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Old 04-23-2011
harling harling is offline
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Lightbulb Are humans badly adapted to water?

Terry has often said that humans are not well adapted to water, we are land animals.

While this is patently true in the sense he means it (i.e. we can't move in water as fast or efficiently as a dolphin, but then neither can a ship which is directly built to be fast in water), it reminded me of an idea we looked at when I did my Zoology degree, some thirty years ago (Based on work by Max Westenh÷fer, Alister Hardy and Elaine Morgan - with even Desmond Morris being mentioned). Though what we looked at was in the context of evolution, the basic thrust still holds whether you believe in evolution or not. A scientist proposed that there is evidence that we might have had at least a partially aquatic recent history (not generally accepted by scientists - see a vehement opponent at http://www.aquaticape.org/).

Whatever is the case, we do seem to to have some features that mean we are not completely hopeless in water.

Are we badly adapted to water?

Yes - we are poorly adapted to being in water: We are very slow compared to whales, dolphins, seals, etc and fish.
No - we are not too badly adapted: We are faster than jellyfish and plankton and they are very highly adapted to life in water. Some creatures can't even move for much of their lives - eg. coral.

Yes: We cannot breathe under water, or struggle to get air.
No: Whales, dolphins, seals can't breathe under water either. However, they don't struggle, at least after they have had their first breath. Seals can drown if they get in the water too young.

Yes: We don't naturally cope in water, we practice struggle.
No: Babies at birth and for a while afterwards do not panic in water, they learn panic and being ill at ease later. Also, unlike any other ape we have a reflex called bradycardia which means that our heart rate lowers when our faces are immersed in water, just like dolphins, whales, seals and other aquatic animals. Other apes panic and their heart rate rises massively if immersed. So do people who have learnt to be fearful.

Yes: We are badly streamlined.
No: We have a hip position that is not only well adapted to walking, but also helps us to adopt a long, horizontal shape, which though not to the level of a diving mammal, is not the doggy paddle shape of four legged animals. Also, our nostrils point downwards and so in water face down they point backwards not forwards, reducing the intake of water (and if you have big enough nose acts like a boat's keel - only joking). I believe that our body hair also point in a generally streamlined direction when we are young as well. Also, we have much less hair than other apes. Swimmers often shave down to emphasize this advantage - if this relative hairlessness is so we don't overheat, why is it that chimps and gorillas that live in hot countries have much more hair than us (thicker and longer - I believe we have the same number of hairs)?

No: we don't think like a dolphin, fish etc
Yes: we have a massively complex brain, especially the frontal lobes and folded surface which means we can adapt behaviourally, when physical features may not be perfect. We can't run as fast as a horse, but we still can catch and control them. Why are more and more women having babies under water? Why do we love baths and being in and around water?

Not sure why I am posting this, but I thought it was interesting. At least it suggests we might be helped by swimming (but then we knew that anyway).

Finally: This is the list in Wikipedia:

Bipedalism out of water causes considerable problems for the back, knees and organs, while water would support the joints and torso and permit breathing[14][15]
Humans are relatively hairless compared to great apes, similar to the hairlessness of land-dwelling rhinoceros and elephant which both have aquatic ancestors;[16] what body hair humans do have also follows water flow-lines[17]
Increased subcutaneous fat for insulation, especially in human infants[5]
A descended larynx[17][18]
A hooded nose, muscular nostril aperture control and the philtrum preventing water from entering the nostrils[17]
Extensive coverage of the skin by sebaceous glands[19]
The requirement of the human brain for certain nutrients including iodine[20] and some essential fatty acids[21] which are most easily found and absorbed in seafood[22]
Voluntary breath control which allows diving and swimming,[14][23] and a more streamlined shape compared to other apes[17]
The mammalian diving reflex which occurs when the head is immersed in cold water[24]
Vestigial webbing between the fingers[25]
The waxy coating found on newborns[17]
Certain morphological adaptations within the kidney[26

See also: http://en.wikipedia.org/wiki/Aquatic_ape_hypothesis
http://www.riverapes.com/AAH/Argumen...ore/JMHome.htm
http://www.elainemorgan.me.uk/

