by What Linnaeus Saw- A Scientist's Quest to Name Every Living Thing (retail) (epub)
Browallius urged Linnaeus to back off. He reasoned that all Linnaeus had done was organize plants into groups to make them easier for students to learn. Making groups is a human activity. Humans make mistakes.
However, Browallius advised, if Linnaeus insisted on rebelling against a commonly accepted natural law, he should follow the rule of the English physicist Isaac Newton. Newton maintained that the only way to disprove a natural law based on other people’s experiences is to prove it wrong with one’s own. In other words, he was suggesting that Linnaeus prove his theory by planting seeds and showing that they would grow.
This was good advice. Linnaeus didn’t take it. There is no evidence that Linnaeus planted any seeds or conducted experiments to prove his peloria theory. He based his conclusions solely on his observations of the dried plant and the ones that were transplanted and grew for a short while in his garden in 1742.
That seems surprising to us today. In the mid-eighteenth century, Linnaeus’s English and French counterparts experimented and observed as part of their routine, following an empirical method. On the other hand, Swedish scientists still operated under a scholastic method, that is, they based their deductions on theoretical principles found in the writings of Aristotle and others, instead of observation and experimentation.
Although he did not try to grow the seeds, he did send to others the few seeds he had available. While rumors of a backlash rumbled, Johann Gmelin, a German botanist working in St. Petersburg, Russia, wrote Linnaeus a letter of support. Gmelin was convinced that new plants could come from a union of different species. In fact, he had evidence that the genus Delphinium also produced weird hybrids. Gmelin and others begged Linnaeus to send them peloria seeds and dried specimens.
Linnaeus predicted that one of the great scientific efforts of the future would be to investigate peloria. “By careful examination of its curiosities, one could gain insights into previously unknown, very important truths.” He did not yet understand where this theory might lead. Despite his great enthusiasm, Linnaeus stewed in a mix of certainty, doubt, and religious caution . . . for twenty-two years.
During that time, Linnaeus’s thinking inched closer to evolutionary ideas. Finally, in 1766, when he revised Systema Naturae for his twelfth and final time, with one stroke of his goose-quill pen he deleted the line “nullae species novae” from his definition of the word “species.”
PELORIA UPDATE
Linnaeus sent some of the seeds from his peloria specimens to Bernard de Jussieu, demonstrator at the Royal Garden in Paris. After seven years of experimenting, Jussieu’s colleague Michel Adanson determined that it was not a new species but a “monstre par excès”: a monster of excess. It had too many spurs and too many stamens. Over a hundred years later, a plant like this would be described as a mutation.
Linnaeus was not the first to see a plant mutation and Adanson was not the first to identify one. In 1590, a German pharmacist found a malformation of another species in his herb garden, and in 1719, a Frenchman discovered a malformed dog’s mercury plant. In 1900, Dutch botanist Hugo de Vries defined the concept of mutation: a change in hereditary genetic material. Linnaeus and his contemporaries were unaware of the existence of genes and chromosomes.
In 1999, British researchers proved that Linnaeus’s peloria was a plant form caused by a hereditary mutation that occurs naturally in regular toadflax, Linaria vulgaris. This mutation is caused when a single gene, the cycloidea gene, which controls the symmetry of the flower, is inactivated.
Mutant linaria survive today and are found in Europe as well as the United States. Some of these mutated, or what are now called “peloric,” plants have been found in Rhode Island and Pennsylvania.
“No new species,” the phrase he wrote in his first edition of Systema Naturae, the phrase he had so often repeated to his students, so often written in his books, the phrase that had channeled much of his thinking, he now dropped quietly and without fanfare.
Consider what this decision—this three-word cut—must have meant for him. Although he was not orthodox, he was a religious man. By deleting the phrase “no new species,” he must have known that he was opening the door to new ideas, specifically to the rebellious, controversial idea that new species could be created.
