At her NY Times blog, Olivia Judson looks at the upcoming year of Darwin celebrations (July 1, 1858 was when Darwin first presented ideas on natural selection, both his own and those of Alfred Russell Wallace, to the Linnean Society in London; Darwin's 200th birthday is coming up in February, and in November 2009 comes the 150th anniversary of the publication of On The Origin of Species - that's a lot of celebrating coming up), and asks, does Darwin really deserve all this credit? According to Judson, the answer is yes. But why, if Darwin wasn't the first to come up with the idea of evolution, and the concept of natural selection? Darwin may not have been the first, but ultimately he was the most persuasive:

The “Origin” changed everything. Before the “Origin,” the diversity of life could only be catalogued and described; afterwards, it could be explained and understood.

In other words, to be a great scientist, you have to have good ideas, and persuasively communicate them to your colleagues. Darwin did this very well - the Origin is filled with detailed evidence from a variety of fields. On top of that, Darwin argued that his ideas were testable, and proposed tests that he himself and others could do. Darwin may not have been first to come up with all of the ideas presented in the Origin, but he was the first to really get evolution going as a healthy scientific field. And for that, the celebrations are justified.