Fossils are the remains of past living organisms.

  • Who discovered it: Nicholas Steno
  • Year of the discovery: 1669
How was it discovered?

The only way we can learn about the ancient past is to examine fossil remains of now extinct plants and animals and try to recreate that long-gone life and environment. Scientists can only do this if they correctly interpret the fossil remains that are dug from ancient rock layers.

That process began with Nicholas Steno. He provided the first true definition of the word “fossil” and the first understanding of the origin and nature of fossils. Steno’s work represents the beginning of our modern process of dating and studying fossils and the development of modern geology.

For 2,000 years, anything dug from the earth was called a fossil. By the middle ages, fossil had come to be used for only those things made of stone that were dug from the earth and that looked remarkably like living creatures. Many thought these fossils were God’s practice attempts to create living things. Some claimed they were the Devil’s attempts to imitate God. Some believed they were the remains of drowned animals from Noah’s flood. No one thought them to be of scientific value.

Nicholas Steno was born Niels Stensen in 1638 in Copenhagen, Denmark. He changed his name to its Latinized form in 1660 when he moved first to Paris and then to Italy to study medicine. Steno was a student of Galileo’s experimental and mathematical approach to science and focused his studies on human muscular systems and on using math and geometry to show how muscles contracted and moved bones and the skeleton. Steno gained considerable fame in Italy for these anatomical studies.

In October 1666, two fishermen caught what was described as “a huge shark” near the town of Livorno, Italy. Because of its enormous size, Duke Ferdinand ordered that its head is sent to Steno for study. Steno dutifully dissected the head, focusing on the musculature of the shark’s deadly jaw.

However, when he examined the shark’s teeth under a microscope, Steno was struck by their resemblance to certain stone fossils called glossopetrae, or “tongue stones,” that were found in rock layers throughout the coastal hills. Glossopetrae had been found and known since the early Roman Empire. The famed Roman author Pliny the Elder thought they were part of the moon that fell from the sky. As Steno compared his monstrous shark teeth with glossopetrae samples, he suspected that glossopetrae not only resembled sharks’ teeth, they were sharks’ teeth.

Italian scientists scoffed that glossopetrae couldn’t be from a sea creature because they were often found miles from the sea. Steno argued that they must have been deposited in shallow water or mud when the ancient shark died and that these areas had somehow been lifted up to become dry land. Others countered that glossopetrae couldn’t be teeth since sharks’ teeth were not made of stone.
Steno expanded his study to include fossils that resembled bones and bone fragments.

When he viewed these under the microscope he was convinced that they, too, had originally been bones, not stones. After months of study, Steno used the then-new “corpuscular theory of matter” (a forerunner of atomic theory) to argue that time and chemical action could alter the composition of teeth and bones into stone.

Steno published his discovery and supporting evidence in 1669. In addition to proving
that fossils were really the ancient bones of living creatures, Steno investigated how these bones came to lie in the middle of rock layers. Through this work, he discovered the process of sedimentation and of creating sedimentary rock layers.

For this discovery, Steno is also credited with founding modern geology. At the height of his scientific career, Steno was ordained a Catholic priest and completely abandoned science because he said that science was incompatible with the teachings of the Church. Luckily, his discoveries remained to advance and benefit science.

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.

Universal Gravitation

Gravity is the attractive force exerted by all objects on all other objects.

  •  Who discovered it: Isaac Newton
  •  Year of discovery: 1666

How was it Discovered?

In 1666, Isaac Newton was a 23-year-old junior fellow at Trinity College in Cambridge. With his fair complexion and long blond hair, many thought he still looked more like a boy. His small, thin stature and shy, sober ways reinforced that impression. His intense eyes and seemingly permanent scowl pushed people away.

In London, the bubonic plague ravaged a terrified population. Universities were closed, and eager academics like Isaac Newton had to bide their time in safe country estates waiting for the plague to loosen its death grip on the city. It was a frightening time.

In his isolation, Newton was obsessed with a question: What held the moon circling the earth, and what held the earth in a captive orbit around the sun? Why didn’t the moon fall down to the earth? Why didn’t the earth fall down to the sun?

In later years Newton swore that this story actually happened. As he sat in the orchard at his sister’s estate, he heard the familiar soft “thunk” of an apple falling to the grass-carpeted ground, and turned in time to see a second apple fall from an overhanging branch and bounce once before settling gently into the spring grass. It was certainly not the first apple Isaac Newton had ever seen fall to the ground, nor was there anything at all unusual about its shortfall. However, while it offered no answers to the perplexed young scientist, the falling apple did present Isaac with an important new question, “The apple falls to Earth while the moon does not. What’s the difference between the apple and the moon?”

Next morning, under a clearing sky, Newton saw his young nephew playing with a ball. The ball was tied to a string the boy held tight in his fist. He swung the ball, slowly at first, and then faster and faster until it stretched straight out.

With a start, Newton realized that the ball was exactly like the moon. Two forces acted on the ball—its motion (driving it outward) and the pull of a string (holding it in). Two forces acted on the moon. Its motion and the pull of gravity—the same pull(force) that made the apple fall.

For the first time, Newton considered the possibility that gravity was a universal attractive force instead of a force that applied only to planets and stars. His deep belief in alchemy and its concept of the attraction of matter led him to postulate that gravitational attraction force did not just apply to heavenly objects, but to all objects with any mass.

Gravity pulled apples to earth, made rainfall, and held planets in their orbits around the sun.

Newton’s discovery of the concept of universal gravitation was a major blow to the prevalent belief that the laws of nature on Earth were different from those that ruled the heavens.

Newton showed that the machinery that ruled the universe and nature is simple.

Newton developed universal gravitation as a property of all matter, not just of planets and stars. Universal gravitation and its mathematical expression lie at the foundation of all modern physics as one of the most important principles in all science.