Read She Has Her Mother's Laugh: The Powers, Perversions, and Potential of Heredity Online
Authors: Carl Zimmer
In 1871, Burbank bought a seventeen-acre farm where he could carry out Darwin's causes and effects. He cross-pollinated beans.
His cabbage seeds and sorghum won prizes at the local agricultural fair. And then, at the tender age of twenty-three, Burbank spotted an odd potato that would bring him agricultural immortality.
One day, as he tended a patch of Early Rose potatoes, Burbank noticed a tiny, tomato-shaped mass dangling from one of the vines. It was, he realized, something wonderfully rare: a seed ball. Farmers typically propagate potatoes by cutting up their tubers and planting the pieces, which can grow into entire new potato plants. Potatoes can also reproduce by having sex. They grow flowers, and once the ovules in the flowers are fertilized by pollen, they develop into seeds. The seeds cling together in a ball-shaped clump.
Over thousands of years of breeding, domesticated potatoes have mostly lost the ability to make seed balls. If farmers noticed one in a potato field, they usually ignored it. But Burbank had Darwin on his mind, and so, to him, finding a seed ball was like stumbling across a jewel. “
Stored in every cherished seed was all the heredity of the variety,” he later said.
When Burbank spotted the seed ball, it was still immature and thus not yet ready to use for breeding. To make sure he could find it again, Burbank tore a strip of cloth from his shirt and tied it around the plant. When he checked back later, however, the seed ball had dropped to the ground and disappeared from sight. For three straight days, Burbank searched for it. When he finally found it again, he opened it up and found twenty-three potato seeds inside. Burbank carefully stored them away for the winter and then planted them in the spring of 1872.
From that single seed ball grew a riot of variation. Burbank ended up with potatoes of different colors, shapes, and sizes. When he tasted the tubers, he found that two were unusually good. They were also smooth, large, and white; they stored well over the following winter. Burbank brought them to the 1874 Lunenburg town fair, where people were stunned at what
he had created. The following year, Burbank sold the potato to James Gregory, a seed merchant, for $150.
The “Burbank Seedling,” as Gregory generously named it, quickly became one of the best-known crops in the United States. A descendant of that variety, the Russet Burbank, carpets much of the state of Idaho. They are the only potatoes that McDonald's, the biggest purchaser of potatoes in the United States, will accept for its french fries.
Burbank's success with his potatoes convinced him that Darwin could guide him to riches. He sold his farm inventory, paid off his small mortgage, and left the stony soils of Massachusetts for California. Later, Burbank would look back in surprise at his rash move. He put it down to some impulsive streak in his ancestry. “
In short I was a product of all my heredity,” he wrote.
Perhaps it was likewise “
an inherited sensitiveness about money,” as Burbank liked to call his frugality, that made him decide not to pay for a sleeping berth on the westbound train. He spent nine days curled up on a seat. Looking out at the prairies, he ate sandwiches out of a basket prepared by his mother. Burbank made his way to Santa Rosa, where one of his brothers had settled.
The plants of California overwhelmed him. The pears were so big that he couldn't finish eating a single one. Yet Burbank struggled to survive even amidst all that plenty. He threshed wheat in the summer and looked for construction work in the winter. Sometimes he found jobs at nurseries. In 1876, Burbank came down with a fever and was bedridden for days in a tiny cabin, where he survived on milk a neighbor provided him from her cow. “
These were indeed dark days,” Burbank later said.
The following year things improved. Burbank had brought ten of his potato seedlings to California, and his brother let him plant a patch on his land. Burbank put an ad in local newspapers for “
this already famous Potato” and found some buyers. His mother and sister moved to Santa Rosa and bought four acres of land, which Burbank began to farm. In his free time, he would hike into the hills, discovering wild plants that botanists had yet to name. Seed companies would pay him for intriguing new species.
