Tuesday, 7 October 2014

Natural selection before Hutton (1794)—Townsend (1786)

Joseph Townsend, public domain
Although Thomas Mathus says to have been unaware of Joseph Townsend's Dissertation on the Poor Laws by a well-wisher to mankind (first published 1786, republished 1817), when he wrote the first edition of his Essay on the Principle of Population (Malthus 1798), he acknowledged Townsend and others in the later editions of his Essay ....

In Townsend's Dissertation ... 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.* 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.
* Ulloa, B. ii. C. 4." Townsend (1817, p. 44-45)
He then gets back to his topic of poor laws, commons and his economic/political agenda.

[Update 05.03.2015: Mike Weale (in press) interprets this passage as an example for an early proposal of natural selection as a stabilising force that keeps the species to its intended form. I do not see that in the passage at all. The goats have been selected to change their behaviour. If that change of behavior had any genetic basis, then the goat population would have evolved.
     But this is a retrospective, Whiggish, discussion. Townsend had not written about natural history and he did not narrate that example in order to say anything about nature. He used it as an analogy to the human condition. As in dogs, only the active humans would be able to sustain themselves, and like, goats, only the watchful would survive. Townsend's, like Malthus's, thrust of the argument went against the poor laws by trying to show that helping the poor now would only increase the misery in the future:
"But by establishing a permanent community of goods, and neither increasing the quantity of food, nor limiting the number of those who are to share it, they divert the occasional surplus of national wealth from the industrious to the lazy, they increase the number of unprofitable citizens, and sow the seeds of misery for the whole community; increasing the general distress, and causing more to die for want, than if poverty had been left to find its proper channel." Townsend (1817, p. 50-51)
To apply the distinction between micro- and macro-evolution to Townsend seems anachronistic.]

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