IQ of biracial children and adults

First snow in Minnesota (c. 1895), Robert Koehler. Biracial children have IQ scores halfway between those of white children and black children, even when they are conceived by white single mothers and adopted into middle-class white families in their first year of life.

You may have heard about the Minnesota Transracial Adoption Study. It was a longitudinal study of black, biracial, and white children adopted into white middle-class Minnesotan families, as well as the biological children of the same families (Levin, 1994; Lynn, 1994; Scarr and Weinberg, 1976; Weinberg, Scarr, and Waldman, 1992). IQ was measured when the adopted children were on average 7 years old and the biological children on average 10 years old. They were tested again ten years later. Between the two tests, all four groups declined in mean IQ. On both tests, however, the differences among the four groups remained unchanged, particularly the 15-point gap between black and white adoptees. 

The biracial children remained halfway between the black and white adoptees. Could this be due to the parental environment being likewise half and half? Well, no. All of them were raised by white parents, and they were adopted at an early age: 19 months on average for the white adoptees, 9 months for the biracial adoptees, and 32 months for the black adoptees. The last figure is emphasized by Scarr and Weinberg (1976) as a reason for the IQ gap between the black and white adoptees. 

Fine, but what about the IQ gap between the biracial and white adoptees? Almost all of the biracial children were adopted at a young age and born to white single mothers who had completed high school. From conception to adulthood they developed in a "white" environment. If anything, the white adoptees should have encountered more developmental problems because they were adopted at an older age.

Could color prejudice be a reason? Perhaps the biracial children were unconsciously treated worse than the white children. By the same reasoning, they may have been treated better than the black children. We can test the second half of this hypothesis. Twelve of the biracial children were wrongly thought by their adoptive parents to have two black parents. Nonetheless, they scored on average at the same level as the biracial children correctly classified by their adoptive parents (Scarr and Weinberg 1976).

The Eyferth study

Another study found no difference in IQ between white and biracial children. This was a study of children fathered by American soldiers in Germany and then raised by German mothers (Eyferth 1961). It found no significant difference in IQ between children with white fathers and children with black fathers. Both groups had a mean IQ of about 97.

These findings were criticized by Rushton and Jensen (2005) on three grounds:

1. The children were still young when tested. One third were between 5 and 10 years old and two thirds between 10 and 13. Since IQ is strongly influenced by family environment before puberty, a much larger sample would be needed to find a significant difference between the two groups.

2. Between 20 and 25% of the “black” fathers were actually North African.

3. At the time of the study, the US Army screened out low IQ applicants with its preinduction Army General Classification Test. The rejection rate was about 30% for African Americans and 3% for European Americans. African American soldiers are thus a biased sample of the African American population.

Another factor is that the capacity for intelligence seems to be more malleable in children than in adults. We see this with the Minnesota Transracial Adoption Study. In the enriched learning environment of middle-class Minnesota families, all of the children showed impressive IQ scores at 7 years of age. By 17 years of age, however, this benefit had largely washed out:

-------------------- Age 7 Age 17

Black children ----- 97 ----- 89

Biracial children - 109 ----- 99

White children --- 112 ---- 106

Does intelligence really decline with age because of wear and tear on the brain? Perhaps we’re programmed to be most intelligent in childhood. That’s when we have to familiarize ourselves with the world. The capacity for intelligence may then be gradually deactivated as we get older because it’s less necessary.

This deactivation may follow different trajectories in different human groups. In early Homo sapiens, it may have begun not long after puberty. As ancestral humans made the transition to farming, sedentary living, and increasingly complex societies, this learning capacity became more necessary in adulthood, with the result that natural selection favored those individuals who retained it at older ages. This gene-culture coevolution would have gone farther in some populations than in others.

The Fuerst et al study

A recent study led by John Fuerst has confirmed the intermediate IQ of biracial individuals, this time in adults. The research team used the General Social Survey, which includes not only ethnic, sociological, and demographic data but also a measure of intelligence (WordSum):

The relationship between biracial status, color, and crystallized intelligence was examined in a nationally representative sample of adult Black and White Americans. First, it was found that self-identifying biracial individuals, who were found to be intermediate in color and in self-reported ancestry, had intermediate levels of crystallized intelligence relative to self-identifying White (mostly European ancestry) and Black (mostly sub-Saharan African ancestry) Americans. The results were transformed to an IQ scale: White (M = 100.00, N = 7569), primarily White-biracial (M = 96.07, N = 43, primarily Black-biracial (M = 94.14 N = 50), and Black (M = 89.81, N = 1381).

