Karen Hill

Dian Fossey was born in San Francisco, California, in 1932. Even though she loved animals and wanted to become a veterinarian, she received a college degree in occupational therapy. She started a career as a therapist, but her mind was still on animals, particularly the rare mountain gorillas of central Africa. In 1963, she went … Read more

Jane Goodall was born in London, England, in 1934. As a child, she never liked school but she loved to read and, most of all, she loved animals. After graduating high school, she had a chance to visit Africa in 1960 and her life changed forever. On this trip, she met Louis Leakey. Even though … Read more

Even though his work lay undiscovered for over 30 years, Gregor Mendel uncovered the basic secrets of genetics. His laws revealed that genes were responsible for inheritance, but what were they made of and how did they work? After 1900, huge advances were made in the power of microscopes. Scientists could now see inside the … Read more

George Washington Carver had many thoughts on the environment that were years ahead of their time. He once said, “There is no better plant food than the things we ignore or throw away every day.” Carver taught his students how to make compost of leaves, garbage, and weeds long before the organic gardening movement of … Read more

Rosalind Franklin’s contribution to the discovery of DNA structure was her photos of the molecule taken with X-ray crystallography. The process had been developed by two British physicists, William Henry Bragg and his son, William Lawrence Bragg. The son would later become head of the DNA research team at Cambridge University. In X-ray crystallography, X-ray … Read more

George Washington Carver was born into slavery during the American Civil War. From the age of 12, he roamed the country alone trying to get the education his bright mind needed so badly. He overcame many obstacles and became the first African American to receive a graduate degree in agriculture. His talents in botany would … Read more

Gregor Mendel knew he had made a great scientific discovery. He wrote a paper on his findings in plant genetics and presented it to the Brunn Natural History Society. They either didn’t know what he was talking about or didn’t understand the significance of it. The paper, Experiments with Plant Hybrids, was also published in … Read more

In the early 1700s, Charles Townshend started experimenting with crop rotation in England. At that time, farmers usually grew the same crop on the same land year after year. Eventually, the crop started to grow so poorly that farmers had to leave one or two of their fields fallow, or unused, for full growing seasons. … Read more

In 1962, Watson, Crick, and Wilkins won the Nobel Prize for physiology. Since then, the contributions of a women scientist to the discovery of the DNA model have been a source of great controversy. Rosalind Franklin produced the first usable X rays of DNA ever taken. Watson and Crick used her pictures to devise their … Read more

Three years after Watson and Crick proposed their model of DNA, American scientist Arthur Kornberg proved its accuracy by producing a molecule of DNA. Other research showed that the exact sequence of the chemical rungs of the DNA ladder determines the identity of the living organism. Even Watson and Crick, however, probably could not have … Read more

James Watson and Francis Crick started with the work of American scientist Linus Pauling, another contestant in the DNA race. Pauling had already determined that many proteins, one of the main components of cells, had the structure of a helix, a spiral chain in the shape of a twisted ladder. Watson and Crick decided to … Read more

In the mid twentieth century, British anthropologist Louis Leakey discovered ancient fossils of humans and other primates in Africa. The fossils ranged in age from 5 million to 1 million years old. These discoveries gave rise to the science of paleoanthropology, the study of the origin of humans. Leakey believed humans and other primates had … Read more

In 1900, an amazing coincidence took place in the scientific world. Three scientists, unknown to each other, had all discovered the laws of heredity simultaneously. They were Hugo de Vries of Holland, Carl Torrens of Germany, and Erich Tschermak of Austria-Hungary. Before announcing their great discovery to the world, they checked the earlier work of … Read more

What Are Gregor Mendel’s Laws of Heredity and When Was the Significance of Mendel’s Work Rediscovered? Gregor Mendel summarized his findings in three laws now known as Mendel’s laws of heredity. The first is called the law of segregation. It states that offspring receive a pair of genes for each inherited trait, one gene from … Read more

