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Francesco Redi

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• Institute and Museum of the History of Sciences - Biography of Francesco Redi
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Francesco Redi (born Feb. 18, 1626, Arezzo , Italy—died March 1, 1697, Pisa) was an Italian physician and poet who demonstrated that the presence of maggots in putrefying meat does not result from spontaneous generation but from eggs laid on the meat by flies.

He read in the book on generation by William Harvey a speculation that vermin such as insects, worms, and frogs do not arise spontaneously, as was then commonly believed, but from seeds or eggs too small to be seen. In 1668, in one of the first examples of a biological experiment with proper controls, Redi set up a series of flasks containing different meats, half of the flasks sealed, half open. He then repeated the experiment but, instead of sealing the flasks, covered half of them with gauze so that air could enter. Although the meat in all of the flasks putrefied, he found that only in the open and uncovered flasks, which flies had entered freely, did the meat contain maggots. Though correctly concluding that the maggots came from eggs laid on the meat by flies, Redi, surprisingly, still believed that the process of spontaneous generation applied in such cases as gall flies and intestinal worms. Redi is known as a poet chiefly for his Bacco in Toscana (1685; “Bacchus in Tuscany”).

Redi experiment (1665)

3.1 Spontaneous Generation

Learning objectives.

By the end of this section, you will be able to:

• Explain the theory of spontaneous generation and why people once accepted it as an explanation for the existence of certain types of organisms
• Explain how certain individuals (van Helmont, Redi, Needham, Spallanzani, and Pasteur) tried to prove or disprove spontaneous generation

Clinical Focus

Barbara is a 19-year-old college student living in the dormitory. In January, she came down with a sore throat, headache, mild fever, chills, and a violent but unproductive (i.e., no mucus) cough. To treat these symptoms, Barbara began taking an over-the-counter cold medication, which did not seem to work. In fact, over the next few days, while some of Barbara’s symptoms began to resolve, her cough and fever persisted, and she felt very tired and weak.

• What types of respiratory disease may be responsible?

Jump to the next Clinical Focus box

Humans have been asking for millennia: Where does new life come from? Religion, philosophy, and science have all wrestled with this question. One of the oldest explanations was the theory of spontaneous generation, which can be traced back to the ancient Greeks and was widely accepted through the Middle Ages.

The Theory of Spontaneous Generation

The Greek philosopher Aristotle (384–322 BC) was one of the earliest recorded scholars to articulate the theory of spontaneous generation , the notion that life can arise from nonliving matter. Aristotle proposed that life arose from nonliving material if the material contained pneuma (“spirit” or “breath”). As evidence, he noted several instances of the appearance of animals from environments previously devoid of such animals, such as the seemingly sudden appearance of fish in a new puddle of water. 1

This theory persisted into the 17th century, when scientists undertook additional experimentation to support or disprove it. By this time, the proponents of the theory cited how frogs simply seem to appear along the muddy banks of the Nile River in Egypt during the annual flooding. Others observed that mice simply appeared among grain stored in barns with thatched roofs. When the roof leaked and the grain molded, mice appeared. Jan Baptista van Helmont , a 17th century Flemish scientist, proposed that mice could arise from rags and wheat kernels left in an open container for 3 weeks. In reality, such habitats provided ideal food sources and shelter for mouse populations to flourish.

However, one of van Helmont’s contemporaries, Italian physician Francesco Redi (1626–1697), performed an experiment in 1668 that was one of the first to refute the idea that maggots (the larvae of flies) spontaneously generate on meat left out in the open air. He predicted that preventing flies from having direct contact with the meat would also prevent the appearance of maggots. Redi left meat in each of six containers ( Figure 3.2 ). Two were open to the air, two were covered with gauze, and two were tightly sealed. His hypothesis was supported when maggots developed in the uncovered jars, but no maggots appeared in either the gauze-covered or the tightly sealed jars. He concluded that maggots could only form when flies were allowed to lay eggs in the meat, and that the maggots were the offspring of flies, not the product of spontaneous generation.

In 1745, John Needham (1713–1781) published a report of his own experiments, in which he briefly boiled broth infused with plant or animal matter, hoping to kill all preexisting microbes. 2 He then sealed the flasks. After a few days, Needham observed that the broth had become cloudy and a single drop contained numerous microscopic creatures. He argued that the new microbes must have arisen spontaneously. In reality, however, he likely did not boil the broth enough to kill all preexisting microbes.

Lazzaro Spallanzani (1729–1799) did not agree with Needham’s conclusions, however, and performed hundreds of carefully executed experiments using heated broth. 3 As in Needham’s experiment, broth in sealed jars and unsealed jars was infused with plant and animal matter. Spallanzani’s results contradicted the findings of Needham: Heated but sealed flasks remained clear, without any signs of spontaneous growth, unless the flasks were subsequently opened to the air. This suggested that microbes were introduced into these flasks from the air. In response to Spallanzani’s findings, Needham argued that life originates from a “life force” that was destroyed during Spallanzani’s extended boiling. Any subsequent sealing of the flasks then prevented new life force from entering and causing spontaneous generation ( Figure 3.3 ).

Check Your Understanding

• Describe the theory of spontaneous generation and some of the arguments used to support it.
• Explain how the experiments of Redi and Spallanzani challenged the theory of spontaneous generation.

Disproving Spontaneous Generation

The debate over spontaneous generation continued well into the 19th century, with scientists serving as proponents of both sides. To settle the debate, the Paris Academy of Sciences offered a prize for resolution of the problem. Louis Pasteur , a prominent French chemist who had been studying microbial fermentation and the causes of wine spoilage, accepted the challenge. In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms, suggesting that the exposure of a broth to air was not introducing a “life force” to the broth but rather airborne microorganisms.

Later, Pasteur made a series of flasks with long, twisted necks (“swan-neck” flasks), in which he boiled broth to sterilize it ( Figure 3.4 ). His design allowed air inside the flasks to be exchanged with air from the outside, but prevented the introduction of any airborne microorganisms, which would get caught in the twists and bends of the flasks’ necks. If a life force besides the airborne microorganisms were responsible for microbial growth within the sterilized flasks, it would have access to the broth, whereas the microorganisms would not. He correctly predicted that sterilized broth in his swan-neck flasks would remain sterile as long as the swan necks remained intact. However, should the necks be broken, microorganisms would be introduced, contaminating the flasks and allowing microbial growth within the broth.

