natural selection – Conservation Sense and Nonsense

Luther Burbank: The Plant Inventor

Luther Burbank was born in Massachusetts in 1849, the 13^th of 15 children. As a child, he had an interest in nature. With an inheritance from his father, who died when Burbank was 18 years old, he purchased a 17-acre farm in Massachusetts.

Burbank bought his small farm intending to be a market farmer, selling seasonal fruits and vegetables. He was handicapped by challenging climate and growing conditions and competition from other market farmers with a head start. He could see that he would have to produce the best produce and offer it before his competitors could, which pushed him down the path of improving the plants he grew.

Burbank’s methods for improving plants

Burbank found his inspiration as a breeder of improved plants in his local library where he found the writings of Charles Darwin. He could see that the concept of natural selection described by Darwin, applied equally to breeding plants. He wrote, “It opened a new world to me. It told me, in plain simple sentences, as matter-of-fact as though its marvelous and startling truths were commonplace that variations seemed to be susceptible, through selection, of permanent fixture in the individual…I doubt if it is possible to make anyone realize what this book meant me.” (1)

Burbank quickly put his new understanding of selection to use as a means to improve the food crops he grew. He developed the Burbank potato that is known today as the Burbank russet potato. He found a seed ball on his potato plants containing 23 seeds. He grew the seeds, selecting the plants that produced the best potatoes in successive crops until he had a potato with smooth skin and few eyes that tasted good and stored well. It was also mildly resistant to the blight that caused the potato famine in Ireland, which killed one million people and caused a mass exodus from Ireland.

He understood that he had created a valuable commodity, but he couldn’t see how he could profit from it because he couldn’t produce it at scale on his small property and he didn’t have the commercial infrastructure to market it widely. At the time, it wasn’t possible to patent new plant varieties, so he sold his new variety to an established seed merchant for $150. It was a paltry sum, even at the time, but it was the beginning of a business model that financed most of Burbank’s career as a plant inventor.

Charles Darwin also introduced Burbank to another method of improving plants in his publication, “The Effects of Cross and Self-Fertilization in the Vegetable Kingdom.” Burbank described how Darwin led him to the realization that hybridization is another means of improving the quality and performance of plants: “One sentence in the very introductory chapter of that volume opened the door of my mind and took possession of my fancy. After discussing briefly the marvel of cross- and self-fertilization in plants, Darwin said: ‘As plants are adapted by such diversified and effective means for cross-fertilization, it might have inferred from this fact alone that they derive some great advantage from the process; and it is the object of the present work to show the nature and importance of the benefits thus derived [from hybridization].’” (1)

Darwin identified natural selection and hybridization as tools of evolution that produced plants and animals best adapted to current environmental conditions. When environmental conditions changed, as they have constantly over 4.2 billion years of the Earth’s existence, natural selection and hybridization enabled the survival of plants and animals best adapted to changed conditions. Using the same methods, but different criteria, Burbank bred the plants that conformed to the needs of humans: the most flavorful fruit, sturdy enough to be transported from fields to tables and the most beautiful flowers, in the opinion of humans. Burbank directed and accelerated evolution to serve humans, using the tools of natural evolution.

Grafting the branches of one type of fruit onto the root stock of another species of tree was the third method Burbank used to create new plants. Most orchard fruit is grown from grafting because growing fruit trees from seeds is unpredictable. The seeds of a flavorful apple, don’t necessarily grow into a tree that produces an equally flavorful apple. It takes years for some fruit trees to produce fruit, which can ultimately produce disappointing fruit. Grafting is a means of reducing risk and accelerating production.

California’s Bounty

After years of economic hardship, Burbank moved to California in 1875 at the age of 26 to join his brothers. Instantly, he was an enthusiastic promoter of the ideal climate and growing conditions of his new home in Santa Rosa. He bought 4 acres of land where he built a greenhouse, nursery, and experimental fields. Later, he bought an 18-acre plot of land in nearby Sebastopol he called the Gold Ridge Farm, where his experiments expanded.

Luther Burbank Home & Garden, Santa Rosa. Creative Commons Attribution-Share Alike 3.0 Unported license.

