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Are human beings more aquatic that we have ever imagined?

Posted by Ricksafer on 18 January 2010 at 04:40 PM

An Ancestral Aquatic Reflex

Are human beings more “aquatic” than we ever imagined? 
An ancestral marine reflex

In my teachings of so many years as an instructor of free diving and spear fishing I have had the opportunity to study the reactions of my students whose ages have ranged from early subjects to the most “ripe” ones .... On many occasions I have been surprised by how quickly adaptation to the aquatic environment occurred in them. It would perhaps be the result of something more than the careful education and knowledge that I was giving to them or does this remarkable adaptation in such a relatively short time had “another” explanation?

Do we, human beings, possess a natural mechanism that allows us to relatively transform from terrestrial beings into aquatic ones in order to adapt to such a drastic change like going from land into a watery world?

Actually yes. Knowing that the source of all life began in the sea and although the evolution of species had some of them specialized to exist on earth, others in the air and perhaps the vast majority remaining at sea, nevertheless in all of them remained ever so latent, there, somewhere deep in their DNA this ‘memory’ of ancient aquatic times.
                                                  The mammalian’s aquatic reflex

We’ve all admired the documentaries programs of animals that, like us, breathe air but still have the incredible capacity to spend most of their entire life, and in some cases, all of their lives at sea. Whales, sperm whales, orcas, dolphins, seals, sea lions, walruses etc… All are mammals like us and yet are able to live, hunt, eat, procreate and thrive in an aquatic environment that we would have thought to be reserved for fish that do have gills. These are their highly specialized breathing organs that extract oxygen from water.

A given amount of sea water contains 35 times less oxygen than the same volume of air. The sea water itself is almost 800 times denser than air depending on its specific salinity. The weight of the gases that make up the atmosphere we breathe only weighs 14.7 pounds per square inch (p.s.i.) at sea level. On the other hand, a column of salt water of only 10 meters (33 feet) carries twice that weight.

The pressure these aquatic mammals are subjected to during their prolonged dives of more than one hour and in some cases reaching depths of hundreds if not thousands of feet (sperm whales and Weddell seals have been recorded up to 2000 feet deep and more than 1 hour permanence) should crush them but it doesn’t happen.
Several physical spontaneous phenomena occur to them in order to prevent this theoretical crushing and to some limited extent to us, too.

The simple fact of physical contact with water whose temperature is lower than the average human being’s 98.6 degrees Fahrenheit triggers innate physiological responses.

The colder the water temperature the faster those changes are triggered and a certain prolonged stay in such conditions is also required. The resulting effect is directly proportional to these conditions. In my experience it requires at least 20 minutes.

First, the skin and underlying muscles contract and begin a “redeployment” of the bloodstream which is “restricted” or “re-routed” from the extremities or limbs towards the viscera and brain nerve centers that need more oxygen in order to resist what the body recognizes as a physiological aggression.
This “vasoconstriction” is called “blood shunt” or “blood shift” in English. The limbs, because they are solids composed of muscles, bones, cartilage are therefore incompressible and remain unaffected by the pressure exerted upon them and do require significantly less oxygen than the heart, lungs, kidneys, brain, liver, etc.

Immersing the face in cold water with its direct contact with the mucous membranes, nostrils, external ear (tympanic membrane) etc. along with the water pressure exerted on the “trigeminal” optic nerves provoke the “oculo-cardiac reflex” which will reduce the rate of heartbeats (bradycardia) and hence will diminish the oxygen consumption as a protective mechanism. The cochlear hearing apparatus detecting that the human organism is in “suspension” and not under vertical pressure mode plus the absence of the “plantar reflex” of the soles of our feet also contribute to the installation of the aquatic mammalian reflex.

It is much more complex than we would rather guess. The spleen will also shrink and begin to release more red blood cells originating in the red bone marrow (hematopoiesis) that will carry a greater amount of oxygen-rich hemoglobin to the neediest tissues as previously explained. This physiological change is actually completely reversible and if the dives are discontinued it will revert back to normal in a given period of time.

But perhaps the most dramatically incredible physiological change is what happens to the species of cetaceans and marine mammals. How is it possible their lungs not be crushed under the immense pressure of thousands of feet of salt water upon their bodies?

The answer is “dilation and thoracic erection”.

The bloodstream, which has been diverted from the extremities or limbs toward the chest cavity containing the precious oxygen needy viscera and as well towards the brain tissue, invades the lungs and pulmonary alveoli causing an engorgement or thickening of them. This is the same principle in action that occurs in the “corpus cavernous” of the penis during male sexual arousal and penile erection. As the space previously occupied by the gas (air) is filled with thickened blood plasma the vessels, alveoli, lung’s spongy tissues, etc. the thorax can no longer be compressed and, just like in the seals case, it will not be crushed under the immense pressure. Let’s remind ourselves of our basic Boyle Mariotte Law of our early diving lessons which only works on gases contained in our human compressible cavities or spaces like the sinuses, synovial, frontal, Eustachian tube, lungs and airways in general.

This thoracic “blood shunt” phenomenon mostly only occurs in cases of professional athletes in the world of diving records who reach depths that greatly exceed the vast majority of us, sub-hunters, free divers and or week-end warriors!

Has Mother Nature reserved an option to “escape” or return to our ancestral watery beginnings?

If mankind continue the abuse and mistreatment of Mother Earth as it has been doing, causing the “greenhouse effect”, the thawing of ice caps at both poles, the colossal increase of water levels many scientists predict it very well might be that it may eventually become most handy.

Perhaps the aquatic mammalian’s reflex is nothing but the first step in the “re-adaptation” of our species, as Charles Darwin stated in his paraphrased “adapt or perish” sentence. In the end, it wouldn’t be but another level in our evolution, as we ALL have already breathed water in the past.  I’m referring to the amniotic liquid in our mother’s womb.

Visit http://www.divesafer.com where you’ll find more detailed information. Now, please do not abuse your aquatic adaptation water too much! Until next time.

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