(from my post at deeperblue.com, re. Rather than listening to conventional i-pod music during a dive...)
I think I prefer to tune in to the sounds of the sea, with the middle ear canals saline-filled to still the dissonance of air conduction against bone conduction while diving. But since I've never done this (being too cold here to try) I'll just have to wait til I get to the tropics again, if ever, to hear as a dolphin hears (in a sense) the echoes of the dive song...
listening most intently at depth while my backfloating wife/dive partner hums a lullaby to our nursing infant son and daughter at the warm sunlit surface of the tropical lagoon, she in turn listens to the water for my dental-lingual clicking, knowing I'm soon to bring up some delicious fresh seafood from the ocean's banquet. I can't think of a better harmony than that little duet...
not a mythical haunting symphony of the sailors' sirens of the seas,
nor the obnoxious cacophony of the chattering rainforest monkeys,
nor the roaring of beached sea lions or trumpeting of sea elephants,
nor the loud whoops or paired call-songs of the inland swamp apes,
just ongoing quiet baby babbling and mothers humming melodies at the surface,
and non-vocalized staccato rhythmic clicking invisible yet audible from beneath,
alternating and complementing each other, the couple's chorus of the seashore,
with the simple message, "
I am here, I hear you, you are there, I'll see you soon".
with nothing but deep & clear, sky-blue waters as the superb conductor,
and colorful fish & corals, jellyfish and urchins the distinguished audience,
and dolphins, dugongs, sharks and sea turtles the occasional stagehands,
Operettas performed repeatedly, daily feasts for more than a million years,
we come from awesome beginnings.
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[inspired by HHamid]
DDeden
___________________
The-Arc-of-a-Diver:
http://the-arc.wikispaces.com/http://the-arc-ddeden@blogspot.comMy post at AAT on humming/sneezing/sleep apnea/prone clicking/supine humming/Nitric Oxide and suckling/etc.
http://tech.groups.yahoo.com/group/AAT/message/48696~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Images Triaxial weaving
http://www.nikonsmallworld.com/gallery.php?grouping=year&year=2008&imagepos=107Carbon nanotubes (sponge)
http://www.nikonsmallworld.com/moreinfo.php?grouping=year&year=2008&imagepos=2Squid embryos
http://www.nikonsmallworld.com/moreinfo.php?grouping=year&year=2008&imagepos=59tree branching
http://www.nikonsmallworld.com/moreinfo.php?grouping=year&year=2008&imagepos=19and finally, pass the peanuts
http://tech.groups.yahoo.com/group/AAT/message/48610
"LOLrus found the bucket"
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Breathing, Backfloating, Diving cycles
MV: Yes, little doubt our ancestors once regularly dived in clear sunlit sea-water, cf.studies on Moken (& later Scandinavian) children (pupil closure), this perfectly fits your photic sneeze idea.
Cheyne-Stokes respiration Pronunciation (chān stōks)
A rhythmical breathing where there is an alteration in the depth of the breaths and there are regularly occurring apneic episodes. The pattern of breathing with gradual increase in depth and sometimes in rate to a maximum, followed by a decrease resulting in apnea; the cycles ordinarily are 30 seconds to 2 minutes in duration, with 5–30 seconds of apnea; seen with bilateral deep cerebral hemispheric lesions, with metabolic encephalopathy, and, characteristically, in coma from affection of the nervous centers of respiration.
MV: Typical human Nasal Cycle suggests our ancestors dived for about 90".
Typical Sleep Apnea Rhythms in humans AFAIK seem to be a bit shorter 60".
Perhaps these 2 cycles synchronised, or perhaps they're remnants of different diving cycles (at different evolutionary periods possibly).
MV: The erectile tissue in vasomotor rhinopathy, allergic rhinitis ("hay fever"), etc.
The nasal cycle is ca.90 seconds. A periodicity of 90 seconds: for what purpose other than diving? Flaring of the nostrils is more anteriorly, at the nose entrance, not
inside the nose at the conchas, where the erectile tissue is.
MV: A lot of people suffer from nasal obstruction (by swelling of venous caverns over the inferior concha - uniquely human): can be complete, more frequent when lying down, see my paper "AAT & some common diseases". An important argument is that there's a nasal cycle in this swelling with a periodicity of c 90 seconds.
MV: Streamlining is extremely important for any actively moving (even slow-moving) animals: water is ~800 times denser than air, and ~60 times more viscous, so streamlining saves a lot of energy for the time they spent in water diving for seafoods.
MV: In Cetacea, the time needed to breathe is a few seconds or less,
DD: Yes. However, this depends on species, diving depth, diving length,
feeding behaviour, size, typical speed in water, association with other intra-specifics (competition, co-op.). There is some variability, like Homo.
MV: but our nasal cycle (about 90", Paul Van Cauwenberge) seems to suggest that our ancestors dived & floated (cf. sea otters) for about half of that time, so perhaps spouting was not necessary?