Pasteur’s set of experiments irrefutably disproved the theory of spontaneous generation and earned him the prestigious Alhumbert Prize from the Paris Academy of Sciences in 1862. In a subsequent lecture in 1864, Pasteur articulated “ Omne vivum ex vivo ” (“Life only comes from life”). In this lecture, Pasteur recounted his famous swan-neck flask experiment, stating that “…life is a germ and a germ is life. Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.” 4 To Pasteur’s credit, it never has.

• How did Pasteur’s experimental design allow air, but not microbes, to enter, and why was this important?
• What was the control group in Pasteur’s experiment and what did it show?
• 1 K. Zwier. “Aristotle on Spontaneous Generation.” http://www.sju.edu/int/academics/cas/resources/gppc/pdf/Karen%20R.%20Zwier.pdf
• 2 E. Capanna. “Lazzaro Spallanzani: At the Roots of Modern Biology.” Journal of Experimental Zoology 285 no. 3 (1999):178–196.
• 3 R. Mancini, M. Nigro, G. Ippolito. “Lazzaro Spallanzani and His Refutation of the Theory of Spontaneous Generation.” Le Infezioni in Medicina 15 no. 3 (2007):199–206.
• 4 R. Vallery-Radot. The Life of Pasteur , trans. R.L. Devonshire. New York: McClure, Phillips and Co, 1902, 1:142.

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Francesco Redi: Founder of Experimental Biology

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Francesco Redi was an Italian naturalist, physician, and poet. Besides Galileo, he was one of the most important scientists who challenged Aristotle 's traditional study of science. Redi gained fame for his controlled experiments. One set of experiments refuted the popular notion of spontaneous generation—a belief that living organisms could arise from nonliving matter. Redi has been called the "father of modern parasitology" and the "founder of experimental biology".

Birth : February 18, 1626, in Arezzo, Italy

Death : March 1, 1697, in Pisa Italy, buried in Arezzo

Nationality : Italian (Tuscan)

Education : University of Pisa in Italy

Published Work s: Francesco Redi on Vipers ( Osservazioni intorno alle vipere) , Experiments on the Generation of Insects ( Esperienze Intorno ​alla Generazione degli Insetti) , Bacchus in Tuscany ( Bacco in Toscana )

Major Scientific Contributions

Redi studied  venomous snakes to dispel popular myths about them. He demonstrated that it is not true that vipers drink wine, that swallowing snake venom is toxic, or that venom is made in a snake's gallbladder. He found that venom was not poisonous unless it entered the bloodstream and that the progression of venom in the patient could be slowed if a ligature was applied. His work paved the foundation for the science of toxicology .

Flies and Spontaneous Generation

One of Redi's most famous experiments investigated spontaneous generation . At the time, scientists believed in the Aristotelian idea of abiogenesis , in which living organisms arose from non-living matter. People believed rotting meat spontaneously produced maggots over time. However, Redi read a book by William Harvey on generation in which Harvey speculated that insects, worms, and frogs might arise from eggs or seeds too tiny to be seen. Redi devised and performed the now-famous experiment in which six jars, half left in open air and half covered with fine gauze that permitted air circulation but kept out flies, were filled with either an unknown object, a dead fish, or raw veal. The fish and veal rotted in both groups, but maggots only formed in the jars open to air. No maggots developed in the jar with the unknown object.

He performed other experiments with maggots, including one where he placed dead flies or maggots in sealed jars with meat and observed living maggots did not appear. However, when he placed living flies were placed in a jar with meat, maggots did appear. Redi concluded maggots came from living flies, not from rotting meat or from dead flies or maggots.

The experiments with maggots and flies were important not only because they refuted spontaneous generation, but also because they used control groups , applying the scientific method to test a hypothesis.

Parasitology

Redi described and drew illustrations of over one hundred parasites, including ticks, nasal flies, and the sheep liver fluke. He drew a distinction between the earthworm and the roundworm , which were both considered to be helminths prior to his study. Francesco Redi performed chemotherapy experiments in parasitology, which were noteworthy because he used an experimental control. In 1837, Italian zoologist Filippo de Filippi named the larval stage of the parasitic fluke "redia" in honor of Redi.

Redi's poem "Bacchus in Tuscany" was published after his death. It is considered among the best literary works of the 17th century. Redi taught the Tuscan language, supported the writing of a Tuscan dictionary, was a member of literary societies, and published other works.

Redi was a contemporary of Galileo, who faced opposition from the Church. Although Redi's experiments ran contrary to the beliefs of the time, he did not have the same sort of problems. This may well have been because of the different personalities of the two scientists. While both were outspoken, Redi did not contradict the Church. For example, in reference to his work on spontaneous generation, Redi concluded  omne vivum ex vivo  ("All life comes from life").

It's interesting to note that despite his experiments, Redi believed spontaneous generation could occur, for instance, with intestinal worms and gall flies.

Altieri Biagi; Maria Luisa (1968). Lingua e cultura di Francesco Redi, medico . Florence: L. S. Olschki.

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Lessons and Courses on Microbiology

FRANCESCO REDI (1626-1697)

Francesco Redi, an Italian scientist was the first scientist to challenge the theory of spontaneous generation by demonstrating that living organisms did not actually originate from non-living things. He developed a scientific experiment to test the spontaneous creation of maggots from fresh meats using two jars (one of the jars was left open while the other was closed).

Redi was famously known for his work on spontaneous generation or abiogenesis . He challenged the concept of abiogenesis by showing that maggots on decaying meat came from fly eggs deposited on the meat and not from the meat itself. Redi explained that flies land on exposed meat and lay their eggs which eventually hatch to produce maggots.

Redi performed series of experiments in the early 1670’s in which he covered jars of meat with fine lace that prevented the entry of flies into the jars. Because the meat was covered, no maggots were produced, and this led Francesco Redi to drop the notion of spontaneous generation.

Francesco Redisuccessfully challenged and refuted the theory of spontaneous generation through his work on maggot and flies, in which he showed that maggots on meat came from egg flies. Though his work was known, the ideaof spontaneous generation was not dropped as other scientist like John Needham continued from where he stopped to unravel the mystery behind it.

Barrett   J.T (1998).  Microbiology and Immunology Concepts.  Philadelphia,   PA:  Lippincott-Raven Publishers. USA.

Beck R.W (2000). A chronology of microbiology in historical context. Washington, D.C.: ASM Press.

