Aquatic Ape Theory Revised

I became interested in the aquatic ape theory of evolution because it pointed me in a fruitful direction — testing omega-3 fatty acids (e.g., flaxseed oil), which turned out to have easy-to-detect benefits (better brain function, better gums). That is more than I can say for alternatives to that theory, such as the savanna theory. Marc Verhaegen, a Belgian doctor, has recently proposed a new version of the aquatic ape theory. Some of his main points:

  • An extensive overview of the literature by Stephen Munro showed that virtually all known archaic Homo [= pre-Homo sapien] sites (including those in ‘savanna’) were associated with permanent water and edible shellfish.
  • Only regular diving can explain archaic Homo’s pachy-osteo-sclerosis (POS), the extreme thickness and density of cranial and postcranial bones of most erectus-like fossils. . . . POS is only seen in slow littoral divers, e.g. dugong and manatee, walrus, Kolponomos, pakicetids, Odobenocetops, and Thalassocnus spp. Marine biologists agree POS has a hydrostatic function (ballast).
  • The abundant brain-specific nutrients in aquatic foods (e.g. DHA, iodine) facilitated fast brain growth (sapiens’ poorer post-aquatic diet required a longer youth to grow the same brain size).
  • Man is the opposite of a savanna inhabitant. Humans lack sun-reflecting fur, but have thermo-insulative subcutaneous fat layers, which are never seen in savanna mammals. We have a water- and sodium-wasting cooling system of abundant sweat glands, totally unfit for a dry environment. Our maximal urine concentration is much too low for a savanna-dwelling mammal. We need much more water than other primates, and have to drink more often than savanna inhabitants, yet we cannot drink large quantities at a time.
  • Maps of human population densities show that, although we have become fully terrestrial today, we are still a waterside species, and almost half of human dietary calories still come from the water (e.g. rice, aquaculture, fish, shell- and crayfish).

I find the water-drinking point especially persuasive. We need to drink throughout the day, or at least feel bad if we cannot. Almost all workplaces, including cafes, have a source of water. This is inconsistent with savanna living and consistent with waterside living. The term aquatic ape is somewhat misleading. A better name would be aquatic-food ape.

17 thoughts on “Aquatic Ape Theory Revised

  1. I recall reading a comment of Buckminster Fuller’s a very long time ago that he believed that man came from the sea.
    This aquatic ape theory is very interesting.

    Seth: He came from near the sea, no doubt.

  2. I don’t find this particularly compelling…

    “Man is the opposite of a savanna inhabitant. Humans lack sun-reflecting fur, but have thermo-insulative subcutaneous fat layers, which are never seen in savanna mammals.”

    We evolved to stand upright to better allow us to survive on the savannah. The hair on the top of our head protects us from the part directly exposed to the sun, the rest of our bodys are obliquely exposed to the sun, and have a high melanin content to protect us from the sun’s rays.

    “We have a water- and sodium-wasting cooling system of abundant sweat glands, totally unfit for a dry environment.”

    This is a bit ridiculous. If we were aquatic, we wouldn’t need the excessive number of sweat glands that we have. These are only of use when we’re in a savannah-type environment, and allow us to cool when running much better than any other savannah dweller. We do not have a “sodium-wasting” system, we sweat excess sodium, and then conserve it, expelling only that sodium we don’t need. This is well-demonstrated.

    “We need much more water than other primates, and have to drink more often than savanna inhabitants, yet we cannot drink large quantities at a time.”

    In fact, we have a unique adaptation to exertion in hot climates: we can lose up to 10% of our body weight in water, without any effect on performance. Being able to operate at such a hugh water deficit is not an adaptation that one would see in an aquatic animal.

    Dan Lieberman and Tim Noakes have both published extensively on this topic, Noakes’ book “Waterlogged” details all the adaptations we have to surviving in a hot, dry climate.

    We certainly have some adaptations to an aquatic life, but they are inconsequential next to our adaptations to savannah life.

    Oh, and for omega-3 fats: the ratio we seem to have evolved to need is that found in the bodies of savannah-dwelling ruminants, our main prey animal. Shell middens do not appear in the archeological record until recently, for millions of years we were eating something else…

    Seth: “We evolved to stand upright to better allow us to survive on the savannah.” If the advantages of standing upright on the savannah were so great, why didn’t other savannah animals evolve to stand upright? Well, because it doesn’t provide an advantage by itself. Walking upright by itself is a huge disadvantage on the savannah because it means you can’t travel as fast as a four-legged creature. You’re a sitting duck. Only when humans were able to arm themselves could they live on the savannah. Just as humans can now live everywhere.

