Although
the house mouse (Mus musculus) is a
single species, fertility is reduced in crosses between geographic populations
(Wikipedia - Bolid74)
It's
widely believed that mating between two species never produces fertile offspring.
Untrue. Interspecific mating sometimes produces fertile offspring, and the
genomes of closely related species often show gene flow from one to the other.
It would be more accurate to say that such crossings are usually compromised in
one way or another—incompatibilities arise during development, which lead to miscarriage,
sterile offspring, or less viable offspring.
There
is a similar misunderstanding about mating within a species. It isn't true that
mating within a species is uniformly possible. Even below the species level,
genetic incompatibilities can arise between different geographic populations.
Keep in mind the arbitrariness of all these terms: “geographic population,”
“race,” “subspecies,” and “species.” These are points on a continuum of
increasing reproductive isolation and genetic incompatibility.
Various
problems have been observed in crossings between geographic populations of the
same species (Presgraves 2010; Turner et al. 2011). In the case of crossings
between two subspecies of the house mouse (M.
m. domesticus and M. m. musculus),
the problems have no single cause. There is not only reduced fertility but also reduced
immune function, as shown by higher loads of intestinal parasites in hybrids.
Even the reduction in fertility has multiple causes: "The type and
severity of fertility defects observed depends on the geographic origin of the
strains and also varies among individuals within regions. This variability
suggests that multiple genetic incompatibilities contribute to hybrid male
sterility" (Turner et al. 2011). Multiple loci seem to be responsible, and
incompatibilities that cause sterility likely act in combination with each
other and with other incompatibilities (Turner et al. 2011).
In
general, as genetic distance increases, so does the risk of faulty interactions
between different gene loci:
The
Dobzhansky-Muller model proposes that populations diverging independently in
allopatry will accumulate differences through drift or selection, but will
maintain coadaptation between divergent loci within each single population. If
secondary contact and hybridization occurs between these populations, these
divergent loci from the previously allopatric populations may interact
deleteriously in hybrids leading to lowered hybrid fitness (Leppälä and
Savolainen 2011)
Icelandic and
Danish studies on outbreeding
The
above model is consistent with two recent studies on humans, one in Iceland and
the other in Denmark. The Icelandic study used a database of couples born
between 1800 and 1965. In the authors' own words, "the advantage of using
the Icelandic data set lies in this population being small and one of the most
socioeconomically and culturally homogeneous societies in the world, with
little variation in family size, use of contraceptives, and marriage practices"
(Helgason et al. 2008). The authors found that fertility rose and then fell
with increasing genetic distance between husband and wife. Specifically, the
relationship was:
[...]
an n-shaped curve from the relatively low reproductive success of couples related
at the level of second cousins or closer, to the maximum for couples related at
the level of third and fourth cousins, after which there is a steady decrease
in reproductive success with diminishing kinship between spouses. A similar
picture emerges when the number of grandchildren per couple is examined
(Helgason et al. 2008)
The
Icelandic study was criticized in a tweet by Jayman:
Doubt
it. The Icelandic study is likely confounded in various ways so I don't think
genetic relatedness is the thing directly affecting fertility.
He
was retweeted by hbdchick, but neither of them identified the
"various" confounds. Nor did I find this criticism in the 140 papers
that cited the study on Google Scholar. So we're not in the realm of common
knowledge.
The
original paper did identify a possible confound. From 1800 to 1965, there was a
decrease in mean fertility and an increase in marriages with more distantly
related individuals. The relationship between fertility and kinship may thus be
an historical confound:
These
results are based on couples born during a period of almost 200 years, in the
course of which there was a marked decline both in the mean fertility and in
kinship between couples. (Helgason et al. 2008)
To
eliminate the confound, the authors broke the data down by 25-year intervals:
Nonetheless,
the same general relationship between kinship and reproductive outcome was
observed within each 25-year subinterval (fig. S2). We evaluated the
correlation between the standardized variables of kinship and reproductive
outcome for all couples and for each time interval separately (Table 2),
adjusting for the impact of geographical differences in the kinship and
fertility of couples within Iceland (10). Each test revealed as significant
association with kinship, with correlation coefficients of 0.063 (P = 1.5 ×
10-129) for the number of children, 0.045 (P = 3.6 × 10-66) for the number of
children who reproduced, and 0.042 (P = 7.6 × 10 -58) for the number of
grandchildren. (Helgason et al. 2008)
There
might be other confounds. That's why the Danish study is important. It went through a number of socioeconomic factors: "education,
family income, urbanicity, mother's age at first birth, and six variables
representing proximity to kin [maternal radius, i.e., distance between mother's
and child's birthplace; paternal radius; and presence of each grandparent in
the child's birth parish or neighboring parish" (Laboriau and Amorim
2008). Controlling for those factors did not change the findings.
