Evolution And History

294 CHAPTER 12 | Modern Human Diversity: Race and Racism

The severe consequences of vitamin D deficiency can

be avoided through cultural practices. Until recently, chil-

dren in northern Europe and northern North America

were regularly fed a spoonful of cod liver oil during the

dark winter months. Today, pasteurized milk is often for-

tified with vitamin D.

Race and Human Evolution

Throughout this chapter we have explored the fallacy of

the biological category of race when applied to the human

species. Generalizations cannot be made about “types”

of humans because no discrete types of humans exist. By

contrast, the paleoanthropological analysis of the fossil

record explored in previous chapters includes defining

specific types of ancestors based on biological and cultural

capacities that go hand in hand.

The increased brain size of Homo habilis noted around

2.5 million years ago supports the notion that these an-

cestors were capable of more complex cultural activities

than australopithecines, including the manufacture of

stone tools. Closer to the present, the same assumptions

do not hold. At some point in our evolutionary history

we became a single, unified global species. Bearing this in

mind, we can frame the modern human origins debate in

the terms of the content of this chapter.

Percentage

frequency

0–5

5–10

10–15

15–20

20–25

25–30

Figure 12.3 The east-west
gradient in the frequency of type B
blood in Europe contrasts with the
north-south gradient in skin color
shown in Figure 12.2. Just as the
clines for skin color and blood type
must be considered independently,
so too must be whatever genes are
involved in the complex of abilities
known as “intelligence.”

Figure 12.4 Bone diseases such as osteomalacia and rickets
caused by vitamin D deficiency can deform the birth canal of
the pelvis to the degree that it can interfere with successful
childbirth. Because sunshine is vital to the body’s production
of vitamin D, this disease was very common in the past among
the poor in northern industrial cities because they had limited
exposure to sunlight. Dietary supplements have reduced
the impact of bone diseases, such as rickets, although they
continue to be a problem in cultures that require women and
girls to dress so that they are completely veiled from the sun.

production of vitamin D, which is essential for healthy
bones and for balance within the central nervous system.
Without sufficient vitamin D, bone growth in children is
impaired, resulting in misshapen, fragile bones, a con-
dition known as rickets (Figure 12.4). There is an adult
form of bone disease resulting from vitamin D deficiency
as well. Dark pigmentation can interfere with vitamin D
synthesis and with calcium^ balance when there is limited
natural light.