aquatic ape hypothesis

[iglak]

ok, really we know that the AAH is obviously false and impossible. and if it was true, we would be very different from what we are now.

 

however:

 

we theoretically evolved in africa, right?

hunting migrating animals, right?

many primates are also constantly migrating animals, and construct of find shelter in a new place quickly every time they move, right?

(yes, those "right?"s are there because i am unsure of whether or not they are true)

 

africa is full of rivers that all migrating animals must cross at one or more points in their migration. these rivers are filled with crocodiles waiting for the right moment to grab prey. these rivers are very violent and often drown a couple migrating animals that were either trampled or slipped and can't swim well enough, or are too short to reach air.

 

would it be likely that those pre-humans crossed the same rivers to follow the migration paths, so that they could have much easier access to food?

primates generally live in small colonies that hunt, gather, and move together.

following logically, the pre-humans would cross the rivers with the migrating animals. since they are so small in number, they have to be aware of the crocodiles and can't easily use such a "shotgun" strategy to crossing the river. since they are crossing the river, anyone too short will be unable to breathe unless they can swim extremely well, but the rivers can get very fast sometimes. i imagine having too much hair would let the water push you around much easier. i'd bet that the slowest crossers would be grabbed by the crocodiles. thus, they were required to be able to swim and walk through water....

how likely is it that that is the main contributor to our standing straight, being tall, being relatively hairless, having relatively webbed hands and feet, and being able to swim as fast as half-aquatic mammals, such as otters, in peak condition (although we aren't nearly as agile in water)?

[Sorcerer]

I think that as humans we lived in a range of environments, some adaptions that we attribute to one environment (the plains) would also apply to other, eg the water, I have however noted one exception.... we have downward facing noses and if we combine this with our index finger and thumb, our soft palate and tounge, we can block our nose and equalise pressure.... very useful in diving.... is this a coincidence or an adaption?

 

Also, I think that ancestral humans would have given birth in water, this is supported by the fact babies can float directly after birth, and the density of water supports heavier babies (large heads/brains) and removes stress from the mother.

 

It is very likely that as opportunistic hunter gathers we stuck close to the shore as we migrated along coast lines, here the temperature is mildered and fluctuates less and there is an abundant source of food, this however doesn't mean we are specifically adapted for this environment. Humans are jacks of all trades, intelligence is the major adaption we have.

[Blackfin]

I'm actually quite fascinated with the AAT, especially because of all the physiological evidence for it. (Humans are the only land mammals who can voluntarily hold their breath, our fat is in larger proportion to our lean body mass in comparison to other primates, we can dive, babies float, etc.) However, it could very well be coincidental, and there's always the fact that the AAT is looked down upon because Elaine Morgan was an author with no formal scientific background and drew her conclusions based only on reading, the work of another scientist who formed a similar proposal, and her own resentment of the savannah theory.

[Hellbender]

we theoretically evolved in africa' date=' right?

hunting migrating animals, right?

many primates are also constantly migrating animals, and construct of find shelter in a new place quickly every time they move, right?

(yes, those "right?"s are there because i am unsure of whether or not they are true)[/quote']

 

there are two schools of thought on the first question. Apes definitely are african in origin, but bioanthropologists aren't sure whether or not Homo sapiens

a) evolved directly out of africa and replaced other hominids living elsewhere in the world (Recent African Origin)

b) are the result of modern human traits evolving in geographically diverse locations, then spreading (Multiregional Evolution)

 

these are both hypotheses that are still being debated.

 

Hominids staarted out as vegetarians/scavengers. They didn't start hunting until I believe Homo ergaster evolved. Before agriculture and industrialization, modern Homo sapiens were hunter gatherers, and some still are. Neanderthals and Homo heidelbergensis were certainly migratory hunters, though.

 

Modern pongid apes are somewhat migratory, especially gorillas. They don't build shelters, but make "beds" out of sticks and leaves in trees to sleep in.

[Hellbender]

I personally reject the aquatic ape hypothesis. All of the reasons given for our supposed semi-aquatic adaptations are features we have for our former savannah habitat as in sparse hair, low body fat etc. I am sure our ancestors did go in the water at some time, but considering the dangers crocodiles and hippopotamuses pose to anything in savannah watering holes, I can't see any small primates swimming around with them. Sure we can voluntarily hold our breath, but remember that humans are smart. It doesn't take a lot of our brainpower to figure out that simpy holding your breath while diving will keep you from drowning.

[Blackfin]

Sure we can voluntarily hold our breath, but remember that humans are smart. It doesn't take a lot of our brainpower to figure out that simpy holding your breath while diving will keep you from drowning.

 

Then why, pray tell, would we dive in the first place?

[Hellbender]

Then why, pray tell, would we dive in the first place?

 

my point being that our ancestors probably never found a reason to need to hold their breath that much, but we have innate reasoning skills that allowed us to figure things like that out. Holding your breath is as simple as thinking about doing it. Thinking about things is something humans have the ability to do all the time. Its not like its' some innate instinct that evolved for a special purpose.

[Mokele]

but we have innate reasoning skills that allowed us to figure things like that out. Holding your breath is as simple as thinking about doing it. Thinking about things is something humans have the ability to do all the time.

 

Then why can't we stop our hearts by thinking about it (aside from the stupidity of doing so)?

 

If our diaphragm was innervated solely by the autonomic nervous system, like it is in many animals, then no amount of thinking or brilliance could change the rythm. But ours has different innervation, allowing us some conscious control.

 

Not that I believe the AA hypothesis; such control over breathing is, IMHO, most likely to have come from the benefit it gives in speech, rather than diving.

 

Plus, if human-ancestors were spending that much time in the water, why would we not develop webbed fingers? It's a common enough mutation, so the variation is there, and it would be an obvious benefit. Webbed-feet have evolved in *numerous* secondarily aquatic vertebrates, from crocodiles to otters. If water was a large part of our evolution, why would we lack webbed digits?

 

following logically, the pre-humans would cross the rivers with the migrating animals. since they are so small in number, they have to be aware of the crocodiles and can't easily use such a "shotgun" strategy to crossing the river. since they are crossing the river, anyone too short will be unable to breathe unless they can swim extremely well, but the rivers can get very fast sometimes. i imagine having too much hair would let the water push you around much easier. i'd bet that the slowest crossers would be grabbed by the crocodiles. thus, they were required to be able to swim and walk through water....

 

While I like the idea of any theory that gives crocodiles credit for humanity's advancement, I'm unconvinced. Why would we evolve to swim, thereby putting ourselves directly into the environment of a 14 foot, 2000lb killing machine, instead of to climb (thereby crossing *over* the river).

 

Or, why couldn't our ancestors simply figure out that if they crossed *immediately* after the herd, the crocodiles would be full and not interested in any extra food?

 

Mokele

[Hellbender]

If our diaphragm was innervated solely by the autonomic nervous system' date=' like it is in many animals, then no amount of thinking or brilliance could change the rythm. But ours has different innervation, allowing us some conscious control.

 

Not that I believe the AA hypothesis; such control over breathing is, IMHO, most likely to have come from the benefit it gives in speech, rather than diving.[/quote']

 

agreed. I never thought about that. I meant that it wasn't something evolved especially for aquatic life.