Mendel vs. Darwin

Gregorian Genetics and Darwinian Evolution

Charles Darwin and Gregor Mendel are two of the most recognizable names in biology. Darwin is famous for his Theory of Evolution, and Mendel is  credited as the Father of Genetics. These two aspects of biology are essential for understanding how life works and are so intertwined with each other that it's impossible to have a full understanding of one without the other. DNA is our genetic material. DNA can be damaged, miscopied, deleted or duplicated everyday in every cell. Some (but not all) DNA damage leads to mutation. Some (but not all) mutations are deleterious. Some (but not all) mutations are beneficial. In fact, most mutations are silent, quiet. shhh. Listen close and you can almost hear the genetic clock ticking away, providing the variation necessary for evolution. Genetics and Evolution are firmly linked, and both are absolutely critical to many, many of the technological developments we have today. 

Mendel was just as wrong as Darwin

In 1871 Caricature of Darwin, who still is heavily criticized

But, for whatever reason, Darwin is both the more famous and the more controversial figure.  You can easily find mocking images of Darwin depicted as a monkey, poking fun of the humbling idea that monkeys and humans (gasp!!) share a common ancestor. These images aren't a recent meme, they popped up soon after Darwin released his famous book, On the Origin of Species (1859). Yet, you’d be hard-pressed to find a similar mockery of Mendel depicted as a pea pod for asserting that inheritance works in predictable ways in both peas and humans. 

Mendel is both less famous and less criticized

So, why not criticize Mendel too? If we wanted to, we could find plenty of flaws in Mendel. For instance, the Law of Independent Assortment has already been proven wrong for many genes! That would seem to indicate that Mendel was wrong. There are only two Laws in Genetics, and if one of them is wrong that sure seems bad.  Well, these genes aren't really law-breakers, they just happen to be close to each other on the same chromosome. But the Law of Independent Assortment is still taught to students, nonetheless. Why? Because Mendel provided evidence for his ideas and his evidence has since been supported many times over. You can find exceptions, but the Law of Independent Assortment provided a critical step in moving towards chromosome theory, an important molecular understanding of genetic inheritance. Darwin was wrong about some things as well (see below). 

So why are Mendel and Darwin treated differently?

There are a number of possibilities: Darwin’s theory was published as a book, On the Origin of Species (1859) and the original run of 1,250 copies quickly soldout. Darwin’s ideas were not accepted by all, but were incorporated into social dialogue in part because the idea that species can change (even humans!) was so polarizing. By comparison, Mendel’s work had a much quieter impact. It was presented as a paper in 1865, just 6 years after Origin of Species, called Versuche über Pflanzenhybriden (Experiments in Plant Hybridization). During the first 35 years after publishing it was cited only 3 times. ‘Plant hybridization’ and its statistical analysis of inheritance in common pea plants didn’t resonate the way Origin of Species did with its descriptions of plants and animals from around the world. Perhaps if Mendel had used a catchier title for his work, such as The Rules of Inheritance, The Origin of Traits, or Mr. Darwin: Please Read This, it would’ve had a bigger initial impact. Mendel's work was re-discovered and widely revered by geneticists after the field took off in the early 1900s.  

How Darwin was wrong

When it comes to inheritance, Darwin was wrong. Darwin's 1868 book on The Variation of Animals and Plants under Domestication, gives a theory of inheritance that was frankly, terrible.  It was based on particles he termed gemmules, and these gemmules carried hereditary information by forming in organs throughout the body, then travelling via the bloodstream and finally accumulating in the reproductive tissue. Offspring would then receive ALL of the traits of both parents, including acquired traits, and blend these traits together somehow. If this were Darwin’s only contribution to science, he would not be a remarkable scientific figure. But if we look again at the publication date – 1868 – three years after Mendel had published his work that included description of Dominant and Recessive traits, and the Law of Segregation and the Law of Independent Assortment. Mendel didn’t use the word genes (or gemmules), but the laws of inheritance he observed explained the transmission of information from parent to offspring way better than anyone ever had. Darwin should have considered Mendel's work in his 1868 book, but it's not clear how much he knew of Mendel.  Either Darwin did not encounter Mendel’s work (not likely), did not think it worthy of mention (maybe), or did not understand it (most likely, but soley by my judgment).   

Darwin and Mendel were both right

So, while Darwin’s ideas on populations being subject to natural selection were excellent, Mendel had a much better observation-based theory regarding inheritance of traits. Together, Evolution and Genetics are an important part of understanding Biology, and both Darwin and Mendel made a huge contribution. It's sad that the two contemporaries never met to discuss their equally profound ideas over a pint or two.