Alex, Rosenberg, a philosopher of science and author of An Atheist’s Guide to Reality says this in his book Philosophy of Science: A Contemporary Introduction:
Many biologists and not a few philosophers have held that after Darwin, evolutionary biology took back from philosophy the problems of explaining human nature or identifying the purpose or meaning of life. These biologists and philosophers hold that Darwinism shows that man’s nature differs only by degrees from that of other animals. They argue that Darwin’s great achievement was to show that there is no such thing as purpose, goals, ends, meaning or intelligibility in the universe, that its appearance is just an “overlay” we confer on the adaptations we discern in nature. Adaptations are really just the result of the environment’s persistent filtration of blind variations creating the appearance of design. It is for this reason that evolutionary theory is so widely resisted. Some people reject the answers biology gives to questions about purpose, meaning and human nature. (p. 4)
He says something similar on p. 26:
… But if Darwin’s mechanistic, purpose-free account of diversity, complexity and adaptation as the result of heritable genetic variation and natural environmental selection is right, there is a strong argument that nothing in the universe has any meaning, purpose or intelligibility beyond the sort of clockwork determinism that Newton’s discoveries revealed. And this is a profoundly philosophical conclusion, which goes beyond mere determinism by showing all purpose in nature to be illusory.
Again on p. 107:
…[What] Darwin did was to show how a purely causal process–blind variation and environmental filtering (“natural selection”)–can produce adaptations, biological structures with functions in the “causal role” sense of the term. In doing this he revealed that the appearance of design and purpose was mere illusion–an overlay that we rolled out on a purely mechanistic world. The appearance of purpose had led scientists and almost everyone else to accept the existence of a deity, designing and executing a plan as the only explanation for the appearance. But now we not only see that no such designing deity is required, we also see that the appearance of purpose is just that, appearance and not reality.
On this interpretation of Darwin’s achievement, if we consider the evidence for Darwinian theory sufficient, we must conclude not only just that the appearance of design was produced without the reality of design, but that there is no deity whose plan gives rise to the adaptation and complexity of biological systems. We may go on to infer that there is no meaning, nor any real intelligibility to be found in the universe, or at least none put into it by anyone but us. There may remain room in the scientist’s ontology for a deist’s conception of God as the first cause, but no room for cosmic meanings endowed by God’s interventions in the course of nature.
Is that something you can live with? According to Rosenberg, Darwinism is not just a theory about events in the past, but makes philosophical claims about the purpose of human life. I think what is helpful about these quotes is that he shows an awareness of the fact that the reason why many people reject Darwinism is not because they are stupid or backwards or ignorant (although for all I know he may think that is true), but rather that people are reacting to the answers that Darwinism provides for philosophical questions about meaning and purpose.