Human drowning: Phylogenetic origin

Because most animals are able to survive much longer when in water than most humans and apes, it is likely that at some time during human phylogeny the-innate-ability to swim like animals has been lost. Paleontology and comparative zoology provide indications for selective pressures and adaptations explaining this phenomenon. Among these are (a) buoyancy having become reduced slightly due to a smaller lung air/body weight ratio, less air trapped in the body covering hairs and reduction in gastrointestinal gas, (b) the caudally directed nasal entrance cranially to which there is the heavy neurocranium, (c) the low position of the laryngeal entrance, (d) the ineffective propulsion by the human innate crawling and walking movements, and (e) the well developed cerebrum being present cranially to the airway entrance, being sensitive for anoxia and hypothermia, and causing behaviour adding to drowning risks.