Discussion on hypothesized ancestral human cyclical ARC dive-foraging

[wet]

(* THE-ARC *): Diving-Surfacing: Parallel Convergence

Humans, sea otters, blue whales: parallel convergence in rest & respiration

Ancient humans 1 million years ago dove for seafood, surfaced and rolled onto their backs to breathe and rest. Fossil skulls of that period show a dense occiput (rearmost bone plate of the skull), this density allowed the nose and mouth to be higher in the water during backfloating. The face bones were thinner and lighter, with paranasal sinuses (small air pockets in the nose bony base). The temporal bone of the ear was very dense, indicating that the ears were submersed, as they are today when humans backfloat, compared to temporal bone pneumatization in the extant apes (Kimbel et al.1984).

DDeden

Fine example of the sort of locale: http://www.world66.com/world/africa/djibouti/tadjoura
Close to Tadjoura you find some good beaches and places to go diving. Sites around this area include Ras Ali, Ras Ouan, Trevally Valley, Alices Fault and Sables Blancs- drop-offs to twenty meters, large schools of trevally, barracuda and batfish. Giant reef rays and turtles. Perfect for a day trip - two dives and relax on the beach with a picnic lunch.

Tadjoura: Afar name Tagórri derives from -tágor-li ("that which has goatskin flasks to draw water") = ("abundant with water")

[Mullins]

I'd normally expect the claim that humans were physiologically adapted to a semi-aquatic lifestyle as late as 1 million years ago to be accompanied by... evidence? Or at least some account of why this may have been the case. Or is there a document here I've missed?

[wet]

It was more a thought than a claim.

I'm not sure what I would claim, perhaps that human ancestors typically lived along (sub)tropical seashores, spending time in water foraging for foods, and via natural selection this resulted in better wading/diving/swimming/backfloating abilities than hominoid relatives, resulting in some features seen in other (semi)-aquatic species that are not closely related to humans.

You might search Deeper Blue for 'human ancestors', 'aquatic ape', 'backfloating' for some information, videos, articles and opinions, if interested.

[Mullins]

Originally Posted by wet

better wading/diving/swimming/backfloating abilities than hominoid relatives

Really?? Put an untrained monkey, gorilla, chimpanzee or human in the water and I expect they'd drown at about the same speed. We're hopeless swimmers compared to almost every other mammal.

[wet]

Originally Posted by Mullins

Really?? Put an untrained monkey, gorilla, chimpanzee or human in the water and I expect they'd drown at about the same speed. We're hopeless swimmers compared to almost every other mammal.

How many trained gorilla or chimpanzee swimmers/divers/backfloaters have you seen?

I haven't seen any.

How many trained monkey backfloaters have you seen?

I haven't seen any.

Not sure what you mean by 'hopeless swimmers'.

Humans can certainly drown, but then so can dolphins, etc.

[Mullins]

By 'hopeless' I mean 'very poor'.

No human would survive in the water for any useful length of time unless they'd been taught how to swim, whereas most other mammals can swim significant distances with no tuition. It doesn't come naturally to us. Similarly, it doesn't come natually to other hominids. I suspect that if you could train them in the same way you can train humans (which you can't, hence the notable absence of trained back-floating chimps), you could get similar results. What would stop a chimp from successfully floating face-up, assuming you could convince the chimp it was a thing worth doing in the first place? What's the physiological advantage we gain from our supposed genetic inheritance? We have the advantage of rational thought and a highly nuanced shared language, and we make use of these to survive in the water (by developing and communicating swimming techniques) but they are no more derived from an aquatic ancestry than our ability to make submarines is.

Humans drown because they're physiologically unsuited to being in the water. Put a human in the water unaided and depending on several factors they'll drown in a matter of minutes or hours, even if they have been taught how to swim. Dolphins on the other hand are well suited to the environment and drown only if something goes wrong i.e. they get sick or are forcibly held under. No comparison whatsoever.

[trux]

Ape backfloater? I found one. Does it mind he swims on the back of someone else?

swimDM3010_600x633.jpg photo credit © Dailymail.UK

[turtle]

what about human babies? they're pretty good swimmers, unlike baby monkeys or apes. I'd call that a pretty big difference.

