The Gene: An Intimate History

Mukherjee begins his history of the science of heredity with the question of “likeness” between parents and children that preoccupied philosophers in the ancient world. Pythagoras used his observed working of reproduction to theorize that the “likeness” was transmitted via semen. He believed that male semen travelled through a man’s body to collect data about each part, such as the color of eyes, and transmitted it into the mother’s womb to grow a baby. Highlighting the central role of semen in determining the features of a child, Pythagoras’s theory came to be known as “spermism.”

Spermism was widely accepted in ancient Greece for nearly two centuries, till Aristotle “systematically dismantled” (22) the theory with an unassailable argument: If semen collected all the information about a future child from the male’s parts, how could it produce a daughter? In a radical departure from the prevailing male-centered view of reproduction, Aristotle proposed that females, like males, contribute material for the fetus.

Path-breaking as Aristotle’s formulation was, the science of heredity would not build on it for several centuries. In fact, the next big idea in heredity was the “homunculus” or a miniature human: By the medieval era it was believed that the fully-formed homunculus lived in sperm, simply inflating into a child in the womb in a process called “preformation.” The science of heredity, it seemed, had stalled once again. Only in the 19th century would a paradigm shift occur, with a quiet monk growing peas in a crumbling monastery.

Gregor Johan Mendel, who is now known as the father of genetics, was ordained in the Augustinian order of monks in Brno in 1847. Mendel applied to be a teacher of natural science (the 19th-century term for science) at the local high school, but failed the qualifying exam, and was sent to Vienna for a degree in natural sciences. In Vienna, Mendel was deeply influenced by the physicist Christian Doppler, who demonstrated through experiments that sometimes artificial conditions were needed to prove a natural law.

Mendel is one of two behemoths in the early history of modern genetics; the other is Charles Darwin. In 1831, 22-year-old Darwin, a fresh graduate in natural history from Cambridge, boarded the HMS Beagle as a “gentleman scientist,” whose job would be to help collect specimens—fossils, bones, plants, and rocks—along the journey of the Beagle. Over the five-years-long round-the-world voyage, Darwin’s most momentous stop would prove to be at the Galapagos islands, a lonely South American archipelago, formed of volcanic rocks. At the islands, Darwin collected carcasses of hundreds of birds, from finches to mockingbirds to albatrosses.

Back in England, the animal remains and fossils threw up a strange fact: Most fossils found in an area were none other than gigantic versions of animals still in existence in the same vicinity. That was not the only odd fact: It was also found that the birds from the Galapagos were not vastly different species, but all linked species of finches. Taken together, the two findings made Darwin wonder if the animals of today arose from former species.

Though Darwin’s question amounted to heresy by implying a force other than God had led to creation, Darwin could not let go of his inquiry. The next logical question was what made species descend from others. Darwin found his answer through two sources. One was the common farming practice of breeding, where farmers bred animals to ensure favorable features. The other source was a paper by the cleric Thomas Malthus, in which Malthus argued that nature confronted the problem of human overpopulation by sending difficulties and sicknesses for “natural selection,” ensuring only the fittest survive. It struck Darwin that natural selection “bred” favorable variants of a species, while unfavorable variants died off. In the Galapagos, for instance, an island evolved the gross-beaked (large-beaked) finch, its beak better for breaking seeds. Since this anomaly was more suited for survival, “the freak became the norm” (38).

In 1859, Darwin published his findings in the book, On the Origin of the Species. Aware of the implications of his discovery, he stopped short of saying that modern humans arose from an ancestor.

According to Mukherjee, Darwin was preoccupied with one particular lacuna or “wide blank” in his theory of evolution: How did nature’s “sports” (Darwin’s word for mutations), which were inconstant, regularly transmit their peculiarity to their offspring? Both the capricious and the constant had to work in tandem for evolution to proceed. Darwin could observe these contradictions, but could not come up with a theory of heredity that reconciled them.

The prevailing view of inheritance in Darwin’s time was the theory suggested by Jean-Baptiste Lamarck, a French biologist. Lamarck thought species gave rise to new species through practice and instruction. For instance, an antelope which had to stretch its neck to get to fruit on trees eventually developed a longer neck, passed this trait to its offspring, ultimately giving rise to a giraffe. Darwin’s theory of evolution was obviously different because it did not rest on continual progression (i.e., all antelopes morphing into giraffes), but on chance and natural selection. In Darwin’s theory, one antelope mutated into a long-necked variant, nature selected it, and the variant branched off into a new species.

In the end, Darwin tried to explain evolution and heredity through the concept of “pangenesis,” a theory that “gemmules” or tiny particles carrying hereditary information passed on to the reproductive cells to meet in the womb and blend together, but the theory was discounted.

Mendel failed the natural history exam in Vienna, and returned to Brno in despair, taking the position of a substitute teacher. In his spare time, he began crossing strains of peas in the walled garden of the monastery, inspired by Doppler’s idea that sometimes artificial experiments were needed to prove natural facts. To this extent, he collected 34 strains of peas and bred them to select “true” traits, that is, the traits that would pass unaltered to offspring, such as tall crops that only produced tall crops. He noted that traits came in at least two variants, such as tall and short plants or white and violet flowers; biologists would later call these variants “alleles.”