Davenport's study
on outbreeding in Jamaica
Jayman
also criticized Davenport's study, apparently in reference to the finding that
between 5 and 30% of the "brown" children did worse than predicted.
As
for mixed race children, you have to keep in mind that people don't enter those
relationships randomly - i.e., also confounded
Jayman
is arguing that the parents of the brown children were atypical, apparently in
the sense of being below-average. In its early days, Jamaica did have many poor
whites, but most of them left because of competition from slave labor. European
ancestry entered the Jamaican population largely from landowners and
businessmen, particularly people of Scottish descent:
Jamaica
has more people using the Campbell surnames than the population of Scotland
itself, and it also has the highest percentage of Scottish surnames outside of
Scotland. Scottish surnames account to about 60% of the surnames in the
Jamaican phone books. The first Jamaican inhabitants from Scotland were exiled "rebels".
Later, they would be followed by ambitious businessmen who spent time between
their great country estates in Scotland and the island. As a result, many of
the slave owning plantations on the island were owned by Scottish men, and thus
a large number of mixed-race Jamaicans can claim Scottish ancestry. (Wikipedia
2020).
Today,
"brown" Jamaicans are generally middle class, and they were even more
so during the time of Davenport's study. It is indeed strange to intimate that
his biracial subjects were the offspring of below-average whites and blacks.
Conclusion
Davenport's
study probably corresponds to the highest degree of outbreeding possible. Even
in that case, adverse mental effects were observable only in a minority of
offspring. The most widespread effect is probably lower fertility and perhaps a
higher risk of testicular cancer. Joffe (2009) suggests that an increase in
outbreeding might explain a century-long decrease in semen quality and a
corresponding increase in testicular cancer:
One
implication of the proposed pathogenesis is that as D&D [duplications and
deletions of genetic material during meiosis] accumulate, mating between
individuals who are genetically unalike would be associated with lower
reproductive success as pairing at the start of meiosis would be more likely to
be impaired. On the face of it, this contradicts the earlier observation that
hybrid vigour would tend to increase fertility in unrelated individuals. Yet
these two ideas may be compatible: both extremes—genetic similarity
(inbreeding) and genetic distance (D&D accumulation)—could decrease
fertility, so that an intermediate degree of relatedness would be associated
with the highest degree of fertility. This could explain the evidence from
Iceland that the greatest reproductive success, measured as the number of
grandchildren, was observed in couples who were third or fourth cousins (Helgason
et al., 2008). Comparable findings have been reported from elsewhere, for
example Denmark (Labouriau and Amorim, 2008).
I
realize this may be a sensitive subject. If you feel offended, please read
something else.
To
produce healthy children, you should marry a third or fourth cousin. Farther
out, the genetic costs of outbreeding begin to outweigh those of inbreeding.
That was what a cohort study found in examining Icelanders born between 1800
and 1964. Fertility was lower if the woman's husband was either closer in or
farther out (Helgason et al. 2008).
That
finding is supported by a Danish study. Using data on Danes born in 1954, the
authors measured the distance between the wife's home parish and the husband's
home parish. Fertility peaked at a distance of around 75 km. The relationship
between fertility and marital radius was not explained by education, family
income, urbanicity, or mother's age at first birth. The authors concluded that
their findings were consistent with those of the Icelandic study, the cause
being the same: fertility rises with decreasing relatedness up to a peak and
then starts to fall. Inbreeding depression gives way to outbreeding depression
(Labouriau and Amorim 2008).
