Passage
In considering the origin of species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species, inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which justly excites our admiration. Naturalists continually refer to external conditions, such as climate, food, &c., as the only possible cause of variation. In one limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the mistletoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself.
Question 1 of 4single select
The author of the passage mentions the 'woodpecker' and the 'mistletoe' primarily in order to:
provide examples of species that were independently created rather than having descended from other species.
illustrate the profound impact that climate and food have on the geographical distribution of species.
demonstrate that highly specialized anatomical structures and complex ecological relationships cannot be fully explained by external conditions alone.
argue that parasitic organisms, such as the mistletoe, undergo more rapid evolutionary changes than non-parasitic organisms like the woodpecker.
highlight the importance of embryological relations in determining the evolutionary lineage of diverse species.
Expert Analysis: The Limits of External Causality
This passage is a masterclass in rhetorical pivoting. Here is how to map the logic.
Structural Breakdown
The author does not merely propose a theory; he engineers a logical trap. He starts by conceding a point (descent is conceivable) only to immediately subvert it as insufficient.
The Hinge Word: 'Nevertheless'This word signals the shift. The author moves from 'Descent is possible' to 'But we don't know the Mechanism yet'.
