Discussion on hypothesized ancestral human cyclical ARC dive-foraging

[wet]

May the force be with you all.


http://news.yahoo.com/s/afp/20090723...20090723160812

Baby whale requires mom's help to breathe:

"It was apparent that the calf was struggling to stay at the surface to breathe and was swimming around in tight, clockwise circles with only the tip of its snout protruding,"

Whales and otters, like humans, must learn how to coordinate their breathing to dive and surface efficiently.

Orcas attack female gray whale with calf, mother keeps calf above her to prevent orca ramming or drowning the calf, move to shallow water so orcas stop attack.
http://creagrus.home.montereybay.com...rcaattack.html

[wet]

Erika Schagatay : static apnoea

The spleen of diving mammals is an extra storage site for erythrocytes when
they are not needed for oxygen delivery.
This supply can be ejected into the circulation during diving to temporarily
enhance gas storage. This effect is also present in mammals specialized in
endurance running, eg, horses & dogs, and also in humans during intense
exercise. The purpose of the storage is likely reduction of blood viscosity
between these periods of activity. Splenic contraction in humans during
apnoea diving was first observed in Ama divers. The resulting Hb increase
is associated with an increased apnoeic duration, which is not present in
splenectomized subjects.
It was recently observed that the best performances in competitive apnoeic
diving were associated with the largest spleens, with volumes of up to 600
ml. The difference in splenic contraction between the smallest versus the
largest spleens measured in the elite divers was equivalent to an increase
of apnoeic duration by 30 seconds (unpublished observations). It is still
unclear if this represents genetic diversity and pre-selection or
training-induced changes, but the observed growth of a small accessory
spleen after removal of the main spleen suggests a high regenerative
ability. The Hb elevation during apnoea is greater in divers than in
untrained subjects and endurance athletes, suggesting a training-induced
promotion of the response.
Splenic contraction has been shown to be an active contractile process. It
is at least partly induced by hypoxia. It was originally suggested to be
part of the human diving response, but it now seems that it is not linked to
the cardio-vascular response, as the two responses are not induced by the
same stimuli and occur on separate time scales. Splenic contraction
develops progressively across an apnoea and may need several apnoeas to
develop fully (Figure 3).

> E Schagatay 2009 Diving and Hyperbaric Medicine 3:88-99
> Predicting performance in competitive apnoea diving
> Part I: static apnoea
>
> Ever since the first deep diving competitions were organized, there has been
> debate about when the ultimate limits of human apnoeic performance will be
> reached, and which factors will determine these limits.
> Divers have thus far surpassed all former predictions by physiologists in
> depth and time.
> The common factor for all competitive apnoea disciplines is apnoeic
> duration, which can be prolonged by any means that increase total gas
> storage or tolerance to asphyxia, or reduce metabolic rate.
> These main factors can be broken down further into several physiological or
> psychophysiological factors, which are identified in this review.
> Like in other sports, the main aim in competitive apnoea is to extend human
> performance beyond the known limits.
> While a beginner may extend apnoeic duration by getting closer to his or her
> personal limit, the elite diver can only extend the duration further by
> pushing the individual physiological limit further by training.
> In order to achieve this, it is essential to identify the performance
> predicting factors of apnoea sports and which factors can be affected by
> training, work that has only just begun.
>
> This is the first of two papers reviewing the main factors predicting
> performance in competitive apnoea diving, which focuses on static apnoea,
> while the following paper will review dynamic distance and depth
> disciplines.
> Great improvements have been made in all diving disciplines in recent years
> and the 10-minute barrier in resting 'static apnoea' has been broached.
> Despite this, current training methods and the strategies employed suggest
> that duration can be prolonged still further, and divers themselves suggest
> the ultimate limit will be 15 minutes, which appears physiologically
> possible, for example, with further development of techniques to reduce
> metabolic rate.