Brooks G.F., Butel J.S and Morse S.A (2004). Medical Microbiology, 23 rd edition. McGraw Hill Publishers. USA. Pp. 248-260.

Chung K.T, Stevens Jr., S.E and Ferris D.H (1995). A chronology of events and pioneers of microbiology. SIM News , 45(1):3–13.

Slonczewski J.L, Foster J.W and Gillen K.M (2011). Microbiology: An Evolving Science. Second edition. W.W. Norton and Company, Inc, New York, USA.

Summers W.C (2000). History of microbiology. In Encyclopedia of microbiology, vol. 2, J. Lederberg, editor, 677–97. San Diego: Academic Press.

Talaro, Kathleen P (2005). Foundations in Microbiology. 5 th edition. McGraw-Hill Companies Inc., New York, USA.

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Francesco Redi (1626-1698)

Francesco Redi, son of Florentine physician Cecilia de’ Ghinci and Gregorio Redi, was born in Arezzo, Italy, on 18 February 1626. He studied philosophy and medicine at the University of Pisa, graduating on 1 May 1647. A year later, Redi moved to Florence and registered at the Collegio Medico. There he served at the Medici Court as both the head physician and superintendent of the ducal pharmacy and foundry. Redi was also a member of the Accademia del Cimento, which flourished from 1657–1667. It was during this decade that Redi produced his most important works.

In 1664 Redi wrote his Osservazioni intorno alle vipere to his friend Lorenzo Magalotti, secretary of the Accademia. In this work Redi states that snake venom is unrelated to the snake’s bile, an idea contrary to popular belief. Redi performed countless experiments on the effects of snakebites, discovering that venom was only effective when introduced into the bloodstream via a bite. In order to prevent the passage of venom into the heart, Redi applied concepts relating to blood circulation to conclude that a tight ligature above the wound would help to reduce the amount of venom that reached the heart. Redi’s work on snakebites marked the beginning of experimental toxicology.

In 1668 Redi completed what is viewed as his masterpiece, Esperienze intorno alla generazione degl’insetti , and sent it to Carlo Dati, a Florentine nobleman and secretary of the Accademia del Cimento . In this work, Redi provided experimental evidence against spontaneous generation in insects, an Aristotelian idea that at the time was widely accepted. This popular idea possibly arose from the observations that worms and other parasites seemed to simply “emerge” from decaying plants and animals. However, using microscopy, Redi discovered an intricate system of reproduction in insects. He examined the egg-producing apparatus and observed the structures of the eggs of a variety of insect species. As a consequence of this work, Redi sought to challenge the doctrine of spontaneous generation in lower animals. He concluded in Esperienze that animals more likely “are born from the eggs laid by their mothers, fertilized by coitus” than through spontaneous generation.

In 1684 Redi published his parasitological treatise, Osservazioni intorno agli animali viventi, che si trovano negli animali viventi . Redi’s research on the generation of insects and parasitology was extended by physician Giovanni Cosimo Bonomo and apothecary Giacinto Cestoni, and their results were presented in Osservazioni intorno a’ pellicelli del corpo umano in 1687. After years of work on toxicology, parasitology, and entomology, Francesco Redi died on 1 March 1697 in Pisa, Italy.

• Belloni, Luigi. “Redi, Francesco.” Dictionary of Scientific Biography , 11: 341–43.
• Cobb, Matthew. The Egg and Sperm Race . London: Free Press, 2006.

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Famous Scientists

Francesco Redi

Francesco Redi’s was an innovative scientist, physician, and poet. His scientific work resulted in a number of significant milestones: he showed that flies breed and lay eggs and do not, as was popularly believed, spontaneously generate; his microscopic examination of parasites marked the founding of modern parasitology; and in studying chemical treatments to kill parasites, he devised and performed the first controlled experiments in scientific history.

Francesco Redi was born on February 18, 1626 in the city of Arezzo in Tuscany, Italy. Francesco’s father was Gregorio Redi, an eminent physician of noble birth, and his mother was Cecilia de Ghinci.

Francesco was educated from an early age in a Jesuit school in the city of Florence about 50 miles (80 km) from his hometown.

His education placed special emphasis on theology and “polite literature” – literature the Jesuits found acceptable. Francesco would have learned nothing officially about the momentous scientific work of his fellow Tuscan, Galileo Galilei . Just a few miles from Francesco’s school, Galileo was nearing the end of a remarkable life. His groundbreaking work had incurred the wrath of the Catholic Church, which prohibited his writings. The Jesuits were among the Church’s most fearsome defenders, zealously enforcing the prohibition.

At perhaps the age of 15 or 16, Francesco left Florence for the University of Pisa, where he graduated in 1647, aged 21, with doctorates in both medicine and philosophy.

Francesco Redi – Physician

Within a year of graduating, Redi returned to Florence as physician to Ferdinand II, Grand Duke of Tuscany. Ferdinand was a member of the famous – or infamous – Medici family. No doubt Redi’s father helped him get the job: six years earlier, in 1642, he himself had been appointed physician to the Medici court.

Francesco Redi’s Contributions to Science

Redi maintained a lifelong loyalty to the Jesuits, but word reached him of the importance Galileo placed on gathering evidence to support scientific ideas. Galileo’s viewpoint sounded so appropriate that Redi applied it in his own investigations.

Also, while studying medicine in Pisa, Redi learned about the rational experiments carried out by William Harvey . These experiments provided Harvey with the data he needed to correctly describe blood circulation around the body for the first time. Redi was highly impressed by Harvey’s research work.

Scientific Approach to Snakes and their Venom

At the age of 38, in 1664, after making a study of snakes, Redi wrote his first major work: Observations about Vipers .

Redi used observations and experiments to disprove these myths.

For the snakes he observed, he established that venom must be injected into the victim’s bloodstream to be deadly. He showed the source of snake venom is two small bladders covering their fangs, which are compressed when the snake bites, squeezing out the venom. And, as Galileo had done in physics, he refuted the biology of Aristotle , who had claimed that snakes are killed by human spittle.

Spontaneous Generation

Aristotle had also promoted the idea that life is generated spontaneously: he said simpler lifeforms such as worms and maggots need no parents – they emerge alive from the earth and from rotting organic matter. This idea had been accepted for over 2,000 years.

Again, Redi used experiments to research this subject. He observed that flies laid eggs on meat. These eggs hatched into maggots. If the meat was protected from flies, no eggs were laid and no maggots appeared.