George Washington Carver really did find over 300 uses for peanuts, and some have become important parts of our lives. Carver wanted poor farmers to grow peanuts both as a source of their own food and as a source of other products to improve their quality of life. He started with different foods he could … Read more

George Washington Carver’s botanical studies were not limited to the peanut. He discovered that other plants renourished the soil and had many uses. Carver found over 100 products that could be made from the sweet potato, including molasses, paste, and rubber. He created a process to obtain paint pigments from clay. This was another economic … Read more

Mendel chose pea plants for his experiments on heredity for several reasons. Pea plants grow quickly, so many generations can easily be studied. They take up little space, so more plants can be studied to verify the findings. They self-pollinate, which creates purebred plants. They also have seven distinct characteristics, including tall or short plant, … Read more

In one way, the science of genetics, the study of how heredity works, is among the oldest sciences. For many centuries, man controlled the mating of domestic plants and animals to produce desired traits. Warriors needed speed in their horses so they would breed the fastest runners. Farmers would breed the strongest oxen to produce … Read more

How Did Louis Pasteur’s Germ Theory Originate and How Did He Discover the Process of Pasteurization? It was known in Pasteur’s time that yeast cells cause fermentation, but it was believed that it was their death and decomposition that caused the necessary chemical reaction. Pasteur had a new theory: fermentation is caused by the action … Read more

Louis Pasteur’s germ theory completely revolutionized medicine. Barbers and blacksmiths no longer performed surgery, and physicians had a whole new way of treating patients. Pasteur made physicians realize that they needed to boil their instruments and steam their bandages to kill infectious germs. He also told them that they needed to wash their hands in … Read more

It is estimated that during the eighteenth century, about 60 million Europeans died of smallpox. The dreaded disease had killed many more than that over the centuries, and those who survived were scarred and often blind. An old English folk cure was that anyone who had ever had cowpox, a very mild disease caught from … Read more

Louis Pasteur always liked his scientific studies to be practical and to serve France and humanity. To begin research into his germ theory, Pasteur studied anthrax disease in sheep and cholera disease in hens. These diseases were chosen because they were hurting the French meat and poultry industry and they could infect humans as well … Read more

The medical profession was not always as scientific as it is today. In the early nineteenth century, barbers performed surgery, the red and white poles outside their buildings stood for blood and bandages. In the case of a dog bite, the village blacksmith was the source of treatment. He would plunge his red-hot iron into … Read more

Charles Darwin had formulated his theory of evolution by 1838. In 1858, he still had not written any papers or books on the theory. Darwin was very concerned about public reaction to a theory that disputed the biblical story of creation. He remembered clearly what had happened to Italian scientist Galileo under similar circumstances. He … Read more

The theory of spontaneous generation was widely accepted in Leeuwenhoek’s time. This theory asserted that lower forms of life, such as worms or lice, originated from inorganic matter. Leeuwenhoek showed that these creatures developed from tiny eggs. He documented the life cycle of ants and the development of larvae and pupae from eggs. The debate … Read more

In 1683, Antoni van Leeuwenhoek made his greatest discovery. He called them “beasties.” One day, he put a drop of stagnant rainwater under his microscope and saw “dozens of little animals, swimming and wriggling in that tiny drop of water, wretched beasties, a thousand times smaller than you can see with the naked eye.” Van … Read more

In 1610, the Italian astronomer Galileo turned the telescope toward the skies and opened up a new universe to exploration. Antonie van Leeuwenhoek did the same with his microscope and a different universe. In a long life of careful observation and recording, he made many discoveries. Leeuwenhoek studied his own blood and discovered red and … Read more

Before Carl Linnaeus became professor of botany at Uppsala, he traveled extensively. Linnaeus traveled to Holland, England, France, and all over Sweden. On each trip, he carefully studied the new plants he came across and filled his notebooks with his observations. After he became a professor, he often arranged to have his students sent out … Read more