Also, bone from blood: how mineral salts are carried in blood to accumulate in collagen matrix to form bone, and how it can be recycled back into the blood for use elsewhere, and its relation to white blood cells.
http://www.eurekalert.org/pub_releas...-bfb072309.php

[wet]

Biological interpretation

30ma Dry-sit-feeding -> 20ma float-sit-feeding ->5ma submersed-crouch-plucking -> 2ma diving-backfloating -> .1ma boats/rafts

(Fruit, invertebrate and egg eating has always been a part of the monkey, ape & human ancestral diet, below specifies human ancestors only)


30,000,000 yrs ago:
Primates fed on dryland vegetation (appendix, dental) [eg. gelada], little swimming or wading

20,000,000 yrs ago:
Hominoids fed on wetland herbs (lily, sedge) [proconsul, upright spine (Aaron Filler on Morotopith), inflatable laryngeal air sacs, lost tail]

5,000,000 yrs ago:
Hominins fed on floating herbs and mangrove oysters, submerged upright crouch-plucking, lost lar. air sacs, descent of larynx, dense femur, gained hooded nose

2,000,000 yrs ago:
Genus Homo fed on benthic/reef seafoods; ARC diving/backfloating cycle, ambushing waterfowl from beneath and thirsty prey with hollow spears at waterside, dense keeled occiput and enlarged paranasal sinuses

100,000 yrs ago:
Species Homo sapiens fed on fish & large prey w/ harpoons, boats, nets, atlatls, fire, gradual reduction of diving/backfloating due to settlement in areas of heavy crocs/hippos (Africa) and cold (Eurasia) and rough waters (Pacific coast).

2,000 yrs ago:
Species Homo sapiens sapiens with increased trade developed weighted apnea sponge/pearl/dye mollusk/seaweed diving.

200 yrs ago:
Technologically advanced ocean whaling, ocean trawling, helmets, subs, scuba

5 yrs ago:
Discovery of ARC cycle as an integral part of human ancestral foraging patterns
-

Based on Sir Alister Hardy's article in New Scientist "Was man more aquatic in the past?", with further in-depth research.
Original article can be found here: Elaine Morgan or here: River Apes... Coastal People


> Hardy is often quoted, as saying ...
> "Man was more aquatic in the past..."
>
> But, when in the past... is in the past?
>
" To my mind, since most of the species-specific distinguishing features of genus Homo are not shared with the chimpanzee, it must have occurred at the time when the l.c.a. of chimp and human began to split into two species" (5ma). > Elaine


All hominoids (apes, humans) can breathe/vocalize with their mouth closed and their nose apically above their body (apes have longer necks than humans with hooded nose), efficient for upright foraging on floating vegetation, whether sitting or standing.

Only humans (with hooded nose) can dunk & crouch below surface to pluck submerged foods, then stand upright and exhale/inhale with mouth.

20ma Floating food = aquatic, surface foraging, part-time at brackish wetlands
5ma Submerged crouching/leaping = aquatic, shallow foraging, part-time at tidal wetlands/mangroves
2ma Diving/backfloating = aquatic, deeper foraging, surface rest, part-time at pocket beach reefed lagoons
.1ma Netting/boating = aquatic + technology, deepest foraging, driest, part-time at harbor settlements

45% of humans today live at coasts, 50% riparian/lacustrine/salt trade dependent

[FreeRestriction]

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

that apes a phony!! hes got a life jacket on!!!...

[wet]

Pleiotropy: Evolving the threatening number response

http://story.news.yahoo.com/news?tmp..._uc/nq20090724

Q: What's a biologists definition of a graph?
A: An animal with a long neck

A fellow accidentally ingested some alpha-L-glucose and discovered that he had no ill effects. Apparently he was ambidextrose.

A bloke walks into a pub, and asks for a pint of Adenosinetriphosphate. The barman says "That'll be 80p (ATP) please!" (note 100p = £1, and ATP is short for Adenosinetriphosphate, but you already knew that.)

Did you hear about the biologist who had twins? She baptized one and kept the other as a control.

Q: Why didn't the dendrochronologist get married?
A: All he ever dated was trees!

