vision long before they get close enough to attack

Crocodiles are very good at not being seen. They frequently attack and kill humans in the water.

While she is suckling, she can’t wade as deeply as the males can. Partly as a result, females tend to be shorter than males

Wouldn't this drive females to become taller than males, so that they can get deeper into the water when suckling? Why would evolutionary pressures make females with infants crowd closer to the shore, where they are more at risk?

[gwolf]

Exaptation is actually Goulds term. ^^

Where did he first use the term?

So, your suggesting that this kicked off in roughly 6mya and continued into the known hominin fossil record, ergo: lucy, java, turkana, etc. were actually lake dwellers?

i have trouble accepting that, a 6mya [assuming the dating stuff I'm looking for pans out] to Lucy era ape, i could see that. a 6mya ape to erectus being primarily fishers and water dwellers.... can't see it.

I think the amphibious migrating lake dweller makes the most sense. Austrolopithecus would have used stones to open bivalve mollusks. Being too small or not smart enough to challenge the crocs, it would have started with smaller water holes. It would have escaped the big cats in the water and big crocs in the trees. Its bipedalism would both have helped fishing and migrating. I didn't say it in my initial "fantasy," but there are still people in the tropics who fish while immersed to their necks.

thats my point, deer and antelope fossils are found in abundance, but we don't take that as a sign that antelope ancestors were water dwellers. they were perfectly talented land dwellers, but like all animals they lived and died around water sources. my point is that we can't take the prevalance of homo fossils over pongo fossils as evidence of water dwelling lifestyles.

It appears then that the fossil evidence favors nobody in this. We know that monkeys avoid being mired in mud the way large animals like hippos could, so this makes it more likely that the fossils are found where hominids died or were taken as prey.

okay then, if we have more carniviourious tendancies then apes, then shouldn't we likewise see a higher tolerance of meat eating in chimps since there ancestors did not share this 'healthy' aquatic stage for such a huge segment of their evolution?

Are you willing to prove to me that the same fish intake that is supposed to be "healthy" for humans is likewise "healthy" for chimpanzees?

wait... a minute ago you had them staying completely still in the water waiting for the fish to swim by, and compared it to some modern fishing practices. now we have them actively pursuing fish? in open water? upright? that's not happening. When i was young it took me an entire day to catch a single small trout in a 2x2m pool at the base of a stream running by my house. and i had the benefit of being out of the water!

When I say "active predation," I don't mean "active chase pursuit." I mean ambush predation as I have previously described. Trout can't be fished by immersed fishermen because they live in waters too cold for it -- unless you always used a wet suit.

we just don't move that well in water, frankly, we'd have to revert to quadrupedal movement. as for the mollusk thing, sure if it's paste you want. ^^ the ones we got down east could be opened reasonably well without inventing tools. if you needed a rock youd hit one in the ground, there is little call for specialization. unlike, say, breaking the bones and slicing the hid eof a prey animal. ^^

We have both sensitive hands and feet. To root for mollusks, hominids would pick through the mud with their toes -- as I used to do at the seashore. When something was found, they would simply duck all the way in the water and pick it up with their hands, holding their breath if necessary. Bipedalism would allow them to forage in deeper water, and make sure their feet were well enough calloused to avoid bites by larger shrimp or other bottom dwellers. Small mollusks (and crustaceans too) require little crushing or breaking force. Big ones are another matter. I could see them being collected in deep water and thrown back to the beach, where somebody else would crack them.

I think you watch alittle bit to much discovery channel[not being insulting, incase you take it that way!], crocs are not as obvious in the wild as a camera pointed directly at a resting croc may imply. ^^

in a slow aquatic environment, nothing our ancestors could do would beta off a croc, heck, modern humans with knives and stones on shore can rarely save a victim once struck. much like sharks, you don't see them coming until it is too late, you can't scare them off with loud noises as a majourity of attacks along the Nile occur when groups of people are bathing or washing clothing.

they'd be better off on land doing what modern chimps do today, acting aggressively and scaring the big cats away.