A few years later his son, Carl Linnaeus the Younger, also a botanist, told him that some specimens of linaria had turned up with both normal and abnormal flowers on the same plant. This would have cast doubt on his conclusions about peloria. But Linnaeus wanted to hear nothing more about the plant. He seemed to still feel trapped on the edge of that cliff.
Even after Linnaeus’s death in 1778, and more than thirty years after his peloria work, a German scientist charged that he had been an atheist. In his diary, however, Linnaeus was clear that his faith in God never wavered, even though it seems that his interpretation of the story of creation had changed. Science historians confirm that his later writings show he eventually came to view species as “the daughters of time”—in other words, that the species could change over time.
That monster of a plant, however, was not the only life form that got Linnaeus into hot water. The animal kingdom brought plenty of conflicts too. One animal in particular was a problem: the human.
9
HUMAN VS. ANIMAL
If I were to call man an ape or vice versa, I should bring down all the theologians on my head.
—CARL LINNAEUS, LETTER TO JOHANN GEORG GMELIN, JANUARY 14, 1747
In 1735, Carl Linnaeus had become the first naturalist to classify humans in the same order as apes and monkeys. It was a move that angered critics and clergymen, who sharpened their quill pens to strike back.
That year, while living in Holland, Linnaeus came face to face with live apes and monkeys for the first time. Their similarities to humans were hard to miss—their teeth, hands, the nails on their fingers and toes, for instance.
At the time, Linnaeus was studying the banana and other exotic plants on George Clifford’s country estate. The Dutch East India Company director also kept a private zoo of tigers, wild dogs, swine, parrots, and monkeys. Sometimes when Linnaeus traveled to Amsterdam, he visited a world-famous tavern called Blue John’s. The tavern was located near the wharf where the Dutch East and West India Companies owned stables and warehouses. Sailors made a little extra income by selling to Blue John natural marvels they’d brought from other countries. The innkeeper displayed wax figures of humans and a large menagerie of exotic animals for customers to admire or, if they could afford the high prices, to buy. The inn sold to royalty and wealthy collectors all over Europe. But for the price of a tankard of ale, a person of modest means, like Linnaeus, could sit at a table for hours and watch animals in the courtyard cages, as long as he kept buying drinks.
This advertisement for Blue John’s tavern was an imaginative interpretation. Patrons did sit at outside tables, but the animals did not roam freely in the courtyard for obvious reasons. Lions were kept inside the inn in flimsy wooden enclosures; to see them cost extra.
At Blue John’s, Linnaeus saw porcupines and civet cats. There were tame ostriches as tall as horses, parrots that spoke Dutch better than he did, anteaters and lions, to name a few. For a young man wanting to compare species, this was the place to be. Assembled before him were animals from Southeast Asia and the Dutch colonies in the West Indies, South America and West Africa. This was armchair travel at its best: the excitement of field research minus the danger of sea voyages and deadly jungle fevers.
Of all the rare animals, he was most captivated by the monkeys. “There are none so delightful, so strange and different.” He described them in a letter to a friend:
They are more amusing than comedies or clowns. God has made the world a theatre, and it would not be right if the only clowns were human beings and never a member of another species.
He was mesmerized. Linnaeus was hunting for similarities and differences between animals. These would guide him as he created groups of animals and di
stinguished individual species from the rest. In fact, he had had a burst of insight three years earlier when, by the side of a road in northern Sweden, he found the lower jawbone of a horse. There were six front teeth. Next came two canine teeth, and in the back he counted twelve molars, six on each side.
This accidental find fit with an idea he’d been mulling over. “If I knew how many teeth and of what peculiar form [each animal has], as well as how many udders and where situated,” Linnaeus speculated in his trip journal, “I should perhaps be able to contrive a most natural methodical arrangement of quadrupeds [four-footed animals].” Already he was seeing patterns useful for his new system of classifying animals, just as he was finding patterns in the reproductive organs of plants.
People at the time knew that humans were “natural beings.” They accepted Aristotle’s two-thousand-year-old idea that “Man is animal.” However, they made a distinction: humans were “animal,” but they were not “beasts” like lions and tigers and apes.
