The Science Book Read online

  SEE ALSO Domestication of Animals (c. 10,000 BCE), Rice Cultivation (c. 7000 BCE) Artificial Selection (Selective Breeding) (1760), Green Revolution (1961).

  The National Grange of the Order of Patrons of Husbandry, an association of farmers, was founded in the United States in 1867 to promote community wellness and agriculture. This 1873 poster, “Gift for the Grangers,” promotes the organization through idyllic scenes of farm life. In 1870, 70–80 percent of the US population was employed in agriculture; by 2008, this number had dwindled to only 2–3 percent.

  c. 10,000 BCE

  Domestication of Animals • Michael C. Gerald with Gloria E. Gerald

  Domesticated animals were initially developed from species that were social in the wild and could breed in captivity, thus allowing genetic modifications to increase those traits that are advantageous to humans. Depending upon the species, such desirable traits might include: being docile and easy to control; having the ability to produce more meat, wool, or fur; and suitability for traction, transportation, pest control, assistance, companionship, or as a form of currency.

  The most familiar domesticated animal, the dog (Canis lupus familiaris), is a subspecies of the gray wolf (Canis lupis), with the oldest fossil remains showing a split in their lineage some 35,000 years ago. Dogs were the first animals to be domesticated with the earliest evidence being a jawbone found in a cave in Iraq and dating back some 12,000 years. Images on Egyptian paintings, Assyrian sculpture, and Roman mosaics show that even in ancient times, domestic dogs were of many sizes and shapes. The first dogs were domesticated by hunter-gatherers but their job description has since been expanded beyond hunting to include herding, protection, pulling loads, aiding police and the military, assisting handicapped individuals, serving as human food, and providing loyal companionship. The American Kennel Club now lists 175 breeds, with most only several hundred years old.

  Around 10,000 years ago, sheep and goats were domesticated in southwest Asia. While alive, they served as a source of manure for crop fertilization and, when dead, as a regular supply of food, leather, and wool. Researchers have long been puzzled about the origins and evolution of the domestic horse (Equus ferus caballus), whose wild ancestor first appeared 160,000 years ago and is now extinct. Based on archeological and genetic evidence, including bit wear on horse teeth that were found at sites associated with the ancient Botai culture, in 2012 researchers concluded that their domestication dates back some 6,000 years in the western Eurasian Steppe (Kazakhstan). As they were domesticated, these early horses were regularly bred with wild horses to provide meat and skin and later to play an essential role in war, transportation, and sport.

  SEE ALSO Agriculture (c. 10,000 BCE) Artificial Selection (Selective Breeding) (1760), Darwin’s Theory of Natural Section (1859).

  Dogs, which have all evolved from the gray wolf, were the first domesticated animals and have been the working partner and loyal companion of humans for some 12,000 years. They are now commonly functionally categorized as companion, guarding, hunting, herding, and working dogs.

  c. 7000 BCE

  Rice Cultivation • Michael C. Gerald with Gloria E. Gerald

  FEEDING ASIA. Rice is among the oldest and world’s most important economic botanical food crop. It is the largest source of calories for the 3.3 billion people of Asia, providing 35–80 percent of their total caloric intake. But, while rice is nutritious, it is not sufficient to serve as the main food source. The worldwide popularity of rice as a food is attributed, in part, to its ability to be grown in areas as varied as flooded plains to deserts and in all continents, except Antarctica. China and India are the major rice-producing and consuming countries.

  Some 12,000–16,000 years ago, rice grains were initially gathered and consumed by prehistoric people in the world’s humid tropical and subtropical regions. Wild cultivated prototypes of rice, which descended from wild grasses, are members of the taxon family Poaceae (also called Gramineae). Based on genetic evidence, recent reports reveal that rice cultivation first occurred in China between 8,200 and 13,500 years ago. From China, cultivation spread to India, then to western Asia and Greece, brought by the armies of Alexander the Great in 300 BCE. The most popular cultivated rices are Oryza satliva japonica (Asian rice and, by far, the most common) and Oryza glaberrima indica (African rice), both of which were domesticated from a common origin.