Then I promise you that the following was not approved by Steve Irwin. It's much easier to kill a croc than you make it sound. Further, I think these hominids would know better than to enter croc infested waters at a newly discovered lake. They'd go after the crocs while they were basking, with a surprisingly simple technique. Attract the croc's attention, causing it to turn towards you with its jaws open in a threat display. Take advantage of this by shoving a branch down its throat, the longer the better. If it charges you, this will simply improve the branch's penetration! This will kill the croc with a combination of brain injury (if the branch penetrates its thin pallet), internal injuries and asphyxiation. It's quite possible that this is how spears got their start.

streamlined works both ways, unless your a grazer. I think it's the lose of fur without any complementary intake of blubber that is most telling of a Savannah, rather then aquatic lifestyle. we just don't see any comparable examples of a thin naked mammal spending large amounts of time in the water. they usually either get big like seals/whales or they get extra furry to trap air bubbles like otters, beavers, platypus and for a good reason, heat lose will always be a problem when your spending large amounts of time in water.

Ah, but the waters I'm talking about are close to skin temperature already, so the loss of fur won't neccessarily mean a cold Australopithecus. On the other hand, if subcutaneous fat does come along, that opens up a few more lakes for settlement, or makes it easier to explore deeper water.

fish have the advantage of being well adapted to water and lakes are most certainly big enough. Savannah herds migrated alot, but they could be easily followed once we started going the way of meat eating. [unlike lucy, or example who had relatively unspecialized teeth]

oh, another thought on lucy. she was still capable of climbing extremely well and provides a rather nice illustration of the 'descent' from the tree tops, now, if lucy was very capable of climbing trees to escape predators why would they rush to the water and risk crocs if they could be perfectly safe up the nearest tree?

As previously mentioned, climb the trees to avoid the crocs and dive in the water to avoid the cats. The trees would make it easier to spot crocs in a new lake, or maybe even let them live with the crocs -- assuming you had good lookouts and only entered the water when you could see the crocs as they swam.

as for h. sapiens doing it, largy has managed to convince me to some extent that archaic sapiens were on a fishy diet, but i wouldn't go as far as to suggest that they[and especially their ancestors] were prolific water dwellers, it goes against what i know of aquatic mammals and the homo lineage. pre-homo maybe, i don't know as much about that group.

I can't comment on objections to the hypothesis that I haven't seen!

we aren't talking about arid environment animals though. africa was drying out, yes, but it didn't come close to being a deathtrap until recently in geologic terms, roughly around the time of the archaic sapiens/cro-magnon. (400,00-100,00 ya) at which point, evidenced by you and me, they developed said tools (apparently*) and/or left Africa.


* potentially false, source is episode 4 of the BBC documentary 'walking with cavemen', as a t.v. show i don't consider it to be that authoritative.

We don't have to talk about arid environments, then. I think the invention of the ancient equivalent of the canteen (a gourd most likely) would still be needed to pursue prey as relentlessly as as you suggest. On the other hand, I know some animals (bears for instance) head for water when under chase and overheated. A hominid prepared to drag prey out of the water (after it has been killed) is better adapted than one afraid of water (as some primates are).

so your saying that the ancestors of modern humans were leaving the lakes around the time of homo erectus and were more specialized to an aquatic lifestyle then modern humans are to a terrestrial lifestyle? If so it'll help me narrow down my searchlight. ^^

I'm saying that all along, some hominids got evicted. Some of them happened to find other environments where they thrived.

golly this is getting fun. :D no creationists to get in the way.

Thanks again for replying. I'm also having a good time with this.

George Wolf

[gwolf]

hmmm, I'm going to let the other things slide for a moment, especially when Jeff answered the crocodile question well.

Please see my response to Jeff's crocodile argument

For the first argument I can say this is a mere hypothesis. One interesting point that Lewin makes in his Human Evolution book is that primate societies are completely different to each other. So to be honest, comparing humans to chimpanzees isn't necessarily fool-proof.