The same study also found a significant negative correlation among African Americans between facial color and WordSum scores. The correlation was low (r = -0.102), but it would be difficult to get a higher correlation because of the measures used. Self-reported skin color correlates imperfectly with actual skin color, which in turn correlates imperfectly with European admixture. Wordsum likewise correlates imperfectly with IQ (r = 0.71). On a final note, the correlation between facial color and WordSum scores was not explained by region of residence, interviewer’s race, parental socioeconomic status, or individual educational attainment.

References

Eyferth, K. (1961). Leistungen verscheidener Gruppen von Besatzungskindern in Hamburg-Wechsler Intelligenztest für Kinder (HAWIK). Archiv für die gesamte Psychologie 113: 222-241.

Fuerst, J.G.R., R. Lynn, and E.O.W. Kirkegaard. (2019). The Effect of Biracial Status and Color on Crystallized Intelligence in the U.S.-Born African-European American Population. Psych 1(1): 44-54. https://dx.doi.org/10.3390/Psychology1010004

Levin, M. (1994). Comment on the Minnesota transracial adoption study. Intelligence 19: 13-20.

http://www.sciencedirect.com/science/article/pii/0160289694900493   

Lynn, R. (1994). Some reinterpretations of the Minnesota Transracial Adoption Study. Intelligence 19: 21-27.

http://www.sciencedirect.com/science/article/pii/0160289694900507   

Rushton, P. and A.R. Jensen. (2005). Thirty years of research on race differences in cognitive ability. Psychology, Public Policy, and Law 11: 235-294.

https://isgp-studies.com/miscellaneous/race-and-iq/2005-APA-Rushton-Jensen-Thirty-Years-of-Research-on-Race-Differences-in-Cognitive-Ability.pdf

Scarr, S., and Weinberg, R.A. (1976). IQ test performance of Black children adopted by White families. American Psychologist 31: 726-739.

http://www.kjplanet.com/amp-31-10-726.pdf   

Weinberg, R.A., Scarr, S., and Waldman, I.D. (1992). The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence. Intelligence 16: 117-135.

http://www.sciencedirect.com/science/article/pii/016028969290028P    

Small effects at many genes, but are the effects non-additive?

 

Allele dominance (source). A single copy of a dominant allele is as effective as two copies of a recessive allele. The current thinking is that intellectual capacity has increased in humans through new alleles that cause small positive effects at a large number of gene loci. It now seems that some of these new alleles display non-additive effects.

 

How has intellectual capacity increased in the course of human evolution? The current thinking is that natural selection has favored new alleles that cause small positive effects at a large number of gene loci. Over the human genome, these little effects have added up to produce a large effect that distinguishes us from our predecessors.

But are these effects simply additive? Many alleles are dominant, i.e., a single copy has the same effect as two copies. Many alleles also interact with alleles at other gene loci. It would be strange if none of the many gene loci involved in intellectual capacity showed no dominance or interaction. This point was made over a decade ago:

The search for genes associated with variation in IQ will be made more difficult, to the extent that genetic effects on IQ are not additive. We used earlier the illustrative possibility that IQ was affected by 25 genes, each with an equal, additive effect (paragraph 7.15). But some genetic effects, dominance and epistasis, are not additive.

[...] For example, it might be the case that allele 5 of the IGF2R gene is associated with high IQ only if it is accompanied by particular alleles at other loci. In their absence, it is accompanied by normal or even low IQ. If that were true, it would clearly be difficult to detect, and replicate, substantial effects.

[...] Is the genetic variance underlying variation in IQ mostly additive? We noted in Chapter 4 that much research in behavioural genetics assumes this to be the case. But two relatively sophisticated attempts to model IQ variation, while both concluding that the overall broadsense heritability of IQ is about 0.50, also argue that additive genetic variance accounted for no more than about 30% of the overall variation in IQ, while non-additive effects accounted for some 20%. (Nuffield Council on Bioethics, 2002)

Yet many researchers still argue for a simple additive model. Davies et al. (2011) estimated additive genetic variance at 40-51%. As some of the same authors later pointed out, however, the methodology of that study (genome-wide complex trait analysis) ignores non-additive effects: "GCTA estimates additive genetic influence only, so that non-additive effects (gene–gene and gene-environment interaction) are not captured either" (Trzaskowski et al., 2013).