He described his work in 1668 in Experiments on the Generation of Insects .

A little over a decade later, Antonie van Leeuwenhoek confirmed Redi’s maggot and fly work, observing the entire lifecycle. In the 1830s, Theodor Schwann showed that microorganisms do not spontaneously generate. Finally, in 1862, Louis Pasteur completely killed off the idea of spontaneous generation in mainstream science. Redi had been the first person to use experiments to show fellow scientists the path, but it took them a long time to follow it to its natural conclusion.

In addition to his refutation of spontaneous generation, Experiments on the Generation of Insects contained Redi’s detailed drawings of a large variety of insects, eggs, and maggots, such as these below.

Redi’s drawing of a donkey louse under the microscope

Redi’s drawing of an ant under the microscope

Parasitology

Redi documented over 100 parasite species, observing once again that creatures popularly believed to generate spontaneously actually hatched from eggs. He documented his observations in his 1684 book Observations on living animals that are in living animals . He made drawings of a large number of parasites, recording the places they had been found. This comprehensive work marked the beginning of modern parasitology.

Redi’s microscope drawing of a parasitical worm found in fish intestines.

Redi’s microscope drawing of a roundworm found in human intestines.

The Controlled Experiment

In his 1684 book, Redi also discussed laboratory trials of chemicals used to treat parasites. Experimental science was in its infancy, and Redi came up with a brilliant new idea: the controlled experiment.

He compared the health outcomes for animals given chemical treatments for their parasites versus animals kept under the same conditions but given no treatment for their parasites. He found that santonin and copper sulfate were particularly effective in treating parasitic worms.

Some Personal Details and the End

After studying literature at school, Redi remained a lifelong enthusiast, building a collection of many old manuscripts. He was also a celebrated poet, famous for his lengthy work Bacchus in Tuscany , dedicated to the joy of wine drinking.

According to Bigelow, (see further reading) Redi did not marry and had no children of his own, although he did have nephews. According to Hunt, Redi had a least one son, who achieved some renown in literature. If Redi married, the name of his wife has been lost in the mists of time.

From an early age Redi was prone to hypochondria, but took comfort from his personal belief that hypochondriacs seldom die at an early age. In his later years he suffered from epilepsy.

Francesco Redi died at the age of 71 on March 1, 1697 in Pisa. He was buried in his hometown of Arezzo.

The Duke of Tuscany, Cosmo III, to whom Redi had been a valued physician struck three medals to honor Redi: one for his work in medicine; one for his contributions to natural history; and one for his Bacchanalian poem.

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Further Reading Francesco Redi Osservazioni intorno agli animali viventi che si trovano negli animali viventi Per Piero Matini, all’insegna del Lion d’Oro, Florence, 1684

Francesco Redi, translated by Leigh Hunt Bacchus in Tuscany John and H. L. Hunt, London, 1825

Francesco Redi, translated by Mab Bigelow Experiments on the Generation of Insects The Open Court Publishing Company, Chicago, 1909

John Farley The Spontaneous Generation Controversy from Descartes to Oparin The Johns Hopkins University Press, 1974

Raffaele Roncalli Amici The History of Italian Parasitology Veterinary Parasitology Vol. 98, pp. 3–30, 2001

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Chen-Ning Yang

Ahmed Zewail

Origins of Life I: Early ideas and experiments

by David Warmflash, MD, Nathan H Lents, Ph.D.

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Did you know that it is much easier to determine when life appeared on Earth than how life came to exist? Evidence points to life on Earth as early as 3.8 billion years ago, but the question of how life came to be has puzzled scientists and philosophers since prehistoric times. In the 1950s, scientists successfully created biological molecules by recreating the atmosphere of primordial Earth in a bottle and shocking it with lightning. This and other experiments give clues to the origins of life.

Theories about the origins of life are as ancient as human culture. Greek thinkers like Anaximander thought life originated with spontaneous generation, the idea that small organisms are spontaneously generated from nonliving matter.

The theory of spontaneous generation was challenged in the 18th and 19th centuries by scientists conducting experiments on the growth of microorganisms. Louis Pasteur, by conducting experiments that showed exposure to fresh air was the cause of microorganism growth, effectively disproved the spontaneous generation theory.

Abiogenesis, the theory that life evolved from nonliving chemical systems, replaced spontaneous generation as the leading theory for the origin of life.

Haldane and Oparin theorized that a "soup" of organic molecules on ancient Earth was the source of life's building blocks. Experiments by Miller and Urey showed that likely conditions on early Earth could create the needed organic molecules for life to appear.

RNA, and through evolutionary processes, DNA and the diversity of life as we know it, likely formed due to chemical reactions among the organic compounds in the "soup" of early Earth.

The work of Darwin and Wallace went a long way in answering the question of how species evolved over time. The theory of natural selection provided a mechanism by which complex life forms, including humans, could arise from simpler organisms . But that still left open a more difficult question, namely, what is the origin of life itself? It’s one of the most challenging questions in science, even today when we can say confidently when life appeared on Earth.

Microscopic fossils called stromatolites and remains of communities of microorganisms called microbial mats suggest that Earth harbored microorganisms 3.5 billion years ago (Figure 1). Also, the presence of particular carbon isotopes in certain metamorphic rocks in Greenland tell scientists that some kind of life may have been present as much as 3.8 billion years ago. This means that 700 million to one billion years after Earth had formed, life was here. It makes sense, because it corresponds to the time when the planet had reached a cool enough temperature for any life to survive. But honing in on the time when life appeared on this planet still does not tell us how life came to exist.

Since prehistoric times, people sought mostly spiritual answers to this question. Around campfires during the Stone Age, each budding culture told and retold tales of how the gods created life from some kind of nonliving material, be it mud, clay, rock, or straw. The details of the ancient creation stories changed noticeably over time, but religion was still the mode of thinking by Darwin’s era when it came to the initiation of life itself. Darwin did consider the origin of life and speculated that it had occurred in a warm pond. He suggested that phosphoric salts and ammonia in the pre-biotic pond somehow had been changed chemically by heat , light , and electricity, leading to the synthesis of the organic compounds needed to produce the first living cells . Darwin was not a chemist and this was a very cursory speculation about Earth’s pre-biotic chemistry. It contrasted sharply with the detail and systematic approach of Darwin’s own theory of natural selection .

