Discussion on hypothesized ancestral human cyclical ARC dive-foraging

One second exhalation/inhalation cycle in sea snakes

Sea snakes are also neat in that they practice cutaneous respiration, being able to absorb up to 20% of their oxygen requiremens through their skin. That’s right: cutaneous respiration isn’t limited to lissamphibians (frogs, salamanders) among tetrapods. They can stay submerged for up to 3.5 hours and might only surface for 1 second (literally): in fact Yellow-bellied sea snakes Pelamis platurus, the only truly pelagic sea snake, spends an average of 87% of its entire time submerged.

Special soft-tissue valves allow sea snakes to close their nostrils while they’re underwater and their lung is highly specialized. ‘Lung’, why not ‘lungs’? In snakes generally the right lung is enlarged relative to the left lung (or, rather, the left lung has reduced in size), but in sea snakes the right lung is modified for air storage. Its posterior part (the so-called saccular lung) has unique thick, muscular walls* that allows stored air to be forced forward into the functional anterior part (termed the bronchial lung) and the anterior projection of the lung (the so-called tracheal lung) is large and extends well forwards relative to that of terrestrial snakes. The presence of the reduced left lung is variable in sea snakes: most species lack it, but it’s present in some laticaudid individuals.

Darren Naish: Tetrapod Zoology: ?A miniature plesiosaur without flippers?: surreal morphologies and surprising behaviours in sea snakes

Seals' muscles hide a built-in scuba tank - life - 14 October 2008 - New Scientist

AN OXYGEN reservoir within seals' muscles could explain how they can
dive underwater for up to 80 minutes at a time without taking a breath.

Seal muscle contains 20 times as much myoglobin - a protein that
stores and transfers oxygen within their cells - as humans. Seals also
stop breathing for 20 minutes at a time while asleep on land, which
probably helps them conserve energy.

Thomas Jue of the University of California, Davis, and his team
measured the levels of deoxygenated myoglobin in two elephant seals as
they fell asleep. They found that as the animals fell into a slumber
and stopped breathing, their blood flow slowed. "The metabolism
drops," says Jue.

Oxygen levels in the seals' myoglobin fell by 20 per cent within the
first minute of sleep, as the cells used up their oxygen stores. This
freed myoglobin to pull more oxygen from the blood, stabilising the
cells' oxygen level until the seals started breathing again (Journal
of Experimental Biology, DOI: 10.1242/jeb.025130).

Jue admits that the animals might use oxygen differently while diving
but says this method is better than forcibly immersing seals in water,
whereby "the animal exhibits the physiology of panic".
From issue 2677 of New Scientist magazine, 14 October 2008, page 16

(sleep apnea occurs in humans, especially humans with abundant subcutaneous fat)

trux said:

Yes, definitely. But what I would like to see is some serious research verifying the speculations, instead of presenting them as facts.

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Presenting them as illustrations rather than facts.

Comparing the speed of exhale with that at whales or dolphins is misleading - their opening is very small in proportions in comparison to us, so the air at exhale escapes under immense pressure, and therefore at great velocity.

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A young vaquita probably has proportionately a larger blowhole than a human using lips or tongue to valve the exhale during a sneeze. Humans have extraordinarily good control of tongue and lips.

Still it is not immediate flushing of the lungs like at the sneeze with possible drop of partial pressures. Quite oppositely, by forcing the air out through a small opening, whales create great overpressure in lungs, hence increasing also the PaO2, and helping so getting the last rest of oxygen to diffuse into blood even during the exhale.

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Human ancestral divers were in no way as efficient in respiration as cetaceans are (with 50 million years of natural selection for improved marine-related respiration). But they were vastly more efficient than their genetic closest relatives, chimpanzees, which do not dive at all, or crab-eating macaques, which dive only a meter or so on occasion. Neither macaques nor chimpanzees appear to have a photic sneeze reflex.

Humans, upon initiation of a sneeze, also pressurize the lungs when the nasal soft palate valve closes and the pursed lips or tongue-hard palate valve closes momentarily then opens to let the air exhale, so it is conceivable that some amount of O2 is absorbed into the bloodstream via the alveoli at that moment. (This may have been more effective long ago)

I am not quite sure if the same can be applied to human sneezing, and really would prefer seeing scientific measurements than speculations.

