"The sole object of this work is to consider, firstly, whether man, like every other species, is descended from some pre-existing form; secondly, the manner of his development; and thirdly, the value of the differences between the so-called races of man."
Darwin in this book is interested in exploring mankind's common ancestry. He wants to discover the significance of diversity among humans as well as to further understand the dramatic role of evolutionary biology on human development, both physical and mental.
"Nevertheless the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind."
Darwin concludes from his study of anatomy among various species that the homo sapien is not an entirely different type of being but one of the same type as the others with a much greater level of advancement. Implications of his conclusion are that perhaps humans are not the only species capable of evolving into intelligent life, perhaps they're just the only ones right now.
". . .Nor could we check our sympathy, even at the urging of hard reason, without deterioration in the noblest part of our nature. . . We must therefore bear the undoubtedly bad effects of the weak surviving and propagating their kind."
Despite the existence of an evolutionary ethic, Darwin concludes that mankind must still ignore this ethic in favor of the sanctity of human life. He argues that humans have a higher consciousness which compels them to preserve life, even if that life is less productive to the evolutionary community than most. He believes the less successful are a necessary part of human life, even if they are not essential to the survival of the species as their more successful counterparts.
". . .There should be open competition for all men; and the most able should not be prevented by laws or customs from succeeding best and rearing the largest number of offspring."
While Darwin understands the necessity of the propagation of good genes, he also acknowledges the role of social and religious conditioning on sexual desires. He notes that people often conduct themselves according to a social rather than an evolutionary ethic, with positive results.
