Where Do Babies Come From What Is March
Nonfiction
Where Exercise Babies Come From? And Why Did It Take Scientists So Long to Notice Out?
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THE SEEDS OF LIFE
From Aristotle to da Vinci, From Sharks' Teeth to Frogs' Pants, the Long and Strange Quest to Find Where Babies Come From
Edward Dolnick
Illustrated. 309 pp. Basic Books. $28.
Where do babies come from? The answer to that question is now common knowledge, even so in "The Seeds of Life," the veteran science writer Edward Dolnick tells the states that for centuries it proved elusive, even to the greatest minds. Profound discoveries were being made in medicine, mathematics, astronomy and other fields, simply information technology would take until 1875 for united states of america to fully comprehend the process of man gestation.
When men and women have sex, children can result. That link was understood for a long time (although well into the modern era there were holdouts, such as the inhabitants of the Trobriand Islands, now part of Papua, New Guinea). Nonetheless the precise ways by which sex activity led to a baby remained hidden. For early on investigators, the biggest obstacle was their inability to look within a living body. Studying the dead might take provided some answers, but that wasn't easy. Church and state considered it a sin or a crime. "You might be stopped by your disgust," Leonardo da Vinci wrote, "and if that did not hinder y'all, then perhaps past the fear of spending the night hours in the company of those expressionless bodies, quartered and flayed and terrifying to behold." Arguably the beginning not bad anatomist, Leonardo was allowed the take chances to dissect infirmary patients and recently deceased criminals, but as interested as he was in the uterus, leaving behind wonderful drawings of the womb with a fetus within, he couldn't say how the fetus had got there. Later on researchers were similarly thwarted. The supply of corpses was simply too limited, even after the dangerous practice of grave robbing emerged to meet such demands.
The male person sexual organs were hands studied. Although semen was an obvious byproduct of sex, its function was unclear. "The standard notion among scientists (virtually all of them male, in these early days)," Dolnick writes, "was that semen was a magical, nigh divine batter. Precisely what form that magic took was in dispute: Did semen exert its influence without physical contact, as sunlight nurtured plants, or did it serve as the key ingredient in a divinely ordained recipe, as a kind of baby concoction?"
Female person beefcake was largely hidden and therefore poorly understood. Even more perplexing was the matter of heredity. "If babies somehow combined features of their two parents, as experience seemed to demonstrate, how was it that newborns were either boys or girls rather than a combination of the ii? And if the two parents each contributed to forming their babe, why weren't babies born as monsters with 2 heads and four arms and iv legs?"
A major impediment was what Dolnick calls "the vexed thing of eggs." After all, many creation myths have the first humans emerging from an egg. "In the 17th century," Dolnick explains, "scientists found however another reason to await with special favor on eggs and ovals of all sorts. God the mathematician, they alleged, had favored the circle in a higher place all other shapes, because it was geometrically perfect."
In the mid-1600s, a Dutchman, Regnier de Graaf, came close to sorting it all out. As he studied the female person reproductive organs of many species, he establish that they all "have ovaries full of eggs" and that the eggs of mammals "are fertilized and reach the uterus in the same way as in birds." He fabricated specially careful observations of the reproductive organs of rabbits. "His tools," Dolnick reminds the states, "were little more than sharp eyes and the ability to count. Instead of dissecting his rabbits only a few hours or even a few days after they had mated, he waited several days. Now he found ruptured follicles in the ovary and tiny embryos in the uterus." De Graaf'southward advance was conceptual, clarifying the stardom between the new living organism and the female person's contribution to it: "De Graaf cleared things up and convinced the world to shift focus. In his picture, the egg emerged from the female'southward ovary and combined somehow with semen from the male to form a new organism." This was a daring proposition, since de Graaf had never seen the egg itself — the tools were simply not in that location. He'd noted the follicles on the ovary, and so seen them ruptured, by which fourth dimension an embryo or fetus (the fertilized egg) could exist constitute in the uterus.
Leeuwenhoek's microscope was the necessary next footstep. A skilled lens maker, he found himself witnessing a tiny world teeming with life. I night, after making dearest with his wife, he examined his own sperm under his microscope and described the tiny creatures he saw, "furnished with a thin tail, almost five or half-dozen times as long as the body," that moved like "a serpent or an eel swimming in water."
This observation triggered a great debate, pitting "spermists" against "ovists." De Graaf had seen the eggs. Others saw the motile creatures in the semen and believed them to exist the source of the future baby. At the heart of the spermists' instance was the merits by a mathematician named Nicolaas Hartsoeker that each sperm "actually encloses and hides an even smaller being nether a tender and delicate skin." As part of his statement, he presented a drawing that, as Dolnick puts information technology, "generations of histories and textbooks accept fabricated notorious e'er since, of a bigheaded person curled up within a sperm cell, hands clutching knees equally if he has merely been told to brace for a crash."
A consequence of this notion was an obsession with not spilling sperm. "Decade afterward decade," Dolnick writes, "medical writers barraged the reading public with horror stories." "Every seminal emission out of nature's route — I must speak obviously, gentlemen! — every act of cocky-pollution is … an earthquake," a London authorisation declared, "a boom, a deadly paralytic stroke." Fifty-fifty as noted a figure as Rousseau warned confronting "the well-nigh deadly habit to which a immature man tin be subject." Dolnick adds more names to the roster: "Kant proclaimed masturbation more than sinful than suicide. By far the well-nigh important and influential of these naysaying authorities was Samuel Tissot, one of Europe's nearly acclaimed physicians. In 1762 he produced a tome called 'A Treatise on the Diseases Produced past Onanism.'"
The perils of onanism aside, information technology would seem an like shooting fish in a barrel matter for the ii sides to come to an understanding of the importance of both egg and sperm. Yet that'southward not what happened. "Instead," Dolnick tells us, "scientists split up into ii warring camps, ovists and spermists, each dedicated to the proposition that their side was truly vital, while the other was necessary, mayhap, simply distinctly secondary."
This fence dragged on and on. It was not till a spring solar day in 1875 that the answer came. A German scientist named Oscar Hertwig put a sea urchin egg nether his microscope. The distinctively transparent nature of the egg lent itself to this kind of voyeurism, as did the fact that fertilization in bounding main urchins takes identify exterior the body, equally it does in frogs. Dolnick sets the scene: "Hertwig poked a drop of sea urchin semen near the egg. A tiny sperm prison cell pushed confronting the egg's outer surface. Moments later the nucleus of the sperm cell came into view, inside the egg, like a message thrust within a bottle. … Suddenly the two nuclei were in contact, and then — before Hertwig's optics — the two nuclei fused into one. No one in history had ever seen the process of fertilization play out. Until Hertwig. The emergence of a single nucleus where at that place had been two, he wrote, in perchance the only lapse into poetry in his long career, 'arises to completion similar a sun within the egg.'"
As a record of a long biological quest, "The Seeds of Life" is total of detours, but that structure mimics the nature of scientific progress, illustrating how science is promoted or held dorsum by colorful characters, by state and church intrusion or assistance, never lacking for rivalries and power struggles. Fascinating reading, Dolnick's book should evoke in us a sense of humility rather than amusement at the ignorance of the scientists of old. In his acknowledgments, he cites the anthropologist Max Gluckman'due south remark that "the fool of this generation tin get beyond the point reached by the genius of the last generation." Scientific questions about equally fundamental every bit the genesis of the embryo remain to be answered — the black box of the brain is far from unlocked. Future historians will wonder what took u.s.a. so long to detect the answers.
Source: https://www.nytimes.com/2017/06/23/books/review/the-seeds-of-life-edward-dolnick.html
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