DD: Spouting depends on length of time sub-surface, not at-surface time.
I think it's likely they sneeze-spouted while surfacing from long deep
dives, whereas shallow swimming dives might have been more voluntary
blowing (seems like seals use this in shallows).
MV: The usual cycle in sleep apnea syndrome is shorter (almost a minute), so there might have been different diving customs (in different phases? or could the cycles be synchronised & used at the same time?)
DD: Perhaps different time cycles reflect different diving-depths, or
different evolutionary periods (freshwater-river vs. marine) or simply
variation due to lack of use more recently, (do vestigial organs
(tailbone-muscles, ribs, adenoids, vestigial veins) vary in shape-size
in modern Homo? I think there is much variety, considering the genetic
bottlenecks of modern HS).
DD: I currently (speculatively) view the diving-breathing cycle as a Homo aquaticus complete package, with most of the cycles in synchrony, (even possibly in synchrony with menstruation, lunar tide, sunspots, whatever).
MV: but this again suggests they stayed at the surface for almost half a minute or so.
DD: Possibly, the larger the mammal, the more explosive the exhalation? Elephants have unusual lungs, explained by their snorkel-trunk, but also possibly due to long-time submergence as well.
MV: As for the (lack of) basicranial flexion in He, if the face/nose was upwards, the body must perhaps have been vertical I'd think.
DD: What would be the largest angle they could comfortably backfloat? I drew it at 90 degrees (sea otters and modern Hs can backfloat at 90 degrees comfortably), you are suggesting 180 degrees when surfacing. Would they backfloat with eyes closed and submerged, or eyes above water? Nostrils may have remained sealed at surface (philtrum-septum valve) while mouth breathing, or alternatively, mouth closed (eating)while nostrils were open above surface.
MV: I suppose they emerged with vertical body & with the nostrils first, so I don't think they spouted in a horizontal position.
DD: Likely more forward position then, perhaps 45 degrees, (sperm whales, some balleens, sirenians?, walrus?).
MV: Did they spout through the mouth (as you drew it) or the nose or both
IYO? IYO the spouting = sneezing?
MV: Our aquarboreal theory: I tend to think early hominoids (suspension in trees) must have swum regularly [DD: face always above water, laryngeal air sacs inflated], eg, to get at the trees of other islands in the Tethys, but not that they dived a lot (although it's difficult to exclude the possibility). Wading came later IMO (early hominids, ie, even after the hominid/pongid split?). Regular diving only in Homo (although, again, earlier periods of diving can't be excluded). An external nose suggests partial aq. adapations (full aquatics have no external noses), and all apes lack this feature (I'm not sure about prenatal stages).
MV: From "The aquatic ape theory: evidence and a possible scenario" Med.Hypoth.16:17-32, 1985: "Intranasal adaptations - All aquatic mammals are able to close the nostrils, and they do so under water. Most terrestrial mammals cannot close their nostrils. Humans have rudimentary compressor and dilatator naris muscles. An even better "nose-closing-system" in our ancestors could have been the erectile tissue of the inferior nasal concha with its uniquely [not present in other mammals AFAWK, eg, not in chimps] abundant and hypersensitive plexus cavernosus. In humans, a very sudden and complete nasal obstruction can be caused by sudden changes in humidity or temperature, e.g. going into the water, or even by laying down
(vasomotor rhinopathy). Moreover, humans have a short cycle of non-alternating fluctuations in nasal resistance: the erectile tissues of the conchae involuntarily swell and shrink with a rhythm of 90 sec (23). This corresponds to the diving-rhythm of the diving women of Korea and Japan (3). In shallow-diving aquatic endotherms, the diving-and-emerging cycle is usually less than 3 min. Enhydra, for example, dives for 30 to 40 sec to catch a few mussels or sea-hedgehogs, and then emerges and floats on the surface for about the same time to crack and eat them (see Stage III)." I still think it's correct, although I would now formulate it more cautiously...
MV: It's true that salt water (eg, sterilised sea water) can well be used to clear the nasal passages (not the sinuses): salt water (more than fresh or even physiologic water?) seems to have some decongestive effect on the nasal mucosa.
DD: What is cause of vasomotor rhinopathy? bacteria, virus, genetic?
MV: Hyperactive erectile tissue on inferior concha, often elicited by laying down, or by cold & wet weather (= the reason why viral rhinitis is often called "a cold" (common cold): it resembles vasomotor rhinopathy (but has more more rhinorrhea - allergic rhinits has more sneezing & itching).
