Defining “species” became one of Darwin’s great challenges. Darwin recognized that among naturalists of the day, the term “species” did not have a consistent definition. Darwin acknowledged what was accepted at the time –
“No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of a species. Generally, the term includes the unknown element of a distinct act of creation.”
In the mid-nineteenth century, the idea of molecular clocks was not even remotely considered, not to mention cellular biology or DNA. The scientific revolution had yet to reach into the realm of molecular biology. Case-in-point, Darwin thought “gemmules” learned by parents were passed on to the next generation through a process of “blending inheritance.”
Today, we know that “gemmules,” whatever they were thought to be, do not learn; it was a fabricated idea. And ironically, blending inheritance was soon recognized as an argument against Charles Darwin’s theory. Without a mechanism of inheritance, interest in Darwin’s theory by the end of the nineteenth century nearly vanished.
Darwin, Then and Now chronicles who Darwin was, how he developed his theory, what he said, and what scientists have discovered since the publication of The Origin of Species in 1859.
The book traces the rise and fall of evolution as a scientifically valid theory. With over 1,000 references from Darwin and scientists, Darwin Then and Now retraces how this once popular theory is increasingly recognized as only a philosophy since the theory has yet to be scientifically validated.