In California, Burbank had the climate and the acreage needed to run many experiments on fruit and nut trees as well as vegetables and flowers simultaneously. Each experiment required planting thousands of individual plants, grown through many generations. These experiments produced hundreds of varieties of many species of plants:

Fruits
113 plums and prunes
69 nuts
35 fruiting cactus
16 blackberries
13 raspberries
11 quinces
11 plumcots
10 cherries
10 strawberries
10 apples
8 peaches
6 chestnuts
5 nectarines
4 grapes
4 pears
3 walnuts
2 figs
1 almond
Grains, grasses, forage
9 types
Vegetables
26 types
Ornamentals
91 types
Source: Wikipedia

Finding His Tribe: Scientist or Businessman?

By the turn of the century, Burbank had made his reputation as the creator of new plant varieties. He captured the attention of scientists who wanted to adopt him into their community, learn his methods, and teach them to their students: “The San Francisco Chronicle advocates the seizing of Luther Burbank at his home in Santa Rosa and placing him in a chair at Stanford University….The main thing is to get the recluse away from his practical experiments long enough to tell people what he has done.” Los Angeles Times, June 7, 1901.

Burbank was invited to give a series of lectures at Stanford University at a time when botanical scientists were newly influenced by the discovery of the role of genetics in producing individual variations in plants and animals. Gregor Mendel’s studies of genetic variation done in the 1860s was buried in the archives of Mendel’s local botanical society until 1900, when they were rediscovered.

Burbank’s audience at Stanford was expecting his lecture to reflect the mechanistic determinism of Mendelian genetics. Instead, they got a dose of Burbank’s almost mystical view of the workings of nature “…as an intricate web of vibrations and magnetic forces where ‘all motion, all life, all force, all so-called matter are following the same law of heredity found in plants and animals, a forward movement toward attraction through lines of least resistance.’” (1)

Today, our understanding of genetics is more nuanced than it was over one hundred years ago and it is more consistent with Burbank’s observations. With the help of molecular analysis, we now know that there are hundreds of unexpressed genes that are latent unless triggered in response to specific growing conditions as well as random mutations. Burbank’s view of variation in nature was based on close, persistent observation and his own subjective intuition, based on decades of experience.

The Carnegie Institute of Technology tried to bridge this gap between science and Burbank’s art of creating new plant varieties by giving him a generous grant of $10,000 per year on the condition that a botanical scientist would trail Burbank in the field and turn his art into a data-driven algorithm capable of replicating Burbank’s accomplishments.

The scientist assigned to that task was immediately frustrated by the haphazard jumble of Burbank’s sketchy record-keeping. Watching Burbank in the field was equally frustrating. Burbank couldn’t translate the choices he made into words because his judgment was intuitive. Finally, The Carnegie Institute lost patience with the project and terminated the grant.

Henry Ford and Thomas Edison came to visit Luther Burbank in 1915 after their visit to the Panama-Pacific Exposition in San Francisco. It was a meeting of the minds and kindred spirits. They were businessmen whose commercial success was based on tireless effort, continuous incremental improvement, and practical invention. They were Burbank’s tribe, who became fast friends for the rest of their lives.

Thomas Edison, Luther Burbank, Henry Ford. Santa Rosa, 1915

Burbank Defends Evolution

It took Charles Darwin nearly 20 years to publish his treatise on evolution, On the Origin of Species, partly because he knew it challenged some of the basic premises of organized religion to which his family was committed. The evidence that life on Earth evolved over millions of years directly contradicted the religious belief that God created all life on Earth, as it presently exists, only 6,000 years ago. Evolution is also inconsistent with the religious belief that humans are chosen by God to rule the world and that all other creatures are subservient to our command.

In fact, pushback to the concept of evolution was minimal in the 19^th century after Origin of Species was published in 1859. Full-throated opposition to evolution emerged in the 20^th century and is epitomized by the Scopes trial that occurred in 1925, just one year before Burbank’s death.

The Scopes trial occurred because the state of Tennessee banned the teaching of evolution in public schools. The ACLU persuaded a high school teacher, John Scopes, to test the law. Two of the greatest orators of the time, stepped forward to try this important case. Clarence Darrow, defended Scopes for the ACLU. William Jennings Bryon was the prosecutor for the state of Tennessee.