MV: The inferior concha is the lower turbinal (I think "turbinal" & "turbinate" are interchangeable): scroll-like, thin, bony processes lined throughout by mucous membrane on the lateral walls & roof of the nasal cavity, which form a labyrinth of so-called turbinals or conchae (Schultz 1969:141). Haplorhini have less turbinals than Strepsirhini, and the olfactory epithelium is withdrawn to the remotest uppermost region, eg, adult hominids-pongids only have 3 conchae (inf.=maxillo-turbinal, middle=endoturb.I, sup.=endoturb.II); gibbons & monkeys usu.still have the naso-turbinal (uppermost turbinal) = rudimentary "agger nasi" in hominids-pongids; "early in the life of man there are still as many as 5 ethmo-turbinals laid down besides the maxillo-& naso-turbinals" (7!).
DD: Does/can Vasomotor Rhinopathy occur both in sea and freshwater?
MV: It occurs on land, of course, but I don't have the impression it's more frequent when I go swimming. Everybody (incl.non-VR patients) seems to have it to some extent: it has a (uniquely human?) nasal cycle of about 90 seconds (dry apers usu.confuse this with the "long" nasal "cycle" (also in other mammals) which is perhaps fifty times longer, and not in both conchae at the same time) with which both inferior conchae synchronously swell & shrink. The only reasonable explanation I can find for such a cycle is cyclic diving, but possibly not in the latest pre-terrestrial phase (otherwise it would have been more functional in us today when we dive I'd think).
DD: Does/can VR occur both in warm (blood temp.) and cold water?
MV: Most VR patients have more problems in misty weather.
DD: Does/can VR occur both in shallow and very deep water? Does/can VR occur
both in Vt. Head up & Head down, Hz. position?
MV: Most patients have more problems at night (horizontal position, but nobody sleeps with his head down). When we lay down on our right side, it's usu.the right nasal passage that is blocked, and v.v. This happens almost immediately. It gradually worsens by abuse of nasodilator drops (Nesivin etc.).
DD: Does/can VR occur both in active swimming and inactive sinking-diving?
MV: Yes, but AFAIK there are no studies on this.
DD: [Closeable nostrils/nares prevent water from entering nasal cavities, you are saying the same applies to VR. Could water enter the paranasal sinuses or any part of the nasal cavity if the erectile tissues are fully erected?
MV: No, the nose is completely blocked, as any VR patient can tell you (it's very frequent).
DD: Do newborns/infants/children/adults all have VR capability?
MV: To some extent, probably yes. About 10-15 years ago (when I read a lot about this), one of the few groups worldwide that studied the (short) nasal cycle was that of prof. Van Cauwenberghe from Univ.Gent (now rector of the university). IIRC he told me that the cycle is more prevalent in children than in adults. Since newborns are obligate nose-breaters, I guess they don't have it (and, see Schultz above ("early in life"=?), they still have more than 3 conchae!).
DD: Are there semi-aquatic animals that use VR in diving?
MV: AFAIK, it's unuquely human. Cetacea have special pump systems that immediately block the nasal passages, but you can hardly compare these to our nasal swelling tissue.
DD: Cetaeceans inhale 3,000 times more air than Hs in 1/2 the time a Hs takes. -Humans exchange 15% of the air we breathe normally (NOT PS), Ceteaceans an exchange 85-90% of their air (How? Sneeze?) -During sneeze, how much air is exchanged? [Critical question] -The diving reflex depends on max. temp. differential, PS does not. -PS depends on max. light differential, diving reflex does not. -Speculation: Cetae (esp. large deep whales) have a
baro-sensor or temperature-sensor which triggers exhale (sneeze IMO) through
blowhole, most likely the sensor is part of the ear or eye region, though possibly part of the blowhole or echolocation equipment. -PS is semi-voluntary in Hs, often can be delayed if necessary. -PS only occurs after in-dark for about a minute.
MV: Is this so, DD?
DD: No. Not absolute, but I've read 4-5 minutes (I doubt this was timed scientifically). [The synovial fluid in finger knuckle joints can "pop", then can't be popped for about 15 minutes, this was timed scientifically.] I don't think the PS was timed this way, and from my own experience, can happen more often than 1 time in 4 minutes. My guess is that if it was done
habitually as part of a diving respiratory cycle, it would be about 1.5 to 2.5 minutes. In modern Hs, it is variable. Problem: at 200 ft down, light is 5% visible in perfect clear seawater, but if they only dived to 50ft, too much light, no PS?
MV: The best moment to sneeze would have been at the exact moment of emerging.
If surfacing-sneezing ever existed, the exact moment must have been fine-tuned by different means: sunlight ("photic") would indeed be a good indicator I'd think, but also some CNS urge to sneeze at emerging (CO2, O2?), and perhaps cutaneous sensory afferents?
DD: -Sneezing can be done vert. or horiz., probably not underwater.
