Vitamins Come from Living Things

Every vitamin is made by living cells — either our own, or in other species. Vitamin D is produced in our skin, for example, when sunlight strikes a precursor of cholesterol. A lemon tree makes vitamin C out of glucose. Making a vitamin is often an enormously baroque process. In some species, it takes 22 different proteins to craft a vitamin B12 molecule. While a protein may be made up of thousands of atoms, a vitamin may be made up of just a few dozen. And yet, despite their small size, v...

 Human Race Differences the Result of Sexual Selection

Most of the genetic differences between races are trivial. And yet others, those physical differences between a Japanese individual and a Finn, a Masai, and an Inuit, are striking. We have the interesting situation, then, that the overall differences in gene sequences between peoples are minor, yet those same groups show dramatic differences in a range of visually apparent traits, such as skin color, hair color, body form, and nose shape. These obvious physical differences are not characteris...