Nat Geo: Genes Are Us. And Them
Genes Are Us. And Them
A Human and a grain of rice may not, at first glance, look like cousins. And yet we share a quarter of our genes with that fine plant. The genes we share with rice—or rhinos or reef coral—are among the most striking signs of our common heritage. All animals, plants, and fungi share an ancestor that lived about 1.6 billion years ago. Every lineage that descended from that progenitor retains parts of its original genome, embodying one of evolution’s key principles: If it’s not broke, don’t fix it. Since evolution has conserved so many genes, exploring the genomes of other species can shed light on genes involved in human biology and disease. Even yeast has something to tell us about ourselves.
Of course, we aren’t really much like yeast at all. The genes we still share we use differently, in the same way you can use a clarinet to play the music of Mozart or Benny Goodman. And our catalogs of genes themselves have changed. Genes can disappear, and new ones can arise from mutations in DNA that previously served some other function or no function at all. Other novel genes have been delivered into our genomes by invading viruses. It’s hardly surprising that we share many more genes with chimpanzees than with yeast, because we’ve shared most of our evolutionary journey with those apes. And in the small portion of our genes with no counterpart in chimpanzees, we may be able to find additional clues to what makes us uniquely human.