race difference and intelligence.pptx

RACE DIFFERENCES IN
INTELLIGENCE
An Evolutionary Analysis
BY: NSUBUGA IVAN
BMS/12264/182/DU
1/11/2024 De Pope

THE MEANING AND MEASUREMENT OF
INTELLIGENCE
• Race differences in intelligence began to be analyzed scientifically in
the middle years of the 19th century.
• In the 1830s, Samuel George Morton (1799-1851) of the United
States assembled a collection of skulls, measured their volume, and
calculated.
• Europeans had the largest brains, followed by Chinese, Malays, and
Native American Indians, while Africans and finally Australian
Aborigines had the smallest brains.
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Continua……..
• He concluded that these differences in brain size accounted for the
race differences in intelligence (Morton, 1849).
• A similar view was advanced a few years later in France by Paul Broca:
“in general, the brain is larger in eminent men than in men of
mediocre talent, in superior than in inferior races” (Broca, 1861, p.
304).
• About the same time Francis Galton (1822- 1911) in England arrived
at the same conclusion by a different route
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Continua……..
• He assessed the intelligence of the races by the numbers of geniuses
they produced in relation to the size of their populations.
• He concluded that the Greeks of classical Athens were the most
intelligent people, followed in descending order by the lowland Scots,
the English, the Africans, and the Australian Aborigines.
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Continua…………..
• The intelligence test was constructed by Alfred Binet (1857-1911) in
France in 1905.
• This made it possible to measure and compare the intelligence of the
various races, and by the end of the 20th century, many hundreds of
studies had been published on this issue.
• Most of these have been concerned with the difference between
Blacks and Whites in the United States
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• Most authoritative studies are by Shuey (1966), who summarized all
the studies from World War I up to 1965,
• Osborne and McGurk (1982), who updated this summary to 1980,
Loehlin, Lindzey, and Spuhler’s Race Differences in Intelligence (1975)
• Richard Herrnstein and Charles Murray’s The Bell Curve (1994), and a
series of publications by Arthur Jensen, culminating in The g Factor
(1998).
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Continua……….
• All of these studies have been concerned with two problems;
evidence on race differences in intelligence and the degree to which
these differences are determined by genetic and environmental
factors.
• It is widely accepted that race differences in intelligence exist, but no
consensus has emerged on whether these have any genetic basis.
• Some authorities have argued that there is some genetic basis for
race differences. However, a number of others have concluded that
there is no compelling evidence for genetic factors.
1/11/2024 De Pope

Definition of Intelligence
• Intelligence maybe defined as is the ability “to understand complex
ideas, to adapt effectively to the environment, to learn from
experience, to engage in various forms of reasoning, to overcome
obstacles by taking thought” (Neisser,1996, p.1).
• This definition is generally acceptable, except for the component of
effective adaptation to the environment.
• All living species are adapted effectively to their environment or they
would not have survived, but many living species, such as snakes and
other reptiles, cannot be regarded as intelligent
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Continua……….
• In economically developed nations, the underclass(vulgar populous),
with its culture of longterm unemployment, crime, drug dependency,
and welfare-dependent single mothers, is well adapted to its envmnt
in so far as it is able to live on welfare and reproduce, but it has a low
average IQ, as shown in detail by Herrnstein and Murray (1994),
• This is not intelligent in any reasonable sense of the word or as
measured by intelligence tests.
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Continua…………
• A definition which avoids this misconception was proposed by
Gottfredson and endorsed by 52 leading experts and published in the
Wall Street Journal in 1994:
• Intelligence is a very general mental capacity which, among other things,
involves the ability to reason, plan, solve problems, think abstractly,
comprehend complex ideas, learn quickly and learn from experience. It is not
merely book learning, a narrow academic skill, or test taking smarts. Rather, it
reflects a broader and deeper capability for comprehending our surroundings
—“catching on,” “making sense” of things, or “figuring out” what to do
(Gottfredson, 1997, p. 13)
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Continua………….
• Intelligence conceptualized as a single entity can be measured by
intelligence tests and quantified by the IQ (intelligence quotient).
• Charles Spearman (1863-1945), formulated the theory of intelligence
as largely a single entity.
• He showed that all cognitive abilities are positively intercorrelated,
such that people who do well on some tasks tend to do well on all the
others.
• Spearman devised the statistical method of factor analysis to show
that the performance of all cognitive tasks is partly determined by a
common factor..
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• He designated this common factor g for “general intelligence” (1904).
• To explain the existence of the common factor, Spearman proposed
that there must be some general mental power determining
performance on all cognitive tasks and responsible for their positive
intercorrelation.
1/11/2024 De Pope

