Darwin was a well known scientist by the time of publication, and the book quickly became internationally known while creating lively controversy. A famous debate at Oxford just seven months after publication saw a showdown between several scientists and philosophers on both sides, with Thomas Huxley being given the nickname of "Darwin's bulldog" for his support of the theory of evolution. You may recognize the name - his son, Aldous Huxley, became a world famous author. Since Darwin's theory was published, much more has been discovered about evolution.
Although Darwin was instrumental in bringing the theory of evolution into the mainstream, there were others before him that had similar observations and ideas on how natural life worked. Darwin's Ghosts: the secret history of evolution by Rebecca Stott shows how scientific ideas circulated in the centuries before Darwin and brings to life the intellectual discoveries of various individuals. Her book is a sort of genealogy of evolution, showing how thinkers and observers from Aristotle up to Darwin considered and built on others' ideas. Erroneous beliefs and mistakes also stymied many of these intellectuals, and Stott demonstrates how bumpy the road of scientific inquiry is. This book won rave reviews and is written in an easily accessible style, so don't be worried if you haven't taken a biology class in years.
The Selfish Gene by Richard Dawkins is another well-reviewed book on evolution, describing how the process works from the point of view of genes, the basic units of heredity in all living things. First published in 1976, the book caused a revolution in the scientific community, extending the explanation of evolution that Darwin provided and causing a paradigm shift in understanding how evolution worked. Almost 40 years later, the book has stood the test of time. Dawkins covers basic biology before jumping into how his theory affects the evolutionary view of altruism, competition, and other behaviours. This book is also written in an entertaining and understandable style for the layperson. This is a classic must-read that will make you reconsider just how this strange world works.
My final book choice for celebrating Darwin's birthday is Your Inner Fish: a journey into the 3.5 billion year history of the human body by Neil Shubin. The author was one of the discoverers of 375-million-year-old Tiktaalik fossils in Nunavut, a species that represents the evolutionary link between fish and amphibians. Shubin starts off the book with this discovery and discusses the source of our various features (such as eyes and noses) and how different animals have common origins. Shubin's entertaining look at how humans came to be the strange creatures we are today takes into account our ancient and diverse ancestors, from fish to reptiles to primates. And if you're overextended on your book commitments, you'll be happy to know that in 2014 Shubin hosted a three-part television series of the same name on PBS.
"There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved." - Charles Darwin