MV: When a mammal starts diving (eg, to collect underwater shellfish), it has to keep the water out of its airways by all means. This can be achieved, eg, by lengthening of the airways, by narrowing them, by evolving closure possibilities... (= in parallel). We see all of this in human ancestors: external nose, longer internal airway (can be seen on transection of human & chimp nasal cavity), cavernous venous sinuses over inferior conchae, splitlike nostrils, nostril closure in young children, upper lip + philtrum to close nostrils, perhaps velum to close posterior nares. I assume that when diving becomes perfected, only one of these remains necessary.
MV: Bronchial hyper-reactivity as well as bronchial sphincters are typical of
humans (asthma) & also of, eg, seals (Elaine "Aq.ape" p.89). - allergy: Some people have stronger IgE allergic reactions than others. I don't know whether humans are generally more allergic than apes?
MV: The nose was closed: at the nostrils & at the cavernous tissue on the conchae & at the velum. The mouth could be closed at the lips & the tongue, voluntarily (BTW, this is how we voluntarily can produce consonants at free will at different places (labial, dental etc., ie, the beginning of human speech): according to suction & eating underwater. During swallowing the larynx was closed by the epiglottis. I can't see any parallelism/convergence here between dolphins & us. Cetacea have ascended larynges, the opposite of Hs. Besides, the pressure upon the glottis would have been far too high. The vocal chords (very fine & mobile structures) are for phonation, not for closing the airways underwater. This was done by the tongue & the epiglottis.
Laryngospasm is a reflex also seen in terr.mammals, to protect against food, fluids, insects... falling/flying into the airways. Of course, they closed when water came in, but not or at least not in the first place because we were semi-aquatic.
MV: - There is a so-called "long" cycle, ill-defined, about 1 to 4 hours, a general fluctuation of the nasal passages, usu.alternating right & left, not typically human. (I guess it has to do with olfaction or with cleansing of the nasal passages?)
- There is a typically-human "short" cycle of ~90 seconds, in which both nasal passages at the same time narrow by swelling of the venous plexus on the inferior nasal concha. I have no doubt this has to do with diving. At the time I corresponded with one of the investigators of this cycle,
prof. Paul van Cauwenberge (now rector of the University of Ghent), who knows what he's talking about. These swelling tissues (comparable to the corpora cavernosa in the penis) are activated by lying down, by sudden cooling & by misty weather (cf. going into the water?) - the reason why "common cold" (in fact, a viral infection by rhinoviruses of the upper airways) is often thought to be caused by "cold". People who suffer a lot from this common condition have "vasomotor rhinitis" (nasal obstruction due to swelling of the veins of the lower concha, ofter made worse by abusus of nasal vasocontrictors). It's the same swelling tissue that is often stimulated in allergic people (eg, pollen allergy).
MV: When a terrestial mammal finds more & more food underwater, it has to dip or dive for it, and therefore to close its airways underwater. Every adaptation that helps to close the airways will be advantageous during these early adaptations to food collection underwater: H as compared to P have longer airways, an external nose, the nostrils underneath the nose, an
inverted U in the nasal passage, narrower airways, swelling tissues on the inferior concha, an upper lip that can seal off the nostrils, nostril-closing muscles, etc.
MV: Interesting is that we seem to have 2 diving cycles: one at the conchae of ~90", and one during SAS (sleep apena syndrome) of ~60" or so. This seems to suggest that our diving habits showed at least 2 different phases?
ice age increases aquaticness? Wet sinuses, VR, venal pooling at depth, bronchial closure... http://tech.groups.yahoo.com/group/AAT/message/38976
http://tech.groups.yahoo.com/group/AAT/message/39630
Clicking
http://tech.groups.yahoo.com/group/AAT/message/40072
Archaic pre-heidelbergensis calvaria at Ceprano Italy
http://scienceblogs.com/afarensis/2008/11/02/sunday_need_to_read_more_from/http://www.citeulike.org/user/EsepBib/article/1122446
Common descent @ Dive Song
http://tech.groups.yahoo.com/group/AAT/message/41529
DD: Why do we sneeze, which is a complex, whole body reaction, only to remove microscopic pollen, when simply blowing the nose is more effective and more efficient? If sneezing is to remove particles, then why do people often blow their nose AFTER sneezing? And why the runny nose AFTER sneezing, if the particles are supposedly removed already? It just does not add up to natural selection for fitness.
MV: Rhinorrhea can be caused allergic reaction, viral damage &/or anti-viral reaction (rinsing away viruses/allergens)? They overlap, but generally allergy = more sneezing, VR = more obstruction, common cold (rhinoviruses) = more rhinorrhea.
Ice Age - Aquaticness effects =====================================================
m3d: While back floating the face/mouth would out of the water, but the ears would be in the water, would you hear a clicking/humming sound emitted above the surface of the water?
DD: Sound moves about 1500 meters per second in seawater. Sound moves much more slowly in air, at about 340 meters per second. Note that both prone clicking at depth and supine humming at surface both produce sound underwater. Humming while exhaling sends sounds out of the nostrils or both nostrils and mouth which are above the water surface, however the sound is actually produced in the larynx at the glottal folds which is submersed, like the ears, while backfloating.
