Chapter 9 described in some detail the major studies investigating genetic contributions to intelligence. In this chapter, we will look at studies investigating the environmental influences on intelligence. We’ll start by looking at the relationship between environment and IQ scores and a brief reconsideration of the most prominent IQ tests, the WISC (Wechsler Intelligence Scale for Children), the WAIS (Wechsler Adult Intelligence Scale), and the Stanford–Binet. Are these measures of IQ true measures of intelligence? The answer is no, but nevertheless we believe that IQ measures skills significant in advanced Western societies like the United States and Great Britain. After exploring this subject, we will explore in some depth how the environment has altered our cognitive abilities over the last 150 years; how it affects the individual competing with other individuals at a given time and place; how it allows for human autonomy; and facets of the environment that lurk in the background and have a deleterious effect on our brains (such as exposure to toxins, lead, and certain illnesses).