One of the great advantages of Linnaeus’s classification system was that it was very easy to make changes or additions to it. He knew future discoveries would alter his system but that his basic outline would remain useful. A French biologist, Georges Cuvier, made the first changes to Linnaeus’s system around 1800. Cuvier created another … Read more

Carl Linnaeus had a much bigger task ahead of him than Aristotle did. By the mid 1700s there were 7,700 known species of plants, 4,400 known species of animals, and still no classification system. It was an age of exploration and more and more plants and animals were being brought into Europe from around the … Read more

In Aristotle’s times, there were 500 different known kinds of animals. With his scientific love of order, Aristotle created a classification system for all 500. The term we still use for classification, taxonomy, is from the Greek for “a system of arrangement.” His system was effective because it arranged animals from the very simplest to … Read more

In Darwin’s time, most people still believed in the theory of special creation. This theory stated that Earth and all its living things had been created a few thousand years before and that everything had remained in its original form. Nothing had changed since the moment of creation. Many religions were based on this belief. … Read more

The young Englishman Charles Darwin came from a family of wealth. Both his grandfather and father were successful physicians. He was supposed to follow in their footsteps, but the first time he saw surgery being performed, he had to leave the room. At 22, he received a theological degree but soon announced he had no … Read more

Charles Darwin proposed his theory of evolution in 1859, more than 100 years after Carl Linnaeus published his classification system. Its basic idea was natural selection, the process by which species changed over many years in order to survive in their environment. These changes led to new species, each specializing in a different way. In … Read more

Charles Darwin almost waited too long before publishing his theory of evolution in On the Origin of Species. Even though he had devised the theory in 1838 and started writing his book in 1844, he was still working on it in 1858. In 1858, another English naturalist, Alfred Russel Wallace, came up with his version … Read more

In 1836, Charles Darwin came home from his trip around the world with crates of specimens and the beginnings of the theory of evolution. New species occurred, but how and why did they occur? It was not until two years later that he had his answer, when he read An Essay on the Principle of … Read more

A belief in astrology was one of the main reasons the ancient world was curious about the positions of the planets. People in the ancient world thought the planets had a direct effect on the world and that the future, especially natural catastrophes, could be predicted by studying the skies. Ptolemy wrote a book on … Read more

Ptolemy might rather be remembered for his contributions to geography than to astronomy. His maps of the world were so accurate for the time that they were used by scholars all over the world for centuries. Christopher Columbus based his theory of finding a westward route to India on Ptolemy’s maps. Ptolemy’s book Guide to … Read more

Galen’s own words express his scientific approach best: “I will trust no statements until I have tested them for myself as far as it has been possible for me to put them to the test. So if anyone after me becomes, like me, fond of work and zealous for truth, let him not conclude hastily … Read more

Galen was particularly interested in blood and its flow throughout the body. He proved that the arteries contained blood, not an air-like substance called “pneuma,” as had been believed. His theory was that blood was produced from food intake and that nutrition was supplied to the body from blood flowing in the veins and arteries. … Read more

In Galen’s time, the Roman Empire ruled Greece. Like the Greeks, the Romans did not believe in human dissection. Galen was able to find other ways to answer his questions about human anatomy. He found out all he could from studying the outside of the body. He felt bones and muscles to understand their structure … Read more

Around A.D. 145 in the Greek city of Pergamum, a father had a dream that his son Galen should become a physician. Dreams were very important to the Greeks of the ancient world because they were thought to be inspired by the gods. The father immediately enrolled his 16 year old son in Pergamum’s medical … Read more

Alexandria was built in 332 B.C. by the Greek conqueror Alexander the Great as a center for learning. For 900 years, scholars came to Alexandria to hear lectures from the greatest minds in the ancient world and to study in the huge library. The lighthouse of Pharos, one of the seven wonders of the ancient … Read more

It was very unusual in the ancient world for a woman to receive the kind of education Hypatia received. It was even more unusual for a woman to become the equal of the greatest minds of the time as Hypatia did. Women had not been totally excluded from having scientific lives in ancient times. The … Read more

