When did Aquatic Humans first leave the water?

Answer 1

Aquatic humans never existed, therefore, they never left the water.

Aquatic Humans and Humans are the same thing. There are a wide range of physiological traits in human beings that can be explained by an evolutionary period in human existence that involved a partial, complete and then semi-aquatic phase in human prehistory.

These features include:

Hairlessness

Streamlined body

Reduced sense of smell

Subcutaneous body fat

Bipedalism

Diving reflex

Exostoses

The Nose

Downward facing nostrils

Philtrum

Breath control

Speech

Salt Tears

Eccrine sweat skin glands

Large Sebaceous glands

Hymen

New-born swim ability

Webbed fingers and toes

Lunar Menstruation cycle

Lowest blood cell count of the apes

Highest haemoglobin per cell of the apes

Seafood diet bias

Humans are the only terrestrial animals that can voluntarily hold their breath at will.

The ability to hold and control breath is necessary for complex speech. This ability would, of course, also be needed for diving. It is likely that the ability of humans and aquatic mammals to hold their breath was an adaptation meant for diving, and that the development of complex speech was a side effect.

Also, humans have a descended larynx, which other apes do not. This allows us to gulp large amounts of air. Most animals only breathe through the nose, but the descended larynx allows humans to breather through our mouths, which allowed us to take deep breaths "prior to diving" (Watson). The larynx thus allowed early humans to spend longer periods of time underwater than they could have if they were taking shallow breaths through their noses. Complex speech is also dependent on the descended larynx. Other aquatic mammals, such as sea lions, walruses, and manatees have descended larynxes.

There is another similarity between humans and aquatic mammals: the diving reflex, also known as bradycardia, a decrease in heart rate and redistribution of blood to the brain and the organs. This is a natural reaction of humans to being submerged. Other apes do not share this ability, as they obviously have no use for it. "Humans can dive to depths of one hundred meters at the extreme but most humans can certainly dive to ten meters," which no ape would do (Watson). The diving reflex makes swimming and diving practical, and humans have no living ancestors that possess this trait. It must have been acquired at some point after humans split from apes, and this supports the idea that man evolved in an aquatic or semi-aquatic environment.

• The pattern of hair on our backs. Like all mammals, humans are covered with short hair. The hair on our backs lays down and towards the center in a streamlined way that would theoretically facilitate swimming.
• Noses. Compared to all other primates our noses are very long and rigid. Our nostrils point down as opposed to gorillas and chimps whose nostrils are almost flush with the face. This is quite useful when swimming for preventing water from getting into the respiratory system.
• Geological evidence. At around the time that Homo sapiens became a species in their own right, sea levels appear to have been higher than they are now in the areas where human fossil evidence is being found.
• Swimming primates. Most primates cannot swim and do not like water. (If I remember correctly, chimps sink like rocks.) One exception is the Probosis monkey which has been seen wading bipedally in waist-deep water. Probosis monkeys have developed longer legs than many primates, and their proportions appear closer to humans than most other monkeys. Humans, however, love water. Look at the modern world and how cities and vacation spots are arranged. Few seem interested in touring savannahs, but we flock to beaches.

• Voluntary breath control. Primates are physiologically unable to hold their breath. However, humans have developed the ability to regulate their own breathing, a necessity for diving.
• Vocalization. The wide range of sounds we can make is due to the orientation of our larnyx. We share this feature with only a few other animals: the dugong, sea lion, and walrus.

• The sensitivity and dexterity of our hands is perfect for searching for food underwater. Our fingernails are stiff and fast-growing, and therefore ideal for prising open shellfish.
• Our tool-making ability. Pebbles are perfect for opening shellfish, as otters have similarly discovered.
• When swimming, all signalling becomes useless apart from vocal signals. If we developed language for the purpose of hunting on land, it would be more useful to create a sign language; hunting is usually a very quiet activity. Other creatures with a highly developed vocal 'language' include whales and dolphins, not creatures such as wolves.
• Of all similar creatures, the elephant is the most striking. Its evolution is really quite remarkable - it is descended from a small pig-like animal, but then over the ages, grew to be the largest land animal in its era. It is very easy to compare it to another mammal whose size swelled remarkably over the ages: the whale. In water, large mass is not the problem it is on land. Indeed, it is a benefit, as larger creatures lose heat much more slowly.
• Its anscestors also had peculiar tusks. Some had spade-shaped ones, perfect for digging in soft, waterlogged soil, but not much good in the plains.
• The early ancestors of the elephants showed a movement of the nose towards the top of the head. This would have been uncalled for on land, but excellent in the water. Nowadays, of course, they have a trunk. And what use is a trunk? It's inefficient for grass eating (a long neck would be better), and unnecessary for tree browsing. But it makes a pretty good snorkel. Not to mention its use for picking water plants.

Suggestion that Pachyderms all shared a more intense evolutionary period with us and the sea. The Seal, Dugong and Walrus quite obviously going the way of the Dolphin, although there is no reason why time and the environment should not leave them where they are or move them in the direction of the land once more.

The Hippopotamus still living a semi-aquatic existence, whilst a distant relative went all the way and became the Blue Whale, fully aquatic and the largest animal to have ever lived as far as we know.

The Elephant, Tapir (both of whom have trunks [read:Snorkel] which have been shown in prehistoric times to have been moving towards the top of the skull, clearly an advantage in the water) and Rhino also share with the other Pachyderms the hairlessness seen in humans and share numerous other similarities not seen in non-aquatic or semi-aquatic mammals.

Elephants by way of interest also have webbed feet although this has atrophied as in humans. They can also swim for six hours straight and their large size is in anycase probably attributable to a long period of permanent water habitation. Elephants also show the crying response when emotional. Hardly any land creatures cry and hardly any sea creatures don't. They are also highly intelligent and have a complex language which includes Infrasound comunnication.

• subcutaneous body fat, similar to aquatic mammals'
• ability of new-born babies to swim
• diving reflex: our breathing slows down underwater
• hairlessness, except on head, that hair floating for infants to hang on to
• long-chain fatty acids composing the brain easily derived from marine food, not easily from Savannah food
• crying salt tears
• resonant voice
• upright posture, bipedalism
• people with their hips together resemble dugongs in streamlining effect
• webbing between fingers

The Aquatic Ape Theory is at least a reasonable hypothesis, if not a fully acceptable scientific theory. It provides a sensible explanation for why human beings, while genetically similar to apes, possess so many different physical features, and how these physical adaptations could have come into being. Without the Aquatic Ape Theory, it is hard to explain the parallels between humans and aquatic mammals. Science, especially evolutionary Biology, is a constantly changing field. Nothing is set in stone. The AAT may someday replace the "Savannah theory of human evolution" which most evolutionary biologists now deny they ever supported which is telling, especially since this coincided with the discovery that the whole basis for the so-called "Savannah theory" was incorrect and the environment which produced upright man was wet and wooded.

Perhaps a third theory will arise. At the very least, Elaine Morgan's books have made some scientists rethink what they have been taught about evolution.