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Of course.

Experiments with people with strong photic sneeze reflex could and should be done to see if the PaCO2 and PaO2 drop during or after the sneeze or not, increasing so the risk of blackout;

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I still see no reason to think a surface sneeze and instant inhalation would cause a blackout. If a diver is that close to losing consciousness, they already went beyond their limits, with or without a sneeze, right? The photic sneeze was presumably part of daily foraging, not record breaking max apnea time clock competitions.

if it really leads to faster oxygenation than proper ventilation;

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If it worked as presumed, it was proper ventilation.

if photic sneezing is really prevented underwater; etc.

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I've never heard of anyone sneezing underwater under any circumstances.

Perhaps genetic mapping of photic sneezers might give some idea about the history and origin of it. The real life experiments with photic sneezers freediving, to see if they drown due to inhlation of water after the sneezing,

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I think you are imagining worst case scenarios that are based on max breath hold attempts, which daily forage divers avoid. Sneezing is near-instant exhalation/inhalation, something which sea snakes, marine iguanas, whales, seals do when they surface after a long dive, whether you call them sneezes, spouts, spurts, blows, etc.

if the surfacing really triggers sneezing, if it helps shortening their recovery time, iand what other side efects it may have ...

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Certainly of interest. I can't think of any. (I'm referring to 1ma divers)

As for pressure sensors preventing photic sneeze - I well believe and hope that the body is clever enough not to sneeze underwater, but I do not think it could be the water pressure on the nose base that prevents it.

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It requires dark adaptation, then bright light in the eyes, for it to happen at all. I agree that it may not be specifically water on the nose base, that was a bit simplified, but the result is the same, no sneezing under the surface. The trigeminal goes through the nasal mucosa, the nose tip, the frontal sinuses, the eyelids, the brows, the forehead, and the eyes via the occulomotor nerve, all of which are involved.

The pressure is equal outside and inside the body - in depth (or in a barochamber), you simply do not feel any increasing depth anywhere else than in body parts with closed cavities filled with air (lungs, sinus). Hence water pressure on the nose base is not a likely mechanism for preventing photic sneezing under water. In such case the photic sneeze would also not work with a helmet, at higher atmospheric pressure, in barochambers, etc (which I doubt is the case).

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To stifle a sneeze on dry ground with a forefinger pressing up on the nose base is voluntary and conscious, while submersed sneeze retention is reflexive, no need for voluntary stifling. For the same reason marine mammals dolphins don't exhale under water at depth, we don't sneeze.

The humpback whale does release bubbles while "bubble-netting" fish, I don't know if that is from the mouth or blowhole, but since it relates to food harvesting, it could be considered a functional modification of respiration, developed long after normal marine breathing was established, similar to dolphins with their nasal whistles and clicks.

DDeden

OT: Discussion/argument on neandertals, sapiens, mammoths, seafood, boats,
harpoons, nets, firepits, shores, etc. A bit too redundant and long,
but some good points brought up, not specific to diving & surfacing efficiently but related to waterside migrations and foraging habits and waterside technology between 100,000 yrs ago and the present.

The Hall of Maat :: Ancient History :: Neanderthals Conquered Mammoths, Why Not Us?

DDeden

[ame=http://en.wikipedia.org/wiki/Lung_volumes]Lung volumes - Wikipedia, the free encyclopedia[/ame]

Modern human lung volumes (adult male average)

I've made many speculations on human ancestors regarding waterside living, mostly at AAT yahoogroup.

The three I consider most significant are:


Human and ape ancestors LCA (Last Common Ancestor, including Hominoid, Hominid, Hominin) (20ma to 5ma?, ma = million years ago), also see Aaron Filler hyp. on Morotopith spinal change etc.) occasional/habitual vertical floating-treading in combination with vertical climbing, vertical sitting, vertical posture, vertical feeding, vertical wading, with enlarged laryngeal throat air sacs inflated 1/2 liter or more, allowing the head to remain above water while aerobically breathing/wading/treading. The key is that the far more normal mammalian habit of horizontal dog paddling was replaced by vertical clinging/wading/treading/sculling at the surface, while surface foraging. This may have occurred in some other animals (sifakas, indris, some macaques) as well, living in tidal-affected coastal forests, typically resulting in tail shrinkage and unequal length of forelimbs and rear limbs and a change from dog-style or monkey gait to hopping/galloping/breast-stroke locomotion. Further enlargement of laryngeal air sacs is probably due to dominance in intra-specific competition and predator/stress calls.