How
far can you marry out before the costs of outbreeding become unacceptable? One
problem lies with that word. What may be perfectly acceptable to one person
may not be to another.
So
let me review what is known and what remains to be known. You be the judge.
A
half-century ago, Ernst Mayr wrote: "Hybridization between species leads
almost invariably to unbalance through deleterious combinations of genes. [...]
in Drosophila even the hybridization
of races may lead to destruction of well-integrated gene combinations"
(Mayr 1970, p. 399). He then went on to say that it is "still
uncertain" whether these findings apply to our species. In fact, "all
investigations of race mixtures in man have failed to produce any evidence of
decreased fitness."
It
would be better to say "indisputable evidence." In fact, there is
evidence from two major studies of the 1920s.
Davenport’s
research in Jamaica
I
will begin with a study by Charles Davenport, a Harvard zoology professor. In
the early years of the twentieth century, he became concerned about human
heredity and the genetic consequences of outbreeding. In 1926, with his
assistant Morris Steggerda, he went to Jamaica and examined 100 black, 100
white and 100 “brown” adults of equal social status, together with 1200
children between the ages of 10 and 16. They were given anthropometric,
physiological, and psychological tests. The psychological results are worth
quoting in full:
Disharmonies
in the mental sphere are socially more significant, perhaps, than those in the
physical sphere, and such disharmonies are apparently common in the adult
Browns [...]. Such disharmony and confusion apparently appear in visualization
and reproduction, as in putting together the parts of the manikin. The
proportion of failures of the Browns is 9.6 per cent, as opposed to 3.1 per
cent in Blacks and 2.1 per cent in Whites. In copying of geometric figures 5
per cent of Browns fail completely, as compared with 3 per cent of the Blacks
and 0 per cent of the Whites. In the Army Alpha Test IV (opposites and
similars) 41 per cent of Browns got only 3.7 or fewer correct, while only 23
per cent of Blacks did so poorly and none of the Whites. In Test V (pied sentences)
30 per cent of the Browns got fewer than 3 out of 24 questions right, while
only 26 per cent of the Blacks and 13 per cent of the Whites did. In Test VII
(of analogies) 45 per cent of the Browns got less than 10 per cent of the
questions correct, while only 30 per cent of the Blacks and 21 per cent of the
Whites did so badly. One gains the general impression that, though on the
average the Browns did not do so badly, there was among them a greater number
of persons than in either Blacks or Whites who were muddled and wuzzle-headed.
The Blacks may have low intelligence, but they generally can use what they have
in fairly effective fashion; but among the Browns there appear to be an extra 5
per cent who seem not to be able to utilize their native endowment. There are
so many variables, however, and the numbers are so small, that the results
merely propose an hypothesis and do not warrant a conclusion.
The
question arises: are there any traits in which, on the average, the adult
Browns are superior to the Whites? We might, theoretically, expect such, yet
when we have tested all of the probably genetically distinct traits between
Blacks and Whites, we find only one in which the mean of the adult Browns is
clearly higher than that of either parental stock.
On
the other hand, if we examine the means for children of 10 to 13 or 13 to 16
years there are a few in which the brown children grade higher than either the
black or the white children. [...] The fact that youthful Browns sometimes
score higher than youthful Blacks or Whites suggests the conclusion that brown
children develop in some mental capacities precociously; and then fall behind
in development.
The
relative underperformance of biracial individuals looks significant, given the
sample sizes. Less clear is its magnitude and, most importantly, its cause. If
we exclude the hypothesis of incompatibilities during development, there are only
two other explanations:
-
The “brown” individuals had suffered some kind of deprivation that the black
and white individuals hadn't.
-
“Brown” individuals with mental problems had been oversampled.
Neither
explanation seems likely. In the Jamaica of the 1920s, biracial individuals
were if anything a privileged group. They dominated the middle class. Nor is it
clear why those with mental problems would be oversampled.
Mjøen’s research
in Norway and Sweden
The
second study was by Jon Alfred Hansen Mjøen, a Norwegian who in 1906 founded
the Vinderen Biological Laboratory, a center for international research in
genetics. He likewise was concerned about the possible negative effects of
outbreeding and became a proponent of eugenics. In 1934, he supported a
Norwegian law for forced sterilization. He died in 1939.