I can only agree, but I have read of political arguments that break up groups in humans, chimpanzees and wolves. As for the status of hypothesis, I claim nothing more than that for any of the aquatic ape idea. If we're lucky, we'll come upon a falsifiable idea or experiment here. So far I haven't found one.

As for the second argument I propose you read my second article that I mentioned which gives an opinion on the geography of the region providing safe havens for the humans. However, the movement that would be required is still an effect birth control.

The lava flows may very well have offered such protection, however the rift lakes could also fulfill this role -- plus they offer a source of fish to eat, and you site some evidence that h.Sapiens has some adaptation to use.

Thanks for your response, the good times with this continue.

George Wolf

[gwolf]

]It is certainly possible for humans to train themselves to do [take advantage of the diving reflex] (pearl divers of South-East Asia are the classic example), but it is certainly not reflexive behaviour. Humans are generally very inefficient divers.

Actually, it is reflexive behavior in all of us. Don't take my word for it, try it out for yourself by quickly immersing and holding your face in a container of cold water since that will activate the reflex. The feeling of becalment is quite amazing -- more relaxing to me than smoking was. Among other things, it is responsible for the survival of young children who have fallen through ice -- and allowed them to be revived several hours later. Now when trained for it, humans demonstrate much more pronounced abilities. In this I'm reminded that seals don't swim instinctively; they won't even attempt it until dragged in by their mothers! You cite pearl divers from southeast Asia. I'm aware of others in the chilly waters of Korea and still others in the Persian Gulf.

The webbing of human fingers is neither greater than that seen in other apes, nor significant enough to be of any benefit while swimming.

If this is the case, it merely switches the hand from being an adaptation to an exaption.

Anything more than trace amounts of minerals (say, the amount found in rainwater, or fresh running streams) tends to make water very unpalatable to humans, and at a fraction of the salinity of sea water it becomes impossible to sustain yourself on. Yes, humans prefer the taste of mineral water to pure, distilled water, but the mineral water you see on the supermarket shelves is far purer than the lake water you're talking about.

The Wikipedia article on the rift lakes says they have many different levels of pH and hardness, ranging from nearly fresh to nearly brine or nearly soda.

Crocodiles are very good at not being seen. They frequently attack and kill humans in the water.

They frequently attack and kill farmers and town dwellers who don't know much about crocodiles. In South America, Amerindian hunter-gatherers have no trouble swimming in Piranha and cayman-infested waters. I'm reminded of Jared Diamond's "Guns, Germs and Steel," where he relates that in New Guinea, the hunter-gatherers think that the farmers are "stupid," and know little about their world.

Wouldn't [suckling while wading] drive females to become taller than males, so that they can get deeper into the water when suckling? Why would evolutionary pressures make females with infants crowd closer to the shore, where they are more at risk?

I'm speculating here, as another reason given for the slightly shorter female stature is male promiscuity. It would allow the females to seek protection in the waters from the cats but at the same time prevent them from going into riskier, deeper waters with a child.

You've brought up some good points, Wintermute. I continue the search for a falsifiable, testable claim.

George Wolf

[Largenton]

can't comment on objections to the hypothesis that I haven't seen!

Check my first reference. It also demonstrates that australopithecus couldn't have been aquatic because the DHA in the fish which increases brain size wasn't seen in any Australopithecus species. Now if you are going on about Homo Erectus and others, you will have a point but I cannot believe Australopithecus would be lake dwelling. The brain capacity evidence disproves it.

Wouldn't this drive females to become taller than males, so that they can get deeper into the water when suckling? Why would evolutionary pressures make females with infants crowd closer to the shore, where they are more at risk?

This is another point that I would like to state about the females. A female Australopithecus was meant to be half the size of the males. They wouldn't be able to get much into the water at all.