Q: What is the only thing worse than a mecium?
A: A Paramecium

Q: As what did the antibody go to the Halloween costume party?
A: As an "immunogobulin".

A red blood cell walked into a busy restaurant. The hostess asked, "Would you like to sit at the bar?"
The red cell answered, "No thanks, I'll just circulate.

Navy SEAL diver: apnea in outer space? http://news.yahoo.com/s/nm/20090724/...ce_shuttle_185

[wet]

Airway cells taste. Oral Cough vs Nasal stimuli->Oral Exhalation Sneeze.

Airway cells use 'tasting' mechanism to detect and clear harmful substances

The same mechanism that helps you detect bad-tasting and potentially poisonous foods may also play a role in protecting your airway from harmful substances, according to a study by scientists at the University of Iowa Roy J. and Lucille A. Carver College of Medicine. The findings could help explain why injured lungs are susceptible to further damage.

The study, published online July 23 in Science Express, shows that receptors for bitter compounds that are found in taste buds on the tongue also are found in hair-like protrusions on airway cells. In addition, the scientists showed that, unlike taste cells on the tongue, these airway cells do not need help from the nervous system to translate detection of bitter taste into an action that expels the harmful substance.

The hair-like protrusions, called motile cilia, were already known to beat in a
wave-like motion to sweep away mucus, bacteria and other foreign particles from the lungs.

The study is the first to show that motile cilia on airway cells not only have
this "clearing" function, but also use the receptors to play a sensory role. The
researchers also found that when the receptors detect bitter compounds, the cilia beat faster, suggesting that the sensing and the motion capabilities of these cellular structures are linked.

"On the tongue, bitter substances trigger taste cells to stimulate neurons,
which then evoke a response -- the perception of a bitter taste. In contrast,
the airway cells appear to use a different mechanism that does not require
nerves," said Alok Shah, a UI graduate student and co-first author of the study. "In the airways, bitter substances both activate the receptors and elicit a response -- the increased beating of the cilia -- designed to eliminate the offending material."

"These findings suggest that we have evolved sophisticated mechanisms to guard ourselves from harmful environmental stimuli," Ben-Shahar said. "Our work also suggests that losing cilia in the lungs, due to smoking or disease, would result in a reduced general ability to detect harmful inhaled chemicals, increasing the likelihood of further damaging an injured lung."

Human infants colic
Pinpointing cause of colic: UT Houston researchers identify organism

Researchers at The University of Texas Health Science Center at Houston say one organism discovered during their study may unlock the key to what causes colic, inconsolable crying in an otherwise healthy baby.

"Right now, pediatric gastroenterologists can treat just about anything that
comes through the door," said J. Marc Rhoads, M.D., professor of pediatrics at
The University of Texas Medical School at Houston, which is part of the UT
Health Science Center at Houston. "With colic, there is no evidence-based
treatment we can offer. Colic can be a dangerous situation for a baby. The
parent's frustration over the crying can lead to maternal frustration,
post-partum depression and even thoughts of harming the baby."

Published in today's online edition of the Journal of Pediatrics, the study
pointed to an organism called Klebsiella, a normally occurring bacterium that
can be found in the mouth, skin and intestines. In the study of 36 babies, half
of which had colic, researchers found the bacterium and gut inflammation in the intestines of the babies with colic.

"We believe that the bacterium may be sparking an inflammatory reaction, causing the gut inflammation," said Rhoads, the lead investigator for the study. "Inflammation in the gut of colicky infants closely compared to levels in
patients with inflammatory bowel disease. Colic could prove to be a precursor to other gastrointestinal conditions such as irritable bowel syndrome, celiac
disease and allergic gastroenteropathies." Babies in the study were fed breast milk and/or formula. Previous research articles have not shown significant data supporting the theory that breastfeeding protects infants against colic.
-

Why would colic be evolutionarily advantageous in infancy? Mildly increased retention of GI gases allowing higher backfloating?
Why would mumps be evolutionarily advantageous in childhood? Mildly improved hydrodynamic profile beneath the jawline, where formerly the laryngeal air sacs had inflated, and during puberty males grew hydrodynamic beards and females tended to develop mild thyroid goiters? Did chicken pox provide a benefit to naked sea divers in the past in some way, perhaps associated with skin glands and drying salt?

