At Last, Evidence That Humans Are Special
The astronomer Martin Rees recently coined the neat phrase “Copernican demotion” for science’s habit of delivering humiliating disappointment to those who think that our planet is special. Copernicus told us the Earth was not at the center of the solar system; later astronomers found billions of solar systems in each of the billions of galaxies, demoting our home to a cosmic speck.
Mr. Rees says further Copernican demotion may loom ahead. “The entire panorama that astronomers can observe could be a tiny part of the aftermath of ‘our’ big bang, which is itself just one bang among a perhaps-infinite ensemble.” Indeed, even our physics could be a parochial custom: Mr. Rees says that different universes could be governed by different rules and our “laws of nature” may be local bylaws.
Copernican demotion is a habit of biologists, too. Charles Darwin told us we were just another species among millions. In the 1950s, cytologists found we had one fewer pair of chromosomes than gorillas or chimpanzees—hardly good for our self-esteem. Anthropologists reported that apes could make tools, while paleontologists told us that our brains are possibly smaller than those of Neanderthals. Then came the news that, even within our own species, relative brain size had been shrinking, not growing, over the past 10,000 years.
Geneticists were no help either. In the 1960s, they discovered the startling fact that we had one-third as much DNA as grasshoppers and one-tenth as much as salamanders. For a while we stroked our egos by telling ourselves that we must have special genes to build and run our special brains. But it turned out not to be true. When the genome was sequenced at the turn of this century, and the genes counted, it transpired that we have the same number of genes as a mouse. Indeed, give or take a handful, we have the same genes as a mouse, just switched on in a different order and pattern.