Lots of animals are good at apnea for hunting/foraging. Humans happen to be one of them, to a greater degree than most apes or monkeys. It sounds like the sinal cavities being there to assist floating & breathing is quite possible - after all no one seems to have an idea what else they are for... apart from snot repositories...?

The idea of the aquatic ape is not that humans were scooting around in underwater packs like Flipper, but that they were wading, and occasionally diving down to relatively shallow depths to forage. Lots of things point to this being a believable stage of human development, but it's easy to get carried away with the romantic connotations of 'coming from the water'.

very nice photo. that's one happy ape.

f

[wet]

Originally Posted by trux

Ape backfloater? I found one. Does it mind he swims on the back of someone else?

Attachment 20767 photo credit © Dailymail.UK

Good one ivo. but...that's piggyback riding, not backfloating! I saw a video of that orang hanging on to a guy that dove in to the water, the video was called 'diving orang', a misnomer, since the orang merely clutched on for dear life.

[wet]

Originally Posted by turtle

what about human babies? they're pretty good swimmers, unlike baby monkeys or apes. I'd call that a pretty big difference.

Lots of animals are good at apnea for hunting/foraging. Humans happen to be one of them, to a greater degree than most apes or monkeys. It sounds like the sinal cavities being there to assist floating & breathing is quite possible - after all no one seems to have an idea what else they are for... apart from snot repositories...?

The idea of the aquatic ape is not that humans were scooting around in underwater packs like Flipper, but that they were wading, and occasionally diving down to relatively shallow depths to forage. Lots of things point to this being a believable stage of human development, but it's easy to get carried away with the romantic connotations of 'coming from the water'.

very nice photo. that's one happy ape.

f

Right, our ancestry includes a shore-based society where swimming, diving for seafoods and backfloating were done along with gathering fruits and veggies, coconuts, seabird and turtle eggs, various hunting. While a dolphin or seal gets all their food under water, human ancestors maybe got 1/4 - 1/3, both at depth and in very shallow water and while beachcombing at low tide.

I emphasize the diving and backfloating, because no apes do it at all, and their anatomy reflects that. They do wade in very shallow freshwater collecting water herbs, fallen fruit, and water bugs, but never dunk their head, and they live far from tidal saltwater shores, which is where our ancestors lived, and about half of all people live today along coasts.

[wet]

Originally Posted by Mullins

By 'hopeless' I mean 'very poor'.

No human would survive in the water for any useful length of time unless they'd been taught how to swim, whereas most other mammals can swim significant distances with no tuition.

Many mammal young can swim, human newborns can swim long before they can walk or even crawl. Today, humans live in a high-tech society, quite different than ancestors a million years ago.

It doesn't come naturally to us. Similarly, it doesn't come natually to other hominids. I suspect that if you could train them in the same way you can train humans (which you can't, hence the notable absence of trained back-floating chimps), you could get similar results. What would stop a chimp from successfully floating face-up, assuming you could convince the chimp it was a thing worth doing in the first place?

Chimps, orangutans and gorillas have laryngeal air sacs in the throat which inflate from air in the lungs, these air sacs presumably keep the head above water, (theoretically but not yet proven) allowing an ape to float vertically and breathe continuously. Human ancestors' air sacs became vestigial (now only rarely visible as laryngoceoles in glass blowers and trumpeters) due to selection for diving and backfloating in saltwater, rather than only wading and vertically floating in freshwater.

Western lowland gorillas nest in or near swampforests, forage on floating water plants, often sitting up so air sacs are just above water surface. - All my Gorillas
Zooillogix : Are you hiding 125,000 western lowland gorillas in your pants or are you just happy to see me?
Fongoli stream chimps at shallow freshwaterwaterhole: National Geographic Magazine - NGM.com
Chimp hooting while wading in shallow freshwater: An Adult Chimpanzee Hoots Aggressively at Visitors Photographic Print by Michael Nichols at Art.com
Orangutan wading bipedally in shallow freshwater: http://www.riverapes.com/Me/Work/Bip...s/image002.jpg