Even so, the pond idea was a start. Despite living in a society that almost universally assumed Earth had an intelligent creator, scientists in Darwin’s time were already comfortable with and accustomed to considering the possibility of life getting started without intervention from the gods. The idea was called spontaneous generation and, while it was already very well established by Darwin’s time, it dates all the way back to the time of the ancient Greeks.

• Early thinkers

About 2,600 years ago, in the Ionian city of Miletus (Figure 2), the natural philosopher Anaximander (c. 610–546 BCE) pondered how human babies were born utterly helpless. Without their parents , young humans had no chance to survive and the state of helplessness continued for years. That reality made for a dilemma when considering the first generation of humans, which, Anaximander assumed, must have begun as infants. To grow up and have their own babies, human ancestors in the very distant past must have been more independent as newborns, Anaximander reasoned. They must have been more like certain other animals whose young are born ready to survive on their own.

Considering the various animals, Anaximander decided the ancestors of humans had to be fish. Unlike mammals, which needed their mothers to get started in life, fish simply emerge from their eggs and either die or survive. This means that distant human ancestors could survive as infants if they were more like fish than like humans.

Even in Anaximander’s time, people saw skeletons from long-dead creatures. Fossils of extinct life were found long before paleontologists went looking for them. Ancient Greeks lived by the sea, and often the sea washed up skeletons or eroded the ground to expose buried bones. Living in this environment , Anaximander had a general idea of skeletal anatomy and how it was similar and different between humans and other animals. Because of this, he decided that the transition from fish to humans must have been gradual. In other words, humans descended from fish through an evolutionary process .

Since Anaximander proposed no idea of how the apparent evolution from fish to human had taken place, it was not an early form of Darwin’s theory of natural selection . But it was the beginning of thinking that life on Earth began with small organisms . Anaximander’s idea quickly led to the idea that small organisms were generated through a natural process from nonliving matter , such as the mud at the bottom of the sea.

Over the next centuries, Greek thinkers such as Anaximenes (588–524 BCE), Xenophanes (576–480), Empedocles (495–435), Democritus (460–370), and finally Aristotle (384–322) developed and modified the spontaneous generation idea so that it corresponded to what people often observed on land. Farmers leaving grain in an open container noticed that pretty soon mice appeared, as if the grain generated the mice. People leaving meat untended returned to find maggots infesting the meat, as if the meat generated the maggots.

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Testing spontaneous generation

By the 18 th and 19 th century, the older Greek idea of spontaneous generation was well ingrained in the minds of everyone who ventured to think that the origin of life might not have required the gods. And living at a time when science was coming to age, some early modern thinkers started treating spontaneous generation less like a philosophy and more like a scientific hypothesis . Gradually, they began subjecting the idea to scientific experimentation.

An early attempt at testing spontaneous generation occurred in the 17 th century, when the Italian scientist Francesco Redi (c. 1626–1697) looked carefully at the meat-maggot phenomenon. After leaving meat in an open jar, he observed that maggots did indeed appear, and that the maggots then developed into flies, which then flew away. However, when he left meat in a sealed jar, the maggots did not appear. Nor did maggots appear when he left the meat in a jar covered with a mesh screen, a precaution he took just in case spontaneous generation required fresh air for some reason. In the terminology of today’s science, we say that the mesh-covered jar “controlled for” the possibility that spontaneous generation required fresh air (Figure 3).

Since the mesh cover prevented the appearance of maggots, it meant that the maggots were not coming from spontaneous generation , but simply from eggs of adult flies. By the standards of experimental methods in contemporary science, it was a rudimentary experiment , but it was as good as it could be given the equipment available in Redi’s time.

Despite the result of his maggot experiment , Redi still believed that smaller creatures, called “gall insects” came from spontaneous generation . At the same time, a developing invention, the microscope, allowed scientists to focus on creatures even smaller: microorganisms. Using his microscope, an English experimenter, John Needham, noticed that broths made from meat were teeming with microorganisms, so he put spontaneous generation to his own test (see our module Experimentation in Scientific Research ). Needham heated a bottle of broth to kill any microorganisms, and left the bottle for a few days. Then, he looked at the broth under the microscope and found that, despite the earlier heating, the broth contained microorganisms again (Figure 4a).

In Needham’s mind, this finding suggested that the lifeless broth had given rise to life. But another scientist, an Italian named Lazzaro Spallanzani , thought that Needham must have done something wrong. Perhaps, he hadn’t heated the broth to a high enough temperature or for a long enough time. To find out, Spallanzani performed his own experiment . He boiled broth in two bottles, left one bottle open and one closed, and found that new microorganisms appeared only in the open bottle. His conclusion: the microorganisms entered the bottle through the air; they were not generated spontaneously in the broth (Figure 4b).

Experiments seeming to prove or disprove spontaneous generation of life went on for another century. Because of the difference between closed and open vessels, arguments focused on the possibility that spontaneous generation of life might require fresh air. Thus, lack of air in Spallanzani’s closed bottle could have been a factor confusing the results. This possibility attracted the attention of the 19 th century’s most famous microbiologist: Darwin’s contemporary, Louis Pasteur .

Pasteur was drawn to the issue, but once involved he knew he that needed to control for the possibility that air was needed to generate life from nonliving matter . To do this, he designed flasks with long, specially curved, swanlike necks. This allowed sterilized broth to be exposed to fresh air from the outside, but any microorganisms from the air would be trapped in a pool of water in the neck. (See our module Experimentation in Scientific Research for more information on designing experiments .)

The sterilized broths in Pasteur’s special flasks did not become infested with microorganisms despite being exposed to fresh air (Figure 5). And so, after a run of more than 24 centuries, the hypothesis of spontaneous generation was finally laid to rest.

This meant that scientists no longer thought that microorganisms, or small animals, could suddenly emerge with no parents , but it didn’t stop people from thinking about life coming from nonliving matter . Pasteur’s publication of his experimental results disproving spontaneous generation of microorganisms came in the very same year as Darwin’s Origin of Species . This made for paradox. Around the world, scientists were fairly certain that evolution really happened, that all modern species came ultimately from pre-existing, living forms. However, as for the question of how life started in the first place, scientists had just disproved the only explanation they had.

Darwin’s pond idea was completely speculative. There was no way to test it the way he tested natural selection through years of observation of numerous species . And so, when it came to the initiation of life itself, scientists of Darwin’s era were stumped. All they could do was to throw up their hands, or chalk it up to the creation stories of their religions.