This means for example the infant nursing on the mother hears the air-born sound (laryngeal-nasal humming or laryngeal-oral song), while the partner below hears primarily the water-born laryngeal vibration of the humming but perhaps not any verbal consonants. One possible reason why humans don't have SC fat covering the throat especially around the adams apple may be because it would weaken (insulate) the hum/song/speech) sound transmission.
Submerged prone clicking, due to it's open mouth (bell jar) method, would travel directly from the air entrapped oral cavity to the water, without skin or fat to obstruct or insulate the sound. Therefore the chubby cheeks did not interfere with click sound transmissions. (That had confused me earlier, when trying to click with closed mouth.)
So apparently human ancestors at seashores used these: underwater open mouth clicking, supine humming in eupnea with nursing infant, clear vision at dark depth followed by whalespout sun sneezing, sunwarmed catnaps while backfloating in apnea.
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Am J Physiol Regul Integr Comp Physiol. 2008 Nov 5.
Repetitive paired stimulation of nasotrigeminal and peripheral chemoreceptor afferents cause progressive potentiation of the diving bradycardia.
Rozloznik M, Paton JF, Dutschmann M. Neuro and Sensory Physiology, Georg-August University Goettingen, Goettingen, Germany.
The hallmarks of the mammalian diving response are protective apnea and bradycardia. These cardio-respiratory adaptations can be mimicked by stimulation the trigeminal ethmoidal nerve (EN5) and reflect oxygen conserving mechanisms during breath-hold dives. Increasing drive from peripheral chemoreceptors during sustained dives was reported to enhance the diving bradycardia. The underlying neuronal mechanisms, however, are unknown. In the present study, expression and plasticity of EN5-bradycardias after paired stimulation of the EN5 and peripheral chemoreceptors was investigated in the in situ working heart-brainstem preparation. Paired stimulations enhanced significantly the bradycardic responses compared to EN5-evoked bradycardia using sub-maximal stimulation intensity. Alternating stimulations of the EN5 followed by paired stimulation of the EN5 and chemoreceptors (10 trials, 3 min interval) caused a progressive and significant potentiation of EN5-evoked diving bradycardia. In contrast, bradycardias during paired stimulation remained unchanged during repetitive stimulation. The progressive potentiation of EN5-bradycardias was significantly enhanced after microinjection of the 5-HT3 receptor agonist (CPBG hydrochloride) into the nucleus tractus solitarii (NTS), while the 5-HT3 receptor antagonist (zacopride hydrochloride) attenuated the progressive potentiation. These results suggest an integrative function of the NTS for the multi-modal mediation of the diving response. The potentiation or 'training' of a sub-maximal diving bradycardia requires peripheral chemoreceptor drive and involves neurotransmission via 5-HT3R within the NTS. Key words: diving response, plasticity, nucleus of the solitary tract.
Electrical stimulation of the anterior ethmoidal nerve produces the diving response
Paul F. McCulloch*, Kevin M. Faber and W. Michael Panneton
Department of Anatomy and Neurobiology, Saint Louis University School of Medicine, 1402 South Grand Blvd., St. Louis, MO 63104, USA Accepted 9 March 1999.
Stimulation of the upper respiratory tract usually produces apnea, but it can also produce a vagally mediated bradycardia and a sympathetically mediated increase in peripheral vascular resistance. This cardiorespiratory response, often called the diving response, is usually initiated by nasal stimulation. The purpose of this research was to investigate the anterior ethmoidal nerve (AEN) that innervates the nasal mucosa of muskrats (Ondatra zibethicus). Electrical stimulation of the AEN (typically 50 Hz, 100 μs and 500 μA) produced immediate and sustained bradycardia and cessation of respiration similar to that of the diving response. Heart rate (HR) significantly decreased from 264±18 to 121±8 bpm, with a concurrent 4.2±0.9 s apnea, during the 5 s stimulation period. BP decreased from 97.9±4.8 to 91.2±6.4 mmHg. Using estimations from (1) cross-sectional areas of AEN trigeminal ganglion cells labeled with WGA-HRP, and (2) electron microscopic analysis of the AEN, we found that approximately 65% of the AEN is composed of unmyelinated C-fibers. In addition, 72.4% of myelinated fibers from the nerves that innervate the nasal passages were of small diameter (<6 n="1142">50 s). DMR decreased by 15%, but did not differ significantly from surface metabolic rates (MR(S)) when dive duration increased from 1 to 7 min. Overall, these data suggest that DMR is almost the same as MR(S), and that Steller sea lions incur an O(2) debt during spontaneous diving that is not repaid until the end of the dive bout. This has important consequences in differentiating between the actual and ;apparent' metabolic rate during diving, and may explain some of the differences in metabolic rates reported in pinniped species.