Also, humans have paranasal air sinuses at the base of the nose and eyebrows (keeping the nose above water), while apes have basicranial air sinuses at the base of the skull (keeping the whole skull above water). Also human infants have fatty cheeks (buoyant), ape infants don't, human infants do not develop paranasal sinuses until later, so the fatty cheeks provide nasal buoyancy. The reason human newborns lack paranasal sinuses is most likely due to human difficulty in childbirth delivery; the human skull is large and has a hard time traveling thru the pelvic birth canal, so a newborn having a big nose with paranasal sinuses would create problems. Instead, the human newborn is very chubby (buoyant), while no apes are born chubby. As human kids grow, they lose their 'babyfat cheeks' while their nose and paranasal sinuses enlarge.

What's the physiological advantage we gain from our supposed genetic inheritance? We have the advantage of rational thought and a highly nuanced shared language, and we make use of these to survive in the water (by developing and communicating swimming techniques) but they are no more derived from an aquatic ancestry than our ability to make submarines is.

Human newborns swim without instruction (before language ability develops), no ape newborn does.

Humans drown because they're physiologically unsuited to being in the water. Put a human in the water unaided and depending on several factors they'll drown in a matter of minutes or hours, even if they have been taught how to swim. Dolphins on the other hand are well suited to the environment and drown only if something goes wrong i.e. they get sick or are forcibly held under. No comparison whatsoever.

Sorry, I don't understand. Most dolphins drown, most people that live along seashores don't.

[trux]

Well, I admit I am no expert, but I've read some articles about the aquatic ape theory, and must tell there are many quite interesting facts and claims. On the other hand, I agree there may be some problems with the theory too, and can understand the skeptics. That's also why it is called a theory and not a fact. Hopefully the research can bring more enlightenment. However, before rejecting the theory, I'd suggest getting some more information about it. David has some interesting articles and links on his website (* THE-ARC *), but there are plenty of other websites dedicated to the topic - just google "aquatic ape" and you get enough of links. You can also check some of the videos, books, and websites listed at http://apnea.cz/index.html?aquatic%20ape The BBC documentary is not bad.

[wet]

Couple posts at my other blog perhaps relevant:

Dude's Coffee Blender: oh yeah
Dude's Coffee Blender: just because
Dude's Coffee Blender: Mothers & Daughters : mengerti?

(pardon the non-English words and writing style)

[Mullins]

Ahh, where do I start. There are some very confused statements there Wet, and it's difficult to answer them. I have more of a problem with the way the aquatic ape theory is presented than with the theory itself.

First of all, if you are positioning yourself as a scientist or researcher then you should realise that you have a responsibility to present theories (and although it has some value this remains very much a fringe theory, not a mainstream one) as theory and not as fact. Is there definitive research that shows our recend (1mya) ancestors let a partially aquatic lifestyle?

As for human babies swimming... they can't as far as I'm aware. They wave their arms and legs in a manner similar to crawling, and do not raise their heads above water. Nor do they show any inclination to. As you say above, most mammals (even those without recent aquatic ancestry!) swim instinctively and we as humans are a fairly long way behind the rest of the pack given that failing to raise one's head to breathe is a pretty poor survival strategy.

So, it seems that pretty much all mammals swim from birth except for hominids. Of the hominids, which are bad swimmers, humans are the least bad but this is a marginal thing because we seem to rely mostly on our intellect for our relative success. This may in fact be a useful point in favour of the AA theory but there is always a tendency to go way overboard when presenting this stuff, probably because it's something some of us would like to be true. The fact is (and I'm no expert here) the AA theory remains much weaker than standard theories of human evolution and making big intellectual leaps in attempts to justify it does its credibility no good whatsoever.

I still have no idea what you mean with regards to dolphins drowning. They always drown because they live in the sea, for goodness sake. We live on land, where there is no water to cover our airways when we get sick. That doesn't mean we're any better at not-drowning, unless you consider staying away from the sea to be a good aquatic survival instinct!!

[wet]

Originally Posted by wet

Couple posts at my other blog perhaps relevant:

Dude's Coffee Blender: oh yeah
Dude's Coffee Blender: just because
Dude's Coffee Blender: Mothers & Daughters : mengerti?