 

Differences among human populations

Davide Piffer (2013) has studied geographic variation in alleles that influence intellectual capacity. He began with seven genes (SNPs) whose different alleles are associated with differences in performance on PISA or IQ tests. Then, for fifty human populations, he looked up the prevalence of each allele that seems to increase performance. Finally, for each population, he calculated the average prevalence of these alleles at all seven genes.

The average prevalence was 39% among East Asians, 36% among Europeans, 32% among Amerindians, 24% among Melanesians and Papuan-New Guineans, and 16% among sub-Saharan Africans. The lowest scores were among San Bushmen (6%) and Mbuti Pygmies (5%). A related finding is that all but one of the alleles seem to be specific to humans and not shared with ancestral primates.

Davide Piffer has now used these geographic differences in allele frequencies to estimate the corresponding geographic differences in “genotypic IQ”, i.e., the genetic component of intellectual capacity:

I had already estimated the African genotypic IQ from my principal component scores extracted from allele frequencies (Piffer, 2013) for different populations. If we take the factor score of people living in equal environmental conditions (Europeans and Japanese), we can figure out how many IQ points each unit score corresponds to. The factor score of Europeans is 0, that of the Japanese is 1.23. The average IQ of Europeans is 99 and that of the Japanese is 105. Thus, 6 IQ points equal a difference of 1.23 factor scores. The factor score of sub-Saharan Africans is -1.73, which is 1.41 times greater than the difference between Europeans and East Asians. Thus, the genotypic IQ difference between Africans and Europeans must be 6*1.41= 8.46. Thus the real African genotypic IQ is 99-8.46= 90.54 (source)

This estimate of 91 seems to contradict the IQ literature, although there is still disagreement over the mean IQ of sub-Saharan Africans. In their review of the literature, Wicherts et al. (2010) argue for a mean of 82, whereas Lynn (2010) puts it at 66. Rindermann (2013) favors a “best guess” of 75. There is some fudging in all of these estimates, since no one really knows how much adjustment should be made for the Flynn Effect. Indeed, what is the potential for IQ gains in societies that are still becoming familiar not only with test taking but also with the entire paradigm of giving standardized answers to standardized questions?

We are on firmer ground when estimating the mean IQ of African Americans, which seems to be around 85, i.e., 15 points below the Euro-American mean. We can argue back and forth over the cause, but the same gap comes up time and again, even when black and white children are adopted into the same home environment. This was the finding of the Minnesota Transracial Adoption Study: a longitudinal study of black, biracial, and white children adopted into white middle-class Minnesotan families, as well as the biological children of the same families (Levin, 1994; Lynn, 1994; Scarr and Weinberg, 1976; Weinberg, Scarr, and Waldman, 1992). IQ was measured when the adopted children were on average 7 years old and the biological children on average 10 years old. They were tested again ten years later. Between the two tests, all four groups declined in mean IQ. On both tests, however, the differences among the four groups remained unchanged, particularly the 15-point gap between blacks and whites. Whatever the cause, it must happen very early in life. Could it be in the womb? We would then have to explain the consistently halfway scores of the biracial children, who were born overwhelmingly to white mothers.

In any case, whether we accept the African American mean of 85 (which is influenced by some admixture with other groups) or the upper estimate of 82 for sub-Saharan Africans, we are still well below the “genotypic” estimate of 91.  Is this an indication of non-additive effects? Do some of the intelligence-boosting alleles display partial dominance? Do some of them interact with other such alleles?

