The most celebrated naturalist, writer, and observer of these animals was Charles Darwin, who visited Galápagos in the 1830s and where he did a good deal of the foundational work and data collection that went into his revolutionary work, The Origin of Species. Below is an excerpt from the field notes he kept on his extraordinary five-year journey, The Voyage of the Beagle (1831-36).

As I was walking along, I met two large tortoises, each of which must have weighted at least two hundred pounds: one was eating a piece of cactus, and as I approached, it started at me and slowly stalked away; the other gave a deep hiss, and drew in its head. These huge reptiles, surrounded by the black lava, the leafless shrubs, and large cacti, seemed to my fancy like some antediluvian animals. The few dull-coloured birds cared no more for me, than they did for the great tortoises.

The Beagle proceeded to Charles Island. This archipelago has long been frequented, first by the buccaneers, and latterly by whalers, but it is only within the last six years, that a small colony has been established here. The inhabitants are between two and three hundred in number ... nearly all people of colour ... banished for political crimes from the Republic of the Equator, of which Quito is the capital . although complaining of poverty, [they] obtain, without much trouble, the means of subsistence. In the woods there are many wild pigs and goats; but the staple article of animal food is supplied by the tortoises. Their numbers have of course been greatly reduced ... but the people yet count on two days' hunting giving them food for the rest of the week. It is said that formerly single vessels have taken away as many as seven hundred, and that the ship's company of a frigate some years since brought down in one day two hundred tortoises to the beach.

... I have already shown, from the numbers which have been caught in a single day, how very numerous they must be. Some grow to an immense size: [a man] told us that he had seen several so large, that it required six or eight men to lift them from the ground; and that some had afforded as much as two-hundred pounds of meat ... [In one region,] we lived entirely upon tortoise meat: the breast plate roasted (as the gauchos do carne con cuero), with the flesh on it, is very good; and the young tortoises make excellent soup; but otherwise the meat to my taste is indifferent.

... I was always amused when overtaking one of these great monsters, as it was quietly pacing along, to see how suddenly, the instant I passed, it would draw in its head and legs, and uttering a deep hiss fall to the ground with a heavy sound as if struck dead. I frequently got on their backs, and then giving a few raps on the hinder part of their shells, they would rise up and walk away; - but I found it very difficult to keep my balance.