Tim Ferriss made the assertion in the 4 Hour Body that what should be a benchmark for health is reproductive fitness ("sexyness"). This is tough to measure obje

Tim Ferriss made the assertion in the 4 Hour Body that what should be a benchmark for health is reproductive fitness ("sexyness"). This is tough to measure objectively, but not subjectively. A significant portion of our brain is devoted to processing exactly that (ever notice how you can instantly spot an attractive member of the opposite/preferred sex out of the corner of your eye?). We use similar criteria for household and farm animals ("shiny coat," musculature, posture and signs of coordination and activity). Back when slavery was widespread, slave traders made their choices the same way.