Both Darrow and Bryon asked Luther Burbank to appear as a witness at the trial, which was an indication that the public was confused about Burbank’s close relationship with the natural world. Much to the disappointment of William Jennings Bryon, who considered himself a personal friend of Burbank’s, Burbank came down unequivocally in support of the teaching evolution.

In a letter submitted as evidence in the trial, Burbank said, “Those who would legislate against the teaching of evolution should also legislate against the teaching of gravity, electricity, and the unreasonable velocity of light, and also introduce a clause to prevent the use of the telescope, the microscope…or any other instrument of precision which in the future may be invented…for the discovery of truth.” (1)

Despite Burbank’s effort, Scopes was found guilty and the ban on teaching evolution in Tennessee remained in effect until 1967. In 2024, the Gallup Poll reported that only 24% of Americans believe in evolution unguided by God, a percentage that has increased steadily since 2000. The dominate view—at 37%–is that humans were created by God in their present form:

In a series of interviews with the news media, Burbank expressed his doubts about the afterlife and his admiration and kinship with Christ as a man rather than a deity: “[Christ] was an infidel of his day because he railed against the prevailing religions and his government. I am a lover of Christ as a man, and his work and all things that help humanity, but nevertheless just as he was an infidel then, I am an infidel today.” (1)

Burbank’s Last Success

By any measure, Burbank must be considered a success. Although he managed to make a living, he was not wealthy because his plant inventions could not be patented. Without patent protection, profits were realized by seed merchants, nurseries, and agricultural operations.

Burbank made many appeals to the US Patent Office for patent protection. His appeals sounded desperate and angry about the unfairness that often threatened him with economic ruin. His death in 1926 at the age of 77 sparked another campaign by other plant breeders to extend patent law to the development of new plant varieties.

The effort to extend patent law to plants was boosted by the Great Depression, which began in 1929. Farmers are always in debt as they must borrow money to plant their next crop. When commodity prices collapsed during the depression, many farmers lost their farms.

The proposal to extend patent law to plant “inventions” was perceived by many politicians as a way to help farmers, although the logic of that connection is questionable because patented seeds are likely to be more expensive. Despite that concern, the Plant Patent Act was passed with little opposition in 1930. There were many limitations on the first patent law, many of which have since been revised.

Sixteen of Burbank’s creations received patents, a small fraction of the plants being developed at the time of Burbank’s death.

We can still learn from Luther Burbank

I encourage readers to visit Luther Burbank’s home and garden in Santa Rosa, which is now a free public park, and the museum that is open during summer months. You will find many informational signs throughout the garden about Burbank’s inventions. You won’t find any hint of a nativist bias in the signs. This sign about creating a garden for butterflies makes it clear that these lovely creatures have no preference for native plants:

Luther Burbank Garden, Santa Rosa, CA. 2025

(1) The Garden of Invention: Luther Burbank and the Business of Breeding Plants, Jane S. Smith, Penguin Books, 2009

Gardening with the help of nature

Juliet Stromberg is a plant ecologist who specialized in wetland and riparian ecosystems of the American Southwest. Her friends call her Julie and I will presume to do the same. She has retired from her position at Arizona State University, but her husband, Matt Chew, is still teaching ecology from a historical perspective at ASU. He is very much her partner in their 20-year project to restore 4-acres of dead citrus grove and an 80-year old Spanish colonial house, long abandoned and derelict. The property came with water rights, without which their project would not have been possible.

In her recently published book, Bringing Home the Wild: A Riparian Garden in a Southwest City, Julie tells us how she and her partner transformed—with the help of natural processes–this dead patch of land in South Phoenix, Arizona into the oasis that it is today. The first step was to restore the irrigation system, which immediately brought much of the dormant seed bank back to life.

Julie & Matt’s garden is in the center of this aerial view

Using the riparian vegetation of the Salt River—the source of their water—as her reference, she chose a half-dozen tree species as the foundation of their garden, such as Fremont cottonwood, Gooding’s willow, and velvet mesquite. Twenty years later, there are now 300 trees, sheltering a community of plants and animals. How did they get there?

