By the time Dr. Jekyll and Mr. Hyde had been written, Darwin had already published his theory on the evolution of man. This is very interesting because one of his major themes in the novel is ignoring the worst instincts of man. Dr. Jekyll represents what man is because of the pressures put onto us by society. He quotes that he is a philanthropist and well known in society because people have come to expect it from him. But his more instinctual side is bored of this do-gooder. And on some level, Dr. Jekyll wants to indulge in these instincts because of the need for pleasure. The question then appears itself though, would he want to indulge in these pleasures as much if the social requirements of men in the Victorian Era weren't as great?
Hope this helps. :)
