Briefly describe the ideas on racial classification of Carolus Linnaeus, Johann Friedrich Blumenbach, William Boyd, and Carlton S. Coon

Briefly describe the ideas on racial classification of Carolus Linnaeus, Johann Friedrich Blumenbach, William Boyd, and Carlton S. Coon. Many people classify “races” on the basis of a single criterion, such as skin color. What are the inherent dangers of using only one or a few criteria to classify human populations?