Book review: Right Hand, Left Hand

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I've recently finished reading Chris McManus's Right Hand, Left Hand: The Origin of Asymmetry in Brains, Bodies, Atoms, and Cultures. Here's McManus's summary of his thesis, coming at the end of the book:
Most people are right-handed because they have a gene called the D gene, and that same gene means most of us also have language in our left hemisphere. The D gene was the principal factor in separating humans from other apes, perhaps two to three million years ago. Language and motor control in right-handers are controlled by the left hemisphere because the D gene is probably a mutation of the situs gene, which has been responsible for humans and all other vertebrates having their heart on the left side. Vertebrates and their predecessors have had asymmetric bodies for about 550 million years. The situs gene causes our heart to be on the left side because, early in embryological development, cilia in the nodal region waft a current containing determinants of development in a clockwise rather than an anticlockwise direction. The cilia beat clockwise because they are made principally of L-amino acides, rather than their mirror-image D- form. Almost all organisms on earth are made of L-amino acids; a predominance that is probably not due to pure chance, since amino acides found in meteorites from deep space show the same predominance. Early life evolved to contain only L-amino acids because they were the most abundant form, at least in the local areas of earth where live evolved; perhaps due to them coming from meteorites. L-amino acids may also predominate because of what physicists call 'failure of conservation of parity', which is reflected in an asymmetry of the weak interaction at the sub-atomic level. The predominance of right-handedness among humans means that many artefacts in daily life on Earth and our use of symbolic terms in language and culture are also highly asymmetric, the association of 'right' with 'good' and 'left' with 'bad' being found in almost all human cultures. It is probably not an exaggeration to suggest that when we read in the Bible of God sorting the sheep to the right and the goats to the left, or when radical politicals are described as being on the left wing and conservatives on the right, these symbolic classifications are directly linked to the organisation of language in our brains, which is linked to our manual dexterity, which is linked to our left-sided heart, which is linked to the clockwise beating of cilia, which, like the rest of our bodies, are composed of L-amino acids, the predominance of which reflects failure of conservation of parity in physics, which is a feature of the deepest laws of physics of which the universe is constructed.

McManus manages to collect a lot of fascinating information from a large variety of sources and fields in support of this thesis. This isn't my field of expertise, so I have a little trouble assessing how accurate it is, as noted in Robert K. Adair's Amazon review (scroll to end of page). However, even if the basic thesis is wrong, it's still a fascinating read, covering everything from the side of the road people drive on to the handedness of coffin screws.