  The rice plants have an outer coating that protects the rice grain, the fruit of the plant. Seeds are milled to remove the chaff (outer husk) to produce brown rice. If milling is continued, and the rest of the husk and grain removed, white rice is left. Brown rice is more nutritious, containing proteins, minerals, and thiamine (vitamin B1), while white rice mainly contains carbohydrates and is virtually devoid of thiamine. Beriberi results from a nutritional deficiency in thiamine, which has been historically endemic in Asian populations, who favor polished white rice because it has a longer shelf life and is not historically associated with poverty. Among cereals, rice is low in sodium and fat, and free of cholesterol, making it a healthy food choice.

  SEE ALSO Wheat: The Staff of Life (c. 11,000 BCE), Agriculture (c. 10,000 BCE) Artificial Selection (Selective Breeding) (1760).

  Rice is the world’s most important food crop and provides the greatest proportion of calories to the people of Asia. Although this crop is typically grown on flooded plains, such as this one in Thailand, it can also be cultivated in deserts.Recent evidence suggests that rice may have actually been domesticated independently on three continents: Asia, Africa, and South America.

  c. 5000 BCE

  Birth of Cosmology • Jim Bell

  In Greek, kosmos means “the universe,” and thus our modern word cosmology refers to the study of the nature, origin, and evolution of the universe. In the classical context, a society’s cosmology refers to its worldview or its way of thinking about where its people came from, why they are there, and where they are going. Civilizations throughout human history have created and nourished their cosmologies through creation stories, mythology, religion, philosophy, and, most recently, science.

  We often hear (or read) such platitudes about how humanity has always been looking to the stars, or how our distant ancestors must have pondered the heavens in this way or that. While it’s fun to speculate, it’s impossible to know what prehistoric people were really thinking because (by definition) there’s no record of prehistory. That’s one reason why the oldest archaeological artifacts that depict or represent astronomical themes are so important: they provide some real data with which to try to understand how ancient people viewed the universe.

  The oldest preserved evidence of a civilization pondering the heavens comes from the Sumerians, in their partial star maps or pieces of crude astronomical instruments that some scholars believe date to between 5,000 and 7,000 years ago. Even the scant fragments of information available from that time reveal a significant degree of sophistication in the Sumerians’ understanding of the motions of the Sun, Moon, major planets, and stars. Perhaps this is not surprising: the Sumerians built the first city-states supported by the cultivation of crops by a year-round, nonmigratory population. Knowing how to read the sky translated directly into knowing when to plant, irrigate, and harvest, and a stable food supply gave them time to invent writing, arithmetic, geometry, and algebra.

  Sumerian cosmology appears to have been the first to make gods of the heavenly bodies, a practice inherited by later Babylonian, Greek, Roman, and other cosmologists. Sumerian cosmology also espoused the idea of many heavens and many Earths in what was a decidedly nongeocentric universe. It’s a worldview that resonates—surprisingly—with modern cosmological thinking, as the reality seems to be a universe without any center at all and apparently brimming with many Earths.

  SEE ALSO Egyptian Astronomy (c. 2500 BCE) Sun-Centered Universe (1534), Telescope (1608), Newton’s Prism (1672), Hubble Telescope (1990).

  Reconstruction of an ancient Sumerian star chart from 3300 BCE known as th
e planisphere of Nineveh, which is believed to be one of the oldest astronomical instruments and data sets ever discovered.

  c. 3300 BCE

  Bronze • Derek B. Lowe

  Bronze is the first metal that gets its own age, which began around 3300 BCE in Mesopotamia. Other metals were certainly in use before it—especially copper—but the addition of a small amount of tin to existing copper technology changed everything. Bronze was a step up in hardness, durability, and resistance to corrosion. Unfortunately, tin and copper ores generally aren’t found together, which meant that an area rich in one ingredient had to trade for the other. Beginning around 2000 BCE, tin from Cornwall (southwest Britain) was in such demand that it turned up in many eastern Mediterranean archaeological sites, thousands of miles away.

