“Harcourt engages with the physical differences between human bodies and the cultural and medical implications of them, addressing such topics as why skin tone varies from region to region or the biological basis of why certain populations have evolved to better digest milk, starches, or seaweed. Harcourt reminds readers that biological conceptions of race should not be confused with sociopolitical conceptions of it, and that there are good reasons to understand the how and why of our biological differences.”