(Today mumps, colic, goiters, chicken pox are diseases, but they may have provided benefits in the past. The idea is that in the past, these highly contagious and uncomfortable but usually not harmful conditions were spread through childhood contacts in dispersed populations along the coastlines. These differ from other more dangerous contagious diseases such as small pox, measles which, if I'm correct, were beneficial to the ancestral population much further back in time, and since the human genome has changed so much since then, the diseases are far more dangerous, largely because of our immune system reactions. Similarly obesity, diabetes, hypertension once provided positive survival traits against starvation, cold and salt shortage, but now cause secondary health problems due to different, modern sedentary lifestyles.)

[Mr. X]

Hi Wet,
Life is short, any chance you could parse the information you are posting and just give us a synopsis of your interpretation of its relevance (maybe just insert links to external references)?

[wet]

Fishing boat finds oldest underwater human bone - Yahoo! News
BERLIN (AFP) – A fishing boat trawling for mussels off the Dutch coast has instead landed a 40,000 year-old human bone, German scientists said on Sunday after examining the find. Anthropologists from the University of Leipzig in eastern Germany confirmed that the forehead bone was "at least 40,000 years old and therefore the oldest ever found underwater," according to August's edition of GEO magazine. The fishermen also found the caveman's "tool kit", consisting of a hand-axe and flints... the man dwelt on land and primarily ate meat [waterside ambush]".

NEWS: Spectacular discovery of first?ever Dutch Neanderthal Fossil skull fragment unveiled by Minister Plasterk in National Museum of Antiquities PalArch
-
http://www.pnas.org/content/105/38/14319
Neandertal exploitation of marine mammals in the Gibraltar caves (Vanguard and Gorham's). The Neandertals left some seals and dolphin bones with cutmarks behind, along with a lot of mollusk shells.
-
Neandertal diet was not dolphin-safe | john hawks weblog
Stiner (1993:191ff) documented shellfish remains in the Middle Paleolithic strata of Moscerini Cave, Latium, Italy. One of the interesting elements of the Moscerini shellfish remains was a fluctuation over time between two kinds of shellfish: mussels and smooth-shelled sand clams. These two kinds of bivalves live on different substrates -- mussels attach to rock, while sand clams, well, bury themselves in sand. Distinct pulses of alternating mussel and sand clam remains occurred in the site, and Stiner interpreted these as a consequence of local abundance of these different bivalves, which may have changed over time due to local sedimentation, sea levels, or other hydrological factors.

