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+--- Thread: Why does the right side of the brain control the left side of the body? (/thread-21693.html)
Why does the right side of the brain control the left side of the body? - C C - Oct 27, 2026
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Why does the right side of the brain control the left side of the body? An evolutionary history
https://www.eurekalert.org/news-releases/1148512
EXCERPT: All considered, we propose that evolutionarily ancient visual pathways biased our central nervous systems towards being organized contralaterally – at least in tetrapods. Given that all living vertebrates have both an optic chiasm and a contralaterally organized optic tectum, we think that Cambrian-era jawless fishes that lived roughly 538 to 486 million years ago had both an optic chiasm and an optic tectum. It may be possible to test this hypothesis by examining fossilized remains of their skulls.
Since evolution is conservative in its innovations – it often retains and builds upon existing structures, pathways, and mechanisms rather than inventing new ones – the organization of the visual system (and in particular, the optic tectum) may have defined the organizational principles required of the sensory and motor pathways that evolved later. We propose that contralateral organization didn’t necessarily evolve as an adaptation, but because evolution is an engineer that builds with the foundation and materials it has at hand. (MORE - missing details, no ads)
RE: Why does the right side of the brain control the left side of the body? - Magical Realist - Oct 29, 2026
Makes sense. More like already in-place proven scaffolding instead of the construction of all new unproven structures.