A lot has been written, and more is sure to be put forth, about the balance of nature and nurture in intelligence and 'raising' IQs. This includes articles about the variability of IQ through the teen years (http://www.wellcome.ac.uk/News/Media-office/Press-releases/2011/WTVM053199.htm
) and observations such as:
"It's analogous to fitness.A teenager who is athletically fit at 14 could be less fit at 18 if they stopped exercising. Conversely, an unfit teenager can become much fitter with exercise."
A fair amount of fuss has been made of this information, prompting stories such as USA Today's http://yourlife.usatoday.com/health/medical/mentalhealth/story/2011-12-27/IQ-isnt-fixed-at-birth-and-can-increase-with-education/52237552/1
- IQ Isn't Fixed at Birth
But when was the last time we thought IQ was fixed at birth?
"The predominant view is that the genetic factors place an absolute ceiling on an individual's intelligence potential, and he may or may not reach this potential, depending on how enriched or deprived his environment is.
"There are many instances in which a young child's IQ increases with an improvement in environment. Skeels (1966) conducted a study in which he took very young girls (under 19.3 months) from an orphanage in which the environment was seriously depressed and placed them in an institution for the mentally retarded. Their IQ's improved from a mean of 65 for the group to a mean of 91.8 during an 18 month period. ... Another group of 12 little girls stayed in the orphanage;their mean IQ dropped from 86.7 to 60.5 in two years."
~Max Vogel (1980), The Psychology Problem Solver: A Complete Solution Guide to Any Textbook
Of course, there are those who would be skeptical of whether the change would last. But what Vogel's quote neglects to mention is that it wasn't Skeels doing this in 1966 - it was Skeels & Dye, in 1939 (A study of the effects of differential stimulation on mentally retarded children - findable in The Best of AAMR - Families and Mental Retardation
, p. 19-33).
Twenty-five years later, Skeels (1966) located all of the subjects in the original study. What he discovered was even more impressive than the IQ gains originally reported. Of the 13 children in the experimental group, 11 had married; the marriages had produced nine children, all of normal intelligence. The experimental group’s median level of education was the 12th grade, and four had attended college. All were either homemakers or employed outside the home, in jobs ranging from professional and business work to domestic service (for the two who had not been adopted). The story of the 12 children who had remained in the orphanage was less positive. Four were still institutionalized in 1965, and all but one of the noninstitutionalized subjects who were employed worked as unskilled laborers. The median level of education for the contrast group was the third grade.
~"William L. Heward (2000), Exceptional Children: An Introduction to Special Education (6th ed.), p. 159
While this is among the oldest of these looks, the chain of evidence is long and ongoing. We know well that we can depress intelligence and that we can stimulate intelligence. We know that performance on IQ tests is not fixed at birth, even without little subtleties like mood, relationship with tester, color of skin, etc.
But here we are, 70 years later, being astounded that "IQ is not fixed at birth."
What Skeels and Dye learned in 1939 was important. Rosemary Salz (Effects of Part-Time "Mothering" on IQ and SQ of Young Institutionalized Children, 1973) took it further - showing that even in an institutional setting with a decent educational program, active nurturing had an impact on children's IQs. One place implemented a foster-grandmother program, hiring impoverished elder women to come in and give one-to-one attention. The other didn't. You know which group showed growth in their IQs.
Education matters. Emotions matter. Physical health matters. Safety matters.
The absence of these matters.
In Nature vs. Anti-Nurture, Anti-Nurture wins far more often than not.
It may be up to Skeels (1966) to close this for us again:
"It seems obvious that under present-day conditions there are still countless infants with sound biological constitutions and potentialities for development well within the normal range who will become retarded and noncontributing members of society unless appropriate intervention occurs. It is suggested by the findings of this study and others published in the past 20 years that sufficient knowledge is available to design programs of intervention to counteract the devastating effects of poverty, sociocultural, and maternal deprivation.... The unanswered questions of this study could form the basis for many lifelong research projects. If the tragic fate of the twelve contrast group children provokes even a single crucial study that will help prevent such a fate for others, their lives will not have been in vain."