Bell Curve

4 10 Living Together Raising Cognitive Ability 41 1many ostensibly successful projects will be cited as plain and indisputableevidence that we are willfully refusing to see the light.CHANGING THE ENVIRONMENT AT BIRTHThere is one sure way to transform a child's environment beneficially:adoption out of a bad environment into a good one. If adoption occursat birth, it is at least possible that the potential effects of postnatal environmentaldisadvantage could be wiped out alt~gether."~' The specificquestion now is: How many points does being raised in a good adoptivehome add to an IQ score?Children are not put up for adoption for the edification of social theorists.There are no controlled experiments on the effects of adoption.Adoption usually means trouble in the biological family; trc~uble usuallylands on families nonrandomly and unaccountably, making it hardto extract clear, generalizable data. The most famous studies were mostlydone decades ago, when she social and financial incentives for adoptionwere different from today's. Legalized contraception and abortion, too,When Environment Is DecisiveLest anyone doubt that environment matters in the development of intelligence,consider the rare and bizarre cases in which a child is hidden awayin a locked room by a demented adult or breaks free of human contact altogetherand runs wild. From the even rarer cases that are investigated andtold with care and accuracy, we know that if the isolation from human societylasts for years, rather than for just months, the children are intellectuallystunted for life." Such was, for example, the experience of the "WildBoy of Aveyron," discovered in southern France soon after the Revolutionand the establishment of the first French Republic, like an invitation toconfirm Rousseau's vision of the noble savage. The 12- or 13-year-old boyhad been found running naked in the woods, mute, wild, and evidently outof contact with humanity for most of his life. But, as it turned out, neitherhe, nor the others like him that we know about, resemble Rousseau's noblesavage in the least. Most of them never learn to speak properly or tobecome independent adults. They rarely learn to meet even the loweststandards of personal hygiene or conduct. They seem unable to hecomefully human despite heroic efforts to restore them to society. From theserare cases we can draw a hopeful conclusion: If the ordinary human environmentis so essential for bestowing human intelligence, we should beable to create extraordinary environments to raise it further.""have altered the pool of subjects for adoption studies. Both the environmentaland genetic legacies of children put up for adoption havesurely changed over the years, but it is impossible to know exactly inwhat ways and how much. In short, although data are abundant and wewill draw some broad conclusions, this is an area in which solid estimatesare unlikely to be found.As a group, adopted children do not score as high as the biologicalchildren of their adopting parents.'791 The deficit may be as large as sevento ten IQ points. It's not completely clear what this deficit means. Onehypothesis is that the adopted children's genes hold them back; anotheris that there is an intellectually depressing effect of adoption itself, orthat being placed in adopting homes not immediately after birth (as onlysome of them are), but only after several months or years, loses the benefitof the nurturing their adopting parents would have provided earlierin their lives.At the same time, researchers think it very likely that adopted chiledren earn higher scores than they would have had if they been raised bytheir biological parents, because the adopting home environment islikely to be better than the one their biological parents would have provided.If so, this would be a genuine effect of the home environment.How large is the effect? Charles Locurto, reviewing the evidence andstriking an average, concludes that it is about six points.Ro As a consensusfigure, that seems about right to us. However, a consensus figure isnot what we want, as Locurto recognizes. It does not identify how widea gap separates the environments provided by adopting homes and thehomes in which the children would have been reared had they not beenadopted. We seek a comparison of the IQs of children growing up inhomes of a known low socioeconomic status and genetically comparablechildren reared in homes of a known high socioeconomic status.What would the increment in IQ look like then?Two approximations to an ideal adoption study, albeit with very smallsamples, have recently been done in France." In one, Michel Schiff andhis colleagues searched French records for children abandoned in infancy,born to working-class (unskilled) parents, who were adopted intoupper-class homes. Only thirty-two children met the study's criteria. Inchildhood, their average IQ was 107. To understand what this means,two further comparisons are in order. First, the adopted children scoredeight points lower on average than their schoolmates, presumably fromcomparable upper-class homes. This confirms the usual finding with