Darwin's great work, The Origin of Species, is now generally accepted as one of the most important books ever written. But when it first came out in 1859, it was both derided and bitterly condemned by scientists and laymen. Much of opposition to The Origin of Species arose from Darwin's claim that all living creatures, including man, are somehow related. Many people were outraged by the suggestion that man shared a common ancestor with animals such as apes and monkeys. They attacked Darwin for saying that man had descended from the apes. But Darwin never actually said this. He believed that modern men and modern apes have both descended from the same ancestor. But at some time in pre-history, millions of years ago, men and apes began to develop separately, and ever since have continued to take on different characteristics. Today, more than 90 years after Darwin's death, this is the opinion which scientists continue to hold. In his works, Darwin described the progression of life from its earliest forms. First came the invertebrate-creatures without a backbone. Then invertebrates evolved into fish fish into amphibians amphibians into reptiles and reptiles into birds and mammals. Fossil remains found after his death show that Darwin was right. Perhaps the most amazing fact about his theory is that he managed to work it out with the aid of only a few fossil discoveries. Fossil remains were not the only information which we now possess but which Darwin lacked. He did not know that apes have the same diseases as men nor that they and men have the same kind of blood. Nor did he know about the modern uses of radiation which enable scientists to tell the age of fossil remains and so estimate the speed at which evolution has taken place. Which of the following best describes the passage as a whole?