Number of words: 242 The clever design of crypts is a direct consequence of how tissues are renewed by stem cells, the “parent cells” in the body. This is particularly important because, given how much material we digest, the lining of the colon is forever being replenished. A few stem cells sit at the base … Read more

Number of words: 875 Cancer starts with the origin of a single cheat: this solitary cell has a dangerous mutation and multiplies to form a small lesion. Now a few thousand cells have this mutation. Nothing might happen for years. Or nothing might ever happen at all. If another mutation allows this ensemble of cheats … Read more

Number of words: 341 Multicellular strings of bacteria were born around 3.5 billion years ago. Filamentous bacteria—so named because they form chains—kill themselves to yield precious nitrogen for the good of their sisters. Every tenth or so cell commits suicide for the benefit of this communal thread of bacterial life. Another, quite different kind of … Read more

Number of words: 555 The extraordinary possibilities of evolution are the result of errors in replication. Mutations are critical. If the replication of RNA were error free, and perfect, no mutants would arise and evolution would stop. Nothing would change. There would be no living diversity. So mutations are required for life to emerge. Equally, … Read more

Number of words: 337 In the traditional picture of the origins of life, the instant the first replicator pops up is a rare and fleeting moment that bootstraps the rest of evolution. This is an enormously lucky event, a fleeting spark that lights the fuse of all life. As in Greek cosmology, from a “vast … Read more

Number of words: 164 Look under the hood, into the cells of the life that thrives around us, and you will find master molecular replicators, the messengers of our inheritance. Today, the most common is deoxyribonucleic acid, DNA. Apart from a few viruses, all life on Earth now relies on DNA to hold the information … Read more

Number of words: 340 Centuries ago, the Scottish botanist Robert Brown became fascinated by the zigzag motion of fragments within pollen grains. In his pioneering observations, made with a primitive microscope, Brown had spotted this random jittery motion as early as 1827. What puzzled him was that this incessant movement did not arise from currents … Read more

Number of words: 441 Legend has it that, one day in a pub in Bloomsbury in 1955, a lively conversation with Haldane over a few pints turned to the serious subject of the lengths that one would go to save another’s life. Would, for example, Haldane risk his life to save a drowning man? Haldane, … Read more

Number of words: 284 Natural selection can act on human culture as well as on genes. Some scholars have scoffed that a scientific theory of cultural evolution that aims to ape Darwinian evolution is impossible because human beliefs and behaviors are so unpredictable and subject to historical contingencies as well as sudden breakthroughs, discoveries, and … Read more

Number of words: 222 The very fact that people decide to live in the same patch, rather than dotted around at random, has to do with cooperation. Why? Some believe, for example, that the first communities evolved as a result of success in agriculture: surplus food from farming enabled people to settle down and specialize, … Read more