Aquatic Ape Theory
Eviscerator
Join Date: 2003-02-24 Member: 13946Members, Constellation
Join Date: 2003-02-24 Member: 13946Members, Constellation
in Discussions
<div class="IPBDescription">Decidedly evolution/science topic</div> Speaking purely on the assumption that evolution is correct. No religion please, since it will break the recently amended forum rules.
The Aquatic Ape Theory. Do you agree or disagree with it? Do you prefer an alternate solution? Let me briefly describe the AAT for people that might not know what it is. Scientists are faced with some puzzles in regards to human evolution, particularly around the time we split off from other apes. Specifically, the following human features are difficult to pin down exactly:
1. General hairlessness
2. Ability to voluntarily control breathing
3. Descended larynx
4. Large amount of subcutaneous fat
5. Bipedalism
These traits are unique to humans in the primate family. No other apes exhibit all of these traits. These traits are most common in aquatic mammals. The Aquatic Ape Theory was put forth as a way to explain how these traits came to be prevalent in the human species. It states that at some point in our past, the homo sapien ancestor lived predominantly in and around water. So much so and for such a long period of time that it gave rise to evolutionary mutations and thus led to the traits we still carry.
Here is some additional information:
<a href='http://www.primitivism.com/aquatic-ape.htm' target='_blank'>Aquatic Ape Theory</a>
<a href='http://allserv.rug.ac.be/~mvaneech/Report.html' target='_blank'>Report of the Symposium 'Water and Human Evolution', Gent, Belgium, April 30th 1999.</a>
<a href='http://allserv.rug.ac.be/~mvaneech/Fil/Verhaegen_Language_SpeculationsScienceTechnology.html' target='_blank'>Aquatic ape theory and speech origins: a hypothesis</a>
I find the theory particularly interesting because it helps to explain a lot about how we came to be. Specifically, our larger brains, our speech as a result of our descended larynx, etc. Many scientists, however, dismiss the theory completely. Not always sure why, other than maybe because it's not the status quo. I don't feel strongly one way or another, but I think it's interesting to discuss it and any alternatives that might help explain how we evolved. I think AAT is plausible, and given some additional evidence I might be more apt to believe it completely. I don't have any compelling reason to dismiss it entirely.
The Aquatic Ape Theory. Do you agree or disagree with it? Do you prefer an alternate solution? Let me briefly describe the AAT for people that might not know what it is. Scientists are faced with some puzzles in regards to human evolution, particularly around the time we split off from other apes. Specifically, the following human features are difficult to pin down exactly:
1. General hairlessness
2. Ability to voluntarily control breathing
3. Descended larynx
4. Large amount of subcutaneous fat
5. Bipedalism
These traits are unique to humans in the primate family. No other apes exhibit all of these traits. These traits are most common in aquatic mammals. The Aquatic Ape Theory was put forth as a way to explain how these traits came to be prevalent in the human species. It states that at some point in our past, the homo sapien ancestor lived predominantly in and around water. So much so and for such a long period of time that it gave rise to evolutionary mutations and thus led to the traits we still carry.
Here is some additional information:
<a href='http://www.primitivism.com/aquatic-ape.htm' target='_blank'>Aquatic Ape Theory</a>
<a href='http://allserv.rug.ac.be/~mvaneech/Report.html' target='_blank'>Report of the Symposium 'Water and Human Evolution', Gent, Belgium, April 30th 1999.</a>
<a href='http://allserv.rug.ac.be/~mvaneech/Fil/Verhaegen_Language_SpeculationsScienceTechnology.html' target='_blank'>Aquatic ape theory and speech origins: a hypothesis</a>
I find the theory particularly interesting because it helps to explain a lot about how we came to be. Specifically, our larger brains, our speech as a result of our descended larynx, etc. Many scientists, however, dismiss the theory completely. Not always sure why, other than maybe because it's not the status quo. I don't feel strongly one way or another, but I think it's interesting to discuss it and any alternatives that might help explain how we evolved. I think AAT is plausible, and given some additional evidence I might be more apt to believe it completely. I don't have any compelling reason to dismiss it entirely.
Comments
<b>1. General hairlessness</b>
Aquatic mammals fall into two varieties: dense, oily fur (e.g. otter) or smooth skin (whales). Clearly hairlessness is the latter, but that group is also noticeable in that they have lost nearly all of their hair (some whales have residual "whiskers" on their chins, I believe). Humans, notably, retain pubic, armpit, and head hair, as well as body hair on arms, legs, and sometimes chest/back. If we had evolved to be more efficient swimmers, we would likely have lost *all* our hair (swimmers shave their bodies before meets because of the noticeable drag produced by even our small remaining amount of hair).
<b>2. Ability to voluntarily control breathing</b>
No clue. Perhaps this developed after living around (man-made, no pun intended) fires?
<b>3. Descended larynx</b>
No clue, and I'm not familiar with what this is or why it applies to the AAT.