In the early 1700s, scientists still followed the general idea of the Great Chain of Being. The concept of a ladderlike scheme to organize nature was devised in ancient Greece by Plato, Aristotle’s teacher, around 400 BC. Together, the visual ideas of a ladder and a chain brought hierarchy and continuity to the way people viewed nature. At the top were the immortal beings; first came God, then the angels. Below them were all the mortal beings. Of those, man stood highest, on his own separate rung. Beneath him were three rungs for beasts, plants, and rocks. However, between Plato’s time and Linnaeus’s, natural philosophers had modified the Great Chain. They completely isolated man from the beasts by not classifying him at all. Man had been separated from the rest of nature.
This made no sense to Linnaeus. He saw no scientific reason to separate humans from the rest of the animals. Nature was a whole. Humans were part of that interconnected web of life.
Linnaeus’s method made it possible to describe every creature—cat, dog, or human—in the same way. To do that, he chose characteristics that were obvious, that could be seen and compared, such as teeth, feet, and anatomical structure, and behaviors such as how they moved, gave birth, and fed their young.
When complaints came his way, he wrote defensively, “No one is right to be angry with me.” After all, he argued, if man was not a stone and not a flower, man must be in the third kingdom—the kingdom of animals. Linnaeus did not tiptoe around what he saw as a fact of nature.
Still, how to define the human species was the big problem. Philosophers had been grappling with this thorny question for thousands of years. What does it mean to be human? Choosing the characteristics to describe humans scientifically was a dilemma for Linnaeus, too. Was it the hairy body, teeth, hands and feet, upright stance? How they moved? How they gave birth to and fed their young? Their ability to speak words? The brain, intelligence, their ability to reason? What characteristics made humans different from the rest of the animal kingdom? And which animals were similar to them? In other words, where did humans belong in the web of life?
Enter the apes.
When Linnaeus was finishing work on his first edition of Systema Naturae in 1735, the year he began living in Holland, he was already convinced that humans belonged in the animal kingdom, probably somewhere near the apes and monkeys.
In that book, he sorted the more than five hundred known animals into six broad classes: four-footed animals, birds, amphibians, fish, insects, and worms. Needing a place for humans, he chose the group most similar to us, the quadrupeds: quad-, from the Latin word for “four,” and -ped, meaning “foot.” This class was used commonly by scientists for other animals. But, humans with four feet? It certainly was not a perfect fit. He rationalized his classification of humans with the four-footed animals by saying that as babies we crawl on all fours. That was a stretch, but other quadruped characteristics did fit, such as having body hair, giving birth to live young, and nursing them.
Next, he divided the four-footed animals into five smaller orders: humanlike animals; predatory wild animals; rodents; beasts of burden; and grazing animals such as cows, deer, and camels.
Then he subdivided each order into genera. The order of humanlike animals, or Anthropomorpha, had three genera: Homo, the Latin word for “human”; Simia, meaning “ape”; and Bradypus, meaning “sloth.” (Sloths have pectoral teats; in other words, their nipples are located on their chests, a characteristic they share only with humans and apes.)
Critics bristled at the thought of classifying humans with the other animals. Some objected that it was wrong because humans had “souls” and animals did not. Linnaeus, however, saw things differently:
Theology decrees that man has a soul and that the animals are mere automata mechanica [mechanical robots], but I believe . . . that animals [also] have a soul and that the difference is in its nobility.
Since the soul and its nobility were not visible physical features, they could not be measured in any scientific way. He explained:
I well know what a splendidly great difference there is [between] a man and a [beast] when I look at them from a point of view of morality. . . . but all this belongs to another forum; it behooves me like a cobbler to stick to my last [a shoemaker’s form shaped like a person’s foot], in my own workshop, and as a naturalist to consider man and his body, for I know scarcely one feature by which man can be distinguished from apes, if it be not that all the apes have a gap between their fangs and their other teeth, which will be shown by the results of further investigation.
Visible physical features and behaviors were, according to Linnaeus, the keys to unlocking nature’s God-given order.
