|Joseph Townsend, public domain|
In it is a passage containing a short statement of natural selection (survival of the fittest). It is also highly reminiscent of later population ecological reasoning.
But it must be remembered that it is given in a context of discussing the poor laws and not organic evolution. That is, it is not proposed as a mechanism for the transformation of species. It could not possibly do so on its own without heritable variation and the other parts of the Darwinian explanatory system in place. On the contrary, natural selection has often be taken to stabilize rather than transform species.
The passage begins with an example of an island that is regularly visited by English sailors, because of a population of goats used for food.
"When the Spaniards found that the English privateers resorted to this island for provisions, they resolved on the total extirpation of these goats, and for this purpose they put on shore a greyhound dog and a bitch. [reference omitted] These in their turn increased and multiplied, in proportion to the quantity of food they met with; but in consequence, as the Spaniards had foreseen, the breed of goats diminished. Had they been totally destroyed, the dogs likewise must have perished. But as many of the goats retired to the craggy rocks, where the dogs could never follow them, descending only for short intervals to feed with fear and circumspection in the vallies, few of these, besides the careless and the rash, became a prey, and none but the most watchful, strong, and active of the dogs could get a sufficiency of food. Thus a new kind of balance was established. The weakest of both species were among the first to pay the debt of nature; the most active and vigorous preserved their lives. It is the quantity of food of food which regulates the number of the human species." (Townsend 1817, Sect. VIII, p. 44f)He then gets back to his topic of poor laws, commons and his economic/political agenda.