With
the support of his laboratory, Mjøen did fieldwork in northern Norway and
Sweden, where he observed and measured about 600 Norwegians/Swedes, about 600
Sami, and more than 300 people of first-generation mixed ancestry. Most
individuals in the last group were described as having "harmonious faces,
general good looks, decent stature, height, and strength, as well as a good
correlation between volume of lungs and body-size, and muscular strength and
body-size." However, "we found more disharmonies, both physical and
mental, than in the two parent races."
The
disharmonies were: "Relatively
large or small ears, disproportionate extremities, unusual length of body in
the F1 generation, abnormal range of variation with regard to such
characteristics as lung-volume and muscular strength [...], greater prevalence
of diabetes [...], loss of balance, and diminished resistance to tuberculosis" (Mjøen 1931).
Mjøen
argued that disharmonies are most likely to occur when a trait is determined by
large numbers of genes acting together, such as when hormones act on genes for
growth and development: "It is highly probable that the frequently
observed exaggerated growth of the hybrid and his disproportionately large
extremities are due to a glandular disturbance of genetic origin." He also
attributed the higher rate of diabetes to errors in hormonal regulation.
After
There
were no subsequent studies. It would be easy to say that research ended with
the widespread revulsion against Nazi Germany in 1945. Actually, the end came
earlier, in the 1930s with the triumph of Boasian anthropology and behaviorist
psychology. Both stressed the plasticity of the human mind and shifted the
focus of research from nature to nurture, i.e., to "society" and
possibilities for social change.
Nonetheless,
even within academia, important people continued to voice support for
hereditarian and eugenic positions. John Maynard Keynes served as the director
of the Eugenics Society of London (1937-1944) and in 1946 was still calling
eugenics "the most important and significant branch of sociology"
(Brignell 2010). The science fiction series Star
Trek ran an episode in 1967 on eugenics ('Space Seed'). The Eugenics Review would be renamed The Journal of Biosocial Science only in
1969. Eugenic laws remained on the books and were enforced as late as the 1970s
in some jurisdictions.
All
of this may seem surprising because there has been an effort to push the
systematic rejection of eugenics farther and farther back in time. The Wiki
entry on Charles Davenport, for instance, states that "only his ardent
admirers" took his research seriously. The truth is that he was widely
respected until the 1930s. His 1911 work, Heredity
in Relation to Eugenics, became a college textbook (Wikipedia 2020). Mjøen
was likewise well regarded:
His
fame was such that he was one of three expert advisors consulted by the US
Congress in the appointment of the first President of the American Eugenics
Society, he gave a lecture tour of eighteen American universities in 1927, and,
in a period in which The New York Times
voiced anxieties about the future of the 'Nordic Type' in America, the
newspaper of record invoked Mjøen repeatedly (Reinert 2015)
Even
on the left, the general attitude was cautious acceptance, as seen in this 1928
report from the Eugenic Society of Leningrad:
P.
I. Ljublinsky remarked that there was not much to be said for the two extreme
views of this problem—the doctrine of complete indifference to the matter and
the system of strict measures. Therefore what must be recognised as most
advantageous is something lying between the two extremes,—a certain system of
compromise, of which he himself was an adherent. The meeting gave its support
to this last standpoint. It was decided that certain legislative prohibitions
in this field are undoubtedly of service. (Philiptschenko 1928)
On
the specific issue of outbreeding, feelings were more mixed:
After
the conclusion of the discussion the meeting decided that, although the
question of race crossing is very important, it is difficult to regard is as
definitely solved. But in contrast to the attitude adopted in the Norwegian
programme it must be stated that, so long as we have no other data available,
we cannot express an opinion against the crossing of different races and
nations. (Philiptschenko 1928)
There
would be no more data. The Soviet Union, like the world in general, looked up to
progressive thought in the West, particularly in the United States. By the
1930s, the shift toward blank slate thinking had become overwhelming among
American intellectuals.