The seeds of some trees such as blue elderberry and mulberry were brought from neighboring gardens by birds and small animals. Julie and Matt have seen 157 species of birds in their garden, so we can assume birds have done some of the planting. The seeds of some plants are aerodynamically shaped and were blown in by the wind, adding to the diversity of the garden.

*Tropical milkweed seeds ready to be launched by the wind from a neighbor’s front yard. Conservation Sense and Nonsense, Oakland, CA, October 2023*

Many of the trees are American in origin, but others are not. Regardless of the method of dispersal, most introductions are welcome in Julie’s garden. She spares her readers the tedious recitation of which plants are considered native and which are not. The Southwestern desert is not an ecosystem with which I am familiar. I was glad to have a tour of Julie’s garden without irrelevant information about the nationality of every plant. For the same reason, I like to travel in distant places where I can’t distinguish natives from non-natives. Everything looks great to me and nothing brings me down more than a guide who wants to inform us of what “belongs” and what doesn’t.

Julie and Matt also planted a fruit orchard and a vegetable garden that bring more birds, insects, and animals to the garden as well as providing food for their table. Eating the fruits of our labors in the garden deepens our respect for what plants do for us and establishes our working relationship with the land.

Managing a wild garden

In keeping with Julie’s opinion that ecological restoration is a form of “glorified gardening,” she actively manages her garden. A few plants that annoy members of her community of plants and animals—such as puncture vine and tumbleweed—are not welcome.

When the delicate balance between predator and prey becomes unbalanced, some protective measures are necessary. If coyotes and dogs can’t keep up with the rabbit population, it’s sometimes necessary to put vulnerable plants into cages to protect them. The root balls of some plants are covered in wire mesh to protect them from hungry gophers.

Plants also assist in their own defense. Where mesquite is grazed by cattle, the tree responds by growing longer thorns to repel the cattle. When plants are attacked by plant-eating insects, some emit a toxin to render themselves inedible. The scent of the chemical wafts to neighboring plants, alerting them to the arrival of predators. These natural defenses are an important line of scientific inquiry that has potential to substitute nature-based solutions for synthetic chemicals.

The population of roof rats in Julie’s home is kept in check with liquid birth control, lest they chew on electrical wires or build nests in car engines.

Gardening with the help of friends

Julie’s is not a manicured garden, but it requires constant pruning to keep trails clear and provide light and space for plants to thrive. The annual scouring of the flood plain by spring floods is one of the natural processes that Julie and Matt could not use to restore their land because irrigation water is channelized and confined by concrete. Julie has come to appreciate the flies and other insects who are the decomposing crew, helping to reduce the accumulation of debris in the absence of annual scouring floods. Sixty-six species of flies assist with decomposition as well as pollination in Julie’s garden.

Julie is happy to have coyotes in her garden, but her dogs disagree. Violent and fatal confrontations between these closely related species required building a wall that confines dogs close to the house at night, while coyotes safely roam most of the garden.

Dogs are an important part of Julie and Matt’s life. Early in the book’s introduction Julie warns readers that they should put her book down “NOW!” if they don’t want to hear dog stories. Julie has walked thousands of dogs in a nearby animal shelter. In addition to her own 4 dogs, there are also occasional foster dogs who need to recover from traumatic experiences to be adoptable. In Julie’s refuge, these traumatized dogs learn to trust again.

Peaceful co-existence

Julie is a recovering academic scientist. Before she retired, she felt that her focus on the accumulation of data needed for scientific analysis was causing her to lose track of the big picture. She needed to stop and smell the flowers, so to speak.

She received her graduate education during the heyday of invasion biology. Julie slowly shifted away from native purism based on her experiences in the field. She has rejected that doctrine, and regrets teaching her students to fear “those who came from somewhere else.”

Julie has a vivid memory of the first step she took on that journey to her gardening ethic of peaceful coexistence. She had been instructed to pull tree tobacco from land along the Salt River that was being restored. The nicotine in the plant was making her feel sick, which seemed to bring her to her senses. She began to wonder what she was doing, “following orders to kill creatures she barely knew.”

