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Possible Aquatic Adaptations in Human

possible aquatic adaptations in human arguments for the waterside models (including the aquatic ape hypothesis) species : Homo sapiens proposed natural habitat : coasts & beaches water birth the natural way of swimming & floating pregnancy & infancy gender & sex walking & running subcutaneous fat layer - prevents heat loss - increases buoyancy - streamlines the body O 2 laboring in human - less painful, low risk - preferred by women - infant mortality & infection rates no higher than land births practiced in primitive cultures O infant are able to swim/dive rare condition of before being able to crawl/walk, no fear or harm caused by immersion e human is the best swimmer webbed toes 2 immersion relieves pain, longer scalp hair (becomes thicker & stronger during pregnancy) for the floating infant to cling on e facial hair & bald & diver among the apes, reduces stress hormones head streamlines (adrenaline) & facilitates "love" hormone (oxytocin) O capability lasts from birth to bipedalism may be enhanced by wading the head and force exerted on the death dark skin pigment blocks sunlight in tropical waters 3 neck for diving 0 first & the last toes fusiform, straight, streamlined body reduces drag O - for shallow water various swimming gaits like breaststroke, front crawl... or (like in seals) O foraging - supported by water buoyancy - overcame various more body fat, facial hair as a > 1 year voluntary movements, starts learning to swim, dive, walk.. O 4-12 months 0-4 months sexual signal protruding buttocks (in extreme case darker & smoother infant floating reflex: infant diving reflex: paddle-like feet with fused toes for skin during pregnancy for open sea immersion O above water opens eyes, holds breath, rhythmic rolls onto the back to reduced body hair & surface lower bone density increases buoyancy O steatopygia) as a platform for carrying baby O float & breathe O smooth skin surface both water & land disadvantages 0® limb movements to reduce drag O locomotion O propel forward O foreskin avoids infection in sea obligatory bipedalism & upright posture due to straight body plan & long legs (diving) © estrogen causes fat stored around water O large floating breasts help feeding while immersed O buttocks, thighs & hips to form the fusiform body O longer penis in response to deeper vagina @ scooper-like hands with thumb webbing for catching water O endurance running only recently evolved - pre-adaptations: strong legs, good balancing. - new adaptations: eccrine sweating, foot hair growth abundant body fat brown fat tissues pattern follows water flow O menstruation prevents heat loss & increases buoyancy O generates heat 3 longer vaginal canal synchronized with circalunar isolates the uterus flexible arms & from sea water O (tidal) cycle O shoulders produce steering strokes O curly hair fibers caused by oval underarm & pubic long legs produce powerful propelling force in swimming, diving & running O lower normal body hair reduces strong muscles in chin, cheek & lips multi-lobed temperature with arches, short toes... cross-section for turbulent flow in labia major, hymen & vaginal ridges waterproof the vagina, low pH ~4.5 & lactobacillus colony in vaginal canal inhibit waterborne pathogens O9 low fluctuations kidney (reniculi) rare condition of reducing drag O concave surfaces O as in marine for close contact like in aquatic webbed fingers e suckling, avoid water goes in O mammals O mammals inherited from ape utilize both drag- (fused later) O umbilical cord ancestors: based & lift-based - climbing, gymnastics - partial bipedalism & partial upright posture - opposable thumb long enough for propulsion O newborn to reach hidden estrus due to visual signals (genital swelling) & scent signals (pheromone) water surface O vernix caseosa (waxy substance with squalene on newborns) with waterproofing & antibacterial properties O6 newborn holds diving & foraging breath until not efficient in water O reaching water no practice of eating placenta (placentophagy) as not possible in water 6 surface O underwater foraging important to early Homo sapiens, still practicing among more face-to-face sex due to straight body plan, vagina coastal tribes directed towards the front fewer & larger red blood cells, higher - collecting shellfish & hunting fish for food, precious shells & pearls for trading head & upper body hair for - waterproofing & thermoregulation head & upper body – usually out of water; insulation in the lower parts myopia & astigmatism correct for light refraction in water 0 concentration of the gre hemoglobin O waterproofing - bimodal diving pattern similar to sea otters (serial short dives to <20m, enlarged semicircular