  3. @Tuck

    If we were aquatic, we wouldn’t need the excessive number of sweat glands that we have.

    To sweat profusely seriously impairs our ability to survive when water is scarce. It seems logical to think that our ancestors were both exposed to hot temperatures and had, simultaneously, access to abundant water throughout the day. The savannah is fine as long as there is always abundant water.

    The argument that we can lose a lot of water without harm does not convince me of anything: we have to be able to lose a lot of water because… we do! It would be really strange if we could sweat a lot, by design, but if we could not afford to lose the water… we would be broken.

    But we still need to replenish the water rather quickly as anyone working out for a few hours knows.

    The problem, of course, is that if you live by the sea, what do you drink? You can probably find fresh water… but unlike many aquatic mammals we *need* a lot of fresh water. This seems like a major inconvenience.

    Our kidneys do not seem well suited to life by the sea.

  4. My own observation is that I digest fish and seafood much better than meat. When I eat meat I can smell and see it some hours later in my stool, even eggs I can smell but after eating fish, shrimp, oysters, squid, etc there is nothing, no smell, it seems to be completely absorbed.
    As our human ancestors have probably spend time in the water (probably more in rivers than the open sea) and in the savannah (having been rainforest for most of the time) I don’t see a conflict that we have adaptions to both environments.

  5. @Seth: “If the advantages of standing upright on the savannah were so great, why didn’t other savannah animals evolve to stand upright?”

    For the same reason other animals didn’t evolve human-sized brains, or opposable thumbs. We’re unique.

    “Well, because it doesn’t provide an advantage by itself.”

    No trait exists in a vacuum… But standing upright allowed us to develop the traits that make us the most efficient endurance hunter *on land*.

    There are other primates that swim for food. There are no other primates that can run long distances in hot climates, which allows us to run down large animals and kill them without the need for weapons, thus allowing us to become a dominant predator.

    @Daniel Lemire: “To sweat profusely seriously impairs our ability to survive when water is scarce.”

    It doesn’t. It’s a short-term cooling process, allowing us to cool faster than an animal that has to pant when it’s running. The body adopts other cooling strategies that minimize water loss when it runs low.

    “But we still need to replenish the water rather quickly as anyone working out for a few hours knows.”

    We can actually go days and days without water, losing massive amounts of body weight, and be perfectly fine upon re-hydrating. There are plenty of hunting societies in African (or Australian) deserts that do well on minimal water.

    Try putting an animal that is actually adapated to an aquatic life in those conditions, like a hippo, and you’ll see what happens to an aquatic mammal.

    I think the evidence for the aquatic ape theory is pretty sparse, compared to the alternative explanation.

    This is an excellent primer on Noakes’ work:

    “Waterlogged – A Dogma-Shattering Book?”
    https://www.irunfar.com/2012/07/waterlogged-a-dogma-shattering-book.html

    Unlike most such works, Noakes’ theories have been put in practice in endurance running events.

    Endurance runners are more at risk from *too much water* than from too little.

    Which makes perfect sense, as we are adapted to hot, dry conditions.

    Seth: “For the same reason other animals didn’t evolve human-sized brains, or opposable thumbs. We’re unique.” I’m afraid I don’t understand how saying “we’re unique” explains anything. I believe that lightning doesn’t strike twice in the same place for different reasons, so the many ways that humans differ from all other animals must be connected. For example, bipedality and extensive tool use must be connected, in the sense that they have a common cause or one led to the other. To say “we’re unique” gives no idea of what the connection is.

  6. The fact that people get sick when they drink huge amounts of water when they are not thirsty has absolutely nothing to do with how we evolved. There are any number of substances that become lethal when over-consumed.

    What a bizarre argument.

    Seth: What is over-consumption is shaped by evolution. An animal that lives close to water has less need to store large amounts of water than an animal that doesn’t live close to water.

  7. @Tuck

    Better arguments against the aquatic ape theory:

    1. We are lousy swimmers by any standard, and without proper training, we are just plain terrible at it. We are probably more likely to get eaten than to eat when swimming in the wild sea.