 

References

Davies, G., A. Tenesa, A. Payton, J. Yang, S.E. Harris, D. Liewald, X. Ke., et al. (2011). Genome-wide association studies establish that human intelligence is highly heritable and polygenic, Molecular Psychiatry, 16, 996–1005.

http://www.nature.com/mp/journal/v16/n10/abs/mp201185a.html  

Levin, M. (1994). Comment on the Minnesota transracial adoption study, Intelligence, 19, 13-20.

http://www.sciencedirect.com/science/article/pii/0160289694900493  

Lynn, R. (1994). Some reinterpretations of the Minnesota Transracial Adoption Study, Intelligence, 19, 21-27.

http://www.sciencedirect.com/science/article/pii/0160289694900507  

Lynn, R. (2010). The average IQ of sub-Saharan Africans assessed by the Progressive Matrices: A reply to Wicherts, Dolan, Carlson & van der Maas, Learning and Individual Differences, 20, 152-154.

http://www.sciencedirect.com/science/article/pii/S1041608010000348  

Nuffield Council on Bioethics. (2002). Genetics and human behaviour: The ethical context. London

http://www.nuffieldbioethics.org/sites/default/files/files/Genetics%20and%20behaviour%20Chapter%207%20-%20Review%20of%20the%20evidence%20intelligence.pdf  

Piffer, D. (2013). Factor analysis of population allele frequencies as a simple, novel method of detecting signals of recent polygenic selection: The example of educational attainment and IQ, Interdisciplinary Bio Central, provisional manuscript

http://www.ibc7.org/article/journal_v.php?sid=312  

Rindermann, H. (2013). African cognitive ability: Research, results, divergences and recommendations, Personality and Individual Differences, 55, 229-233.

http://www.sciencedirect.com/science/article/pii/S0191886912003741  

Scarr, S., and Weinberg, R.A. (1976). IQ test performance of Black children adopted by White families, American Psychologist, 31, 726-739.

http://www.kjplanet.com/amp-31-10-726.pdf   

Trzaskowski, M., O.S.P. Davis, J.C. DeFries, J. Yang,  P.M. Visscher, and R. Plomin. (2013). DNA Evidence for strong genome-wide pleiotropy of cognitive and learning abilities, Behavior Genetics, 43(4), 267–273.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3690183/  

Weinberg, R.A., Scarr, S., and Waldman, I.D. (1992). The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence, Intelligence, 16, 117-135.

http://www.sciencedirect.com/science/article/pii/016028969290028P  

Wicherts, J.M., C.V. Dolan, and H.L.J. van der Maas. (2010). A systematic literature review of the average IQ of sub-Saharan Africans, Intelligence, 38, 1-20.

http://mathsci.free.fr/survey.pdf

Does Nyborg's study make sense?

 

Immigrants to Denmark come largely from the Muslim world, where fertility rates are converging to the European norm. In the future, most immigrants will come from sub-Saharan Africa, where the fertility decline has stalled and has actually reversed in some countries. (source)

 

My last post dealt with Helmuth Nyborg’s study and the decision by the Danish Committee for Scientific Dishonesty to have it deleted from the scientific literature. Please note: this is not about barring a study from publication. That happens all the time. This is about removing a study that has already been published.

Let me now turn to the study itself. What do I think? Does it make sense?

First, I seldom see a paper I fully agree with. Something usually seems wrong. Often, the authors overstate their case, out of enthusiasm or fear of being ignored. This is normal, and the only way to learn the whole truth is to encourage others to speak up and provide their views.

But, yes, Nyborg’s study does make sense, if only because his population projection holds true regardless of how imperfect his data may be. The result is overdetermined. If a population opens up its territory to immigration while having below-replacement fertility, it will eventually become a minority within its own borders. The actual timeline may be unsure. Things may happen slower or faster than predicted. But the end result is a sure thing.

Of course, immigration might stop. And Danish fertility might return to replacement level. But such an eventuality will not happen unassisted. It will come about through deliberate changes to public policy. And that will happen only through free debate—the very thing that Nyborg’s critics apparently wish to prevent.

So please let me state what I think, at the risk of being likewise erased from the scientific literature. 

Nyborg’s model: fertility rates and birth rates

Clearly, Danes are below the replacement level of 2.1 children per woman (the figure was 1.73 in 2012). And since their mean age is rising, their birth rate is falling despite a constant fertility rate. Fewer and fewer Danish women are of childbearing age.

Meanwhile, immigrants to Denmark have a rising birth rate because they increasingly come from high-fertility societies in the Muslim world and sub-Saharan Africa. Nyborg thus argues that their natural increase will eventually overtake immigration as the main impetus for Denmark’s population growth: “Whereas 72% of growth in 2010 was due to new immigration, by 2072 more than three quarters of further growth will be driven by the higher fertility of non-Western immigrants” (Nyborg, 2011).