Last edited by harling : 04-23-2011 at 12:44 PM.
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Old 04-23-2011
Rhoda Rhoda is offline
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I don't know if 200,000 years ago is enough time to affect those changes, but there is a theory that humans nearly became extinct at around that time and the survivors were driven to coastal areas of Africa that were rich in such things as shellfish to survive.
http://www.scientificamerican.com/po...arthy-10-08-12
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Old 04-24-2011
terry terry is offline
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Harling
Thank you for taking the time to post a detailed and entertaining/informative analysis of humans' adaptation and maladaptation to water.
I think the two most persuasive piece of evidence for me are
1) the research by DARPA engineers who estimated the energy efficiency of 'untutored' humans at 3% in water - compared to dolphins' 80%.
2) 45 years of keen observation. It's rare to see a graceful swimmer, exceedingly common to see swimmers wasting energy.
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Old 04-24-2011
Rhoda Rhoda is offline
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Whales and dolphins started out as dog-like land animals. Perhaps humans had only just started the transformation and it was arrested by improving climate conditions that drew us back to the land.
It took about 15 million years for whales to go from this
http://dinosaurs.about.com/od/mesozo.../pakicetus.htm
To this
http://dinosaurs.about.com/od/mesozo...silosaurus.htm
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Old 04-24-2011
Richardsk Richardsk is offline
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So if we keep trying to swim without using our arms and legs and concentrate on undulation of the body, in a few million years we may be speeding through the water like dolphins. And maybe in a year or so I'll be able to swim a passable butterfly.
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Old 04-27-2011
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I thought swimmers shaved just before a swim meet because it exposed new slippery skin? It is not related to the removal of hair. I was just told that it is prohibited to shave at the pools locker room, disqualified team even if one swimmer does it.

This may be too far out, and I do not subscribe to this theory, but it has been theorized aliens may have tampered human DNA in our distant past. Perhaps the aliens came from a water world.

After watching a recent video interview with Alex Popov's coach, a video posted here on the ti forum, I had to try dolphin kick with the freestyle stroke, very interesting how it could relate to the 2 beat kick. It was fun.
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Old 05-06-2011
RobM77 RobM77 is offline
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I'm quite amused by the comment about "believing" in evolution, given that multiple sources have proven it to be a fact for decades!

Seriously though, how well adapted to water we are is an interesting topic. Our evolutionary past is obviously from fish, but that's a long time ago. Some mammals have gone back to the water, like seals, but our evolutionary lineage has stayed dry for a very long time now. Some throwbacks to our aquatic past still survive of course; some are benign, like the dimple between your top lip and your nose; but others functional, like the dive reflex in cold water which increases your breath hold time. Oh, and as I've found out to my detriment, the spine is a rubbish design for a bipedal mammal! These are largely vestigal curiosities though, we are undoubtedly better adapted to life on land than we are in water. Incidentally though, going back to the spin issue, one of the reasons I like swimming is that the buoyancy gets the weight off my back and relieves a permanent pain I have at the base of my spine.
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Old 05-06-2011
KatieK KatieK is offline
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Quote:
Originally Posted by harling View Post
Are we badly adapted to water?

Yes - we are poorly adapted to being in water: We are very slow compared to whales, dolphins, seals, etc and fish.
No - we are not too badly adapted: We are faster than jellyfish and plankton and they are very highly adapted to life in water. Some creatures can't even move for much of their lives - eg. coral.
Rock on, Human Beings! Faster than jellyfish, plankton and coral, baby!

I love this example. Swimming skill aside, I know that I personally am well adapted to *being* in water. If the water's warm enough, I can stay in forever. I only need to come out to eat and re-apply sunscreen.

Plus, on my worst day, I am Faster Than a Jellyfish. I need a t-shirt that says that.
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Old 05-07-2011
tab tab is offline
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"Faster than a jellyfish" imprinted on the back of my jammers. Very fitting.

I have lots of pains for different reasons. What I find also is that they seem not to bother while swimming, its a wonderful feeling.

I was told that the little dimple on your upper lip is given to you by an angel. Just before you are born (note: in a real water world) an angle comes up to you and tell you everything there is to know, then in a quieting gesture, presses the index finger to your lips, telling you to keep it all secret.
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Old 05-15-2011
Lawrence Lawrence is offline
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I find the two items Terry mentions pretty conclusive: 3% v 80% efficiency and the fact that graceful swimmers appear to be outnumbered by billionaires.
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