The critical question behind Mendel’s experiments was the outcome of crossing two plants with true traits, such as a tall plant and a short plant. Over tedious and painstaking experiments that took eight years, Mendel found that the hybrid character was not a blend; rather, offspring tended to follow one parental trait, that is, a plant was either tall or short. The traits which showed up in hybrid offspring were termed ‘dominant,” while the disappeared traits were called “recessive.” The second pattern, to Mendel’s surprise, was that the disappeared recessive traits were not vanished for good. They showed up, perfectly intact, in the cross of two hybrids.

Mendel found that when a plant inherited two recessive alleles, the recessive allele asserted itself as a trait. The persistence of the recessive allele showed the information carried by an individual allele remained intact and indivisible. Though he would not coin the term, Mendel had “discovered the most essential features of a gene” (53).

Despite the enormity of his findings, Mendel would not enjoy acclaim in his lifetime, as his published study attracted little attention. When Mendel shared his findings with the Swiss botanist Carl von Nageli, Nageli dismissed Mendel’s experiments. Mendel eventually gave up on his studies to focus on administrative work as the abbot of the monastery. Mendel died in 1884.

In the last two decades of the 19th century, Dutch botanist Hugo de Vries conducted experiments similar to those of Mendel, though he still “lacked Mendel’s crucial insight” (58) about the alleles. It was during this time that a colleague shared an old paper by “a certain Mendel” (59) with de Vries. De Vries discovered the solution to his experiments in Mendel’s work and rushed off his own paper to publication, though he did not mention Mendel’s contribution.

De Vries took the Mendelian experiment further, planting 50,000 seeds of primroses, and cross-breeding their plants to achieve spectacular mutations such as plants with enormous leaves. De Vries’s biggest achievement was finding a link between evolution and heredity, Darwin and Mendel. Observing the primrose mutations, de Vries proposed that as species compete for resources, nature occasionally and randomly produces unknown traits or alleles. The best adapted alleles are selected, eventually leading to the generation of a new species.

Nearly two decades after his death, Mendel did get his due. Rediscovering the work of Mendel and its contribution to the experiments of De Vries, the English botanist William Bateson “made it his personal mission to ensure that Mendel, once forgotten, would never be ignored” (62). It was also Bateson who coined the term “genetics” for this science, and Bateson who predicted the dangers of pursuing “desirable” genetics.

Mukherjee unpacks the evolution of the idea of “eugenics,” or the now-discredited belief that humans could be “bred” for superior characteristics. The man who coined the term was Francis Galton, Darwin’s first cousin. In 1844, Galton began a series of travels to Africa, which emphasized to him the supposed difference between racial groups. By contrast, Darwin’s interaction with the locals of South America had only proved to him the common ancestry of all human beings.

Galton became consumed with the idea of proving the genetic “superiority” of certain “races.” To this extent, he began to tabulate traits across a population, including subjective attributes like beauty and intelligence. Another set of data Galton collected was on notable men: He found that eminence ran in families. Although Galton acknowledged that eminent men produced eminent sons also because they provided the sons with the necessary social and economic advancement, he refused to further explore the connection between success and environment.

In 1904, Galton presented an argument for eugenics at the London School of Economics, stating that “good specimens” (73) could be bred through favorable marriages. Although Galton’s remarks faced significant opposition from scientists who questioned the very notion of a “superior” human being, other eminent members of society were far more receptive. One of the people supporting eugenics was the novelist H.G. Wells, who went one step further in supporting “negative eugenics,” or the sterilization of “inferior” humans. Wells argued that a “superior” breed could be achieved only in tandem with the weeding out of the weak. Incendiary as they may seem now, these notions were gaining increasing popularity at the turn of the 20th century, soon to lead to the dangerous notion of a “master race” that would be at the heart of Nazi ideology.

Interest in eugenics was on the rise in Germany in the early decades of the 20th century, but in America, it had already become a live national project. By 1920, confinement centers had been formed in the US to isolate people with inheritable conditions so they could not breed further. The Virginia State Colony for Epileptics and the Feebleminded in Lynchburg was one such center for “feebleminded” women. “Feeblemindedness” ostensibly referred to cognitive disability, but often included any woman on the margins of society, including sex workers and feminists.

Mukherjee describes the case of Buck vs Bell, heard before the Supreme Court in 1927, to show the zeal with which eugenicists pursued sterilization. The case was about Emma and Carrie Buck—an impoverished mother-daughter pair. In 1920, Emma was arrested for sex work and dispatched to Lynchburg, where she was sentenced to confinement for life. Young Carrie was sent to foster care, where she was raped by the nephew of her foster parents. After she gave birth to Vivian, Carrie too was sent to Lynchburg in 1924. Soon, Carrie was chosen by Lynchburg’s superintendent Dr. Albert Priddy as a model example for the supposed necessity of mass sterilization.

To pre-empt objections to his project, Priddy had Carrie appear before various courts, where nurses and social workers testified to Carrie’s “feeblemindedness.” Sterilization was approved for Carrie at every pit stop. After Carrie’s lawyers filed an appeal, the case landed up in the US Supreme Court in 1927. Priddy having passed away, the plaintiff was now John Bell, the new prison superintendent. The Supreme Court too quickly declared Carrie fit for sterilization, even though Mukherjee notes, reports had suggested she could read and write well, and showed no signs of mental illness.

The cinching argument was an examination of young Vivian, now herself in foster care, who, according to a nurse, already showed signs of mental “enfeeblement.” The court declared that “three generations of imbeciles” in a family was enough; the bad strain had to be arrested. Carrie underwent tubal ligation in 1927, never to bear another child.