http://www.utm.edu/research/iep/e/evol-eth.htmCharles Darwin
The biologization of ethics started with the publication of The Descent of Man by Charles Darwin (1809-1882) in 1871. In this follow-up to On the Origin of Species, Darwin applied his ideas about evolutionary development to human beings. He argued that humans must have descended from a less highly organized form, in fact, from a "hairy, tailed quadruped ... inhabitant of the Old World" (Darwin, 1930: 231). The main difficulty Darwin saw with this explanation is the high standard of moral qualities apparent in humans. Faced with this puzzle, Darwin devoted a large chapter of the book to evolutionary explanations of the moral sense, which he argued must have evolved in two main steps.
First, the root for human morality lies in the social instincts (ibid. 232). Building on this claim by Darwin, today’s biologists would explain this as follows. Sociability is a trait whose phylogenetic origins can be traced back to the time when birds 'invented' brooding, hatching and caring for young offspring. To render beings able to fulfil parental responsibilities required social mechanisms unnecessary at earlier stages of evolutionary history. Amoebae, for example, which reproduce by division or frogs, which leave their tadpole-offspring to fend for themselves do not need the social instincts present in birds. At the same time as facilitating the raising of offspring, social instincts counterbalanced innate aggression. It became possible to distinguish between 'them' and 'us' and aim aggression towards individuals that did not belong to one’s group. This behavior is clearly adaptive in the sense of ensuring the survival of one’s family.
Second, with the development of intellectual faculties, human beings were able to reflect on past actions and their motives and thus approve or disapprove of others as well as themselves. This led to the development of a conscience which became "the supreme judge and monitor" of all actions (ibid. 235). Being influenced by utilitarianism, Darwin believed that the greatest-happiness principle will inevitably come to be regarded as a standard for right and wrong (ibid. 134) by social beings with highly evolved intellectual capacities and a conscience.
Based on these claims, can Darwin answer the two essential questions in ethics? First, how can we distinguish between good and evil? And second, why should we be good? If all his claims were true, they would indeed support answers to the above questions. Darwin’s distinction between good and evil is identical with the distinction made by hedonistic utilitarians. Darwin accepts the greatest-happiness principle as a standard of right and wrong. Hence, an action can be judged as good if it improves the greatest happiness of the greatest number, by either increasing pleasure or decreasing pain. And the second question why we should be good does not pose itself for Darwin with the same urgency as it did, for instance, for Plato (Thrasymachos famously asked Socrates in the Republic why the strong, who are not in need of aid, should accept the Golden Rule as a directive for action).
Darwin would say that humans are biologically inclined to be sympathetic, altruistic and moral as this proved to be an advantage in the struggle for existence (ibid. 141).
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For some reason I don't think that last sentence fits when * is part of the conversation. I was looking for a link on the "origins of the apology" and this came up.