18.01.2013 Views

The Descent of Man

The Descent of Man

The Descent of Man

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

and by the display <strong>of</strong> their bright colours or<br />

other charms endeavour to attract the males,<br />

we can understand how it is that they have<br />

gradually been rendered, by sexual selection<br />

and sexually- limited transmission, more beautiful<br />

than the males—the latter being left unmodified<br />

or only slightly modified.<br />

Whenever the law <strong>of</strong> inheritance at corresponding<br />

ages prevails but not that <strong>of</strong> sexuallylimited<br />

transmission, then if the parents vary<br />

late in life— and we know that this constantly<br />

occurs with our poultry, and occasionally with<br />

other birds—the young will be left unaffected,<br />

whilst the adults <strong>of</strong> both sexes will be modified.<br />

If both these laws <strong>of</strong> inheritance prevail and<br />

either sex varies late in life, that sex alone will<br />

be modified, the other sex and the young being<br />

unaffected. When variations in brightness or in<br />

other conspicuous characters occur early in life,<br />

as no doubt <strong>of</strong>ten happens, they will not be<br />

acted on through sexual selection until the pe-

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!