    2. Our children are sure to drown quickly if left unsupervised near water.

    As for your hypothesis that we are desert animals…That one athlete claims that we can go days without drinking is… frankly, garbage. I once went an entire day without drinking water and I almost collapsed. This is documented. Maybe one particular runner is able to run for days without drinking. Well, he is an oddity.

    We are more like Zebras… we need to stay near a water hole.

  8. Seth, I wasn’t calling your argument about water consumption bizarre; your point was completely logical. What was bizarre was Tuck’s using Tim Noakes’ work on hyponatremia to support his point.

    Hyponatremia is caused when marathoners drink way too much water, reducing serum electrolytes to dangerous levels. Hyponatremia has nothing to do with evolution, any more than the fact that we can overeat to the point of throwing up means we evolved to thrive without food.

  9. “To say “we’re unique” gives no idea of what the connection is.”

    True, but your question: “If the advantages of standing upright on the savannah were so great, why didn’t other savannah animals evolve to stand upright?” requires a longer answer, even though “we’re unique” is sufficient. I didn’t want to get sidetracked. :)

    Standing upright is an advantage in the savannah if you have several other traits. If you don’t, it’s not.

    I’d argue that the other traits are; hands that can use tools (which even chimps have, to some extent); a physique that allows running while standing up (chimps cannot for more than a few feet); sweat glands that allow running while standing up for long distances in hot temps; and a large brain that allows us to track prey over long distances even if the prey is out of sight, which allows us to keep the prey moving until it overheats and becomes helpless.

    No other animal has that unique set of features, and the combination results in a uniquely lethal predator.

    @Tom: “What was bizarre was Tuck’s using Tim Noakes’ work on hyponatremia to support his point.”

    It’s not bizzare if you’re familiar with Noakes’ work. Central to Noakes’ argument about hyponatremia is the fact that we’re well suited to running in a dry climate. It’s hard to square that with the aquatic ape hypothesis.

  10. @Daniel Lemire:

    “1. We are lousy swimmers by any standard…”

    Agreed, but if you’re arguing against the aquatic ape theory, it’s good to present the alternative first.

    “That one athlete claims that we can go days without drinking is… frankly, garbage.”

    I suggest you go do a little research, then. Familiarize yourself with the evidence. You’re clearly not familiar with it now.

    Noakes has a ton of citiations of the research and evidence in his book, start there. He’s not “one athlete” btw, he’s one of the leading researchers in human exercise physiology, he’s written the medical guidelines used for many international endurance running events, and he’s also worked with many of the top atheletes and endurance events.

    Next you can look up some of Daniel Lieberman’s work on how man evolved as an endurance-running predator in the savannah’s of Africa. He knows a thing or two about human evolution.

    Once you’ve done that you can come back and we’ll have a discussion.

  11. Thanks a lot, Seth!
    The poor anti-littoral “arguments” here show that there’s no doubt that archaic Homo during the Pleistocene trekked along the coasts & rivers rather than running over savannas:
    Tuck thought: “We evolved to stand upright to better allow us to survive on the savannah. The hair on the top of our head protects us…”‘ Yes, that’s why all savanna mammals stand & run on 2 legs, and why the bald & bearded men rest in the shaddow while the women are running after kudus… :-D
    He also thought: “If we were aquatic, we wouldn’t need the excessive number of sweat glands that we have.” ?? AFAWK, only furseals & humans sweat abundantly thermo-actively on land. Sweat = salt + water = scarce in savannas.
    Enough said. Please infor a bit first:
    Humans didn’t descend from aquatic apes, of course, although our ancestors were too slow & heavy for regular running over open plains as some anthropologists still believe.
    Instead, Pleistocene Homo populations simply followed the coasts & rivers in Africa & Eurasia (800,000 years ago, they even reached Flores more than 18 km overseas).
    – google “econiche Homo”
    – eBook “Was Man more aquatic in the past?” introd.Phillip Tobias https://www.benthamscience.com/ebooks/9781608052448/index.htm
    – guest post at Greg Laden’s blog https://scienceblogs.com/gregladen/2013/01/30/common-misconceptions-and-unproven-assumptions-about-the-aquatic-ape-theory
    https://greencomet.org/2013/05/26/aquatic-ape-the-theory-evolves/

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