Human ancestors (5ma-.1ma?) at tidal lagoon seashores developing continuous vocalization (humming, song, speech, clicks), alternating diving partnerships, hair patterns for both diving and surface backfloating with infant, unusual nursing pattern and care compared to primates, chubby-cheeked pug-nosed infants (birth constraints) and adults with protruding nose and large paranasal sinuses, etc. http://forums.deeperblue.com/739636-post17.html


Human ancestors (5ma-.1ma?) at offshore reefs developing improved diving cycle, where, as typical among marine (part-time and full-time) air breathing animals, shallow water (2meter, 30 second) dives were repeated with normal brief breath-holds and voluntary exhales (under sunny or not sunny conditions); were alternated with deep dives (3m-30m+, 4 minutes+) for deeper benthic foods (and possibly ambush spearfishing at times), wherein the exhale/inhale correlated to bright sunshine at the surface and strong dark adaptation (and visual accomodation) at depth. This was a combination of the Photic Sneeze Reflex and the Mammalian Diving Reflex, both associated with the trigeminal nerve in the face, brow, nose and ears, and the lack of sensory vibrissae in primates unlike typical marine mammals (but parallel to sea snakes and marine iguanas).

===

I've written extensively about these, some info is outdated (eg. I now doubt hyperventilation was ever used while dive foraging, though I stated elsewhere the possibility earlier.)

I've been asked if I support AAT, I do, if these are included, since they each fit what I perceive to be the prehistoric pattern of Human ancestors, and answer many questions about why humans are so unusual compared to our closest related mammalian kin.

DDeden / Oct.18, 2008 / Deeper Blue dot com / Freediving-science / Diving & Surfacing efficiently

sweat breathing of human skin

http://forums.deeperblue.com/freediving-science/80570-breathing-throug-skin.html


(humans have many active eccrine sweat glands 2.6m, people from arid regions typically have fewer, apes have many inactive eccrine sweat glands.)

Blood: your private ocean
http://www.nytimes.com/2008/10/21/science/21angi.html?partner=rssyahoo&emc=rss

Yes, indeed so.

I added something here:

http://forums.deeperblue.com/736703-post80.html

http://forums.deeperblue.com/753618-post57.html
Wiley InterScience :: Session Cookies

The paranasal sinuses (PNS)

I figure they initially developed due to arboreal rainforest habitat foraging, then enlarged in human ancestors living along seashores, naturally selected both for better diving/backfloating facial buoyancy and humming (transmission of anti-biotic Nitric Oxide) between parent and newborn during backfloat nursing.

Newborn humans lack PNS but have chubby cheeks for buoyancy of nose. A few years of growth, children develop PNS and larger nose and slimmer cheeks.

Savanna baboons lack PNS, while closely related rainforest macaques have PNS.

So most probably when human ancestors lived in more forested coastal habitat 20-5ma, the PNS were somewhat small but significant (preventing humid airborne pathogens) alongside the laryngeal air sacs, then after the apes split away into the inland jungles and enlarged their laryngeal air sacs for vocalizing dominance, Human ancestors shrank their laryngeal air sacs but enlarged their PNS (and infant chubby cheeks) due to selection for more daily dive foraging and backfloating.

Note that NO is also produced regularly on the tongue and eccrine sweat glands (from Nitrate -> Nitrite -> NO), providing anti-biotic armor to the gut and skin. [See Dive Song for more information.]



this from article:

Paranasal Sinuses Implicated as the Site of Nitric Oxide Production

Lundberg ([2008], this issue) chronicles his discovery that the paranasal sinuses are the sole site of production of nitric oxide (NO) gas in the upper respiratory system. The fact that mammals lacking paranasal sinuses have a low NO concentration in gases exhaled by the nasal airway lends further credibility to the concept that the sinuses have a significant role in respiratory physiology. This by itself alters the traditional explanation of sinus physiology. Lundberg's article reports on an ongoing investigation of sinus physiology beginning with the discovery of NO gas production in the paranasal sinuses that began in 1994, and upon the impact that his finding has had, both in the basic science and clinical arenas (Lundberg, 1995). As NO gas from the nose and sinuses is inhaled with every breath, and as it reaches the lungs in a more diluted form, it enhances pulmonary oxygen uptake via local vasodilation. In this sense, NO may be regarded as an aerocrine hormone that is produced in the nose and sinuses, and transported to a distal site of action with every inhalation. The clinical value of this observation is that NO measures can be used for the diagnostic evaluation of sinusitis and other disease processes like primary ciliary dyskinesia, which causes low nasal NO levels.

