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The Descent of Man

The Descent of Man

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through the increased or decreased use <strong>of</strong> parts,<br />

the facts now given shew that his liability in<br />

this respect has not been lost; and we positively<br />

know that the same law holds good with the<br />

lower animals. Consequently we may infer that<br />

when at a remote epoch the progenitors <strong>of</strong> man<br />

were in a transitional state, and were changing<br />

from quadrupeds into bipeds, natural selection<br />

would probably have been greatly aided by the<br />

inherited effects <strong>of</strong> the increased or diminished<br />

use <strong>of</strong> the different parts <strong>of</strong> the body.<br />

ARRESTS OF DEVELOPMENT.<br />

<strong>The</strong>re is a difference between arrested development<br />

and arrested growth, for parts in the<br />

former state continue to grow whilst still retaining<br />

their early condition. Various monstrosities<br />

come under this head; and some, as a cleft palate,<br />

are known to be occasionally inherited. It<br />

will suffice for our purpose to refer to the arrested<br />

brain-development <strong>of</strong> microcephalous

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