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Show 32 THE DESCENT OF MAN. PART I. .explanation to assert that they have all been formed on the same ideal plan. With respect to development, we can clearly understand, on the principle of variations supervening at a rather late embryonic period, and being inherited at a corresponding period, how it is that the embryos of wonderfully different forms should still retain, more or less perfectly, the structure of their common progenitor. No other explanation bas ever been given of the marvellous fact that the emuryo of a man, dog, seal, bat, reptile, &c., can at first hardly be distinguished from each other. In order to understand the existence of rudimentary organs, we have only to suppose that a former progenitor possessed the parts in question in a perfect state, and that under changed habits of life they became greatly reduced, either from simple disuse, or through the natural selection of those individuals which were least encumbered with a superfluous part, aided by the other means previously indicated. Thus we ean understand bow it. has come to pass that man and all other vertebrate animals have been constructed on the same general model, why they pass through the same early stages of development, and why they retain certain rudiments in common. Consequently we ought frankly to admit their community of descent: to take any other view, is to admit that our own structure and that of all the animals around us, is a mere ·snare laid to entrap our judgment. This conclusion is greatly strengthened, if we look to the members of the whole animal series, and consider the evidence derived . from ~he~r a_ffinities or classification, their geographical cl1stnbutwn and geological succession. It is . only our natural prejudice, and that arrogance wluch made our forefathers declare that they were descended from demi-gods, which leads us to demur to CHAP. I. THE DESCENT OF MAN. 33 this conclusion. But the time will before IonO' h · 'll b 0 w en It w1 e thought wonderful, that naturalists,c owmhoe were well acquainted with the comparative structure and dev~lopment of man and other mammals, should h~ve be~1eved that each was the work of a separate act of creatwn. VOL. I. D |