Many new articles related to Para-Nasal Sinuses and larynges.

Wiley InterScience :: Session Cookies

The physiology and pathophysiology of human breath-hold diving.
Peter Lindholm & Claes EG Lundgren 2008 J Appl Physiol
doi:10.1152/japplphysiol.90991.2008

The diving response (MDR), exhibited by all air breathing vertebrates, is elicited by apnea and consists of peripheral vasoconstriction due to sympathetic activity, connected with initial hypertension, and a vagally induced bradycardia with reduction of the cardiac output. These circulatory changes are further strengthened by cooling of the facial area and/or hypoxia. In particularly responsive subjects, apnea has been noted to elevate peripheral circulatory resistance up 4-5 times concomitant with correspondingly intense bradycardia & reduced cardiac output. The bradycardia may be part of a reflex response to apnea, but there are observations that the blood pressure increase precedes the slowing of the heart frequency, suggesting that baro-reflex activation plays a role in the development of the bradycardia, as may chemo-receptor stimulation from hypoxia during the later part of the breath-hold. It is generally held that the diving response causes blood & lung oxygen stores to preferentially be distributed to the heart & the brain.

Another sympathetic reflex, which is part of the multi-faceted diving response, has attracted attention in recent years, namely the effect of breath-hold dives to enhance the hemoglobin concentration of circulating blood by splenic contraction, which occurs early during the diving-response cascade, actually preceding the bradycardia. Healthy, splenectomized persons do not exhibit the Hb increase when breath-holding. Higher Hb levels in breath-hold divers than in non-divers were found in one study,
which suggested long-term enhancement of Hb levels in breath-hold divers may be a consequence of an observed 24% increase in erythropoietin levels. These findings contrast with another study in which elite breath-hold divers had normal Hb concentrations & total Hb mass. To the extent that breath-hold divers do have increased Hb levels, it may be of the same nature as in persons suffering from obstructive sleep apnea, in whom the blood changes reportedly correlate with the severity of hypoxia during sleep, although, between the 2 groups, there are obvious quantitative differences in the exposure to hypoxia.

Cooling of the face, in particular the forehead & the eye region, is particularly effective in eliciting bradycardia. However, due to a marked increase in metabolism, breath-holding time during whole body immersion in cold water (20�C) was 55 % shorter than in the thermo-neutral non-immersed condition even if the heart rate was reduced by 26 % in the water. The diving response is highly variable among humans during both rest & exercise. Systematic differences also exist depending on age & presence or
lack of diving experience. The diving bradycardia is quite pronounced in children 4-12 months of age, and may have survival value during hypoxic episodes proximal to birth. The diving response weakens with advancing age

[wrong IMO, it weakens with absence of use, in the same way the the neonate swimming response weakens with advancing age due to absence of use. Both of these responses remain throughout a lifetime if diving is done daily. DD]

and is more marked among habitual breath-hold divers than non-divers. The diving response is rel.more pronounced during exercise than during rest. The oxygen sparing effect appears to be proportional to the degree of the bradycardia.

[The Diving Response MDR is only one half of the Aqua-photic Respiratory Cycle (ARC) equation.]

Laboratory and Field Investigations ... - Google Book Search

Two types of diving in marine mammals:

1) dense ribs/bones, full lungs (sea otter, manatee, seashore human ancestors) (dives not so deep, foraging non-mobile prey)
2) flexible rib cage, non-dense bones, collapsible lungs (seals, whales) (dives shallow to very deep, hunting mobile prey)

Both of these types need to exhale/inhale very quickly and efficiently except while resting. Sleep apnea is not uncommon.

