Wednesday, 10 November 2010

Chapter Five - The Aquatic Ape Theory

[Photo by Fosco Maraini from the book, Hekara, The Diving Girl’s Island of two Japanese ama divers foraging for shellfish and editable seaweed.]
The human is different from any other ape because it is naked, and it is only the Aquatic Ape theory that has a sensible explanation for this.  For instance; the Savannah Theory claimed we are naked so men will be cooler when running after game.  The problem with this explanation is that apes and men are very slow runner in the animal world and wouldn’t be able to run down any animal living on the Savannah.  The fastest animal on the planet, the cheetah, didn’t need to lose its fur to run fast.
The vast majority of animals that live on the African plains have fur. The exceptions are animals like elephants and hippos and the reason why these animals do not have fur is that they are semi-aquatic. (The elephant is a remarkably good swimmer, and its closest relation in the animal world, is the sea cow, also the elephant is the largest land animal and its large size keeps it warm.). Fur is not a very good insulator in the water unless the animal develops very dense fur with very large oil glands that can keep the water out, like you see with otters and mink. For most marine animals the best insulation is fat, which covers the bodies of dolphins, whales, seals and penguins. This is what humans also have.
Humans have ten times as many fat cells under the skin as would be expected in a non-aquatic animal of the same size. It is true some mammals, which hibernate can also retain fat, but this fat is seasonal; aquatic mammals and humans retain fat throughout the year. Also humans don’t hibernate, not even the Eskimos, who for thousands of years endured dark arctic winters living in Igloos. Human infants are especially fat compared to apes and most other fully terrestrial mammals. The human fatty layer is also attached to the skin of the central body parts, as is the case with most medium- or larger-sized semi-aquatic mammals, rather than to the muscle as in almost all land mammals. Humans also lack the layer of cutaneous muscle possessed by land mammals including non-human primates, which allows many land animals to twitch their skin, and which is not present in aquatic mammals.
Being naked is not a good idea in the hot African sun. (Even black people can get sun burnt, or can get skin cancer from too much sun). Fur protects the skin from the deadly effects of the sun and is also a far better insulator than fat for land animals. This is because a land animal can shed fur in the summer and grow it again in the winter. It can also fluff up fur in the heat, to allow the air to get to its skin, to cool down. Or it can bring the hairs closer to the body, trapping the air in the fur to allow better insulation in the cold. Fur also makes it far easier for animals to adapt to very cold conditions. In the 19th century when the first zoos were created in Europe they attempted to house tropical animals in heated rooms, but the animals quickly died. So they tried leaving the tropical animals outside and they quickly adapted to the cold by growing thicker fur. It was found that even Russian zoos have no problems in caging tropical animals out in the open, as their fur grows thick enough to adapt to the Russian weather.
Another problem with fat as an insulator is that it is heavier than fur. In the African Savannah, most animals survive by being fast runners, either to escape predators or being a predator itself, to catch prey. So an animal doesn’t want to be weighed down by excess weight like fat. Fur gives far better insulation qualities, with far less weight than fat. It seems the only advantage of the fat we have around our bodies is that fat is a better insulator in water and it gives us buoyancy when floating.
There is also the problem about how humans became so brainy. It is of interest that the biggest brains on the planet belong to aquatic or semi-aquatic animals. For instance, dolphins have bigger brains than humans, while a killer whale has a brain five times the size of humans and the sperm whale has a brain six times bigger than us. On land, the only animal that has a brain larger than humans is the elephant, which has a brain twice our size. So why is it that marine animals have on average, larger brains than those on land?
It seems this has to do with fat and trace elements. Sixty percent of the brain is fat, and the food needed to create large brains is omega-3 fatty acids and iodine. Without this vital brain food it is impossible for the body to grow a large brain. The marine environment has an abundance of these vital nutrients but they are in short supply on land. Iodine is a trace element that is vital for brain development, but there are many parts of the world where it is not present in the soil, like North America, Russian, Australia and parts of Africa. Iodine not being present in a mother’s body when she is pregnant, is a major cause of mental deficiency in babies. Both WHO and UNICEF see this as a major worldwide health problem and both organizations have encouraged countries to produce iodized salt that is sold to the public. Iodine is abundant in seawater and therefore the food richest in iodine is found in seafood.
So let’s compare a dolphin with a zebra, which has the same body weight. A zebra has 360 grams of brain while the dolphin has 1.8 kilograms. In other words, a dolphin has a brain about five times the size of that of a zebra. This is also true with apes. Human beings have a body size comparable with chimpanzees and gorillas, the chimpanzee being slightly smaller and the gorilla slightly larger. Yet humans on average have brains over three times bigger than both ape species.
The savannah theory claims that men could obtain the vital DHA fat from bone marrow. Yet hyenas, which have powerful jaws to crunch up bone and eat the bone marrow of the animals they kill and scavenge, do not have large brains like us. Also the savannah is not rich in the vital trace element iodine, which is vital for brain development. This then makes sense of a puzzle about early humans. We would expect that as humans evolve more, our brains would get bigger and bigger, but this hasn’t happened. Neanderthal humans had brains larger than the average human today; this is also true of the Cro Magnon humans who had a brain 15 percent larger than modern day people.
So why did this happen? An obvious explanation would be that many humans rejected the sea and moved back inland. This would mean they wouldn’t find the same abundance of brain food as they found on the coast, resulting in their brains becoming increasingly smaller. It is of interest that the size of human brains can vary enormously, some humans having brains as low as 800 cc or as high as 2,000 cc. This big variation could be to do with the different diets humans have and how much brain food they consume. It has to be said, however, that brain size is not a very good indication of individual intelligence.
