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Careful imitation could also explain why hand axes managed to stay so similar to each other for over a million years. If Homo erectus simply looked over old hand axes to guess how to make them, they would have accidentally introduced little variations to their craft. Over a few thousand years, those mismatches would have caused the hand ax to drift far away from its original shape.
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Carl Zimmer |
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Goddard died at age ninety. In their obituary, the Associated Press remembered him for two accomplishments: coining the word moron and discovering the Kallikaks.
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Carl Zimmer |
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Montaigne was a French courtier who retired from political life in 1571 to sit in a castle tower and reflect on vanity and happiness, on liars and friendship. While he found comfort in this solitude, pain intruded on his contemplation from time to time, thanks to his kidney stones. One day, Montaigne transformed the stones into grist for an essay. "It is likely I inherited the gravel from my father," Montaigne guessed, "for he died sadly af..
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Carl Zimmer |
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A child's humors might be able to weaken that impression. Or a healthy parent's seed could sometimes counter a diseased one. The defect still lurked in the child, who could then pass it down to its own children. If they didn't inherit a countervailing seed from their other parents, the disease could flare up out of hiding. Some hereditary diseases could be treated, Mercado argued, but only slowly and incompletely. "Let us in some secluded s..
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Carl Zimmer |
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eugenicists made a mess of traits like intelligence. They were obsessed with splitting people into two categories--healthy and feebleminded--and then they would cast the feebleminded as a "class of vast and dangerous dimensions." Penrose saw intelligence as a far more complex trait. He likened intelligence to height: In every population, most people were close to average height, but some people were taller and shorter than average. Just bei..
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Carl Zimmer |
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In the early 1900s, a Florida farmer found a notable bud sport while inspecting his grove of Walters grapefruit trees. Tree after tree bore white fruit, except one. On that tree, the farmer spotted a branch weighed down with pink fruits. From that single bud sport, all pink grapefruits descend.
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Carl Zimmer |
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One reason that cells break down bone is that in old age they make less of a protein called TERT. In 2012, researchers at the Spanish National Cancer Research Centre coaxed old mice to make extra TERT by giving them an extra copy of the gene. Their osteoporosis reversed, and their bones strengthened. It's conceivable that doctors could use CRISPR gene therapy to treat people as well. CRISPR molecules would home in on the TERT gene in bone c..
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Carl Zimmer |
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The strange stripes on apples--known as twin spotting--might occur because a cell had two copies of a gene for color. One copy might be a light variant, the other dark. When the cell divided, it accidentally bequeathed two dark variants to one daughter cell, and two light ones to the other. When those cells multiplied, their daughters would inherit those new combinations. And since they grew next to each other, the result would be dark and ..
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Carl Zimmer |
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In 2011, a seventeen-year-old Israeli girl named Chen Aida Ayash was killed in a car accident. After her death, her parents asked for doctors to collect some eggs from her cadaver. They had to go to court to get permission, explaining to a judge that they wanted to fertilize Chen's eggs, after which Chen's aunt would bear them to term. After her own death, Chen would give her parents grandchildren.
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Carl Zimmer |
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In 1814 the breeders founded an organization, the title of which was--deep breath--"The Association of Friends, Experts and Supporters of Sheep Breeding for the achievement of a more rapid and more thoroughgoing advancement of this branch of the economy and the manufacturing and commercial aspects of the wool industry that is based upon it." Those who didn't want to lose too much oxygen uttering the full name simply called it the Sheep Bree..
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Carl Zimmer |
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A virus does not reproduce by copying its own genes and dividing in two. Instead, it invades a host cell.
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Carl Zimmer |
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We humans have 23 pairs, but pea plants have only 7. Yeast have 16. Some butterflies have 134.
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Carl Zimmer |
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Chromosomes were chemical mixtures, including proteins as well as a mysterious molecule called deoxyribonucleic acid, or DNA for short.
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Carl Zimmer |
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Goddard seemed comfortable with the notion that 40 percent of immigrants were morons. "It is admitted on all sides that we are getting now the poorest of each race,"
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Carl Zimmer |
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Each gene is a stretch of DNA, made up of thousands of bases.
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Carl Zimmer |
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A, C, G, T for short. A cell carries out a series of chemical reactions to translate a gene's sequence of bases into a protein. A cell first makes a copy of the gene, creating a single-stranded series of bases called ribonucleic acid, or RNA. That RNA molecule is taken up by a molecular factory called a ribosome, which reads the sequence of RNA and builds a corresponding protein.
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Carl Zimmer |
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single base may change from A to C. A stretch of a hundred bases may be accidentally copied out twice. A thousand bases may be cut out altogether. These are the mutations that scientists like Hugo de Vries and Thomas Hunt Morgan spent years trying to figure out. Mutations can produce new versions of genes--alleles, as they came to be known.
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Carl Zimmer |
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In fact, there's no single species of bacteria that we humans all share. We house personalized zoos.
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Carl Zimmer |
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The idea of a pure race is not even a legitimate abstraction," Dobzhansky wrote. "It is a subterfuge to cloak one's ignorance."
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Carl Zimmer |
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It is true that humans have physical differences, and some of those differences are spread geographically across the plant. But clinging to old notions about race won't help us understand the nature of those differences--both the ones we can see and the ones we can't.
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western-society
heredity
race
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Carl Zimmer |
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b8bd2e4
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When Nature Neuroscience published Dias's study on memories of smells, they put a picture of Lamarck on the cover, complete with a thatch of gray hair and a high cravat. New
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Carl Zimmer |
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If heredity is a kind of memory, methylation suffers radical amnesia in every generation.
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Carl Zimmer |
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history of heredity
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Carl Zimmer |
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The concept of genes driving people's appetite caused them to lose some control of their own.
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Carl Zimmer |
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Today's Europeans are fairly uniform, genetically speaking. But that uniformity came out of a biological blender.
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Carl Zimmer |
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Skinner and his colleagues launched a new study to see how far this effect could get passed down. They exposed more female rats to vinclozolin and then bred descendants for several generations. Even after four generations, they found, males kept on developing damaged sperm. Exposures to other chemicals, like DEET and jet fuel, could also alter the rats for generations.
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Carl Zimmer |
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Traveling across Australia, Asia, and Africa, he searched for people with little contact with the West who he could examine. Porteus found that the so-called Bushmen of the Kalahari scored a mental age of seven. Yet his subjects were navigating their way through Porteus's printed mazes in the middle of a vast desert that they could navigate without a map, finding all the food and shelter they required.
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Carl Zimmer |
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After a few years of breeding a type of lily, Burbank found a single specimen that met his standards. A rabbit ate it.
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science
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Carl Zimmer |
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When a cell divides, it needs another army of molecules to make a second copy of its DNA.
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Carl Zimmer |
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We have a working majority of voters who have children's minds,
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Carl Zimmer |
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When Adolf Hitler was imprisoned in 1924, he learned of the Kallikaks in a book he read about heredity. Soon after, Hitler wrote Mein Kampf, in which he mimicked the language of American eugenicists, declaring that sterilization of defective people "is the most humane act of mankind."
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Carl Zimmer |
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When he bred them, he would discover variations among their offspring.
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Carl Zimmer |
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Something must happen to 'stir up their heredities,' as I am fond of saying--to excite in them the variability that normally lies dormant," Burbank later explained"
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Carl Zimmer |
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Burbank might produce thousands of hybrid offspring from which he might pick just a few to propagate into a new generation.
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Carl Zimmer |