Hearing, air vs bone/water conduction, equalization
outer ear
middle ear (to nasal cavity/throat via eustacian tube)
inner ear

http://forums.deeperblue.com/equalisation/81602-hearing-ear-treatment-devices.html

(hypothetical)
backfloating before diving, tilt head back, allow (sterile pure) seawater into nose while (fake) swallowing/yawning, water enters eustacean tubes and middle ear, continue until all air is removed from middle ears on both sides. (how to know?) no need to equalize ears while diving. When diving is done, remove water, hum & click.

need funding for testing...

Arboreal apes (chimps, siamangs, orangutans) vertically hang, swing and climb through the air acrobatically, they don't leap or dive in an aerodynamic fashion.

Humans can do this, but tend to streamline while diving, hydrodynamic/aerodynamic.
http://forums.deeperblue.com/beach-bar/81550-ot-wingsuit-skydiving-through-mountain-passes.html

Orangutans wading across stream, use measuring stick, small one stays dry.
[ame=http://www.youtube.com/watch?v=ZLF1tqyNt_4]YouTube - Orangutan measure depth of the river[/ame]

Gorilla wading with measuring stick at Ndoki swamp
[ame=http://www.youtube.com/watch?v=z5310MMBaWc]YouTube - Ndoki Rain Forest[/ame]

Vertical stability (keep nose/mouth above water) more important than speed or efficiency while wading or floating when foraging, aerobic breathing only.

Breath-hold dive foraging replaces vertical stability with apnea ability (oxygen/energy efficiency), significant selection for hydrodynamic streamlining.

A brief biological interpretive glimpse of the past five million years: "aquatic & terrestrial" in complement.

The human - chimpanzee genetic division occurred about 5 million years ago along coastal tidal brackish & freshwater mangrove forests & seaside cliffs, where they lived and dined on nearby fruit trees, mangrove oysters, shorebird and turtle eggs, aquatic herbaceous vegetation etc. and locomoted by vertically climbing/wading/floating/walking but not much swimming or diving. Some event caused a split, perhaps a climate change, which caused chimp ancestors to expand inland into closed coastal African forest and eventually along gallery (riverside) forests & seasonal swamps becoming more arboreal (tree climbing), while human ancestors expanded to more open coastal shores becoming less arboreal, and adapted to dip diving for deeper foods, probably at pocket beaches associated with sea caves, perhaps at Afar Danakil alps and coastal Arabia.

2.6ma conchoidal stone tool making was done north of the African Rift valley at Gona, near the Red Sea / Afar/Awash / Omo region. These were probably useful for cutting meat from bone, as seashells were similarly used in Java, Indonesia later on. Gona river valley soil overlaid mollusk shells, so they may have been seasonally at Gona much earlier than the stone tools found.

Some stone tool artifacts seem to resemble the later Acheulian bifacial hand axe (sharp all-around edges) so perhaps were used as bait traps against predators and scavengers, inserted in entrails / meat chunks / fish, getting trapped in the GI tract (cutting gut tissues or blocking respiration) of predators which wolf down their food without chewing, after a habit of using shells in the same way (similar to eskimos protecting caribou herds from wolves by inserting a knife into a hunk of meat or fish, or Karnataka trappers inserting wood splints in melons to snare antelope). Great apes and monkeys will typically urinate, defecate and throw food items at predators or others below them, so throwing shells with food may have eventually produced this correlation. (The capuchin monkey uses oyster shells to pry open other oysters off of mangrove trunks.)

I think that by 4ma face dipping while reaching for deeper items in water, prone floating, shallow dives selected for the uniquely human hooded protruding nose, and habitual wading/bipedal walking using a sharpened stick spear while foraging waterside, and probably baiting crocs and cats with various debris/waste as part of an overall predator avoidance method. Slowly (3-2ma) they became more adept at submersed foraging and breath control, losing their laryngeal air sacs and thick fur and developing baby fat, and backfloating in dense warm seawater allowed more foraging options in safety.

Likely during the annual monsoon rainy season the seashores became murky, so they went inland to collect various seasonal foods (fruits, nuts) and stone to break the nutritious mongongo nuts, inland tortoises and ostrich eggs, gathering and knapping stone in dry caves with some limited quarrying, any sign of initial quarrying would later be lost due to deeper digging but the many stone chips would be thickly buried alongside nearby rivers like the Gona. Men move mountains over time, just like water does.