But this fluctuation raised a point about the Neandertals: they weren't carrying the clams or mussels very far. They left in the cave a small fraction of the species variety of shellfish in the environment; the two kinds of bivalves are approximately equivalent in calories and nutritional yield. Their choices of which shellfish to bring into Moscerini appear to have been guided foremost by locational convenience: one kind of shellfish patch, on rock or in sand, may have been closer to the cave entrance at any given time in the past. The case of Moscerini, contrasted with the lack of much evidence for shellfish exploitation at neighboring Mousterian caves only slightly farther inland, indeed suggests the influence of this simple energetic principle. Assuming that transport distance is generally limited by the relatively low caloric yield of these bivalves, regardless of substrate source, hominids may have been willing to carry the shellfish to shelter only from the closest patches before eating them. Otherwise, hominids might have preferred to eat the shellfish where they found them (Stiner 1993:191) [Johnhawks.net.]
-
Australasia Hunter-Gatherers Used Shell Tools: Discovery News
In published research to date, Szabo reports having excavated shell tools dating back 32,000 years from a cave site in eastern Indonesia, and comparing them with stone tools from the same cave. "It transpired that the shell tools were in fact much more complex to produce than the stone tools," she said. The stone tools were randomly chipped, but the shell tools had been carefully chosen and shaped.
-
ScienceDirect - Journal of Archaeological Science : Shell tool use by early members of Homo erectus in Sangiran, central Java, Indonesia: cut mark evidence
Shell tool use by early members of Homo erectus in Sangiran, central Java, Indonesia. Cut mark analysis of Pleistocene mammalian fossils documents 18 cut marks inflicted by tools of thick clamshell flakes on two bovid bones created during butchery at the Pucangan Formation in Sangiran between 1.6 and 1.5 million years ago.
-
Sibudu_CaveAt a rockshelter 15 km (9 mi) inland of the ocean, evidence has been found of some of the earliest modern human technology including the earliest bone arrow (61ka),[2] needle (61 ka),[2] and (72 ka) use of heat treated mixed (plant & ochre) compound gluing. (Birch pitch, mineral tar, fish glues, tendons, palm fibers, roots used in other locales for hafting)
-
Access : Early human occupation of the Red Sea coast of Eritrea during the last interglacial : Nature
Early human occupation of the Red Sea coast of Eritrea during the last interglacial: "Here we report the discovery of early Middle Stone Age artefacts [Acheulean Hand axe] in an emerged reef terrace on the Red Sea coast of Eritrea, which we date to the last interglacial (about 125 kyr ago) using U–Th mass spectrometry techniques on fossil corals. The geological setting of these artefacts shows that early humans occupied coastal areas and exploited near-shore marine food resources in East Africa by this time."
-
Blombos_CaveNatl Geographic Jan 1999: Standardized bone spear points, drilled ochre, large fish vertebrae in cave 905, - 80 ka. "Henshilwood thinks that fish were lured with bait and then speared with bone points tied to wood shafts"
-
Earliest Evidence Of Modern Humans Detected
Abstract for presentation at XVII INQUA Congress 2007: Cave life history at Pinnacle Point (Mossel Bay, South Africa):
Scientific optical dating techniques show from 164,000 years ago three hallmarks: harvested and cooked seafood, reddish pigment from ground rocks, and early tiny blade technology. Most of what Marean found were the remnants of brown mussels, but he also found black mussels, small saltwater clams, sea snails and even a barnacle that indicates whale blubber or skin was brought into the cave.
-
World’s Oldest Manufactured Beads Are Older Than Previously Thought
82ka marine shell beads in Morocco cave (Homo sapiens, not neandertals, transported shell beads)
-
Middle Paleolithic Shell Beads in Israel and Algeria -- Vanhaeren et al. 312 (5781): 1785 -- Science
100-135ka marine shell beads brought inland in Algeria, Israel
-
cont'd next post

[wet]

The selection for diving and surfacing efficiency (in reference to foraging effectiveness) increased up until hand crafted technology prevailed (harpoons, hooks, nets, rafts/boats) giving rise to mass foraging whilst above the water surface. This technology allowed foraging success in areas where diving had been hazardous (cold rough water, fast predators) or marginally productive. By 40,000 years ago, fast swimming tuna was regularly caught using technology, whereas a million years prior the catch had been largely limited to slow or non-moving prey (eg. benthic sessile oysters, marine snails) and aquatic herbaceous vegetation (eg. water lily/lotus, papyrus pith, cattails, seaweed, water fern).

The development of the hydrodynamic jabbing spear and the later aerodynamic throwing spear and atlatl allowed hunting from a greater distance and speed. The parallel development of the hydrodynamic hand axe/ tomahawk and associated blade production improved food procurement as well.