Conclusion
If
we go back to the recent studies on fertility and outbreeding, we see that
fertility progressively declines when outbreeding takes place beyond one's
fourth cousin. A growing proportion of embryos or fetuses fail to develop
beyond a certain point, apparently because of some incompatibility.
Outbreeding
depression seems to be a real phenomenon, but how serious is it? Davenport
examined perhaps the maximum degree of outbreeding possible, and only a
minority of individuals showed a degree of dysfunction that was higher than
expected. The proportion varied according to the mental test, from a low of
about 5% to a high of 30%. It is likely that subsequent generations would show
progressively lower proportions, with natural selection removing the least
functional individuals through reduced fertility, inability to find a mate, or
higher risk of illness.
Davenport
was cautious in interpreting his results, noting the difficulty in estimating
the size of the adverse outbreeding effect. His self-criticism was taken up by
his critics, and the current prevalent view is that his study has been
thoroughly discredited, if not by methodological problems, then by Hitler.
Elderly
Shanghai woman practicing tai-chi (Wikipedia – Tom Thai)
Two
years ago I wrote about "The Crisis of the 2020s." I argued that this
decade would see a worsening confrontation between two world views:
On
the one hand, the globalist consensus will continue to radicalize in the core
countries of the Western world. On the other hand, a very different consensus
will dominate most of central and eastern Europe, with inroads being made into
France and Germany. These opposing consensuses will diverge more and more, if
only because mutual antagonism will make dialogue impossible. (Frost 2017a)
This
confrontation is taking place at a time when the "consensus" no
longer seems to be delivering the goods. Economic growth is sluggish not only
throughout the West but also in the supposed beneficiaries of globalization—China,
in particular. For some, this slowdown means that the current system has failed.
For others, it means that the failings of globalization can be resolved only through
more globalization.
The
Crisis of the 2020s is thus primarily ideological. People are split into
opposing camps, and it is far from clear which one will win. While the
globalist consensus is losing ground in eastern, central, and southern Europe,
it still dominates the western core of the UK, France, and Germany ... as well
as North America. The West has lost its manufacturing base but is still
culturally dominant. That dominance, not so much in ideas as in the packaging
of ideas, is critical to promoting a model of society where people are
interchangeable units in a global marketplace.
The
ideological crisis will nonetheless be made worse by real-world problems:
China: a shrinking
work force
China’s
exports will become more expensive as its work force shrinks and grows old.
This shrinkage will be worse than expected because the Chinese authorities have
been overestimating the country’s fertility rate for almost two decades. The
current rate is not 1.6 children per women. In fact, it had already fallen to
1.4 by 2003 and is now probably one child per woman. And this is happening even
though the one-child policy is no longer in effect. The fertility rate is even
lower among Han Chinese and lower still in the industrialized northeast—where
it is down to 0.75 (Frost 2019a; Wang 2018).
There
are already fewer Chinese workers with each passing year, and this decrease
will accelerate as the smaller cohorts of the noughts and teens enter the job
market. Inevitably, the price of labor will rise. This will be good for China,
which needs to reorient away from exports and toward its domestic economy. Western
countries, however, will have to be weaned off their dependence on cheap
Chinese goods.
Can
the same goods be produced elsewhere? Unlikely. None of the alternatives sources
of cheap labor have the same worker quality or, just as importantly, worker
quantity. In hindsight, China was a lucky find for globalization—a country
where the average worker was not only inexpensive but also intelligent and
disciplined.
Western
consumers are already cash-strapped, with most of them living from pay check to
pay check. Where will they get the money to pay for a steep increase in the
price of consumer goods?
The global food
crisis
The
Arab Spring was triggered by a surge in food prices. That surge was no fluke.
We are reaching the end of a long increase in food production, a “green
revolution” made possible by large-scale monoculture, intensive plowing, and
heavy use of chemical fertilizers. That increase has come at a price, particularly
degradation of soil fertility. Further increases will be modest and will
require a more sustainable model of agriculture, as well as more investment in
automation and robotization. Unfortunately, such changes, especially the
latter, are impeded by the current heavy reliance on cheap migrant labor.
Agribusiness,
particularly in the U.S., has become a conservative force that will stubbornly
resist change. Like the culture industry, it will push for more of the same.