Respir Physiol Neurobiol. 2008 Oct 9.
Estimating the effect of lung collapse and pulmonary shunt on gas exchange during breath-hold diving: The Scholander and Kooyman legacy. Fahlman A, Hooker SK, Olszowka A, Bostrom BL, Jones DR.
Global Diving Research, Ottawa, ON, Canada K2J 5E8; Department of Zoology, The University of British Columbia, 6270 University Blvd., Vancouver, BC, Canada V6T 1Z4.
We developed a mathematical model to investigate the effect of lung compression and collapse (pulmonary shunt) on the uptake and removal of O(2), CO(2) and N(2) in blood and tissue of breath-hold diving mammals. We investigated the consequences of pressure (diving depth) and respiratory volume on pulmonary shunt and gas exchange as pressure compressed the alveoli. The model showed good agreement with previous studies of measured arterial O(2) tensions ( [Formula: see text] ) from freely diving Weddell seals and measured arterial and venous N(2) tensions from captive elephant seals compressed in a hyperbaric chamber. Pulmonary compression resulted in a rapid spike in [Formula: see text] and arterial CO(2) tension, followed by cyclical variation with a periodicity determined by Q (tot). The model showed that changes in diving lung volume are an efficient behavioural means to adjust the extent of gas exchange with depth. Differing models of lung compression and collapse depth caused major differences in blood and tissue N(2) estimates. Our integrated modelling approach contradicted predictions from simple models, and emphasised the complex nature of physiological interactions between circulation, lung compression and gas exchange. Overall, our work suggests the need for caution in interpretation of previous model results based on assumed collapse depths and all-or-nothing lung collapse models.
Cheetahs of the deep sea: deep foraging sprints in short-finned pilot whales off Tenerife (Canary Islands)
Authors: Aguilar Soto, Natacha; Johnson, Mark P.; Madsen, Peter T.; Díaz, Francisca; Domínguez, Iván; Brito, Alberto; Tyack, Peter
Source: Journal of Animal Ecology, Volume 77, Number 5, September 2008 , pp. 936-947(12) Publisher: Blackwell Publishing
Summary: Empirical testing of optimal foraging models for breath-hold divers has been difficult. Here we report data from sound and movement recording DTags placed on 23 short-finned pilot whales off Tenerife to study the foraging strategies used to catch deep-water prey. Day and night foraging dives had a maximum depth and duration of 1018 m and 21 min. Vocal behaviour during dives was consistent with biosonar-based foraging, with long series of echolocation clicks interspersed with buzzes. Similar buzzes have been associated with prey capture attempts in other echolocating species.
Foraging dives seemed to adapt to circadian rhythms. Deep dives during the day were deeper, but contained fewer buzzes (median 1), than night-time deep dives (median 5 buzzes). In most deep (540-1019 m) daytime dives with buzzes, a downward directed sprint reaching up to 9 m s−1 occurred just prior to a buzz and coincided with the deepest point in the dive, suggestive of a chase after escaping prey.
A large percentage (10-36%) of the drag-related locomotion cost of these dives (15 min long) is spent in sprinting (19-79 s). This energetic foraging tactic focused on a single or few prey items has not been observed previously in deep-diving mammals but resembles the high-risk/high-gain strategy of some terrestrial hunters such as cheetahs. Deep sprints contrast with the expectation that deep-diving mammals will swim at moderate speeds optimized to reduce oxygen consumption and maximize foraging time at depth. Pilot whales may have developed this tactic to target a deep-water niche formed by large/calorific/fast moving prey such as giant squid.
Heart rate and blood pressure time courses during prolonged dry apnoea in breath-hold divers
Authors: Perini, Renza1; Tironi, Adelaide2; Gheza, Alberto2; Butti, Ferdinando2; Moia, Christian3; Ferretti, Guido2
Source: European Journal of Applied Physiology, Volume 104, Number 1, September 2008 , pp. 1-7(7) Publisher: Springer
To define the dynamics of cardiovascular adjustments to apnoea, beat-to-beat heart rate (HR) and blood pressure and arterial oxygen saturation (SaO2) were recorded during prolonged breath-holding in air in 20 divers. Apnoea had a mean duration of 210 ± 70 s. In all subjects, HR attained a value 14 beats min−1 lower than control within the initial 30 s (phase I). HR did not change for the following 2-2.5 min (phase II). Then, nine subjects interrupted the apnoea (group A), whereas 11 subjects (group B) could prolong the breath-holding for about 100 s, during which HR continuously decreased (phase III). In both groups, mean blood pressure was 8 mmHg above control at the end of phase I; it then further increased by additional 12 mmHg at the end of the apnoea. In both groups, SaO2 did not change in the initial 100-140 s of apnoea; then, it decreased to 95% at the end of phase II. In group B, SaO2 further diminished to 84% at the end of phase III. A typical pattern of cardiovascular readjustments was identified during dry apnoea. This pattern was not compatible with a role for baroreflexes in phase I and phase II. Further readjustment in group B may imply a role for both baroreflexes and chemoreflexes. Hypothesis has been made that the end of phase II corresponds to physiological breakpoint.
