Have you heard about this theory? It makes a lot of sense to me, but the scientists in the know discredit it, saying it doesn't align with the fossil record. In a nutshell, it supposes that we evolved to lose our body hair and adopt an upright stature due to coastal living; living off the sea. Also, many essential omega 3's derive from sea food.
Is this a "theory" in the scientific sense (fits the the known observations and makes testable predictions) or a "theory" in the Facebook sense (whacky idea from someone totally unqualified in the field - a hypothesis if being charitable)?
The debate's too polarised imo. It makes sense that evolutionary pressure coaxed our biology to take advantage of the coast. There surely exists (within the Venn diagram of believer versus non-believer) a segment where both hypothesis are partially true.
Do you mean the theory popularised by Elaine Morgan in her 1982 book 'The Aquatic Ape' ? As said by others, now very out of fashion and many (all ? not checked & a long time since I read the book) of her arguments have been disproved.
I thought the upright stature /ability to run as we do was a decisive advantage in the plains/savannah where we evolved. There is said though to be a link to omega 3/6, plentiful in shellfish and coastal living, and an increase in brain size. All fascinating stuff but I only pick things up, as most do, on an ad hoc basis
> But last I recall, our loss of hair was likely due to cooling requirements. Our upright positions makes us great long distance runners so we need to cool.
There is also the 'radiator theory.' Homo sp. not only has a much bigger cranium than other apes but also features a much more extensive system of capillaries around the skull which helps cooling. This was argued to be a key evolutionary response to bipedalism and a condition for an increase in brain size. It was not an unproven theory at the time when I studied this stuff, I'm not sure about now as I haven't kept up. Current understanding of human evolution is always inherently unstable as new discoveries are rare and as such have real potential to upend everything we thought we knew already. It's an extremely interesting subject.
C&P'd from Brain evolution in Homo: The “radiator” theory1 by Dean Falk: Behavioral and brain sciences, 1990•cambridge.org
"The “radiator” theory of brain evolution is proposed to account for “mosaic evolution” whereby brain size began to increase rapidly in the genus Homo well over a million years after bipedalism had been selected for in early hominids. Because hydrostatic pressures differ across columns of fluid depending on orientation (posture), vascular systems of early bipeds became reoriented so that cranial blood flowed preferentially to the vertebral plexus instead of the internal jugular vein in response to gravity. The Hadar early hominids and robust australopithecines partly achieved this reorientation with a dramatically enlarged occipital/marginal sinus system. On the other hand, hominids in the gracile australopithecine through Homo lineage delivered blood to the vertebral plexus via a widespread network of veins that became more elaborate through time. Mastoid and parietal emissary veins are representatives of this network, and increases in their frequencies during hominid evolution are indicative of its development. Brain size increased with increased frequencies of mastoid and parietal emissary veins in the lineage leading to and including Homo, but remained conservative in the robust australopithecine lineage that lacked the network of veins. The brain is an extremely heatsensitive organ and emissary veins in humans have been shown to cool the brain under conditions of hyperthermia. Thus, the network of veins in the lineage leading to Homo acted as a radiator that released a thermal constraint on brain size. The radiator theory is in keeping with the belief that basal gracile and basal robust australopithecines occupied distinct niches, with the former living in savanna mosaic habitats that were subject to hot temperatures and intense solar radiation during the day."
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