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Of the 20,000 to 30,000 genes now thought to be in the human genome, most cells express only a very small part - which makes sense, a liver cell has little need for the DNA code that makes neurons. But as almost all cells carry around a full copy ('distribution') of the genome, a system is needed to #ifdef out stuff…
Anomaly (2) was observed by Fred Griffith, decades before DNA and the genetic code. He found that if you inject a heat-treated, dead, virulent species of bacteria (pneumococcus S) into a rat previously infected with a nonvirulent species (pneumococcus R), then species R became transformed into species S, thereby…
It’s a common misconception that chimp DNA differs from Homo sapiens sapiens genes by only a single percent, but this number is apocryphal. In actuality, the degree of similarity of human and chimp genetic code depends mostly on how you count. Since all complex organisms from Earth possess great swaths of junk DNA…
Piaget concluded that babies aren't just born in possession of adult knowledge, either from a past life or from DNA. Instead, Piaget thought that children must have powerful learning mechanisms that allow them to construct new pictures of the world, pictures that might be very different from the adult picture. When we…
The glib words of years past from our politicians are hollow nightmares indeed when we are confronted with the staggering realities of what has to be done. But the key is there--technology, using it-and we hardly do now. The future may be unpredictable, but we can make a few well-aimed guesses about what life will be…
In one of his most popular essays, "The Colloid and the Crystal," the nature writer Joseph Wood Krutch wrote about these opposing forces in nature. "Order and obedience are the primary characteristics of that which is not alive," he wrote. "Life is rebellious and anarchical." He was wrong to identify obedience and…
Caenorhabditis elegans was chosen in the 1960s as an ideal experimental animal by the formidably brilliant South African biologist Sydney Brenner. He had recently completed his work, with Francis Crick and others at Cambridge, on cracking the genetic code, and was looking around for a new big problem to solve. His…