(pardon the non-English words and writing style)

You've probably heard of the mammalian divers reflex, that's half of it.

The Aquaphotic Respiratory Cycle (ARC)

Explanation:

The Aquaphotic Respiratory Cycle (ARC) contains two components:

1) submergence - Mammalian Divers Reflex (MDR) (stifled inhale)
2) emergence - Photic Sneeze (PS) (instant exhale)

The MDR (from air surface to ~2m+ water depth) occurs when the face is suddenly pressured, chilled and darkened which results in a inhale reflex BUT since the face is submerged underwater, the inhaling reflex is stifled and converted into O2 conservation or Mammalian Divers Reflex.

The PS (from ~2m+ water depth to air surface) occurs when the face is suddenly well lit after dark adaptation, (pressure and thermal changes increase neural stimulus) -> fast forced CO2 exhale reflex in the form of a sneeze and oxygenation of tissues.

Mullins: As for human babies swimming... they can't as far as I'm aware.

You were given information which included videos of infants swimming and backfloating. Since you remain unaware that infants can swim, I think I'll stop here, as I see no point in continuing. Arguments are for lawyers and beached barking sea lions, not divers.

Trux: I am afraid, David, that you did not chose the best examples to support the aquatic ape theory.

Do not be afraid, Ivo. I merely intended to show parallel convergence of human (ancestors) and blue whales and the ARC-MDR-PS link. That is what I did, no more, no less. Support AAT? I have no idea, I'll take your word on that. Oh, the MDR is probably common in lunged fish too and most tetrapods when the lung-air aerobic metabolism is dysfunctional due to being underwater and gills can't get enough oxygen from the water, like some tidal areas and still waters.

Addendum on pygmy right whale air sac: Full size right whales forage at the water surface, swim slower than human sport swimmers, and are the fattest whales (float at the surface when dead, which is why whalers called them "right whales"). Pygmy right whales are far less fatty due to their small size and metabolism, so their laryngeal air sac adds buoyancy when foraging on krill copepods near the surface. Apes in shallow water generally seek surface Aquatic Herbaceous Vegetation (AHV) (see the gorilla videos) and only seek bottom foods (water bugs under rocks/leaves) while wading in ankle-deep fresh non-tidal water. Human ancestors at saline tidal seashores foraged for food from the shallows to perhaps 30+m deep. Because they were enveloped in a thin layer of buoyant thermoinsulative skin fat, denser bones were selected for, bringing the body to neutral buoyancy in seawater (similar to sea otters and walruses).

update: bowhead whales also surface feed and have lar. air sacs, AFAICT no other whales have lar. air sacs and do not typically feed at the surface. So, bowhead whales, pygmy right whales and apes forage near the water surface and possess laryngeal air sacs; while ancestral humans, sea otters, blue whales forage near the sea bottom and lack laryngeal air sacs.

Since the development of dugout boats/rafts, nets, hook-line fishing, mollusk rakes, etc. humans lost the habit of daily dive foraging, and expanded to non-tropical areas and up river systems. This happened before 50,000 years ago (People using boats at "inaccessable" East Timor left tuna fish bones 44,000 years ago), and probably after 100,000 years ago or so. (1 million year old Homo erectus had keeled dense skull rear and dense bones, while 200,000 year old Homo sapiens Idaltu apparently still had dense occiput/skeleton (with less hydrodynamic face and non-keeled skull) especially femur, indicating less significant daily dive foraging but more wading (with nets, per Marc Verhaegen), and later Homo Sapiens sapiens with lighter bones and skull indicating more walking/running, dugout boat/raft use, much less bottom diving, probably using throwing spears and atlatl spear throwers around inland waterholes and shores. Evidence of shore foraging: hand axes from 125,000 years ago at Eritrean reef, seal and shellfish remains from 164,000 years ago in cave at Mollusk Bay, Pinnacle Point, South Africa, ancient bare-foot-prints at Langebaans beach, South west Africa, Klasies River cave shellfish remains and ochre crayons, South Africa, Java shell tools.

By the way, the modern Australian crawl was actually derived from a Polynesian swimming stroke.
DDeden [AAT, Deeper Blue, The ARC, DCB]