Hypatia was one of the earliest known female scientists and was renowned in her time as an astronomer, mathematician, and philosopher. Scholars came from all over Egypt, Greece, and Rome to hear her lectures, but some despised her for her beliefs. In fact, she was one of the first scientists to die for her beliefs. … Read more

In Galen’s time, a strange conflict broke out between the two intellectual centers of the world, Alexandria, Egypt, and Pergamum, Greece. Manuscripts at the time were written on a paper derived from the Egyptian plant papyrus. The Egyptian ruler Ptolemy, not related to the scientist of the same name, tried to sabotage Pergamum by forbidding … Read more

Antoni van Leeuwenhoek’s trade was producing fabrics and he was the janitor for his town’s city hall. He had no university degrees and did not leave his hometown for the last 70 years of his life. It was not the usual background for a scientist in the seventeenth century’s Age of Enlightenment, but this scientist … Read more

Hypatia’s murder was an omen of what was coming. In A.D. 476, Rome fell to barbarian tribes and the Dark Ages began. The Dark Ages were the period in Europe from the 400s to the 900s, when very little scientific discovery took place. There were several reasons why this happened. There was no longer a … Read more

Hypatia also taught philosophy and became the leader of the Neoplatonist movement in Alexandria. Neoplatonism was based on the teachings of the fifth century B.C. Greek philosopher Plato. Followers of Neoplatonism believed in the perfection of the human soul through virtue, love of beauty, and intellectual pursuits. They also believed in the existence of a … Read more

In Hypatia’s time, it was common for scientists to share their knowledge by writing commentaries, or new versions of old books. By the fourth century A.D., many of the books in the Alexandria library were aging. For example, Ptolemy’s Almagest was over 200 years old. New copies of these manuscripts had to be copied by … Read more

Antonie van Leeuwenhoek made tremendous improvements to the microscope of his time. First, Leeuwenhoek became an expert lens grinder, even working with lenses only 1/8 inch wide. Lenses must be ground into a curved surface to bend light rays and produce images of objects. He then decided to scrap the compound system of lenses. Instead, … Read more

Even though Hippocrates lived nearly 2,500 years ago, many of his ideas sound very familiar today. He would inquire about the family health history to see if any relatives had suffered from similar diseases. He asked questions about the patient’s home to see if his or her environment might be causing the illness. He discovered … Read more

Before Hippocrates’ time, the only medical treatment available to most Greeks was the ill-informed efforts of the doctor-priests. However, Greek athletes had received expert care since the first Olympian games were held in 776 B.C. in Olympia, Greece. Athletic trainers were highly respected and paid well for their services. Males in ancient Greece took pride … Read more

Treatment from the Asclepiads seemed effective simply because most patients recovered from illness themselves. The Asclepiads also had an excuse for their failures: they said that those who didn’t recover had angered the gods too much. Hippocrates’ approach to medicine was scientific. The symptoms of the patient were observed and recorded daily. The condition of … Read more

When Rome invaded Syracuse in 213 B.C., Archimedes was 72 years old but his mechanical genius was needed to save the city. The weapons he invented to defend the island from the Roman invasion were amazing. He used his knowledge of levers to design catapults, devices that hurled spears and stones with force over great … Read more

In 213 B.C., Rome attacked the beautiful Greek city of Syracuse on the island of Sicily. Rome had the greatest army and navy the world had ever known, but they were helpless against the weapons of one old man. The old man was one of the most brilliant scientists of the ancient world. Archimedes was … Read more

Hippocrates’ contributions to medicine were not just scientific. He wrote extensively on all aspects of medicine and his writings are included in a volume of works known as the Hippocratic Collection. It is not known exactly which of the volumes Hippocrates wrote himself and which his followers wrote. Included in this collection is the Hippocratic … Read more

Not all of Hippocrates’ ideas were accurate. Hippocrates believed that illness occurred when body fluids were out of balance. These fluids were called humors and included blood, phlegm, yellow bile, and black bile. The humors occurred when the four main elements of Greek thought: fire, air, earth, and water, mixed with dryness, dampness, heat, and … Read more

