This theme -- that science and knowledge could damn humanity -- was around long before Lovecraft gave it a voice. (It still exists today; look at the anti-nuclear or anti-genetically modified foods movements.) For much of human history, man might have been living in what Lovecraft would term a "dark age," but at least man was at the center of things. Man's interpretation of himself as described in his religions and fables was that of the most important thing in the universe. Indeed, the Earth was said to be the center of the universe, until a scientist named Copernicus refuted the idea. And from then on, the realm of science began uncovering one uncomfortable truth after another. Man had descended from apes. The universe operated on cold, mechanical principles unconcerned with human needs or torments. Living things were constructed out of tiny molecules and atoms and the difference between life and death was merely a restructuring of these basic elements. When one considers all this, it's easy to understand people's fear of science. And it's easy understand how a canny horror author could mine this fear for powerful fiction.
The science of Lovecraft's era was a goldmine of controversial discoveries about reality. Take the field of genetics. Men had long known that certain physical traits were inheritable -- a father's pointed nose could be passed to his son, a mother's ample bosom could be passed to her daughter etc. But the process by which traits were inherited was ill-defined and accompanied by many questions. Could behavioral traits such as mental calm or a propensity for violence be inherited? Could learned abilities such as piano playing be passed on from parent to child?
Much of the progress of 20 century genetics stemmed from the rediscovery in 1900 of the work of a Austrian monk named Gregor Mendel. Several decades previous, Mendel had conducted extensive research on the cultivation of garden peas (exciting stuff!) In particular, Mendel studied how physical aspects (size, shape, color etc.) of peas were passed through generations. Based on his observations, Mendel theorized a biological system driven by factors (what we now call genes) that could be passed from parent to child. These factors could be dominant or recessive and the physical representation of these factors, say, red hair, could skip generations.
As the science of genetics continued into the 20 century, the search to locate the exact location of these factors/genes fired off in earnest. Eventually they were isolated in DNA -- long molecules of nucleic acids housed in the chromosomes in cells. (An in-depth description of the functionality of DNA is outside the realm of this article, but it's fascinating stuff. If you're interested, this Wikipedia entry is a good place to start.)
Via Mendel's experiments, it was easy to see the logic of a natural system that led to inheritance of physical traits. But the obvious question was whether behavioral or mental traits could also be passed on from parent to child. In England during the 1860s, a cousin of Charles Darwin, Sir Francis Galton, had argued in literature that, indeed, broadly defined and desirable mental traits such as genius and talent were inheritable. And the argument went that the inverse was true: negative mental traits such as feeblemindedness and sloth could be passed on as well.
This theory eventually coalesced into the concept of eugenics, a political/scientific movement that took hold in the early 20th century. Eugenicists argued that society should take an active role in encouraging the breeding of superior humans. The suggested means for this breeding varied, from the general encouragement of the intermingling of "superior" humans, to laws allowing for the forced sterilization of the insane. While most recoil at the concept now, eugenics achieved popularity across the political spectrum of many countries and had prominent supporters such as author H.G. Wells, politician Teddy Roosevelt and economist John Maynard Keynes.
Ultimately, eugenics was embraced most ardently by the German Nazis who determined that, while controlled breeding was a good way to eliminate undesirables, out and out genocide was even better. As a result of eugenics' association with the Nazi atrocities, the theory quickly fell out of favor after the end of World War II. Additionally, the science behind it never panned out. By the 1930s scientists had shown that broad categories of mental traits or abilities (such as "genius" or "feeblemindedness") were not passed on in single genes, but were rather a complex interplay between different units of genetic material as well as environment. As a result, it would be very difficult to breed humans for a broadly defined trait.
(Warning: the following paragraph contain some spoilers to certain Lovecraft stories.)
The grand theme of eugenics -- the idea that one could be rewarded or damned by their genetic inheritance -- was often tackled in Lovecraft's work. (Much of his writing was authored during the height of eugenics' popularity.) In the short story "The Shadow over Innsmouth" a character comes to a horrific realization about his lineage. In "The Lurking Fear" a small human population is damned to idiocy by generations of inbreeding. The narrator of "Rats in the Walls" loses his battle with the demented form of madness carried in his bloodline. And "The Dunwhich Horror" tells the story of the Whateleys, a family who all seem to share a predilection for madness, mutation and sorcery.
Lovecraft probably had several reasons for his interest in eugenics. Eugenics was a pseudoscience which offered a defense of racist attitudes towards the European immigrants whom were pouring into the United States; Lovecraft's negative view of these immigrants (as well as his general racism) is well commented on. But eugenics also spoke to a specific fear Lovecraft had in regard to his own family. His father had gone mad when Lovecraft was a child and had died in an institution. His mother followed suit when Lovecraft was a young man. He was acutely aware of the fact that madness ran in his family and that there was some possility that he would experience it.
Lovecraft's exact views on eugenics are hard to discern. It is known that eugenics in the United States was strongly championed by many progressives, and Lovecraft was a man of the left. (We should keep in mind that the political left and right of the early 20 century were in many ways different from their modern contemporaries. And socialist scientists played a prominent role in falsifying the eugenics theory.) However, Lovecraft's stories do make clear that he was aware of the ideas of eugenics and ruminated on them deeply.
Next issue: X-Rays, Radiation and the Invisible Realm!