The world in each of us
DNA is a dazzling, if dull, language. With only four chemical building blocks — known in short form as A, C, G, and T—repeated over and over in different orders some six billion times, it’s not the sort of story anyone curls up with. But it is the story of you, biologically speaking. Inherited as 23 pairs of chromosomes from your parents, DNA is a compilation of the generations of parents who also came before them. Changes can spring up in DNA each time it’s passed down to the next generation. And for various reasons, certain changes only became common in specific regions of the world. The...
Read MoreThe Genetic Eve: Everybody’s Mum
Most of human history has been told by men, and for the most part, about men. But the world’s genetic history was first assembled by the biological legacy of women. Inside every human cell are hundreds of tiny parcels that only mothers pass down to their children. Known as mitochondria, they were free living bacteria once upon a primordial time. But today, they contain the machinery human cells need to produce their power. They also contain a unique ring of genetic code, well outside the regular genome, that rarely changes. This means people who do share the same mutations in their...
Read MoreY: The Male Chromosome
If size matters, the Y chromosome may be a source of little merriment to men. The male sex chromosome is the smallest in the genome. But proportions aside, it is nothing short of a surprising archive of human history, and the sharpest genetic tool in the genealogy shed. Passed down through the ages from fathers to sons, the Y chromosome is like the genetic signature of a male line. All other chromosomes in the human genome have a matching pair. But in the chromosomal square dance that precedes reproduction, the Y dances alone. This means it has little chance to change or mutate by swapping...
Read MoreMy Dear Michael, we’ve discovered DNA
The Wall Street Journal recently reported that on April 10, 2013, the letter Crick wrote to his son describing the discovery sold at Christie’s for $6 million. It was a record for a letter, eclipsing a record price for an Abraham Lincoln letter that went for $3.4 million in 2008. In a March 19, 1953, handwritten letter to his then-12-year-old son, Francis Crick describes his discovery of the structure of DNA as something “beautiful.” The note tells his son how he and James Watson found the copying mechanism “by which life comes from life.” It includes a simple...
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