The Hierarchical Model of Intelligence
• Spearman also proposed that, in addition to g, there are a no. of
specific abilities that determine performance on particular tasks over
and above the effect of g.
• In the 1930s, an alternative theory was advanced by Louis Leon
Thurstone (1887-1935) that there are seven “primary abilities,”
• Which he designated reasoning, verbal comprehension, numerical
ability, spatial ability, word fluency (the ability to produce a number of
words as exemplars of a concept in a short period of time), memory,
and perceptual speed (1938).
1/11/2024 De Pope

• In the second half of the 20th century, a general consensus emerged
that both the Spearman and the Thurstone models were partially
correct and that intelligence is best conceptualized as a hierarchical
structure.
• This can be envisioned as a pyramid in which there are some 70
narrow abilities at the base (Spearman’s specific abilities), eight to 10
second-order or group factors at the next level (Thurstone’s primary
abilities), and a single general factor (Spearman’s g) at the apex.
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• Contemporary formulations of this model have been set out by John
L. Horn (1991), John Carroll (1993), and Kevin McGrew and Dawn
Flanagan (1998).
• Their models propose that the eight to 10 second-order factors
consist of “fluid ability” (reasoning), “crystallized ability” (verbal
comprehension), long-term memory, short-term memory,
visualization (visual and spatial ability), numerical ability (arithmetic),
mathematical ability, cultural knowledge, processing speed, and
reaction time.
1/11/2024 De Pope

THE MEANING AND FORMATION OF RACES
• A race is a breeding population that is:
• to some degree genetically different from neighboring populations as a result
of geographical isolation, cultural factors, and endogamy, and
• shows observable patterns of genotypic frequency differences for a number
of intercorrelated, genetically determined characteristics, compared with
other breeding populations.
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Continua……………
• Geographical contact zones between races generally contain racial
hybrids who show intermediate values of gene frequencies from the
more central distributions of the breeding groups.
• These hybrid and mixed race populations are known as clines
1/11/2024 De Pope

The Formation of Races, Varieties, and Breeds
• General principle of evolutionary biology is that when populations of
species become isolated from one another, they evolve into two or
more sub-species.
• Generally termed varieties, strains, or breeds, in humans → races.
• These different varieties evolve as a result of the four processes of
founder effects, genetic drift, mutation, and adaptation.
1/11/2024 De Pope

Continua………………
• The founder effect →population splits and one group migrates to a
new territory to form a new population, the group that migrates will
not be genetically identical to the one left behind→ the two
populations differ genetically.
• The genetic drift effect: gene frequencies change over time to some
extent as a matter of chance→leads to differences between
populations.
• Drift continues with time, increasing differences between races
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Continua……….
• The mutation effect: new alleles (alleles are alternative forms of
genes) appear through chance in some populations and, if they are
advantageous for survival and reproduction, will gradually spread
through the population.
• An advantageous new allele may appear as a mutation in one race,
but not in others.
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• The adaptation effect: when a population migrates to a new territory,
some alleles will be advantageous that were not advantageous in the
old location.
• Individuals possessing advantageous alleles in the new territory have
more surviving offspring, so their alleles will be selected for and will
gradually spread though the population.
• New varieties of several species have evolved as adaptations when
populations have migrated into arctic environments.
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Continua………………….
• Eventually the new advantageous alleles entirely replace the less
advantageous alleles and are then said to have become “fixed.”
1/11/2024 De Pope

Taxonomies of Races
• In the middle years of the 18th century, biologists and anthropologists
began to analyze and classify races.
• The first taxonomy was advanced by the Swedish biologist Carl
Linnaeus (1708-1778) in 1758.
• He proposed that there are four races, which he designated
Europaeus (Europeans), Afer (Black Africans), Asiaticus (Asians), and
Americanus (Native Americans).
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• In 1776, the German physician Johann Friedrich Blumenbach (1752-
1840) added a fifth race, proposed a classification based principally
on skin color.
• He designated these; the Caucasian (white), Mongolian (yellow),
Ethiopian (black), American (red), and Malayan (brown).
1/11/2024 De Pope

• These taxonomies were based on the clustering of morphological
features and coloration in different races:
• Europeans’ white skin, straight hair, and narrow nose, the sub-
Saharan Africans’ black skin, frizzy hair, and wide nose.
• Mongolians’ (East Asians) black hair, yellowish skin, and flattened
nose.
• Native Americans’ reddish skin and beaky nose, and the Malaysians’
brown skin.
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Continua………..
• Morton (1849) used Blumenbach’s five race classification when he
made the first analysis of brain size in relation to race.
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EUROPEANS
• Linnaeus (1758) described them as Europaeus.
• Frequently designated as Caucasians or Caucasoids because of the
belief that they originated in the Caucasus.
• A number of anthropologists have categorized them together with
the South Asians and North Africans in a single Caucasoid group.
• However, the Europeans are distinguishable from the South Asians
and North Africans by their lighter skin color and, in the northern
Europeans, blonde hair and blue eyes.
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Continua……………..
• This distinction has been confirmed by Cavalli-Sforza, Menozzi, and
Piazza (1994) in their classification of the human races on the basis of
a number of genetic markers.
• This has shown that Europeans represented by Italians, Danes,
English, and Basques comprise a homogeneous “cluster”
differentiating them from other races.
1/11/2024 De Pope

