Order in Nature

All living plants and animals can be grouped and organized into a simple hierarchy.

  • Who Discovered it?: Carl Linnaeus
  • Year of Discovery: 1735

How was it Discovered?

Carl Linnaeus hated disorder. He claimed he could never understand anything that was not systematically ordered. Born in Sweden in 1707, he was supposed to become a priest like his father. But Carl showed little aptitude for, and no interest in, the priesthood and was finally allowed to switch to medicine.

He entered the University of Lund’s School of Medicine in 1727 but spent more time in the university’s small botanical garden than in class. Linnaeus had been fascinated by plants and flowers since he was a small child. In 1728 Linnaeus transferred to the University of Uppsala (partly because they had bigger botanical gardens). There he read a paper by French botanist Sebastian Vaillant that claimed (it was considered shockingly revolutionary at the time) that plants reproduced sexually and had male and female parts that corresponded to the sexual organs of animals.

The idea appealed to Linnaeus. As an obsessive cataloger, he had always detested the notion that each of the thousands of plants he saw in botanical gardens was individual and separate species. Linnaeus began to wonder if he could use the differences in plants’ reproductive parts as a means of classifying and ordering the vast array and profusion of plants. His dream of bringing order to the chaos of nature was born.

Glib, cordial, and with a natural talent for ingratiating himself with rich and powerful supporters, Linnaeus was able to arrange financial support for a series of expeditions across different areas of Sweden to study and catalog plant species. He spent months tramping across the countryside listing, describing, and studying every plant he found. His expeditions were always the picture of perfect order. He started each day’s hike precisely at 7:00 in the morning. Linnaeus stopped for a meal break at 2:00 P.M. He paused for a rest and lecture break at 4:00 P.M.

During these expeditions, Linnaeus focused his studies on the reproductive systems of each plant he found. Soon he discovered common characteristics of male and female plant parts in many species that he could group into a single category. He lumped these categories together into larger groups that were, again, combined with other groups into yet larger classifications. He found that plants fit neatly into groups based on a few key traits and that order did exist in the natural world.

By 1735 he had described more than 4,000 species of plants and published his classification system in a book, Systema Naturae. This system described the eight levels Linnaeus finally built into his system: species, genus, family, order, Class, Subphylum, Phylum, and Kingdom. This system—based solely on the sexual elements of plants and (later) animals—was controversial with the public. But botanists found it easy to use and appealing.

Linnaeus’s system spread quickly across Europe and was often drawn as a tree, with giant branches being classes, down to the tiniest twigs of species. From these drawings came the concept of a “Tree of Life.”

Linnaeus spent the next 30 years touring Europe adding new plants to his system. In 1740 he added animal species into his system. By 1758 he had described and classified 4,400 animal species and more than 7,700 plant species.

In 1758, with the tenth edition of his book, he introduced the binomial (two-name) system of naming each plant and animal by species and genus. With that addition, Linnaeus’s system was complete. He had discovered both that order existed in the natural world and a system for describing that order—a system still very much alive and in use today.


Fun Facts: The world’s most massive living tree is General Sherman, the giant sequoia (Sequoiadendron giganteum) growing in the Sequoia National Park in California. It stands 83.82m (274.9 ft.) tall and has a diameter of 11.1 m (36 ft., 5 in.). This one tree is estimated to contain enough wood to make five billion matches—one for almost every person on Earth.


The Existence of Cells

The cell is the basic building block of all living organisms.

  • Who discovered it: Robert Hooke
  • Year of Discovery: 1665
How was it Discovered?

Robert Hooke was a most interesting fellow. Weak and sickly as a child, Hooke’s parents never bothered to educate him because they didn’t think he would survive.

When Hooke was still alive at age 11, his father began a half-hearted, homeschool education. When Hooke was 12, he watched a portrait painter at work and decided, “I can do that.” Some initial sketches showed that he was good at it.

The next year Hooke’s father died, leaving Hooke a paltry inheritance of only £100.
Hooke decided to use the money to apprentice himself to a painter but quickly learned that the paint fumes gave him terrible headaches.

He used his money instead to enter West minster school. On one of his first days there, Hooke listened to a man play the school organ and thought, “I can do that.” Hooke soon proved that he was good at it and learned both to play and to serve as a choirmaster.

Unfortunately, the new English puritanical government banned such frivolity as
church choirs and music. Hook’s money had been wasted. Not knowing what else to do, Hooke hired himself out as a servant to rich science students at nearby Oxford University.

Hooke was fascinated with science and again thought, “I can do that.” As it turns out, he was exceptionally good at it. His servitude at Oxford (mostly to Robert Boyle) was the start of one of the most productive science careers in English history.

Hooke soon developed an excellent reputation as a builder and as an experimenter.

Microscopes were invented in the late 1590s. By 1660 only a few had been built that
were able to magnify objects 100 times normal size. As microscopes became more powerful, they maintained focus on only a tiny sliver of space and were increasingly more difficult to focus and to use.
Hooke was hired onto the staff of the Royal Society (an early English scientific organization) in 1660 and soon began a long series of microscopic studies. By 1662 he had helped design a 300-power microscope, which he used to examine the microscopic structure of common objects. Using this microscope and his artistic talent, Hooke created the first detailed studies of the microscopic world, rendering with lifelike accuracy the contours of a fly’s compound eyes, the structure of a feather, and a butterfly’s wing. He also drew and identified a series of microscopic bugs.

In 1664 Hooke turned his microscope onto a thin sheet of dried cork and found it to be composed of a tightly packed pattern of tiny rectangular holes. Actually, cork has large, open cells. That’s why Hooke was able to see them at all. The cells of other plants and animal tissue he studied were all too small to be seen through his microscopes.

Hooke called these holes CELLS (the Latin word for small chambers that stand in a row—as in prison cells). These cells were empty because the cork was dead. Hooke correctly suspected that, while living, these had been filled with fluid.

Fun Fact: The name “cell” stuck. More important, the concept galvanized biologists. The living world was constructed of countless tiny cells stacked together like bricks in a wall.The entire field of biology shifted toward a study of cell structure and cell function.