Geological evolution, MSC to Pliocene Mediterranean, NW Europe, 5ma - 2ma
http://www.searchanddiscovery.com/do...0/plate_20.jpg
http://www.searchanddiscovery.com/do...0/plate_21.jpg

Hydrodynamic hand axe tomahawk
http://failedartists.com/heidi/galle...aleolithic.jpg
Red Eagle Gallery - Tomahawk L-Th-109
Anthropologist professor Greg Laden: "There were about eight of us down below high tide line at Marblehead, Mass. Marblehead is a head of land (that's a coastal/nautical term) made of rhyolite, which is a workable stone for making stone tools. We were harvesting the rhyolite to use in the lab, but also, we were making a lot of stone tools on the spot. If you are at a source, you might as well spend several hours working the rock". gregladen.blogspot

Whereas a club is useful only in the shallows and ashore due to poor hydrodynamic profile:
Yahoo! Image Detail for http://www.silvermane.com/images/ke-2606.jpg

Atlatl spear thrower and harpoon:
File:Wells Reindeer Age articles.png - Wikipedia, the free encyclopedia
(I think a modified atlatl can function underwater as a spear thrower, if the wood stick is narrower (sword-like?) than the spear (sharpened reed, barbed with bone, shell or stone microblade tip).

BlowgunBlowgun: The blowgun can also double as a breathing pipe and straw (inhaled while submerged, forcibly exhaled while shooting). Its propulsive power is limited by its user's respiratory muscles. In Borneo, a bayonet-like speartip was attached for use against wild boar attacks. Blowguns were rarely used by indigenous tropical tribes as anti-personnel weapons, but primarily to hunt small game such as monkeys. North American Cherokees were known for making blowguns out of river cane to supplement their diet with rabbits and other small creatures.

[wet]

Originally Posted by Mr. X

Hi Wet,
Life is short, any chance you could parse the information you are posting and just give us a synopsis of your interpretation of its relevance (maybe just insert links to external references)?

1) Gathering of immobile floating food at water surface (lily, sedge)
2) Gathering of slow moving food at water bottom (clams, oysters)
3) Probing/spearing of prey at waterside (crabs, ducks)
4) Group ambush hunting/bait fishing of fast moving pelagics (deer/fish)

Diving and surfacing efficiently were strongly selected for within coastal populations in stages 2 & 3, less so in stages 1 & 4. Stage 5 would include pastoral herding, sedentary agriculture, further advanced technology, which has resulted in aerobic endurance walking/running/working having been selected for more recently in the evolutionary sense.

[wet]

[Maternal/medical section] [Note: Not medical advice, only hypothesis]

Ancestral backfloating (on reed mats?) & breastfeeding, Possible correlates

infant nursing prone (on belly), mother semi-supine (on back)
infant resting supine is anti-SIDS (Sudden Infant Death Syndrome)
Infant resting supine with gas bubbles in GI tract lifts belly and nose up
Human infants have colic, why advantage? Atypical condition for mammal.
Baby elephant seals have sleep apnea, prevents inhaling water when asleep.
Fat human children/adults more often have sleep apnea
-

Study Suggests Mothers Should Be Semi-Reclined to Nurse: Optimal positions for the release of primitive neonatal reflexes stimulating breastfeeding. Colson SD, Meek JH, & Hawdon JM (2008), Early human development, 84 (7), 441-9 PMID: 18243594

Maternal and infant postures were characterized by whether they were consistent with "biological nurturing" (BN), a breastfeeding approach in which the mother is encouraged to lean back and the baby is held prone, facing the mother and in contact with her body contours. [Other apes do not nurse this way, only humans.]

When mothers who were experiencing breastfeeding problems assumed BN positions, often became the active agent controlling the feed, aided by the different types of [reflexes]" (p. 5). In contrast to prevailing advice that breastfeeding mothers should sit upright and support the baby's back and head, biological nurturing involves semi-reclined positioning with the baby prone and in close contact with the mother's body. Babies in full-biological nursing positions employ anti-gravity reflexes to locate the breast and latch without dorsal support, and their mothers assist them in that task.
[So when the mother nurses while standing or sits up like a mother chimp on a tree branch, the human baby's reflexes are confused, but when the mother is semi-supine-reclining, the baby's reflexes fit. This doesn't mean ancestral nursing was done while backfloating, but it is possible, perhaps while sitting in shallows.]
-

[From Elaine Morgans' AAT books, on SIDS]

A paper published by J. J. McKenna in 1986 gives a valuable background to the nature of the problem and the way it was being discussed at that time. One point made very clearly is that the problem of SIDS is 'unique among mammals'. 'SIDS does not occur in other species.' McKenna laid most stress on breath control. J. T. Laitman 'We have noticed that the first instances of oral tidal respiration are found in infants between 4 and 6 months'. The salient factor, then, seems to be not when the larynx is fully descended (by that time the danger of SIDS is over) but when it first loses its secure contact with the palate.