There is a real mystery why human beings are the only animals to walk upright. As, running upright makes human beings slow runners. A four-legged animal has a far longer stride, using both the back and front legs which makes then far better runners than humans.. Also we pay a price for our upright stature through knee and back problems as well as varicose veins, hemorrhoids and hernias.
Yet the big advantage is that being bipedal leaves human beings hands free to carry objects and use tools. It is doubtful we evolved bipedalism for this reason; chimpanzees also use tools but chimps are still happy to walk around on four legs, and only use tools squatting on the ground.
In the past, there was another ape, which was bipedal like us. This was the long-extinct Oreopithecus, known as the swamp ape. Scientists have found it had a pelvis like ours, making it also suitable for bipedalism. In modern times the two primates that are able to walk upright are the proboscis monkey and the bonobo ape. The proboscis lives in the mangrove swamps of Borneo and is a real swimming primate as some have been found swimming in the sea by fishermen. The bonobo lives in forests that are seasonally flooded every year. Both species wade through the water in a similar way to human beings, so this suggests that bipedalism in primates comes from living in flooded or swampy areas.
The aquatic ape theory suggests like the great hunter theory, that our ape ancestors were forced to come out of the trees because of changing climatic conditions, but instead of living on the savannah, these apes found they could survive by gathering shellfish and seaweed on the seashore. The result would be that they became a wading ape, as the ape could walk in deeper water by walking upright. The advantage of living in trees is that it is a good protection against predators, most of whom can’t climb trees. The same protection can be given to an upright wading ape simply because it can wade out to deeper water than a four legged predator. It is true that the predator might swim, but it loses all its advantages of speed, size and power swimming in the water. To this ape, the water will become a safe haven in much the same way  trees are, so instead of climbing a tree to escape from a predator it can run into the ocean instead. In fact, a beach is a difficult hunting ground for predators as there is not much cover a large cat can hide behind to stalk its prey. This then would make shell hunting more popular among females if they are pregnant or breast-feeding a child, as the water protects them. This could explain another scientific mystery.
Most animals reach full maturity within a few years; this is because the young of most species are very vulnerable to attacks from predators. So the quicker they grow to full size the better chance they have of survival. But the human child can take up to 20 years to reach full maturity, and it is totally helpless in the first two years of its life. Now having a long time to mature is an advantage for human brain development, but for early humans to evolve to this means mothers had to be able to keep their children in a safe environment away from predators. Living on the savannah alongside lions and hyenas would be a very unsafe environment for the young of early humans. Monkeys and most apes are able to keep reasonably safe by living in trees, though there is also the danger of infant primates falling, out of trees.  So it means that the ocean would be a safer environment for early humans than even trees. It is true that there are sharks in the sea but sharks would be far less of a threat than big cats or hyenas on land. All over the world, sharks kill only a handful of people every year, in spite of the large numbers of people who swim in the ocean. Statistically, a person has a better chance of being hit by lightning, than being attacked by a shark.
So there are a lot of advantages to female apes becoming marine food gatherers. It’s not so true for male apes, who would be bigger and stronger anyway and don’t have the burden of trying to save a helpless baby from a predator as well. So it would cause a division of labour, men gathering on land while women gathered in the sea.
This is why the Aquatic Ape theory seems to have a great appeal to women, and why many male scientists don’t like it. Instead of having a hunter, coming home from a hard day of hunting to be greeted by his adoring wife, we now have women who are more than able to feed themselves and their children without any help from men.
Other human characteristics that support the Aquatic Ape theory are that we sweat salt and water from our skin glands. For a land animal this is a waste, more so in a hot country like Africa, as water is very scarce at certain times of the years. So sweating water is a very inefficient method of keeping cool for a tropical animal. This is exacerbated in a human because it is naked, so when a human sweats it quickly evaporated by the sun. A fur covering means that moisture is shaded and evaporates more slowly. Salt is also scarce for land animals, who will travel a long way to find salt licks. Yet sweating salt makes a lot of sense to aquatic animals that need a way to get rid of an excess of salt in their bodies because they are living in a salty environment.
There are many other reasons why we evolved from an ape that foraged in the water for food, but to get back to why women have breasts.  As previously mentioned, only fat animals in the wild are marine animals. There is simply no advantage for a land animal in carrying excess fat, which women have on their chests, bottoms and thighs. It is true that a fit man carries less fat than a woman but we cannot leave women out of any evolutionary theory, in the way man the Savannah theorists have done. It is also claimed that large female breasts and bottom are not very streamlined in the water. This would be a consideration if humans were fully aquatic. In sport men can outperform women because of their great strength, but in long distance swimming women can match or even outperform men. This is because fat floats in water and the subcutaneous fat around women makes them more buoyant; they float better than men, so when swimming, more of the woman’s body is out of the water. Women need marginally less effort to propel themselves along in the water than men, so the fat around women’s chest, bottom and thighs does benefit them when swimming.
So according to the Aquatic ape theory large breasts in women are only about keeping women warm and buoyant in the water.  Certainly having large breasts is a help to women when swimming in rough water, because the extra buoyancy of extra fat on their chests will help keep their head out of the water.  Which might suggest that men’s attractiveness to women with large breast may not have anything to do with sexual attraction.  Yet we have to admit that some women do have very large breasts, perhaps too large to be a help when swimming in the water.  So even though sexual attraction may not be the original reason why women have breasts, sexual attraction may be the reason why some women have extra large breasts.  I will discuss this in the next chapter.