  We don’t know much about these early chemists and metallurgists, but it’s clear that they experimented with whatever they had on hand. Bronze alloys have turned up with all sorts of other metals in them—lead, arsenic, nickel, antimony, and even precious metals like silver. Those must have taken especially large amounts of nerve to add to the mix, since it was almost certain at the time that you would never see them again (the techniques to repurify such metals would not arrive for many centuries).

  And thus, the long human adventure with metallurgy began—one that is nowhere near over. Bronze itself has been improved over the years—the Greeks added more lead to make the resulting alloy easier to work with, and the addition of zinc takes you into the various forms of brass. Modern bronzes often have aluminum or silicon in them, which were completely unknown to the ancients. If you want to see real, old-fashioned bronze of a kind that would have been recognized thousands of years ago, take a close look at a drum kit. Bronze has been the preferred metal for bells and cymbals for hundreds of years. The more tin in the mix, the lower the timbre, but there is no record of what adding arsenic or silver might do to the sound.

  SEE ALSO Iron Smelting (c. 1300 BCE) Roman Concrete (c. 126), Bessemer Process (1855).

  This ancient, Chinese bronze bell may have been part of a larger set, tuned and shaped to produce different notes. Casting bronze instruments to such specific tolerances is a serious technical challenge.

  c. 3000 BCE

  Dice • Clifford A. Pickover

  Imagine a world without random numbers. In the 1940s, the generation of statistically random numbers was important to physicists simulating thermonuclear explosions, and today, many computer networks employ random numbers to help route Internet traffic to avoid congestion. Political poll-takers use random numbers to select unbiased samples of potential voters.

  Dice, originally made from the anklebones of hoofed animals, were one of the earliest means for producing random numbers. In ancient civilizations, the gods were believed to control the outcome of dice tosses; thus, dice were relied upon to make crucial decisions, ranging from the selection of rulers to the division of property in an inheritance. Even today, the metaphor of God controlling dice is common, as evidenced by astrophysicist Stephen Hawking’s quote, “Not only does God play dice, but He sometimes confuses us by throwing them where they can’t be seen.”

  The oldest-known dice were excavated together with a 5,000-year-old backgammon set from the legendary Burnt City in southeastern Iran. The city represents four stages of civilization that were destroyed by fires before being abandoned in 2100 BCE At this same site, archeologists also discovered the earliest-known artificial eye, which once stared out hypnotically from the face of an ancient female priestess or soothsayer.

  For centuries, dice rolls have been used to teach probability. For a single roll of an n-sided die with a different number on each face, the probability of rolling any value is 1/n. The probability of rolling a particular sequence of i numbers is 1/ni. For example, the chance of rolling a 1 followed by a 4 on a traditional die is 1/62 = 1/36. Using two traditional dice, the probability of throwing any given sum is the number of ways to throw that sum divided by the total number of combinations, which is why a sum of 7 is much more likely than a sum of 2.

  SEE ALSO Law of Large Numbers (1713), Normal Distribution Curve (1733), Laplace’s Théorie Analytique des Probabilités (1812)

  Dice were originally made from the anklebones of animals and were among the earliest means for producing random numbers. In ancient civilizations, people used dice to predict the future, believing that the gods influenced dice outcomes.

  c. 3000 BCE

  Sundial • Clifford A. Pickover

  “Hide not your talents. They for use were made. What’s a sundial in the shade?”

  —Ben Franklin

  For centuries, people have wondered about the nature of time. Much of ancient Greek philosophy was concerned with understanding the concept of eternity, and the subject of time is central to all the world’s religions and cultures. Angelus Silesius, a seventeenth-century mystic poet, actually suggested that the flow of time could be suspended by mental powers: “Time is of your own making; its clock ticks in your head. The moment you stop thought, time too stops dead.”

  One of the oldest of time-keeping devices is the sundial. Perhaps ancient humans noticed that the shadows they cast were long in the early morning, grew progressively shorter, and then grew longer again as the evening approached. The earliest known sundial dates to about 3300 BCE and is found engraved in a stone in the Knowth Great Mound in Ireland.