After six years in California, Burbank finally got his big break in 1881. A Petaluma banker named Warren Dutton wanted to get into the prune business and was ready to pay a small fortune for twenty thousand plum trees that would be ready to be planted in the fall. It was an absurd demand, but Burbank figured out how to meet it. He bought almonds and planted them on rented land in the spring. The almonds quickly sprouted into seedlings, whereupon Burbank and a hired crew of laborers grafted twenty thousand plum buds onto them. The buds took hold and grew. When their branches became big enough, Burbank cut the almond branches back. Burbank delivered the trees on time, and Dutton proclaimed him a wizard to anyone who would listen. It was the first time someone described Burbank that way, but it wouldn't be the last.
Dutton's praise helped Burbank's business explode. But unlike other nurserymen who prospered in California, Burbank rolled much of his profit into experiments. Following Darwin's guidance, he crossed different varieties to produce new combinations of traits. For his crosses, Burbank used the native California plants that he was becoming familiar with. He also developed a network of contacts in other countries, who supplied him with exotic plantsâplums from Japan, blackberries from Armeniaâthat he could also combine. When he bred them, he would discover variations among their offspring.
Something must happen to âstir up their heredities,' as I am fond of sayingâto excite in them the variability that normally lies dormant,” Burbank later explained. As he ran his experiments, he sometimes felt barely in control of the powers he was summoning. “When you stir up the heredity of any living thing too much
it is like stirring up an ant-hillâyou find the results much more startling and unsettling than useful or helpful.”
Burbank might produce thousands of hybrid offspring from which he might pick just a few to propagate into a new generation. He might breed them for years before reaching the proper form. After a few years of breeding a type of lily, Burbank found a single specimen that met his standards. A rabbit ate it.
Despite these setbacks, Burbank had produced enough varieties by the mid-1880s to start selling them to nurseries. His mysterious power to create
new fruits and trees attracted visitors to his farm, to puzzle over his “mother trees”ânative plants to which he grafted many different species at once to grow them as quickly as possible.
By 1884, Burbank could advertise a stock of half a million fruit and nut trees. Word of his creations spreadâof oranges that could grow in the north, of flowers that would not fadeâand before long, newspapers and magazines began publishing profiles of him. They crafted a public persona for Burbank as a botanical alchemist. “
In his laboratory garden he has done for Nature in part of one man's lifetime what Nature couldn't do for herself in thousands and thousands of years,” one newspaper declared. Others promised his work could feed the hungry and enrich the nation. One reporter wrote that, thanks to a giant prune Burbank developed, “
one California townâVacavilleâwas literally built by prunes.”
Burbank's humble origins helped him become famous. He became an American icon along the lines of Thomas Edison, able to make great discoveries without a college degree. Yet the American scientific community came to admire Burbank as well. They could see (and taste) for themselves that his magic was real.
“In his field of the application of our knowledge of heredity, selection, and crossing to the development of plants,” declared David Starr Jordan, the president of Stanford University, “
he stands unique in the world.”
Luther Burbank's self-education in heredity seems to have stopped with reading Darwin. After plowing through
Burbank relied on his own instincts to carry out Darwin's vision. As he built his empire in Santa Rosa, he seemed unaware that in the late 1800s, Darwin's theory of pangenesis collapsed.
The early reviews of
didn't bode well. The psychologist William James dismissed pangenesis as empty speculation. “
In the present state of science, it seems impossible to bring it to an experimental test,” he said. To James, the book's only value was demonstrating just how baffling heredity remained.
“At the first glance,” James wrote, “the only âlaw' under which the greater mass of the facts the author has brought together can be grouped seems to be that of Caprice,âcaprice in inheriting, caprice in transmitting, caprice everywhere, in turn.”
But some scientists stood by Darwin, and none so passionately as his cousin Francis Galton.
Galton, thirteen years his cousin's junior, fashioned his life after Darwin's. After a disappointing stint at Cambridge, Galton led an expedition through southern Africa, and came back a famous geographer. He wrote bestselling travel books and dabbled in many different branches of science, making clever contributions along the way. He attempted to make the first national weather forecasts and designed the first weather maps. In 1859, he began turning his attention to biology, thanks once more to his cousin. Reading
The Origin of Species
, Galton later wrote, “
made a marked epoch in my own mental development.”