The decline of
high-trust societies
The
evolution of social complexity is far from easy. One of the main challenges has
been the creation of large societies in which economic transactions take place
mostly between unrelated individuals. Such societies are impossible in most of
the world because of the high level of mistrust between unrelated individuals.
Each transaction has to be checked and double-checked for lying, cheating, and
outright theft. Many transactions never take place because they just aren't
cost-effective.
This
obstacle has been overcome in northwest Europe and East Asia. In both areas, the
solution is behavioral and psychological. Northwest Europeans are more
individualistic, less loyal to kin, and more trusting of strangers. Because
they attach less importance to kinship, they have been able to build large,
functioning societies on the basis of “impersonal prosociality,” i.e.,
willingness to obey universal social rules, affective empathy toward nonkin, and
feelings of guilt for unwitnessed rule breaking (Frost 2017b; Frost 2019b;
Schulz et al. 2019). East Asians are less individualistic but just as willing
to obey universal rules, which are enforced more by shame than by guilt. Empathy is also at a high level, but less differentiated between affective
and cognitive empathy:
The
main difference is in the relationship between self and society. Whereas a
greater sense of self has helped Northwest Europeans to transcend the limitations
of kinship and, thus, build larger societies, East Asians have relied on a
lesser sense of self to create a web of interdependence that extends beyond
close kin. (Frost 2015)
Northwest
Europeans and East Asians are now in steep demographic decline. Inevitably, less
wealth will be created. I say "inevitably" because those two groups
produce most of the world’s wealth. When they go, most of the wealth will go
too. This is not a problem we can resolve by passing laws or changing the
school curriculum. To some extent, we could force people to adopt the behaviors
of a high-trust society, but that would take time and will. And we don't have
much of either.
A name with a nice
ring to it
When
I wrote that post two years ago I settled on the name "Crisis of the
2020s." It had a nice ring to it. While doing research for this post, I googled
the same name ... and got over 56,000 hits. The oldest hit seems to be a 2011
article: "Global Aging and the Crisis of the 2020s." I hadn't read it
previously, but it points to the same underlying problem:
The
working-age population has already begun to contract in several large developed
countries, including Germany and Japan. By 2030, it will be stagnant or
contracting in nearly all developed countries, the only major exception being
the United States. In a growing number of nations, total population will begin
a gathering decline as well. Unless immigration or birthrates surge, Japan and
some European nations are on track to lose nearly one-half of their total
current populations by the end of the century. (Howe and Jackson 2011)
That
article differs from mine in its implied advocacy of immigration as a solution.
To be sure, it does mention "the lawlessness of immigrant youths in large
cities [of Western Europe]," but it remains upbeat about the United States
"because of its higher fertility rate and because of substantial net
immigration, which America assimilates better than most other developed
countries" (Howe and Jackson 2011). That optimism was already exaggerated in
2011. Today, mass immigration is just as much a process of cultural and
demographic replacement in the U.S. as it is in Western Europe.
Let's
be frank. The high productivity of North America, Western Europe, and East Asia
has profound behavioral and psychological causes. It is not due to political
ideals, universal education, or a particular legal system. It is due to a higher
level of social trust, as well as a higher level of cognitive ability and a
lower level of personal violence. When immigrants enter that kind of
environment, their productivity dramatically rises. They are now working in a
society where laws are observed, where information is reliable, and where
disputes are not normally settled through violence. We all benefit from that
kind of society—simply by virtue of living in it.
That’s
the "unearned privilege" that antiracists and right-wing economists love
to denounce. Their argument is deceptively simple: “By what right do we deny
this privilege to others? It’s a mere
accident of birth! Just think, they’re less productive because we’re keeping
them out. So let them in! We’ll all be better off!”
Frost,
P. (2019b). Was Western Christianity a cause or an effect? Comment on: J.F.
Schulz, D. Bahrami-Rad, J.P. Beauchamp, and J. Henrich. The Church, intensive
kinship, and global psychological variation. Science 366 (6466) https://science.sciencemag.org/content/366/6466/eaau5141/tab-e-letters