Edmund Crelin published a paper on it, suggesting that the difficulty arises when the infant's larynx is no longer securely locked in above the palate, and not yet safely tucked away below the base of the tongue, but at the back of the mouth on its way down. He thought that at this vulnerable time, when the baby was lying prone, there was a possibility that the uvula could enter the opening of the windpipe and block it up, causing asphyxia and death. The advice to lay the babies on their backs was promoted in Holland in a nation-wide campaign, and it cut cot deaths by 40 per cent in one year. In 1991 Britain launched a 'Back to Sleep' campaign (that is, 'on their backs to sleep') and in 1994 a newspaper headline proclaimed: 'Cot deaths show 70 per cent drop over past 5 years'. There may be other factors involved, such as general health or infections, but the scale of success of the 'Back to Sleep' advice seems to provide overwhelming evidence that Crelin got the priorities right. The only thing changed by following this advice is the direction of the force of gravity relative to the baby's respiratory organs, acting on the only organ loose and mobile enough to be affected by it. That is the unattached upper end of the infant's larynx."

[wet]

Drinking at seashores.

The idea that since humans can't drink saltwater, so our ancestors must not have spent much time in the sea, is rather odd, since the purpose of slow dive foraging was to consume prey rich in hypotonic (low salt) fluids. Humans like other mammals need to consume salt daily to maintain a healthy metabolism, as part of the diet. When marathon runners or swimmers rehydrate, they can't just intake freshwater, they need mineral salts as well.

The reason that marine mammals don't typically drink much seawater is because they don't develop water-thirst and salt-hunger patterns that terrestrial animals do, since their food contains hypotonic (low salt) fluids, they don't sweat, and their excreted/exhaled fluid is conserved.

Apes get most of their fluids from fruits and herbs, and living in the rainforest many plants (bromelids, epiphytes) accumulate small water puddles high in the canopy, lianas may contain watery saps.

Freshwater streams and sub-marine spring seeps along coasts provide drinking water and tropical coconuts contain sweet watery fluids. Coastal rains provide a brackish sea surface less saline than deeper denser sea water.

Cooking removes fluids, and salt is added to vegetables and meats, so additional fluids are drunk alongside; not necessary when eating fully hydrated fresh fruits or seafood. To avoid drinking ponded stagnant 'freshwater' which might contain parasites, when freshwater rains were insufficient, historically, either boiled teas with anti-microbial tannins, bitter or mint herbs, pinch of salt or low alcohol drinks (beer, mead, palm wine) were served.

The only time that saltwater consumption would occur was during extended exercising, such as while climbing seacliffs searching for seabirds and eggs, long distance swimming and while beachcombing/jogging, when body salts ran low due to eccrine sweating in tropical heat and humidity.

So saying that humans can't drink seawater isn't very significant, like marine animals, it is only done to replace lost mineral salts.

Responses from/with Marc Verhaegen at AAT group: Yahoo! Groups

[wet]

On carrying and drinking saltwater inland

"70,000 to one" by Quenton Reynolds about a Mr. Manuel, a US pilot shot
doen in WWII over the island of New Britain (near Papua).