My Aquatic Ape Theory Video on Youtube

The Aquatic Ape Theory was mentioned in the fake Animal Planet Mermaid TV documentary


  1. Another idea about breasts: when a woman is chest deep in water, breasts float. (mature, lactating breasts that have not been bra-trained.) This would be advantageous to feeding a baby, who could hold onto the breast. Feeding babies (rather than drowning them) is pretty important to getting genes into the next generation.

    And breasts are very disadvantageous to survival on land, as any woman with medium large to large breasts who has tried to run without a bra can tell you. Such a disadvantage would have to be outweighed by a considerable advantage--such as babies being able to survive.

  2. Not having breast i cannot comment on this. Though because breast float in water it would help women swimming in keeping their heads above the water in rough water.

  3. IMO back-floating mothers with breasts full of milk could more easily feed their baby (secondarily, this feature might have been subject to sexual selection).

    We did not descend from aquatic apes, of course, although our ancestors were anatomically & physiologically not adapted to running over open plains as some anthropologists still believe. Instead, Pleistocene Homo populations simply followed the coasts & rivers in Africa & Eurasia (800 ka they even reached Flores >18 km overseas), google, eg, “econiche Homo”.
    –eBook “Was Man more aquatic in the past?” introd.Phillip Tobias
    –guest post at Greg Laden’s blog