German naturalist Jacob Theodor Klein wrote to Linnaeus and offered two practical arguments against his classification. First, he pointed out that man walked on two feet, not four, so he could not be a quadruped. Second, he noted that man was man, not merely “manlike.” Of the man–ape–sloth group, only the apes were really like humans. Reasonable points, of course. Linnaeus took them under consideration.
Several years later, in 1754, still contemplating how similar humans and apes were, Linnaeus was thrilled to receive a guenon monkey. Since the death of his raccoon Sjupp in 1747, no other animal in his expanding menagerie influenced him as much as this beautiful monkey from Africa’s west coast. She was typical of her kind—black with a white goatee. Linnaeus thought the white crescent moon that fringed her forehead looked like a hairpiece in the latest style. Reminded of the mythical goddess of the hunt and wild animals, who wore a moon-shaped crown, he called her Diana. In 1758 he named her species Simia diana (currently Cercopithecus diana).
About the size of a cat, Diana had teeth similar to those of humans and other apes. Her favorite foods were rutabaga, turnip, fruits, nuts, almonds, and raisins. She also ate all kinds of greens and vegetables, porridge, eggs, and blood, but never meat.
Diana, a tropical monkey, loved being warm. During the cold Swedish winters, she lived in the medical garden’s orangery with its large, bright windows. At night, after the garden boys threw extra logs on the fire, she climbed high in the building. Up there, it was as warm and steamy as a sauna. On the hottest summer days, she escaped the extreme heat by hanging out in the shade of the garden’s trees. But on chilly summer nights, she cried out to every passerby for sympathy.
Diana’s humanlike ways were a marvel to Linnaeus. She could “grasp, sit, eat, threaten, [and] smile.” Her “mild eyes,” he said, reflected her gentle temperament. Like a proud father, he even wrote down her first two words: “Grech,” her reply when someone shouted at her, and “Hoi!” when she was frightened. Unleashed indoors, she scampered around, toppling chairs and dumping food on the floor, seemingly for fun.
An engraving of Linnaeus’s guenon monkey, Diana, from his 1754 report.
Intrigued by the intelligence displayed by Diana and her kind, Linnaeus told his students that monkeys in the wild took turns watching for tigers so the rest of their group could sleep and that one ape in captivit
y had learned to play backgammon.
The botanic garden in Uppsala. In summer, monkeys were chained to tall poles outside where they could sit on platforms below their specially-built houses.
Meanwhile, scientific knowledge was increasing rapidly. Previously unknown plants and animals were being discovered around the world. Linnaeus’s notes reveal something important about him: when new facts came along, he was open to changing his mind. He jotted thoughts, corrections, and additions in the margins of his personal copies of his published books. He used these notes to revise his works for later editions.
His list of known animal species grew from 569 in 1735 to more than four thousand in 1758. By then, it had become even clearer that earlier classifications needed fixing. Therefore, in 1758, when he overhauled Systema Naturae, he did a lot more than simply add species. He took the opportunity to make fundamental changes.
Critics and friends had shown him that some terms didn’t match their assigned animals. In Paris, the comte de Buffon—who, like Linnaeus, had a big ego—gleefully pointed out that some of Linnaeus’s groups were artificial, not natural, for instance, the one in which he lumped together humans and two-toed sloths. So Linnaeus replaced the order Quadrupedia, or four-footed animals, with a new one he called Mammalia. The number of feet didn’t matter anymore. He also got rid of the class Anthropomorpha, or humanlike animals, and created in its place a new class he called Primates, meaning primary or ranked first among the animals. After making those two changes, he shuffled the species between them, like puzzle pieces, to places where they fit.
The sloth joined the order Mammalia, in the class Bruta with the elephants. Another species he moved was the bat. Previously bats had been classified as birds. Linnaeus now called them primates, maybe because of what appeared to be finger bones. The year after Linnaeus died, these mammals were separated from the Primates and given their own order, Chiroptera, meaning “hand-winged.”