The lava flows may very well have offered such protection, however the rift lakes could also fulfill this role -- plus they offer a source of fish to eat, and you site some evidence that h.Sapiens has some adaptation to use.

I doubt the big cats would be scared of water. Plus, we don't swim that fast. I've looked at how fast an average swimmer swims at today and its below walking speed (I can probably swim 25 metres in 15 seconds, if I remember my times, one of my friends could swim up to a person in deep water and tow the person back in 35 secs for just under 50 metres). The lakes aren't as good for protection as the lava flows. Plus the lava flows provide a safe place to sleep, which Hamadryas baboons used today. I would estimate on that basis that it is more likely that the lava flows could be used rather than water. The protection given by these would far outweigh the protection given by water, especially when there are crocs around.

[DavidMcC]

... It also demonstrates that australopithecus couldn't have been aquatic because the DHA in the fish which increases brain size wasn't seen in any Australopithecus species. Now if you are going on about Homo Erectus and others, you will have a point but I cannot believe Australopithecus would be lake dwelling. The brain capacity evidence disproves it.

Sure, brain size didn't increase very much in any of the australopithecines (that came later, in the homo line on the savanna). However, this doesn't prove that none of them ate fish. Also, the australopithecines cover a wide range of species, from before to after the hominin split, and not all were on the hominin side. (The evidence for this statement is in a graph plotting cranial volume for all the australopithecines against time, showing a branching point. Unfortunately, I can't find the URL for this graph.)

[Muchy]

]It is certainly possible for humans to train themselves to do [take advantage of the diving reflex] (pearl divers of South-East Asia are the classic example), but it is certainly not reflexive behaviour. Humans are generally very inefficient divers.

Actually, it is reflexive behavior in all of us. Don't take my word for it, try it out for yourself by quickly immersing and holding your face in a container of cold water since that will activate the reflex. The feeling of becalment is quite amazing -- more relaxing to me than smoking was.

This statement is, as it is made, wrong. According to Human Physiology, Klinke, Silbernagel et al., 2006, we indeed have such a reflex, as every other mammal. To be more specific, trigeminal cranial afferent nerve (V) relays the information that the nasal and mouth cavities are submerged, which triggers the autonomus nervous system to

* bradicardia, meaning a reduction of heart rate to about 4/5 of normal rate
* blood "shift"(?) to the thorax to support the lung when under pressure to keep it from collapsing (which would be bad for numerous reasons)
* vasoconstriction, first in the limbs to protect vital organs, and later of everything except the heart and the brain, which creates a heart-brain circuit

I hope I did not mistranslate anything here. The mammalian diving reflex is rather weak in humans, though. Additionally, it is a mechanism to keep someone from dying when submerged; it is not beneficial for hunting, living or anything else. Peripheral vasoconstriction weakens muscles needed for swimming, the blood plasma shift to the thorax additionally lowers your peripheral blood pressure and over time everything but the heart and the brain will fail due to low to none oxygen supply, thus it is, while better in an emergency situation, not designed for long-term use. And to wrap up the whole thing, centralisation of the blood circulation system will over time make it harder to keep from breathing, thus if there is no chance to break water surface in time one will drown or die of a hypothermic shock.

Among other things, it is responsible for the survival of young children who have fallen through ice -- and allowed them to be revived several hours later.

No. Sudden immersion in very cold water triggers a breathing reflex within 10(!) seconds, as many kajak accidents show. Very cold water triggers reflexes which are stronger than the weak diving reflex of humans. The following things will happen:

