Amazon.com description: Product Description: Biology was forged into a single, coherent science only within living memory. In this volume the thinkers responsible for the "modern synthesis" of evolutionary biology and genetics come together to analyze that remarkable event. In a new Preface, Ernst Mayr calls attention to the fact that scientists in different biological disciplines differed considerably in their degree of acceptance of Darwin's theories. Mayr shows us that these differences were played out in four separate periods between 1859 and 1947 -- and thus enables us to understand fully why the synthesis was necessary and why Darwin's original theory -- that evolutionary change is due to the combination of variation and selection -- is as solid at the end of the twentieth century as it was in 1859.