This is a fairly long chapter, and much of it is a journal, from commentary on religious tolerance to the scientific education of the population (there are locals who express astonishment to learn that the world is round). And, then, suddenly, in the last couple of pages, we’re suddenly hit with biogeography, natural history, and the economy of nature. But more on that when we get there.
Having been delayed by the rebellion in Las Conchas for some time, Darwin rides to catch the Beagle before it leaves Monte Video. When he gets there, however, he discovers that the Beagle isn’t sailing for a couple of weeks, and so decides to travel across the plains of Patagonia.
A local breed of cattle, called the niata, differ from normal cattle. There’s an inkling of natural selection here: common cattle are able to browse on trees, but the niata are less able – and so die sooner during a drought. Darwin comments that this sort of thing has implications on the extinction of species – it is determined often by irregular, but nonetheless natural, events.
It is impossible to doubt that the extreme liberalism of these countries must ultimately lead to good results. The very general toleration of foreign religions, the regard paid to means of education, the freedom of the press, the facilities offered to all foreigners, and especially, as I am bound to add, to every one professing the humblest pretensions to science, should be recollected with gratitude by those who have visited Spanish South America.
Sailing on the Beagle, the ship is swarmed by butterflies, moths and beetles – even ten miles out to sea. There are even beetles swimming in the ocean 17 miles offshore! The deck becomes home to thousands of small spiders, which catch the air with a strand of silk to spread to new territories.
Trailing a net, he catches a number of crabs, and, in the open sea only catches a few minute crabs – this causes him to wonder what the albatross and whales feed on.
Back on land in Port Desire, he discovers a new species of cactus that Professor Henslow names Opuntia darwinii, and a half skeleton of a camel-like species, Macrauchenia patachonica, which he figures to be a closer relation of camels than of guanacos or llamas.
Darwin notes how the relationships between current species are more distant than between the extinct species he’s discovering, and how there exist closer relationships still between extinct species and current species.
This wonderful relationship in the same continent between the dead and the living, will, I do not doubt, hereafter throw more light on the appearance of organic beings on our earth, and their disappearance from it, than any other class of facts.
It is impossible to reflect on the changed state of the American continent without the deepest astonishment. Formerly it must have swarmed with great monsters: now we find mere pigmies, compared with the antecedent, allied races…
It appears from the character of the fossils in Europe, Asia, Australia and in North and South America, that those conditions which favour the life of the large quadrupeds were largely co-extensive with the world: what those conditions were, no one has yet even conjectured…
Did man, after his first inroad into South America, destroy, as has been suggested, the unwieldy Megatherium and the other Edentata? … Did those plains fail of pasture, which have since been overrun by thousands and hundreds of thousands of the descendants of the stock introduced by the Spaniards? Have the subsequently introduced species consumed the food of the great antecedent races? Can we believe that the capybara has taken the food of the Toxodon, the Guanaco of the Macrauchenia, the existing small Edentata of their numerous gigantic prototypes? Certainly, no fact in the long history of the world is so startling as the wide and repeated extermination of its inhabitants.
Nonetheless, if we consider the subject under another point of view, it will appear less perplexing. We do not steadily bear in mind, how profoundly ignorant we are of the conditions of existence of every animal; nor do we always remember, that same check is constantly preventing the too rapid increase of every organized being left in a state of nature. The supply of food, on an average, remains constant, yet the tendency in every animal to increase by propagation is geometrical; and its surprising effects have nowhere been more astonishingly shown, than in the case of the European animals run wild in the last few centuries in America. Every animal in a state of nature regularly breeds; yet in a species long established, any great increase in numbers is obviously impossible, and must be checked by some means. (emphasis added)
Darwin read Thomas Malthus in 1838, before any of the editions of The Voyage of the Beagle were published, and here we can see the influence.
If asked how this is, one immediately replies that it is determined by some slight difference, in climate, food, or the number of enemies: yet how rarely, if ever, we can point out the precise cause and manner of action of the check! We are therefore, driven to the conclusion, that causes generally quite inappreciable by us, whether a given species shall be abundant or scanty in numbers.
Darwin did not figure that natural selection could be observed in the field – modern evolutionary shows that little could be further from the truth. However, it seems fairly obvious by now that Darwin was fairly far along in his thinking, at least by the time he wrote this edition (I am reading James Watson’s Darwin: The Indelible Stamp, which does not specify which edition was selected, but I think it’s a late one).