In the 1870's, the support for evolution came under attack from several directions. Alfred Russell Wallace, the co-discoverer of evolution, had started to argue that humanity was exempt from evolution and that there was mystical guiding force that gave evolution direction. This idea was a direct attack on what had made Darwin's theory so revolutionary: the idea that evolution was an orderly process that resulted from random variation and the survival of the fittest. Another attack came from physicists such as Lord Kelvin, who argued on the basis of measurements of the earth's temperature that the earth had existed for only twenty-five or thirty million years. An evolutionist required more time–on the order of hundreds of millions of years–for all of life to have evolved.
There were also attacks from other unexpected quarters: a mathematician, Henry Jenkin, argued that any newly evolved trait, no matter how beneficial, would immediately be washed out of the population as the animal with that trait bred with other animals without it. Unfortunately for Darwin, genetics was not well enough understood for him to refute this criticism, which depended on a blending theory of inheritance instead of a gene theory. These attacks caused Darwin to revise his theory in successive editions of the Origins. He started to minimize the most important part of his theory, the mechanism of natural selection, and to allow that other processes, such as the Lamarckian inheritance of acquired traits, might help speed evolution along. But aside from these revisions, Darwin spent most of the 1870's shifting away from the theory of evolution and towards the garden, researching and publishing books on plants and earthworms.
As he reached the end of the decade, Darwin found that his ideas were still controversial but that he himself was regarded with nothing but respect. In 1877 he was given an honorary doctorate by the University of Cambridge. His health improved in his old age, leaving him free to enjoy his time with Emma and the children, now grown, and to continue his routine of study and long, solitary walks on the Down House estate. The only controversy to roil Darwin's last years was a bitter dispute with Samuel Butler, the grandson of Darwin's old headmaster at the Shrewsbury School. Butler, who is now best known for his satirical novel Erewhon, had initially been an enthusiastic supporter of Darwinism, even making an occasional visit to Down House. But he had become more critical recently, and the tension came to a head when Darwin helped publish a translation of a German book that dismissed some of Butler's criticisms of Darwinism as groundless. Darwin was unwilling to apologize, and was not even certain that he had done anything wrong. Butler was enraged even further. In the end, the combination of Butler's enmity and Darwin's silence led to an escalating, one-sided war that Darwin regretted deeply but was unsure how to end.
In March 1882, Darwin started to weaken, his old sickness creeping up on him again. He died at the Down House on April 19, 1882. At first, his family planned to bury him at Down, next to his children and brother, where he had expected to be buried. But as the news spread of his death, a campaign was mounted by Huxley and Darwin's cousin Francis Galton to have him buried in the most honorable place of all: Westminster Abbey. It took some doing, both to convince the family and the proper authorities, but within a week a place had been reserved for him, his eminence in science enough to counteract his well- publicized enmity towards the Church.