Continua………
• Europe is defined as ending at the Dardanelles, the Ural mountains,
and the Caucasus mountains, therefore excludes Georgia, Armenia,
Kazakstan, and Azerbijan, which are included in South Asia
1/11/2024 De Pope

Intelligence of Indigenous Europeans
• The most striking features of the results are that IQs in central and
western Europe are generally close to 100.
• The only exception is Ireland where the median of the 11 studies is an
IQ of 93.
• Two probable explanations for this;
First, long history of emigration in which there has been some tendency for
the more intelligent to migrate, leaving the less intelligent behind.
Secondly, a dysgenic effect of Roman Catholicism, in which clerical celibacy
has reduced the fertility of some of the most intelligent, who have become
priests and nuns.
1/11/2024 De Pope

• The adverse effect of selective emigration has also been present, but
to a lesser extent, in Scotland, where the average IQ in the 1940s was
calculated at 97, in relation to an English IQ of 100 (Lynn, 1979).
• There is also strong evidence for the higher IQ of Scottish emigrants
(Lynn, 1977c).
• Approximately the same lower IQ in Scotland was still present in the
2009 PISA study (given in row 129), in which the IQ in Scotland is
computed at 97.4, compared with 100.2 in England.
1/11/2024 De Pope

• IQs in Eastern Europe are a little lower than in Western and Central
Europe: 98 in Poland, 97 in Russia and Latvia, 96 in Lithuania, and 95
in Ukraine, and Moldova 94, although Estonia is an exception with an
IQ of 100. These six results have a median 96.5.
• These slightly lower IQs are probably attributable to the much lower
living standards that have been present for several centuries.
• In the case of Russia→numerous Bolshevik executions and the large
numbers of deaths in the Second World War, both of which probably
affected predominantly the more intelligent.
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Continua…………….
• Considering all these adverse conditions, it may be surprising that the
intelligence of the populations has been so little impaired
1/11/2024 De Pope

SUB-SAHARAN AFRICANS
• A variety of terms have been used for the Sub-Saharan African
peoples, including Afer (Linnaeus, 1758), Ethiopians (Blumenbach,
1776), and Negroids (Cole, 1965).
• Sforza, Menozzi, and Piazza (1994) confirmed the distinctive genetic
characteristics of the Africans in their classification of humans into
genetic “clusters,”
• These are represented by West Africans of the region west of Nigeria,
Nilotics of the upper Nile in South Sudan, Ethiopians, and Bantus, a
large group present in most of sub-Saharan Africa from Nigeria in the
west to Kenya.
1/11/2024 De Pope

• Most distinctive features of Africans: very dark skin, dark eyes, broad
nose, thick everted lips, and woolly hair.
• Their blood groups differ from Europeans in having a lower frequency
of group A, which is present in about 27 percent of Africans
(compared to around 46 percent in Europeans), and a higher
frequency of group B, which is present in about 34 percent of the
population (as compared to around 14 percent in Europeans)
1/11/2024 De Pope

Intelligence of Sub-Saharan Africans in Africa
• The first attempt to estimate the intelligence of Sub-Saharan Africans
was made by Sir Francis Galton (Galton 1869)
• Studies have been made of the IQs of Africans in sub-Saharan Africa.
• The first of these was carried out in the mid-1920s by M. Laurence
Fick (1929) using the nonverbal American Army Beta.
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• He found that a sample of Black 10- to 12-year-olds at school
obtained an average IQ of 65 in relation to an IQ of 100 of South
African European children
• Remarkably, “Coloreds,” a largely mixed race African-European in
South Africa, obtained an IQ of 83, exactly half way between that of
Europeans and the Blacks
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Continua………..
• The most striking feature of the IQs of sub-Saharan Africans in sub-
Saharan Africa is that they are consistently so much lower than those
of Europeans.
• Also remarkable that the average IQ of sub-Saharan Africans has
shown little change since the first studies published by Laurence Fick
(1929, 1939) and Dent (1937) obtained IQs of 65, 72, and 68 for
Africans in South Africa.
• The three most recent studies of Africans in South Africa published
between 2005 and 2010 found virtually the same IQs of 71 (Knoetze
et al., 2005; Linstrom, 2008) and 69 (Malda et al., 2010).
1/11/2024 De Pope

Brain size and intelligence
1/11/2024 De Pope

• From the above data it can be concluded that there’s a clear
difference between races and intelligence, though there is still debate
on whether the differences seen are more of nature or nurture.
Thanks for your time
For more information read Lynn’s textbook on race differences and
intelligence
1/11/2024 De Pope

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