• Old and new ideas

In addition to spontaneous generation , the ancient Greeks produced another idea for the origin of life on Earth: panspermia . An Ionian Greek named Anaxagoras (510–428 BCE) thought that life arrived on Earth as seedlings that came through space from other worlds. Often people think of panspermia as an alternative to the idea of life emerging from nonliving matter , but it’s actually not. Instead, panspermia only moves the origin of life off the Earth to another planet or moon, and further back in time. Thus, after Pasteur’s disproval of spontaneous generation , the motivation was stronger than ever to determine how life got started.

By the late 19th century, English biologist Thomas Henry Huxley (1825–1895) coined the term abiogenesis to describe life forms emerging from non-living chemical systems . On first hearing the term, it may sound as if abiogenesis is merely a more modern take on spontaneous generation , but there is a major difference. With spontaneous generation , the idea was that certain materials, be it meat, grain, or mud, were capable of constantly producing some kind of creature. What Huxley had in mind was the chemical reactions of life slowly emerging on the early Earth over a long period of time. Huxley knew that the mixture would have to be more complex than Darwin’s ammonia and phosphoric salts , but he did not attempt to work out the details. Somehow, though, he thought an optimal mixture of simple chemicals generated the complex chemicals needed for life, such as enzymes , and the earliest living cells .

• Abiogenesis

As for how abiogenesis could occur on the primordial Earth, serious thinking about this began in the 1920s with two scientists working entirely independently of one another.

In 1922, Aleksandr Oparin, a Russian biochemist, gave a lecture on the origins of life, which was published as a booklet in 1924. For several years, the booklet was not translated from Oparin’s native Russian, so his ideas were unknown outside of the USSR. Meanwhile, British biochemist John Burdon Sanderson Haldane (usually known by his initials JBS Haldane) was working on similar ideas. Unlike his Russian counterpart, Haldane and his work were extremely visible. He was a great popularizer of science, doing for the early 20th century what astronomer Carl Sagan did later, making science understandable and fascinating for the masses. Haldane’s hands were in numerous areas of life science. He was the author of dozens of scientific papers and spent a great deal of time explaining his work and its importance to people outside the scientific world.

In connection with other questions of biology, Haldane was working with enzymes , which he thought were on the border between living and nonliving chemistry. Consequently, he hypothesized that abiogenesis took place through a complex mechanism involving enzymes and viruses. By Haldane’s time, scientists figured out that the atmosphere of the primordial Earth had been a reduced atmosphere. This means that it contained reduced carbon chemical compounds , such as methane, in contrast to oxidized chemical compounds, such as carbon dioxide (which could be present, but in much lower quantities compared with methane). It also contained hydrogen, ammonia, some water vapor, and, importantly, no oxygen.

Oxygen can come only from organisms that carry out photosynthesis to make their own food. Such organisms are called autotrophs. Haldane reasoned that the first cells must have been heterotrophs, organisms that take their food from the surrounding environment . Methane is a gas , but other simple, organic compounds made from it are liquid and would have rained down on the early Earth. They accumulated as pools of liquid on the surface , forming a kind of organic broth that became known as “Haldane’s soup” (Figure 6).

Because there was no oxygen in the atmosphere , the early Earth lacked a layer of ozone to block out powerful ultraviolet radiation from space. Haldane hypothesized that the ultraviolet radiation from space, along with lightning constantly hitting the primordial organic soup, delivered energy to the various simple organic compounds . This caused chemical bonds between the atoms of the molecules to break and reform, creating new and different molecules, leading to extremely large, complex organic molecules . Haldane speculated that this happened over millions of years, until finally a molecule arose that could copy itself crudely using other molecules in the “soup” as building blocks.

Molecules that could copy better than their neighbors multiplied and gradually dominated the soup. Some of these self-copying molecules became surrounded by a kind of barrier, the precursor to what we call a membrane . This happened by accident, so it was very rare, but when it did happen, Haldane explained, the enclosed, self-copying molecules had an enormous survival advantage. So they came to dominate, ate up the soup, and life had begun.

Haldane’s idea was purely hypothetical. No one tested it yet, but it was far more elaborate than Darwin’s phosphoric salt idea. Moreover, it was perfectly consistent with the state of science in the 1920s and 30s regarding the chemistry of the early Earth. Then, in 1936, Oparin’s work was finally translated from Russian. It turned out that he was proposing almost the same thing as Haldane, so the idea became known as the Oparin-Haldane hypothesis .

• Putting ancient Earth into the lab

As for testing the Oparin-Haldane hypothesis , that role fell into the hands of a graduate student, Stanley Miller. In the early 1950s, Miller was looking for a thesis project in the Department of Chemistry at the University of Chicago. In 1952, his academic mentor, Professor and Nobel laureate Harold Urey, suggested that he try putting the origins of living molecules to a test. That meant recreating the kind of atmosphere that scientists thought had existed on primordial Earth: hydrogen, methane, ammonia, and water. It also meant providing what Haldane thought set the stage for creating more complicated molecules needed for life: lightning and ultraviolet light .

Once the ancient atmosphere was created and contained in a flask, Miller and Urey exposed the mixture to powerful ultraviolet light . They also put electrodes inside the flask and sent an electric current through the apparatus, creating sparks to simulate lightning, which interacted with the gases in the flask. After several days, they checked the contents of the liquid that accumulated at the bottom of the apparatus (Figure 7). They found that different molecules had been created, including various important biological molecules, such as the amino acids glycine, alanine, and valine. They ran the experiment over and over and, depending on how they changed around the gas mixture, different varieties of amino acids and other biological molecules were created. This showed that it was possible for biologically important molecules to form on a planet under abiotic conditions.

Over the years, as Miller progressed through his career, scientists studying planetary atmospheres and the ancient Earth had second thoughts about Earth’s primordial atmosphere. Perhaps it had not been dominated by methane, hydrogen, and ammonia, and possibly it could have been more oxidized as opposed to reduced. But as theories about the ancient atmosphere were refined, Miller tried variations of his original experiment with the adjusted gas mixtures . Although chemical products changed with each new mixture, in each case they included compounds that were vital to life, such as amino acids , or nitrogenous bases , the building blocks needed to make DNA and RNA . The emerging answer seemed to be that, almost regardless what the precise mixture and conditions were, complex organic molecules would result.

