Not only is the struggle between the animals and inanimate nature, the plants and inanimate nature, plant and animal, rival animals, and rival plants; it goes on between man and his environment, and, very fiercely, between man and man. Darwin was moved by intense indignation at the slavery on the east coast and the cruel oppression of the laborer on the west coast. He was in close contact with the sanguinary political struggles of South America, and with a war of attempted extermination against the Indian. He refers to the shocking but "unquestionable fact, that [in the latter struggle] all the women who appear above twenty years old are massacred in cold blood! When I exclaimed that this appeared rather inhuman, he [the informant] answered, 'Why, what can be done? they breed so!'"
In all his travels nothing that Darwin beheld made a deeper impression on his sensitive mind than primitive man. "Of individual objects, perhaps nothing is more certain to create astonishment than the first sight in his native haunt of a barbarian--of man in his lowest and most savage state. One's mind hurries back over past centuries, and then asks, could our progenitors have been men like these?... I do not believe it is possible to describe or paint the difference between savage and civilized man." It was at Tierra del Fuego that he was particularly shocked. He admired the Tahitians; he pitied the natives of Tasmania, corralled like wild animals and forced to migrate; he thought the black aborigines of Australia had been underestimated and remarked with regret that their numbers were decreasing through their association with civilized man, the introduction of spirits, the increased difficulty of procuring food, and contact with European diseases. In this last cause tending to bring about extinction there was a mysterious element. In Chile his scientific acumen had been baffled in the attempt to explain the invasion of the strange and dreadful disease hydrophobia. In Australia the problem of the transmission to the natives of various diseases, even by Europeans in apparent health, confronted his intelligence. "The varieties of man seem to act on each other in the same way as different specimens of animals--the stronger always extirpating the weaker."