Nyborg’s model assumes that the immigrant birth rate will remain high. Yet this is already less and less true, as shown by a Statistics Denmark study in 2010:

The fertility rate has fallen among immigrants of non-Western background and is now flush with the fertility rate among women of Danish background. [...] For many years, immigrants born in non-Western countries had far more children than women of Danish origin. In 1993 immigrants born in non-Western countries had 3.4 children on average, while Danish women gave birth to 1.7 children on average. The fertility rates have since converged, and in 2009 both immigrants from non-Western countries and Danish women gave birth on average to 1.9 children, according to figures from Statistics Denmark. (Nielsen, 2010)

While this convergence may reflect assimilation to Danish cultural norms, we should remember that fertility has sharply declined throughout most of the Muslim world, which is Denmark’s leading source of non-Western immigrants.

Of course, despite this convergence of fertility rates, the birth rate will still be higher among women of non-Western origin because they are younger on average. And, unless the immigration tap is turned off, they will be continually joined by immigrant women who are drawn disproportionately from the childbearing age bracket. Nonetheless, even if immigration continues unabated, this factor will lose importance as the community of non-Western origin grows larger and larger. Over time, the birth rates of both communities should converge, just as their fertility rates have already converged. This point was actually made by Nyborg’s critics. So his model may be too pessimistic.

Or maybe not. Although Nyborg’s model took into account the current shift toward non-Western sources of immigration, it did not allow for the likelihood that non-Western immigrants will increasingly come from sub-Saharan Africa. While fertility rates have fallen sharply throughout most of the Muslim world, there has been little or no decline in most of sub-Saharan Africa (see previous post). In some countries, like Somalia, fertility rates are actually rising. This trend has been noted in the latest UN population projections:

In the new revision, the estimated total fertility rate (TFR) for 2005-2010 has increased in several countries, including by more than 5 per cent in 15 high-fertility countries from sub-Saharan Africa. In some cases, the actual level of fertility appears to have risen in recent years; in other cases, the previous estimate was too low. (United Stations, 2013, p. 2) 

[…] Between 2013 and 2100, the populations of 35 countries, most of them LDCs, could triple or more. Among them, the populations of Burundi, Malawi, Mali, Niger, Nigeria, Somalia, Uganda, United Republic of Tanzania and Zambia are projected to increase at least five-fold by 2100. (United Nations, 2013, p. 5)

In any case, Nyborg’s predictions will come true even if the immigrant birth rate converges to the Danish norm. The immigrant community will expand through immigration alone. And the ethnic Danish community will shrink once its deaths begin to outnumber its births. One group will replace the other.

Nyborg’s model and IQ

Human populations differ statistically in mean IQ. We can argue why this is so. Genetics? Poor upbringing? Racism? Whatever the reason, these differences exist. The only real debate is whether they will persist over time or gradually disappear as the immigrant community assimilates and becomes increasingly Danish-born. Some observers see this problem as a generational one. The older immigrants may be too set in their ways, but their children should turn out all right.

Intelligence does seem to be more malleable in children than in adults. If one intervenes early enough, differences in cognitive ability should therefore be erased, and these equal outcomes should persist into adulthood. This was the thinking behind the Head Start Program, which provides American 3 and 4 year-olds from disadvantaged backgrounds with early educational training. Unfortunately, even its proponents have concluded that the IQ benefits fade away and are usually gone by Grade 2. Longer-term benefits tend to be non-IQ-related, such as a greater willingness to stay in school and comply with the school regimen. Moreover, all of these improvements tend to be larger and longer-lasting in white children than in black children, even when the white children are initially more disadvantaged (Wikipedia 2013).

Do these different outcomes reflect the different family and community environments of white and black children? This is the currently favored explanation: no matter how poor a white child may be, he or she benefits from a society that allocates fewer resources to black families and black communities. The IQ gap will thus disappear only when white and black children share the same resources.