<b>4. Large amount of subcutaneous fat</b>
My guess is that expanding our territory into cooler climates prompted this adaptation to aid survival during the winter, when food would be harder to come by (fat is also good for retaining body heat). Notice that natives of tropical areas tend to have lower body fat percentages.
<b>5. Bipedalism</b>
Being bipedal allowed early humans better visibility and freed hands for more dextrous applications. Additionally, human legs are pretty horribly designed for swimming. ^^
<b>Additional arguments against:</b>
1) It's generally believed that the first humans evolved in Africa, where there's a pretty serious shortage of large bodies of water. We're pretty big creatures; we probably wouldn't become aquatic without a large body of water in which to live. Few freshwater creatures are human sized or larger, which would mean we'd likely have been marine creatures, which leads me to...
2) We're not suited for a marine (i.e. salt-water) existence. Our skin under our remaining hair still resembles the skin of a terrestrial mammal. Salt water is a harsh environment requiring special adaptations (most freshwater fish will die in salt water, and vice versa). Whales and dolphins have developed thick, rubbery skins to keep salt out and water in, but our skin is still very porous. It is unlikely that we would go from porous to rubbery *back* to porous skin (re-evolution sometimes happens, but generally it is the opposite way around: body parts are gained and then lost, not lost and then regained).
As for what I think:
1) There have been several studies done on the implications of hairlessness in heat dissipation in a terrestrial environment. Most of the data supports the idea that hairless humans would deal better with extreme heat than hairy humans. However these studies did bring up the fact that water loss in hot climates is a serious problem for humans.
I find it strange that we would have an adaptation that supposedly arose to deal with heat, and yet have such an inordinately high need for water. Other animals that are adapted to hot environments have evolved very efficient water conservation methods.
AAT would also explain human's highly saline sweat and tears. Organisms that live in a saltwater environment, especially marine birds, have similar methods to rid the body of excess salt.
2) the ability to control breathing does not necessarily support AAT. If voluntary breathing arose because we lived in an aquatic environment, you would think that we would have a better method of conserving oxygen and holding our breath longer. Aquatic mammals have very complex methods of maximizing oxygen usage when holding thier breath. Whales and dolphins actually shut down blood flow to most of thier body to save oxygen. There is nothing like that in humans. Most aquatic mammals wwould scoff at at the human world record for holding your breath. ( I think its around 8-10 minutes)
I have class now, more later
Or have you actually considered it from a defensive point of view? Consider that the eyes do not have immune cells running around in them, the simple reason for this is you do not want them annihilating your eye cells. We kill these cells it is that important!
So you have to come up with an alternative defensive scheme. In humans (and many other creatures) we secrete enzymes and heavily salty material onto our eyes. This helps in two ways: Salt INHIBITS bacterial growth extremely well by denying them water (think about why Jam doesn't go off as fast as say Yoghurt) and by increasing the osmotic stress on the organism. We secret lysozyme with this to destroy those gram positive organisms that are halotolerant or halophilic (that live on our skin).
Our skin has high salt for <b>exactly</b> the same reason. Even so, you are covered right now with many different <i>Staphylococcus</i> species. Your back, armpits and forehead are literally swarming with them. However, because of your highly salty skin, the fact you flake it off and other factors, you prevent the rampant growth of these bacteria all over your skin.
So it isn't nearly as straightforward as you claim, there are several other reasons to secrete salt onto your eyes and especially skin that at first glance. Defensive reasons explain the salt just as well as a 'supposed' aquatic heritage.
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misleading
allowed variants more amenable to an aquatic existence to have far more offspring than their non aquatically adapted relatives.
or
the environment selected for those traits, which enable the bearers to live more successfully in an aquatic environment and have more children than those without appropriate traits
perhaps.
also I came across an article debunking the theory but I do not remember the details, save the hair thing. Other aquatic mammals have hair. However to see if this is truly a valid point we would have to establish y having hair or not having hair is irrelevant to an aquatic existence, and/or find out exactly y haired aquatic animals retain their hair, and/or figure out the advantages of hairless humans and try to extrapolate the kind of environment that would favor such, with valid reasons. The aquatic environment theor is of couse such an example.
I just think it's fascinating to piece this into our history and think about what it meant to us as we evolved. Without some of these traits, it's possible to speculate that we would not be where we are today. Larger brains, speech, bipedalism, et al. An aquatic past can help to explain how they came to be. Surely there are additional theories for how these traits evolved, and any trait that lives on in a species almost assuredly has some kind of use so it's easy to dismiss competing ideas. What we need is more evidence to fill in the blanks. Unfortunately, not many scientists like the theory (for whatever reason) and don't want to pursue finding any evidence for it. I think this has to do with the original proponent, Elaine Morgan. Had it been Einstein claiming this theory, things might be totally different.
If you are studying biology and/or evolution, keep an open mind and discuss it with your professors and colleagues. Maybe something good will come of it <!--emo&:)--><img src='http://www.unknownworlds.com/forums/html/emoticons/smile.gif' border='0' style='vertical-align:middle' alt='smile.gif'><!--endemo-->