* sudden laryngospasmus -> shortly breathing is inhibited. This is why people who are pulled out of ice water quickly can still suffocate as it takes time for the larynx to relax
* if there is no spasm, shortly afterwards a breathing reflex due to increased heart rate (which is a reaction to the vasoconstriction triggered by cold water) makes it hard not to breathe
* Drowning if still submerged
* if not, hyperventilation and chaotic breathing occur
* hyperventilation triggers a "tetanie", for which I do not know an english word. What happens is that hyperventilation increases the percentage of CO[sub]2[/sub] lost on expiration, thus the blood pH value raises (respiratoric alkalosis), triggering cramps, amyostasia (muscle tremor), reduced blood supply to the brain and disorientation. Keep in mind those are _not_ reflexes. It is a biochemical imperative and has not evolved within the last few thousand years to keep us out of cold water.
* hyperventilation has the paradox result of dyspnoea. Control over the breathing is lost.
* subsequent chaotic breathing guarantees water will fill the lung or stomach with water
* drowning or hypothermic shock, resulting in certain death without immidiate advanced medical aid.

What you are referring to is the fact that lower body temperature reduces the metabolic rate, thus death is prolongated. Everyone drowned for hours is well dead. About 3 years ago 2 brothers drowned in a pool in autumn, if I remember correctly. The older of the two tried to rescue his brother (who fell into the pool) and drowned, too. After about 20 minutes someone spotted their bodies and pulled them out. Paramedic response time is about 15 minutes for rural areas here, so they had their circulatory system revived within 35 minutes of the accident (of course sustained by machinery). While the younger of the two survived and is in good shape, which, as it seems, is due to his smaller body cooling quickly in the 5°C cold water and his stronger diving reflex, the older brother suffers from a severe mental retardation and will probably never recover. And that was after 35 minutes!

Now when trained for it, humans demonstrate much more pronounced abilities. In this I'm reminded that seals don't swim instinctively; they won't even attempt it until dragged in by their mothers! You cite pearl divers from southeast Asia. I'm aware of others in the chilly waters of Korea and still others in the Persian Gulf.

Neither of those oceans is chilly in any sense or compatible with ice. Additionally human skin is not fit for staying in water a long time.

On female shortness

I'm speculating here, as another reason given for the slightly shorter female stature is male promiscuity. It would allow the females to seek protection in the waters from the cats but at the same time prevent them from going into riskier, deeper waters with a child.

The whole thread is mere speculation. Most mammal females are smaller than their male counterparts. All aquatic?

Then there is the "escape the cat"-idea. Big cats are not necessarly afraid of water nor is this an intrinsic feature. Look at tigers, some races of domesticated cats, smaller african cats and so on. The fact that lions tend to stay out of the water can not be extrapolated to every species of cat.

M.

[DavidMcC]

Discussion of the response to cold water is surely not relevant to a species that is postulated to have evolved in an environment with warm water.

[Muchy]

Discussion of the response to cold water is surely not relevant to a species that is postulated to have evolved in an environment with warm water.

True. I did not, however, try to claim that the diving reflexe allows people to be revived after hours of being dead. The other point, however, which is an attempt to clear up what the diving reflex does, is valid for warm water.

The whole idea was to clean those two things up before someone begins to discuss it and probably end up with a frozen ape theory.

M.

[Largenton]

... It also demonstrates that australopithecus couldn't have been aquatic because the DHA in the fish which increases brain size wasn't seen in any Australopithecus species. Now if you are going on about Homo Erectus and others, you will have a point but I cannot believe Australopithecus would be lake dwelling. The brain capacity evidence disproves it.

Sure, brain size didn't increase very much in any of the australopithecines (that came later, in the homo line on the savanna). However, this doesn't prove that none of them ate fish. Also, the australopithecines cover a wide range of species, from before to after the hominin split, and not all were on the hominin side. (The evidence for this statement is in a graph plotting cranial volume for all the australopithecines against time, showing a branching point. Unfortunately, I can't find the URL for this graph.)

OK, since people haven't noticed my first reference, I'll explain its findings. The study from the examination of DHA demonstrated that an increase in the consumption of DHA, increased the brain development. Since fish is the prime source of DHA, eating that boosts brain development. So that is why I am stating Australopithecus didn't eat fish in any particular large quantities, we would have seen it demonstrated by an increase in brain capacity. For a fuller description, please check the first reference I make in my post.