Fly on desert tobacco. Photo courtesy Juliet Stromberg

Part of Julie’s skepticism about such eradication projects is based on her understanding of how little we know. She realizes that the harm done by non-native species is exaggerated and their benefits are underestimated. Given the limits of our knowledge, we should be obligated to give introduced plants the benefit of the doubt before killing them. She now appreciates the beauty of tree tobacco, which also feeds birds, fixes carbon, and stabilizes the soil. Its seeds were naturally dispersed to Julie’s garden and tree tobacco is welcome there.

Imperatives imposed by climate change

Julie says, “The preoccupation with provenance diverts conservationists and gardeners from critical issues,” such as climate change, food security, and extinction (which, studies show, are not caused by introduced plants). Living in the Southwest, Julie has a front row seat on climate change. It’s always (within the context of our lifetime) been hot there, but now it is blisteringly hot during summer months. She watches hummingbirds in her garden seek shelter in the shade, close to the irrigation drip. She watches dogs panting, birds gasping for breath and plants wither and die in the heat. And she knows that both native and non-native plants store carbon that would otherwise contribute to greenhouse gases causing climate change. Carbon storage varies according to certain plant characteristics, but those characteristics are unrelated to the nationality of plants.

Those who insist on replicating the landscape that existed 200-400 years ago in America are depriving nature of the evolutionary opportunities that will enable survival. We don’t know what life will be capable of living in the climate of the near-future. Nature needs as many alternatives as possible to find the species that can survive. Plants and animals are blameless in this struggle of survival of the fittest. The least we can do is to get out of their way as natural selection finds the life that is adapted to the current and future climate.

Showing respect for nature

Julie does not use any pesticides in her garden….no herbicides, fungicide, or insecticide. She is concerned about the pesticides used by her neighbor across the road who grows cotton. She notices the blue cotton seeds scattered on the ground and surmises that they were coated in insecticide or herbicide that will infuse pesticide into the plant as it grows. The poisoned seed can kill seed-eating birds and other animals and the plant itself will be poisonous as it grows. The dust from the cotton field blows into her property when the field is plowed and after the cotton is harvested because no cover crops are grown to tamp down the dust and prevent the loss of carbon stored in the soil. Julie can see firsthand the damage caused by industrial agriculture and is confirmed in her commitment to avoid using pesticides.

Julie shows her respect for everything living in her garden by her choice of pronouns to describe them: “who” not “what,” “she/her” not “it.” She asks her readers to show the same respect for plants and animals, regardless of their nationality. Avoiding the use of pesticides in our gardens is another way to show our respect for the plants and animals on which we depend, with the added benefit of not poisoning ourselves.

Thank you, Juliet Stromberg, for telling us about your garden and congratulations for what you have accomplished and learned from the experience of nurturing it back to life with the help of nature.

Darwin’s Finches: An opportunity to observe evolution in action

The finches on the Galápagos Islands are called Darwin’s finches because of the important role they played in the development of his theory of natural selection and evolution of species.

Galapagos Islands - satellite photo — Galapagos Islands, satellite photo. Daphne Major is too small to be visible.

Charles Darwin spent five weeks on the Galápagos Islands in 1835, near the end of a five year expedition. Although he noticed the similarity of the birds on the different islands, he didn’t realize they were all related to one common ancestor until he returned home. Fortunately, he collected many specimens of the birds to bring home for study. It wasn’t until those specimens were examined by an ornithologist that he learned they were 13 species of finches, distinguished primarily by variations in the size of the bird and its beak size and shape.

Unfortunately, he hadn’t recorded which islands the specimens were from, so the implications of their differences were somewhat of a mystery. He lamented in Voyage of the Beagle, “It is the fate of every voyager, when he has just discovered what object in any place is most particularly worthy of his attention, to be hurried from it.”