• After the Miller-Urey experiment: Exploring proteins and membranes

While ideas about Earth’s primordial atmosphere were in flux from the 1970s onward, NASA’s exploration of the outer Solar System revealed some amazing things about the moons orbiting Jupiter and Saturn. In particular, the space probes Voyager 1 , Voyager 2 , and Cassini and an atmospheric entry probe to Saturn’s moon Titan called the Huygens probe revealed the exact makeup of Titan’s atmosphere. This inspired other scientists, such as Carl Sagan , to redo Miller’s 1952 experiment with a Titan atmospheric mixture. This too produced important biological compounds . Thus, today, the moon Titan is a prime focus for astrobiology studies in the Solar System. It may have exotic life forms, or it may be a model of how Earth was prior to life.

Several years after the original Miller-Urey experiment , another investigator, Sidney Fox, ran experiments showing that some of the Miller-Urey compounds – the amino acids – could join together to form polymers , bigger molecules known as peptides , or small proteins . This happened when amino acids made through a Miller-Urey mechanism were splashed onto surfaces of clays and other materials, under hot, dry conditions. On the ancient Earth, such conditions would have occurred at the boundary between ancient ponds or seas and ancient land. Given enough time, complex proteins could arise.

Other researchers later found that spheres of lipids (the class of organic molecules that includes fats) also could form under conditions thought to exist on the ancient Earth. This would create a water environment inside the sphere that was separated from the outside. In other words, crude membranes can form spontaneously under the same conditions in which biological compounds like amino acids and small proteins can form. The fact that membranes can form spontaneously is key to origins of life research . This is because to move from non-living chemistry to biology, very complex networks of chemical reactions need to emerge. Like a car being made on an assembly line, biological molecules are put together section by section. They also are converted into different molecules section by section, so there is a series of intermediate chemicals in addition to a starting molecule (called a substrate) and final product of each reaction .

In an open environment like Haldane’s primordial soup, or in an ocean, the various intermediates would simply diffuse away before the chemical pathway had a chance to evolve. But a membrane would enclose all of the chemicals within a compartment. That compartment would then act as a chemical laboratory, holding inside any reactions that happened to emerge. Since we know that membrane spheres can spontaneously form, the primordial soup of early Earth must have had billions of these little chemical laboratories in which the chemistry of life was sputtering along.

• Moving to a DNA world

Demonstration that biological molecules and membranes can arise in an abiotic environment is not a demonstration of the emergence of life. It shows only what might have happened in the transition from non-living chemistry to the eventual formation of life. It does, however, show that a necessary step in abiogenesis – the spontaneous emergence of complex organic molecules – is not only possible, but likely under the right conditions.

Theoretically, continuous rearrangement and construction of larger and larger organic molecules from chemical building blocks that would form on the early Earth should eventually lead to molecules that can copy themselves. That’s because the bigger an organic molecule gets, the more functional chemical groups it has. Functional groups are sections of molecules with atoms other than carbon, such as oxygen, nitrogen, and phosphorus, which like to hold onto electrons . This allows for electrons to be moved around between parts of the molecule and between the molecule and other molecules. Also, the bigger a molecule gets, the more it’s able to bend and twist around. This capability, together with the capability to move around a lot of electrons, &^means it’s possible, simply by luck, for any random, very large organic molecule with a lot of nitrogen, oxygen, and phosphorus atoms to have some enzymatic capability –that is, to be able to catalyze chemical reactions .

Certain sets of reactions catalyzed by a molecule can result in the molecule making a copy of itself. Thus, with plenty of building materials in a Haldane soup, as time goes on, it is likely that self-replicating molecules would emerge. The first self-replicating molecule would have only crude copying ability. But, since it would not copy itself exactly, each new “copy” would be a little different than the “parent” molecule. Randomly, a newly copied molecule might have the ability to copy slightly better than the molecule that made it. Natural selection would then work for non-living chemical molecules similar to how Darwin described it working for living organisms . Those molecules copying better would make more copies using building blocks taken from the breakdown of other molecules that could not copy themselves so well.

Self-copying molecules enclosed in membranes would fare even better because they would be held close together with other chemicals. But for life to really begin, there has to have been a molecule whose copying ability was extremely good. Today, there is such a molecule: DNA . However, DNA is incredibly complex and this makes for a chicken and egg kind of dilemma.

In the 1980s, scientists began to realize that not all enzymes are proteins . Scientists dissected some cell components called ribosomes and found that they are made of protein and RNA . What was strange was that some of the RNA molecules actually work as enzymes. They can catalyze chemical changes in themselves and in other RNA molecules.

Like DNA , RNA can hold genetic information, but RNA is less complex than DNA (Figure 8). Consequently, a hypothesis called the “RNA world” was proposed independently by three different researchers: Leslie Orgel, Francis Crick , and Carl Woese. It’s a keystone in origins of life research today. The idea is that RNA emerged on Earth prior to DNA and was the genetic material in the first cells (or in the first cells on a different world, if life began somewhere else).

Today, no known bacterial cell or other fully-fledged life form uses RNA the way that we use DNA , as the storage molecule for genetic information. But there are RNA viruses. Not all viruses are RNA viruses; some use DNA to hold genetic instructions, just as our cells do. But if RNA is adequate as the only genetic material in some viruses, it’s easy to imagine RNA also being the only genetic material in an early bacterium, or other singled-celled creature that could have existed on the early Earth.

It’s not hard to image how the transition from RNA to DNA might have occurred. As with the evolution of everything else, there would have been mistakes. In living organisms today, DNA stores genetic information over the long term and DNA sequences are transcribed into RNA sequences, which then are used to put together sequences of amino acids into proteins (see our Gene Expression: An overview module). Essentially, DNA is an additional layer beyond RNA and the proteins that RNA makes. RNA sequences could have been the genes before a mistake created DNA. Being more stable chemically than RNA, DNA took over the job of storing genetic information. This gave RNA a chance to get better at translating genetic information into proteins.

That would have been an enormous step in life’s evolution . It also would mean that life was not here all at once. Rather, abiogenesis occurred in increments or steps during prebiotic, chemical evolution. Thus, entities must have existed along a spectrum from nonliving to living, just as viruses today have characteristics of both living and nonliving entities. We don’t know the precise abiogenesis pathway, but scientists have worked out each of the major steps necessary to go from nonliving chemistry to self-sustaining cells . Importantly, scientists also have conducted laboratory experiments demonstrating that each step is possible. Unlike the days of Anaximander , Darwin, or even Haldane, there are no big holes or theoretical barriers to abiogenesis. Scientists have a good idea of how it probably happened. Still, in terms of the details within each major step, that is where science is now focused on getting some answers.

