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The Descent of Man

The Descent of Man

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ecent mammals belonging to the same groups,<br />

has come to the remarkable conclusion that the<br />

brain is generally larger and the convolutions<br />

are more complex in the more recent forms. On<br />

the other hand, I have shewn (83. <strong>The</strong> 'Variation<br />

<strong>of</strong> Animals and Plants under Domestication,'<br />

vol. i. pp. 124-129.) that the brains <strong>of</strong> domestic<br />

rabbits are considerably reduced in bulk,<br />

in comparison with those <strong>of</strong> the wild rabbit or<br />

hare; and this may be attributed to their having<br />

been closely confined during many generations,<br />

so that they have exerted their intellect,<br />

instincts, senses and voluntary movements but<br />

little.<br />

<strong>The</strong> gradually increasing weight <strong>of</strong> the brain<br />

and skull in man must have influenced the development<br />

<strong>of</strong> the supporting spinal column,<br />

more especially whilst he was becoming erect.<br />

As this change <strong>of</strong> position was being brought<br />

about, the internal pressure <strong>of</strong> the brain will<br />

also have influenced the form <strong>of</strong> the skull; for

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