But Darwin was no dummy, so despite lacking the data necessary to prove his point, he speculated in his memoir, “…in the thirteen species of ground-finches, a nearly perfect gradation may be traced from a beak extraordinarily thick, to one so fine, that it may be compared to that of a warbler. I very much suspect that certain members of the series are confined to different islands…”

Such development of new species from a common ancestor in response to varying environmental conditions is called adaptive radiation. Species also diverge from one another to reduce competition by specializing in a particular food forage type or technique. Nearly 200 years later, science has proven Darwin’s hunch, but just as he had no way of knowing how long this process of speciation took, modern science still cannot answer that question.

Darwin’s finches continue to change in response to changing conditions

Geospiza magnirostris. Linda Hall Library — Large ground finch (Geospiza magnirostris). Linda Hall Library

Rosemary and Peter Grant have studied the finches on two Galápagos Islands (Daphne Major & Genovesa) for about thirty years. Nearly every year they visited the finches, weighing and measuring every appendage of the birds, especially their beaks. They banded the birds so they could follow their breeding success. They also measured their food: how much food but more importantly how accessible the food is to the birds such as the difficulty of opening seeds.

The availability and type of food is what determines the shape and size of the birds’ beaks. In a year in which there is plenty of rain, there is usually plenty of food which is relatively easy for the birds to eat. When it doesn’t rain, the birds are reduced to the difficult task of trying to crack open a large, hard seed pod. That’s when a big bird with a big beak has an advantage.

Extreme weather is therefore a “selection event,” a time when not every bird is equipped to survive. And the birds that survive are best equipped for those extreme conditions. When the conditions improve, the bird that survived the hard time is not necessarily best equipped for the good times.

These are the principles of natural selection, but they were largely theoretical until the Grants spent many years watching the birds and how they survived such selection events. They had the good fortune to witness two such events in the first twelve years of their study.

The drought

In the fifth year of the Grants’ study, 1977, there was a severe drought. After one short storm in early January, there was no more rain for the remainder of the year. In January, there were 1,300 finches on the island they studied that year. At the end of the year, there were less than 300 finches left on the island.

The Grants measured and weighed the birds that survived the drought. Then they returned to their lab at Princeton University to study their data:

Not a single finch was born and survived on the island in 1977
The surviving birds were 5-6% larger than the dead birds
The average beak size of the birds that survived was 11.07 mm long and 9.96 mm deep. The average beak size of the birds that did not survive was 10.68 mm long and 9.42 mm deep. These critical differences were too small to see with the naked eye, but became evident when the measurements were analyzed by computer. This makes a strong case for scientific measurement verses anecdotal observation, which passes for “evidence” amongst native plant advocates.
Few female birds survived the drought, presumably because male birds are larger than females.

In the years following that drought, sexual selection played an important role in maintaining the population of larger birds with larger beaks. Because the female birds were scarce, they could be very selective in their mates. Who did they choose? Of course, they chose the males with the traits that allowed the birds to survive the drought year. When the ratio of males to females is more even, sexual selection plays a less important role in natural selection in monogamous species such as the finches.

The flood

Here on the West Coast, we are familiar with the weather phenomenon of El Niño, the nickname given to a heavy rain year resulting from an unusually warm ocean current. In 1983, we experienced the strongest El Niño on record, as did the Galápagos Islands.

In 1983, the Grants witnessed the reversal of the results of the 1977 drought: “Natural selection had swung around against the birds from the other side. Big birds with big beaks were dying. Small birds with small beaks were flourishing. Selection has flipped.” *

Lessons learned

Darwin’s finches give us reason for optimism about the future. Nature can and will respond to changes in the environment. Natural selection is not just an historical process that stopped when The Origin of Species was written nearly 200 years ago. Natural selection is operating at all times, whether we notice it or not.

However, the loss of nearly 80% of the birds on a Galápagos Island during a severe drought is not cause for celebration. Although the species survived, hundreds of individual birds did not. So, we are quick to add that our confidence in the adaptive abilities of nature is not an argument for abusing the environment.

Climate change has caused extreme weather events which are undoubtedly selection events for many species of plants and animals. Unless we take action to reduce greenhouse gas emissions we can predict more of such events. Destroying millions of trees solely because they are not native is irresponsible given the contribution their destruction makes to the greenhouse gases causing climate change.

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*Jonathan Weiner, The Beak of the Finch, Vintage Books, 1994