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Francesco Redi: History and Significance

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Francesco Redi was an Italian scientist most famous for his experimental work that refuted the spontaneous generation theory. His experiment with meat in glass containers was one of the earliest controlled experiments.

Who is Francesco Redi?

Francesco Redi was a scientist born in Arezzo, Italy on February 18, 1626. He completed degrees in medicine and philosophy at the University of Pisa. After graduating, Redi moved to Florence to become the physician to the Grand Duke of Tuscany.

Redi was inspired by the work of William Harvey, who correctly described blood circulation around the body. It led him to develop his own experimental work. His most famous work was a paper entitled, Esperienze Intorno alla Generazione degl'Insetti (Experiments on the Generation of Insects) which he published in 1668. This work provided evidence against the spontaneous generation theory.

The spontaneous generation theory, which claims living things can form from non-living objects, had been put forward by Aristotle and had been widely accepted for centuries. People believed that maggots would just emerge from rotting meat. In the experiment Redi prepared three groups of jars, each with a pieces of meat inside them. One group of jars was covered with gauze, one group was left open, and one group was completely sealed.

In the group of jars that were left open, Redi found maggots on the meat. Redi noticed that in the jars that were completely sealed, there were no maggots. In the group of jars that were covered in gauze, he noticed that there were no maggots on the meat, but maggots did appear on top of the gauze. This experiment provided evidence which refuted the spontaneous generation theory. He showed that maggots came from eggs laid by flies. This experiment was important as it was one of the first controlled experiments in history. Modern day scientific experiments require controls to eliminate the impact of other variables on the results of the experiment.

Redi died on March 1, 1697 in Pisa.

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Francesco redi’s accomplishments.

• Use of controlled experiments
• Disproving the spontaneous generation theory
• Discovery that snake venom is not produced in the gallbladder

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Scientists Once Dressed Frogs in Tiny Pants to Study Reproduction

In the 18th century, fertility research got particularly creative..

You might value pants for their leg-sheathing, buttock-concealing and pocket-generating powers—but they can also serve as frog genital shackles, and they played a crucial role in 18th-century fertility research.

Reproduction wasn’t always a settled science. Prior to cell theory and the invention of the microscope, inquisitive minds engaged in quite a bit of guesswork over where babies come from. As early as 350 B.C., Aristotle proposed a theory of epigenesis—which was essentially correct. But not everyone cared for the idea of a sperm-and-egg collaboration.

So-called preformationists believed organisms developed from miniature versions of themselves. For instance, in the 17th and 18th centuries, Dutch physicist Nicolaas Hartsoeker took a hardline “spermist” approach, postulating that each sperm contained a complete preformed humanoid, or homunculus . Ovists, on the other hand, believed the egg contained all that was needed and merely required male seed as a chemical trigger. Still others pointed to maggots or fermentation as proof of spontaneous generation, at least in simpler organisms.

To reach our current understanding of reproduction, these fanciful theories would need to fall by science’s sword—and fall they did. Physician Francesco Redi’s classic 1668 experiment, in which he separated meat from swarming flies with gauze, struck a crucial blow to spontaneous generation. The ovists and the spermists would prove more difficult to defeat, which brings us to Italian physiologist and priest Lazzaro Spallanzani (1729-1799)—and his tiny frog pants.

Spallanzani was a devoted ovist. As evolutionary geneticist Kenneth Weiss points out in his 2004 paper The Frog in Taffeta Pants , Spallanzani and other microscope-users of the day knew semen contained “wormified beings in a thicker component, and a thinner liquid.” Based on popular theories concerning inheritable intestinal worms, Spallanzani thought the sperm might be mere parasites and that the seminal fluid alone served as a chemical trigger for the all-encompassing egg.

In the 1760s, to better understand the process, Spallanzani repeated a 1736 experiment by French scientist René Antoine Ferchault de Réaumur. In the original experiment, Réaumur enshrouded the posteriors of male frogs in pants made from pig’s bladder and taffeta. He aimed to prevent the dousing of frog eggs and examine any male frog secretions caught in the pants to gain a better understanding of how fertilization works. The frogs’ tendency to wriggle out of the pants made these experiments challenging.

In his follow-up experiment decades later, Spallanzani described the prophylactic garment as “pants,” but without illustration or artifact, we’re left to imagine the most ridiculous possibilities. (Tiny lederhosen, perhaps?). Spallanzani’s pants prevented the thicker portion of the semen from reaching the egg, though he was still loathe to credit its wormlike contents with fertilization.

According to Ernesto Capanna’s Lazzaro Spallanzani: At the Roots of Modern Biology , Spallanzani went on to throw pants on various amphibian species. In each case, he collected semen from the taffeta pants and successfully carried out artificial insemination on a female of the same species. In time, he even upgraded to dogs, but didn’t need special pants for canine semen collection.

Spallanzani remained an ovist his entire life, always finding a way to credit the egg alone as the human “tadpole.” He died of bladder cancer in 1799 and the bladder itself remains preserved in Pavia, Italy .

The scientific understanding of reproduction has changed a great deal over the last two centuries, but animal breeding programs continue. The methods of semen collection remain, if we’re being honest, a bit awkward. Plus, every now and then, a well-meaning scientist busts out a pair of experimental pants. In 1993, Egyptian sexologist Dr. Ahmed Shafik dressed rats in polyester pants to study the fabric’s effects on sexual activity.

Never doubt the research potential of tiny trousers.

For Centuries, People Celebrated a Little Boy’s First Pair of Trousers

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The Discovery of Electrokinetic Phenomena: Setting the Record Straight

Affiliation.

• 1 Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, VIC, 3010, Australia.
• PMID: 27902877
• DOI: 10.1002/anie.201608536

Electro-osmosis and electrophoresis were discovered by F. F. Reuss in Moscow in 1807. Or so the story goes. This Essay critically examines the contributions of three scientists to the discovery of electrokinetic phenomena. The evidence suggests that Reuss did indeed discover electro-osmosis, which takes its name (indirectly) from the work of Porrett. Contrary to current consensus, Gautherot made the earliest known observation of electrophoresis.

Keywords: electro-osmosis; electrokinetics; electrophoresis; history of science.

© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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