Undersea Hyperb Med. 2008 May-Jun;35(3):163-7.
Barotraumatic orbital emphysema of rhinogenic origin in a breath-hold diver: a case report. Bolognini A, Delehaye E, Cau M, Cosso L. Sardinian Institute of Hyperbaric and Subaquatic Medicine, Sassari, Italy.
Orbital emphysema is a well-recognized complication of fractures involving the orbit. Commonly, it occurs when high pressure develops in nasal cavity as during nose blowing, coughing or Valsalva's maneuver and usually occurs in the subcutaneous tissues. We report the case of a young breath-hold diver who developed spontaneous, non compressive orbital emphysema during underwater fishing, with a maximal depth of 25-30 meters in the Sardinian sea. He was otherwise healthy, without previous cranio-facial trauma and nasosinusal diseases or surgery were not present in the history. When he was referred to our attention the patient presented right eyelid ptosis but diplopia and vision impairment were absent. Computer tomography scans showed subcutaneous air in the right upper eyelid and around the eyeball, particularly near the orbit's roof but optic nerve area, intraconal, was free of air. A dehiscence in lamina papyracea was evident. In our opinion, this has been the point of air entry into the orbit. A supportive therapy was advised and two weeks later the emphysema was recovered completely and the subject was symptoms free. The literature has been revised and to our knowledge no previous cases of barotraumatic orbital emphysema, in a breath-hold diver, are referred.
J Comp Physiol [B]. 2008 Nov 5.
Terrestrial apnoeas and the development of cardiac control in Australian fur seal (Arctocephalus pusillus doriferus) pups.
Deacon NL, Arnould JP. School of Life and Environmental Sciences, Deakin University, 221 Burwood Highway, Burwood, VIC, 3125, Australia.
The development of cardiac control in association with terrestrial respiration patterns was examined throughout the period of maternal dependence in Australian fur seal pups. Resting eupnoic heart rate and respiration rate were significantly correlated (r (2) = 0.49) and both decreased with age (P < href="http://news.bbc.co.uk/2/hi/science/nature/7358868.stm">http://news.bbc.co.uk/2/hi/science/nature/7358868.stm
A humid corridor across the Sahara for the migration of early modern humans
out of Africa 120,000 years ago AH Osborne cs 2008 PNAS 105:16444-7
It is widely accepted that modern humans originated in sub-Saharan Africa 150-200 thousand years ago (ka), but their route of dispersal across the currently hyperarid Sahara remains controversial. Given that the first modern humans north of the Sahara are found in the Levant 120-90 ka, northward dispersal likely occurred during a humid episode in the Sahara within Marine Isotope Stage (MIS) 5e (130-117 ka). The obvious dispersal route, the Nile, may be ruled out by notable differences between archaeological finds in the Nile Valley and the Levant at the critical time. Further west, space-born radar images reveal networks of now-buried fossil river channels that extend across the desert to the Mediterranean coast, which represent alternative dispersal corridors. These corridors would explain scattered findings at desert oases of Middle Stone Age Aterian lithic industries with bifacial and tanged points that can be linked with industries further to the east and as far north as the Mediterranean coast. Here we present geochemical data that demonstrate that water in these fossil systems derived from the south during wet episodes in general, and penetrated all of the way to the Mediterranean during MIS 5e in particular. This proves the existence of an uninterrupted freshwater corridor across a currently hyperarid region of the Sahara at a key time for early modern human migrations to the north and out of Africa.
http://news.bbc.co.uk/2/hi/science/nature/7668250.stmPrevious data show there was increased rainfall across the southern part of the Sahara between 130,000 and 170,000 years ago; in a gap between Ice Ages known as the last interglacial period.
Although it is unclear which routes they took to get there, Homo sapiens had reached the Levant by around 100,000 years ago, where their remains are known from Es Skhul and Qafzeh in Israel. However, this appears to have been an early, failed foray outside Africa by modern humans (??). By 75,000 years ago, Neanderthals had replaced our species in the region. Then, about 45,000 years ago, modern humans reoccupied the area. Genetic evidence suggests that populations living outside Africa today are the descendents of a migration which originated in the east of the continent between 60-70,000 years ago.
Scientists have identified a major climate drought crisis that struck Africa about 70,000 years ago and which may have changed the course of human history. http://news.bbc.co.uk/2/hi/science/nature/4505516.stm The evidence comes from sediments drilled up from the beds of Lake Malawi and Tanganyika in East Africa, and from Lake Bosumtwi in Ghana. It shows equatorial Africa experienced a prolonged period of drought.