The most radical solution would be to raise black and white children together in the same households. Yet even that kind of environment fails to eliminate the IQ gap. This was the finding of the Minnesota Transracial Adoption Study —a longitudinal study of black, biracial, and white children adopted into white middle-class Minnesotan families, as well as the biological children of the same families (Levin, 1994; Lynn, 1994; Scarr and Weinberg, 1976; Weinberg,Scarr, and Waldman, 1992). IQ was measured when the adopted children were on average 7 years old and the biological children on average 10 years old. They were tested again ten years later:

Test ------------------ 1^st --- 2^nd 

Black children ----- 97 ---  89

Biracial children - 109 ---  99
White children --- 112 --- 106 (adopted)
White children --- 117 --- 109 (biological)

Between the two tests, all four groups showed a decline in mean IQ that may or may not have been due to changes in testing and norms. On both tests, however, the differences among the four groups remained unchanged, particularly the 15-point IQ gap between blacks and whites that comes up in one study after another. Whatever it is that causes this gap, it must happen very early in life. In the womb? But how do we explain the poorer showing of the biracial children? They were born overwhelmingly to white mothers.

In sum, early intervention does help, but it helps all children equally. And this benefit seems to fade away in all children as time goes by.

Perhaps there is another explanation. Perhaps, in early humans, learning was just a means of encoding information while a young child is becoming familiar with the world. Once this critical period was over, the brain no longer had to be so malleable and lost its plasticity.  This developmental trajectory then began to take place more slowly in some human populations than in others. Why not? Different populations have to cope with different physical and cultural environments, and some of those environments require more lifelong learning than others. This adult retention of mental plasticity may be analogous to adult retention of lactase (the enzyme that infants use to digest milk) in those populations that have domesticated cattle.

Yes, this is just theorizing. Nothing has been proven. But isn’t the burden of proof on those who seek irrevocable change? In any case, whatever the cause, this IQ gap seems almost intractable. If it cannot even be narrowed in the shared environment of a nice Minnesotan household, how are you going to eliminate it in a country where a native European population has so little in common—culturally, linguistically, and ideologically—with an increasingly African immigrant community?

Closing thoughts

One other thing bothers me. So please let me say it.

Why must the Danes prove that they deserve to keep their country to themselves? Isn’t that a basic right? They have only one land to call home … unlike the many “refugees” who regularly visit their own homelands. Once the Danes lose majority status in their country, they’ll be like the Copts of Egypt and other minorities in this world. They’ll have to live by their wits, trying to balance off one potential enemy against another. 

I wouldn’t wish that fate on anyone, let alone on the Danes.

References 

Levin, M. (1994). Comment on the Minnesota transracial adoption study, Intelligence, 19, 13-20.

http://www.sciencedirect.com/science/article/pii/0160289694900493 

Lynn, R. (1994). Some reinterpretations of the Minnesota Transracial Adoption Study, Intelligence, 19, 21-27.

http://www.sciencedirect.com/science/article/pii/0160289694900507 

Nielsen, J.B. (2010). Indvandrerkvinder og danske kvinder føder lige mange børn, July 27, Kristeligt Dagblad.

http://www.kristeligt-dagblad.dk/artikel/374994:Danmark--Indvandrerkvinder-og-danske-kvinder-foeder-lige-mange-boern 

Nyborg, H. (2011). The decay of Western civilization: Double relaxed Darwinian Selection. Personality and Individual Differences, 53, 118-125.

http://emilkirkegaard.dk/da/wp-content/uploads/Helmuth-nyborg-2011-the-decay-of-western-civilization-double-relaxed-darwinian-selection1.pdf 

Scarr, S., and Weinberg, R.A. (1976). IQ test performance of Black children adopted by White families, American Psychologist, 31, 726-739.

http://www.kjplanet.com/amp-31-10-726.pdf 

United Nations, Department of Economic and Social Affairs, Population Division (2013). World Population Prospects: The 2012 Revision, Key Findings and Advance Tables. Working Paper No. ESA/P/WP.227.

http://esa.un.org/wpp/Documentation/pdf/WPP2012_%20KEY%20FINDINGS.pdf 

Weinberg, R.A., Scarr, S., and Waldman, I.D. (1992). The Minnesota Transracial Adoption Study: A follow-up of IQ test performance at adolescence. Intelligence, 16, 117-135.

http://www.sciencedirect.com/science/article/pii/016028969290028P 

Wikipedia. (2013). Head Start Program

http://en.wikipedia.org/wiki/Head_Start_Program