Were they running over open plains in the hot sun? Far more likely they were beachcombing and backfloating in the warm sunlit waters and diving into the cool depths at the coasts during the dry season. But during the rainy season, they found inland seasonal fruits/nuts/stone/caverns or rockshelters, collecting freshwater fishes & shrimps, making sharp stone blades to cut freshwater papyrus stems and nutsedge tubers etc. and attacking small ungulates at waterside in ambush fashion as did neandertals on larger prey later.

Various groups would split off, many would go extinct, others that left the seacoasts permanently lost the tide effects and evolved local adaptations.

Were early human ancestors aquatic? Yes, groups swimming and diving in tropical bluewater coves. Was early man terrestrial? Yes, groups trekking inland when the foliage was turning green in the rains. Was early man arboreal? Not much, but was dependent on forest products, often found lower at waterside. Was early man an endurance runner? No, only walking routes inland during the rainy season I'd say, perhaps carrying seashells, tortoise and ostrich shells for water at some point in time.

By 1ma, they were well adapted to this combination of aquatic dive foraging (pairs in groups) and terrestrial gathering and quarrying (cliff cave climbing), of waterside ambush, scavenging and trapping, and had spread around the subtropical old world, seeking rich open quiet shores, peripheral woodland fruits with wading-stick spears and volcanic lands with sharp stones.

By 100ka, primitive hollow log dugouts and papyrus/bamboo rafts, harpoons and woven nets reduced the selection for forage diving, improved the overall efficiency of harvesting mass quantities of offshore fish for consumption and trade, limited by the technology, dangers of the open sea, storms and need to return to the shore. These boats allowed expansion and permanent settlement inland and in colder regions of the continents while maintaining an open line to the sea which our arboreal hominoid kin (apes) had severed long before.

DDeden ~ 2009

(not sure about the fruit & nut mast drop occurring during the rainy season in east Africa, but tubers and papyrus were available)

Variation and modalities of growth and development of the temporal bone pneumatization in Neandertals

A Balzeau & J Radovèiæ 2008 JHE 54:546-567

The temporal bone is used frequently to determine taxonomic affinities as it contains several features that differentiate Neandertals from anatomically modern Homo sapiens. However, only little information is available about temporal bone pneumatization in Neandertals. This study provides descriptions and comparisons of the disposition and the extensiveness of the
pneumatization of the temporal bone in large samples of Neandertal specimens of different geological and developmental ages (25 individuals and 33 temporal bones from the sites of Engis, Krapina, La Chapelle aux Saints, La Ferrassie, La Quina, Pech de l'Azé, and Spy).

Although temporal bone pneumatization shows some individual variability, a similar pattern of distribution is found in all adult Neandertal individuals from Krapina and Western Europe. Pneumatization is restricted mainly to most parts of the petromastoid areas. We also retrace for the first time the modalities of growth and development of this pneumatization in Neandertals.
Finally, this study provides new information about possible correlations between the extension and position of temporal bone pneumatization and some of the morphological features used to characterize the temporal bone of the Neandertals. These latter features include the relatively low and short temporal squama, the robust zygomatic process with a relatively marked lateral projection, the strong supramastoid crest, the significant thickness of the tympanic part of the temporal bone, and the relatively small mastoid process and large juxtamastoid eminence. Our results suggest that the development of pneumatization in Neandertals is related to available space and to temporal bone morphology. Moreover, it appears that the development of pneumatization does not play an active role in determining the morphology of the apomorphic features of the temporal bone in Neandertals.
===
I don't know exactly how the density-pneumaticity of neandertal temporal bones compares to arboreal apes, modern humans and million-year-old Hominins at the shores. I suspect, compared to apes, the bone is more porous towards the face, (like the pneumatic paranasal sinuses used in backfloating), less porous towards the rear (more dense occiput used in backfloating) and less porous near the bottom of skull (where apes have basicranial sinuses for vertical flotation but Humans don't). Neandertals have slightly different inner ear bone structure than modern humans, I don't know if that affected the pneumaticity of the temporal bone, nor if their dietary/masticatory habits did (less cooked foods? more or less meat, fruit, reeds, or tubers? more or less chewing/suction feeding?).

This paragraph is from my initial post in this thread:

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) (and fatty cheeks unlike arboreal apes). 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).