Quaternary fossil fish from the Kibish Formation, Omo Valley, Ethiopia
J Trapani 2008 JHE 55:521-530
The late Quaternary Kibish Fm preserves environments reflecting a history of fluctuations in the level of
nearby Lake Turkana over the past 200 ky. The Kibish Fm has yielded a diverse mammalian fauna (+ birds & crocodiles), stone tools, & the oldest anatomically modern Hs. Fish, the most common vertebrate fossils in this unit, are reported in this study. Catfish (esp.clariids & Synodontis) &
Nile perch Lates niloticus predominate, but the gymnarchid Gymnarchus, a cyprinid (Barbus), tigerfish (Hydrocynus) , pufferfish (Tetraodon) & other catfish are also present. In total, 9 teleost genera are found in the Kibish Fm, representing a subset of
the 37 genera that constitute the modern Omo-Turkana ichthyo-fauna. Several taxa present in the modern fauna, incl.Polypterus & members of Cichlidae, are not found in the Kibish deposits. Most spms are preserved as disarticulated or broken skeletal elements, but some preservation of articulated elements (eg, sets of vertebrae, crania with lower jaws or cleithra) also occurs. Many of the catfish and Nile perch spms are larger than the largest reported from the modern river or lake. Faunas of Kibish Members I & III closely resemble one another; the fauna from Member IV contains only the 3 most common taxa (Clarias, Synodontis, Lates), though
this may result from insufficient sampling. Barbed bone points have been collected from the upper part of the fm, indicating a long association (200ka? 40ka?) between the human inhabitants & the fish fauna of the Omo Valley.
Stewart suggests that the hominid fishers would not have needed elaborate harpoons, fishhooks or other fishing paraphernalia : hyenas, leopards, baboons & other mammals occasionally catch fish without the benefit of technology. And traditional African fishers today sometimes
scoop fish up by hand. Several common African freshwater fish are easy to catch,
esp.at certain
times of year. The best catching times would have been when fish congregated to spawn in shallow water during the
rainy season, and when they were stranded in pools during the dry season : fat reserves in some fish increase towards the end of the dry season, just before spawning, which makes them esp. nutritious. Only at rel. recent African sites dating up to 50 ka have fish bones been considered as evidence that fish were an important
seasonal food. Fish remains have been recorded from several early hominid sites, among them E. & W.Turkana in
Kenya, Senge in
Zaire,
Olduvai Gorge in Tanzania, eg, at Olduvai Gorge, >4000 fragments of fish bone (catfish or
Tilapia) were recovered from deposits ass.x H.habilis or the later H.erectus. The hominids lived close to a shallow, saline, alkaline lake.
M174
http://dienekes.blogspot.com/2008/10/60000-year-old-y-chromosome-haplogroup.htmlhttp://www.nyu.edu/gsas/dept/anthro/disotell/vitae.html paper on mol. clock
Divergence dates
- Homo-Pan 6.0 Ma,
- Pongo-hominines 14.0 Ma,
- hominoid/cercopithe coid 23.0 Ma.
Because a uniform mol.clock does not fit the catarrhine mtDNA data, we
estimated divergence dates using a penalized likelihood & a Bayesian method
(both take into account the effects of rate differences on lineages),
phylogenetic
tree structure & multiple calibration points.
The penalized likelihood method applied to the coding regions of the mtDNA
genome yielded the following divergence date estimates:
- cercopithecine- colobine 16.2 Ma (14.4-17.9),
- colobin-presbytin, 10.9 Ma (9.6-12.3),
- cercopithecin- papionin, 11.6 Ma (10.3-12.9),
- Macaca-Papio, 9.8 Ma (8.6-10.9).
Within the hominoids :
- hylobatid-hominid 16.8 Ma (15.0-18.5),
- Gorilla-Homo+ Pan 8.1 Ma (7.1-9.0),
- Po. py. pygmaeus-Po.py. abelii 4.1 Ma (3.5-4.7),
- Pan troglodytes- paniscus 2.4 Ma (2.0-2.7).
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technology(from plucking, nut cracking, oyster shelling, nest weaving)
from simple to complex craft
stone simple (hand axe)
pebble + chop outside -> sharp core + chips
stone/bone complex
punching maul/awl, hafted axe/adze
wood simple (dugout canoe)
hollow log + chop inside -> dugout + chips
wood complex
dugout + adze -> thin side planks, lighter boat portage
fiber simple
strips + bundle/braid/weave -> nest, mattress
fiber complex
basket, basket boat, tri axial weave, knotted net
pelt simple
fur/skin/rawhide + deflesh/defat -> fur cape
pelt complex
cape + punch/sew -> leather clothes, skin boats
Stone - detach to create, attach hafting
Wood - detach to create, attach planking
Fiber - attach to create
Pelt - detach to create, attach sewing