P 105 Many years before the Maculculs and Baining tribes
had an argument. Both tribes lived inland [mountains], their fathers and
grandfathers lived within ten miles of the beach but had never
seen the ocean. Now somehow, the natives had always known
that salt was necessary to maintain their good health. This belief
had been handed down from generation to generation. Once a
week, natives would make the trip to the sea to bring salt water
back to their villages. They would carry the water in bamboo
containers. These were ordinary bamboo logs, about 4 inches
thick, hollowed out, but closed at both ends. The Bainings would
bore several holes near the end of the log, fill it with water, and
then carry it back. The maculculs used the same type of
containers, but would cut off one end. They insisted that the
Bainings follow their method to conform to custom, which was
rejected by the Baining, so they went to war.

[wet]

Spleen

http://www.nytimes.com/2009/08/04/sc...er=rss&emc=rss

...the spleen is a reservoir for huge numbers of immune cells called monocytes, and that in the event of a serious trauma to the body like a heart attack, gashing wound or microbial invasion, the spleen will disgorge those monocyte multitudes into the bloodstream to tackle the crisis.

In one study that appeared in The Lancet in 1977, for example, researchers compared a group of 740 American veterans of World War II who had had their spleens removed as a result of battle injuries with a similar size sample of veterans who had suffered other war injuries but had kept their spleens. The splenectomized men, the researchers found, were twice as likely to die of cardiovascular disease as were the veterans in the control group. More recently, researchers determined that the spleen is like an elaborate wetlands, a Mississippi bayou for filtering and freshening the blood. In other organs, blood flows through an interconnected mesh of increasingly narrow arteries, veins and capillaries. The spleen, by contrast, has a so-called noncapillary circulatory system: as the blood flows in, it is dumped into puddle-like sinusoids, and to get back out it must squeeze between cells. That dumping and squeezing help filter out blood-borne parasites, aging blood cells too brittle for compression and the little oxidized pellets, the BB’s, with which red blood cells are often pocked. The spleen has often been called a graveyard for red blood cells, but it is more of a recycling center, for the iron and other components are plucked out of the cells and used to stock new hemoglobin cages.

By the researchers’ reckoning, monocytes, like all blood cells, are born in the bone marrow and at some point migrate to the spleen, lured by cues yet to be identified. They sit and wait, a sessile bunch, but when aroused by such chemical signatures of damage as angiotensin, the cells surge forth without hesitation,

[wet]

Conjectural thoughts: Sneeze vs Contraction

Both MDR and ARC depend on the trigeminal nerve to engage via apnea/eupnea reflex, the MDR at dark cool depth, the ARC at sunny warm surface.

If the ARC is inverse/reverse of MDR, are repeated photic sneezes inverse of diaphragm contractions? Both diaphragm contractions and sneezes are repeated involuntary thoracic muscle twinges which vary in intensity with individuals. [But they seem very different and unrelated to each other?]

MDR: Mammalian Diving Reflex, engaged in apnea at depth
ARC: Aqua-photic Respiratory Cycle, where sun sneeze/exhalation induced eupneic breathing at surface alternated with diving apnea in MDR at depth.

Where presumably diaphragmatic contractions function as an accessory pump mechanism to move oxygenated blood to the core from the extremities, in addition to the MDR extremity vasoconstriction.

Do repeated sneezes move blood from the body core outwards, as a supplemental pump? (I would say yes, but how effectively?)

photic sneeze: triggered by dark to light at trigeminal nerve
contraction: triggered by high CO2 at chemoreceptors (via vagus?)

Do people with photic sneeze have stronger/weaker contractions or no correlation?

Note: Recurrent laryngeal nerve is very strange in all mammals, it loops from the larynx down around the aorta and back up to the brain. Might this relate to tension of the aortic flow, and the MDR, and possibly sneezing? (doubtful, but compare human to ape laryngeal air sac/thyroid/larynx descent and to sea otter, whale and seals.)

Is a person with alkaline blood more susceptible to sneezing/asthma/allergy?
... acidic blood ... ?

If I inhaled through the nose strong CO2, I'd get contractions/inhale. (ADR's post)
If I sniffed through the nose strong scented dark chocolate/mint/liquor, I'd sneeze/exhale, just like a sun sneeze after dark adaptation.