Ptolemy was one of the most influential astronomers who ever lived. His theories on the movements of the planets and stars, called the Ptolemaic system, stood unquestioned for 1,400 years. The Arab world of the Middle Ages admired his book on astronomy so much that they renamed it the Almagest, Arabic for “the greatest.” Unfortunately, … Read more

Legend has it that Archimedes once ran through the streets of Syracuse naked yelling, “Eureka!” because he had discovered an amazing scientific principle. King Hiero had given a craftsman a certain amount of gold to make him a crown. When the crown was presented to the king, he suspected the craftsman of keeping some of … Read more

Archimedes’ first great mechanical invention was a water pump he invented while still a student in Alexandria. Transporting water from the source was a huge task in the ancient world, particularly for farmers. The Archimedes’ screw was so ingenious that it is still used today for irrigation in some countries. Archimedes used his favorite form, … Read more

One of Archimedes’ achievements was discovering the mechanics of the lever. He knew a small force at one end of a lever could move a great weight if the pivot, or fulcrum were in the right spot. “Give me a place to stand and I can move the world,” he said. King Hiero asked for … Read more

We know of at least three tools Ptolemy used in his calculation of the position of the Sun, the planets, and the stars. To measure the Sun’s position, he probably used a quadrant. A quarter of a circle was ruled on a square board and a special line was attached to make sure it was … Read more

The Almagest was Ptolemy’s first and most ambitious work. Written in about 147 A.D., it is a 13 volume set of books that attempted to include all the astronomical knowledge available at the time. Its main goal was to allow people to calculate the positions of all celestial bodies the Sun, the Moon, planets, and … Read more

The Ptolemaic system was a series of theories proposed by Ptolemy to explain the order and movements of the universe. Because Ptolemy’s system of predicting planetary movement was so accurate, all the theories of the Ptolemaic system became the accepted view for centuries even though many were inaccurate. Ptolemy did realize that Earth was a … Read more

Just as Aristotle brought the scientific method to biology, a Greek physician brought science to medicine. He discovered so much about diagnosing illness and treating the sick that he is known as the father of medicine. Hippocrates was born on the island of Cos in the Aegean Sea around 460 B.C. Both his grandfather and … Read more

Aristotle’s scientific research followed several consistent steps. It was his version of the scientific method. His approach consisted of the following: He determined the subject matter of the investigation and stated the problem to be solved. He described traditional solutions to the problem. He presented his doubts about these solutions. He presented his own solution, … Read more

There is no exact date when the period known as the ancient world began. There are, however, two important developments that mark the transition of mankind’s history from prehistoric to ancient: farming and written language. Around 8000 B.C., the human lifestyle started to change as people learned to be farmers. Before this, most humans roamed … Read more

Before Aristotle, a Greek education included reading, writing, music, poetry, and athletics. Older students were also taught politics and citizenship. Teachers called Sophists would travel from city to city and lecture in public squares. Plato established the first permanent school in Athens with his Academy. Philosophy became an important course for students at the Academy. … Read more

Aristotle’s great strength as a scientist was observation, and he put this strength to good use in studying Earth’s animals. He compared their anatomy, studied their habits, and recorded thousands of these observations. In one of his books, the History of Animals, he described more than 500 different species. Without the use of any scientific … Read more

Aristotle did not simply record his observations. His greatest contribution to biology was the creation of a system of classification. He devised a system of grouping animal species by type that remained the best system for over 2,000 years. Aristotle’s classification divided the animal kingdom into two groups: those with blood and those without blood. … Read more

Aristotle did not have any major contributions to astronomy and physics. Aristotle was a brilliant biologist, but almost all his ideas on astronomy and physics were wrong. He believed heavier objects fell faster than lighter ones. He believed all matter was composed of the basic elements of earth, water, air, and fire and the heavens … Read more