  A primitive sundial can be made from a vertical stick in the ground. In the northern hemisphere, the shadow rotates around the stick in a clockwise direction, and the shadow’s position can be used to mark the passage of time. The accuracy of such a crude instrument is improved if the stick is slanted so that it points to the Celestial North Pole, or roughly toward the position of the Pole Star. With this modification, the pointer’s shadow will not change with the seasons. One common form of sundial has a horizontal dial, sometimes used as an ornament in a garden. Because the shadow does not rotate uniformly around the face of this sundial, the marks for each hour are not spaced equally. Sundials may not be accurate for various reasons, including the variable speed of the Earth orbiting the Sun, the use of daylight savings time, and the fact that clock times today are generally kept uniform within time zones. Before the days of wristwatches, people sometimes carried a folding sundial in their pockets, attached to a small magnetic compass to estimate true north.

  SEE ALSO Egyptian Astronomy (c. 2500 BCE) Time Travel (1949), Radiocarbon Dating (1949), Atomic Clocks (1955).

  People have always wondered about the nature of time. One of the most ancient of timekeeping devices is the sundial.

  c. 3000 BCE

  Sutures • Clifford A. Pickover

  Galen of Pergamon (129–199), al-Zahrawi (936–1013), Joseph Lister (1827–1912)

  “In an era of escalating surgical technology,” writes surgeon John Kirkup, “it is tempting to downgrade the minor craft of wound closure when compared to more sophisticated operating skills. Indeed, before antiseptic and aseptic procedures were established, closure was a source of many disasters. Even today, successful operations depend on prompt reliable healing of skin, bowel, bone, tendon and other tissues, and neither healing nor a cosmetically acceptable scar can be guaranteed.”

  Today, a surgical suture usually refers to a needle with an attached length of thread that is used to stitch together the edges of a wound or surgical cut. However, through history, the suture has taken many forms. Needles have been made of bone or metal. Sutures were made of materials such as silk or catgut (sheep intestines). Sometimes, large ants were used to pinch wounds together. After the ant’s pincers had bitten into the flesh and closed an opening, the body of the ant was removed, leaving just the head and closed pincers behind. The ancient Egyptians used linen and animal sinew to close wounds, and the earliest reports of such suturing date back to 3000 BCE. Galen, the second-century Greco-Roman physician, used sutures made from animal materials, as did the Arab surgeon al-Zahrawi. British surgeon Joseph Lister investigated ways to
sterilize catgut, a suture material the body gradually absorbed. In the 1930s, a major manufacturer of catgut sutures used 26,000 sheep intestines in a single day. Today, many sutures are made from absorbable or nonabsorbable synthetic polymer fibers, and eyeless needles may be premounted to the suture in order to lessen trauma to body tissues during the threading process. Adhesive liquids are also used to assist in wound closure.

  Depending on use, sutures vary in width, with some smaller than the diameter of a human hair. In the nineteenth century, surgeons often preferred to cauterize (burn) wounds, an often gruesome process, rather than risk the patients dying from infected sutures.

  SEE ALSO Paré’s “Rational Surgery” (1545), Antiseptics (1865), Laser (1960).

  Surgeon’s gloved hand holding a needle holder with an atraumatic curved cutting needle attached to a 4-0 monofilament nonabsorbable synthetic suture.

  c. 2500 BCE

  Egyptian Astronomy • Jim Bell

  The great pyramids of Giza are a monument to the technological (and labor management) prowess of ancient Egyptian civilization. They are also testaments to the designers’ astronomical skill, which figured prominently in Egyptian society and religion 4,500 years ago.

  Because the earth’s spin axis slowly precesses, or wobbles like a spinning top, back in 2500 BCE Polaris was not the North Star. Indeed, much like the skies near our south celestial pole today, there was no bright star near the north celestial pole in those days. To the pharaohs, astrologers, and commoners, the sky at night appeared to spin around a vortex-like dark hole, thought to be a gateway to the heavens. In ancient Egypt, this gateway was located about 30 degrees above the northern horizon, and so the pyramids were carefully aligned to the north, with a small shaft leading from the pharaoh’s main burial chamber to the outside, pointing directly into the center of the gateway. If the plan was to join the gods in the afterlife, why not go in through the main door?