canals give better balance under water & recent brain shrinkage round-shaped head (reduced brow ridge, flat face, flat ears) reduces drag O scalp hair blocks high utilization of lungs (VC/TLC > 75%) O agile neck for searching O - oral cavity modified for aquatic diet, later enabled speech spleen contracts sunlight in the tropical waters O due to change to riverine & terrestrial habitat to release extra separated by recovery intervals, in extreme cases dive to 100m) O on land (bipedalism) O good underwater vision by maximally constricting pupils 6 red blood cells 6 brain enlargement enabled by marine diet countercurrent senses attuned to aquatic environment brain enlargement enabled by marine diet (seafood, seaweed) - high availability & reliability - essential micronutrients (DHA, iodine, zinc, selenium..) O veins in limbs ear wax (contains sebum) repels water entering the ears0 able to equalize reduce heat loss color vision & eyebrows & eyelashes prevent water flow into eyes O ears at depth 6 from body O color blindness descended larynx allows mouth breathing for inhaling more air before dives / during swim © adapted to aquatic environment 6 flexible backbone paranasal sinuses assist the head floats brain enlargement & reorganization led to higher intelligence, creativity & syntactic ability O allows lift-based fine breath "dolphin kick" above water surface O sebaceous glands reduced smelling secret sebum better voluntary breath control for planning of control pre- adapted for speech under water 2 sense as useless in (with squalene) for waterproofing (in head, upper body, back) O downward nostrils avoid or above water e inhalation e water splashes in O multi-pyramidal kidneys excrete salt from sea water 6 thicker lips for syntax + speech/song = human language breathing pattern (quick inhale & slow exhale) similar to speech ® bradycardia: heartbeat reduces during immersion e upper lip & philtrum enable sealing of nostrils while diving © O testing allergens in seafood O sweat evaporates through the upper body (highest rate in head, upper body, back) O speech, song & facial expressions replaced body expressions as more efficient peripheral vasoconstriction: high output of water & - specialized oral cavity (small mouth, round jaw & palate, reduced teeth, round versatile tongue) for suction feeding of slippery seafood, pre-adapted for speech salt: abundant sweat & no salt hunger & high tolerance in salty taste since salt is everywhere in the sea 3 blood flow to limbs cuts dexterous, sensitive hands for collecting & hunting, started tool-making on the shore O down to save oxygen for important organs 6 tears, saturated expiration, dilute urine, watery faeces O enhanced above water surface O diving reflexes vocal learning, speech & song enabled by - fine breath control (for diving) - enhanced articulating apparatus (for aquatic diet) © remnant brown blood shift: blood fills lung low drinking vestigial air sacs (laryngeal saccule) used to aid floating fat tissues vessels & cavities in extreme capacity, low sweat (perhaps also tears) excretes - blunter molars with thick enamel for cracking hard generate heat (only in neck, umami taste is the depth to prevent organs crushed 6 tolerance to most prevalent in dehydration O in ape ancestors 6 excess salt 2 shellfish 6 upper chest) O seafood O References: 0 Hardy AC (1960) Was man more aquatic in the past? New Scientist 17 Mar 7 (174): 642-645 0 Morgan E (1982) The Aquatic Ape. Stein & Day Pub ® Morgan E (1990) The Scars of Evolution. Souvenir Press O Morgan E (1997) The Aquatic Ape Hypothesis. Penguin 6 Roede M, Wind J, Patrick J, Reynolds V (eds.) (1991) Aquatic Ape: Fact or Fiction? Souvenir Press 6 Vaneechoutte M, Kuliukas AV, Verhaegen M (eds.) (2011) Was Man More Aquatic in the Past? Fifty Years After Alister Hardy - Waterside Hypothesis of Human Evolution. Bentham Science Publishers O Cunnane SC, Stewart KM (eds.) (2010) Human Brain Evolution: The Influence of Freshwater and Marine Food Resources. Wiley-Blackwell ® Niemitz C (2010) The evolution of the upright posture and gait – a review and a new synthesis. Die Naturwissenschaften 97 (3): 241-263 O Odent M (1996) We are All Water Babies. Celestial Arts 0 Verhaegen M et al.: various publications in Medical Hypotheses (1985, 1987), Nutrition and Health (1993), Ecology Research Progress (2007) O unpublished idea composed by CHAN Wang Chak, email: [email protected], Oct 2013

Possible Aquatic Adaptations in Human

shared by chakazul on Apr 02
According to the controversial idea(s) of "Waterside Evolution" (including the infamous "Aquatic Ape Hypothesis"), numerous features of human can be explained as adaptations to a semi-aquatic environm...


Bert Chakovsky


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