Like Darwin, Galton realized that understanding evolution would depend on making sense of heredity. Half a century later, when Galton wrote his autobiography, he struggled to convey to his readers just how mysterious heredity remained in the 1850s. “
It seems hardly credible now that even the word heredity was then considered fanciful and unusual,” he wrote. “I was chaffed by a cultured friend for adopting it from the French.”
In the early 1860s, Darwin and Galton both investigated heredity, but in profoundly different ways. While Darwin pictured the invisible gemmules, Galton looked for evidence of heredity in the traits that the English upper class valued most. He looked over the biographies of notable menâmathematicians, philosophers, patriotsâand was struck by how many of them had notable sons. “
I find that talent is transmitted by inheritance to a remarkable degree,” he wrote in
If talent was indeed hereditary, Galton wrote, then it could be bred like the plumage of a pigeon or the fragrance of a rose. In fact, Galton believed England's future well-being depended on a national breeding program to produce more talented humans. He imagined this program as a joyous ritual, bringing gifted young people together to have better and better
children. The result would be a species capable of handling all the power that Victorian science and technology was providing it.
Men and women of the present day are, to those we might hope to bring into existence, what the pariah dogs of the streets of an Eastern town are to our own highly-bred varieties,” Galton predicted.
In 1869, Galton published a book-length version of his study, which he entitled
He declared with remarkable certainty that eight out of a hundred sons of distinguished men were distinguished themselves, a rate far higher than one in three thousand people chosen at random. Here, Galton declared, was proof of the heredity of talent. Yet for all Galton's questionable data, there was a giant void in his book: He had no idea how heredity actually occurred.
, Darwin electrified his cousin a second time.
Galton became convinced that pangenesis “is the only theory which explains, by a single law, the numerous phenomena allied to simple reproduction.”
Galton set out to prove pangenesis by showing that gemmules existed. Darwin had written that gemmules “circulated freely throughout the system,” and so Galton reasoned that if he transfused blood from one animal to another, he should also transfer some gemmules.
Galton wrote his cousin a note: “I wonder if you can help me. I want to make some peculiar experiments that have occurred to me.”
He asked Darwin to put him in touch with breeders from whom he could buy rabbits. Over the next few months, Galton had silver-gray rabbits injected with blood from other rabbits of many different colors. He hoped the injected gemmules would change the color of their kits.
Good rabbit news!” Galton wrote to Darwin on May 12, 1870. “One of the litters has a white forefoot.”
But with the birth of more litters, Galton's excitement faded. Injecting blood into rabbits showed no further hint of being able to change their color.
The experiments proved “a dreadful disappointment,” Emma Darwin wrote to her daughter, and, in March 1871, Galton came before the Royal Society to recount his failure.
The conclusion from this large series of experiments is not to be
avoided,” Galton said, “that the doctrine of Pangenesis, pure and simple, as I have interpreted it, is incorrect.”
Galton thought he and Darwin belonged to the same team, together searching for heredity. But as soon as Galton gave up on pangenesis, Darwin publicly chided his younger cousin. He wrote a letter to
, disassociating himself from the rabbit experiments. “
I have not said one word about the blood,” Darwin declared.
Darwin pointed out that in his own writing, he had talked about pangenesis in plants and single-celled protozoans, which had no blood at all. “It does not appear to me that Pangenesis has, as yet, received its death blow,” Darwin protested.
Writing in 1871, Darwin was technically correct. But in the years that followed, another scientist would kill pangenesis for good.
That scientist was a German zoologist named
August Weismann. Unlike Darwin or Galton, Weismann didn't start his scientific life as they did with an exotic adventure. Rather than sailing around the GalÃ¡pagos Islands or crossing Namib deserts, Weismann spent his best years squinting through a microscope, observing the fine details of butterflies and water fleas.