The Economist - USA (2021-02-20)

The Economist February 20th 2021

Graphic detail Monarchy and genetics

73

The reign in Spain

K

ing charles iiof Spain had an under-
bite so extreme he could not chew, a
tongue too big to speak clearly and a body
so weak he struggled to support his weight.
“The Story of Civilisation”, a history of the
West, said he was “always on the verge of
death but repeatedly baffling Christendom
by continuing to live”. When he died in
1700 aged 38, the coroner found his body
“did not contain a single drop of blood; his
heart was the size of a peppercorn; his
lungs corroded; his intestines rotten and
gangrenous; he had a single testicle, black
as coal, and his head was full of water.”
Charles was more inbred than an aver-
age child of a brother-sister pairing: his
parents, both born to first cousins, were
uncle and niece. And Spain fared poorly
under his reign. His failure to produce an

heir set off a war that cost the country parts

of modern Belgium and Italy.

Was Spain’s misfortune under Charles a

coincidence? Its power was already in de-

cline beforehand. Perhaps a different king

would have done even worse. Determining

how much credit or blame to assign to rul-

ers for their countries’ fates has long been

seen as an unresolvable debate. But a re-

cent working paper by Nico Voigtländer

and Sebastian Ottinger of the University of

California at Los Angeles argues that lead-

ers’ impact can indeed be isolated—thanks

to the genomes of kings like Charles.

For centuries, European nobles often

married close relatives. This practice, at

which Charles’s Habsburg clan excelled,

kept power and titles closely held. It also

led to the copying of recessive genes,

which can cause rare diseases and reduce

cognitive ability. In theory, each round of

inbreeding should have made monarchs

slightly stupider—and thus worse at their

jobs. This yields a natural experiment. As-

suming that countries’ propensity for in-

cest did not vary based on their political

fortunes, the periods in which they had

highly inbred (and probably dim-witted)

leaders occurred at random intervals.

The authors analysed 331 European

monarchs between 990 and 1800. They

first calculated how inbred each ruler was,

and then assessed countries’ success dur-

ing their reigns using two measures: histo-

rians’ subjective scores, and the change in

land area controlled by each monarch. The

authors only compared each ruler against

their own country’s historical averages.

Sure enough, Spain’s tailspin under

Charles was predictable. Countries tended

to endure their darkest periods under their

most inbred monarchs, and enjoy golden

ages during the reigns of their most genet-

ically diverse leaders. The change in their

land areas tended to be about 24 percent-

age points greater under their least inbred

rulers than under their most inbred ones.

Incestuous monarchs and fluid borders

sound remote from modern politics. Yet

the study’s finding—rulers who preside

over setbacks tend to be relatively unintel-

ligent—has timeless implications. Voters

may overestimate governing parties’ influ-

ence over what happens on their watch.

But absolving leaders of responsibility en-

tirely would probably be a worse error.

Data on inbred nobles boost the case

for a leader-driven theory of history

Philip of

Castile

b.1478-d.1506

Joanna of

Castile

b.1479-d.1555

Isabella of

Portugal

1503-39

Charles V HRE*

(Charles I of Spain)

1500-58

Ferdinand I

HRE*

1503-64

Anna of Bohemia

and Hungary

1503-47

Isabella of

Austria

1501-26

Christian II

of Denmark

1481-1559

Philip II

of Spain

1527-98

Maria

of Spain

1528-1603

Maximilian II

HRE*

1527-76

Charles II

of Austria

1540-90

Anna of

Austria

1528-90

Albert V, Duke

of Bavaria

1528-79

Christina

of Denmark

1522-90

Francis I, Duke

of Lorraine

1517-45

Anna of

Austria

1549-80

Maria Anna

of Bavaria

1551-1608

William V,

Duke of Bavaria

1548-1626

Renata of

Lorraine

1544-1602

Philip III

of Spain

1578-1621

Margarita

of Austria

1584-1611

Ferdinand II

HRE*

1578-1637

Maria Anna

of Bavaria

1574-1616

Philip IV

of Spain

1605-65

Maria Anna

of Spain

1606-46

Ferdinand III

HRE*

1608-57

Mariana

of Austria

1634-96

Charles II of Spain 1661-1700

*Holy Roman Emperor †Qualitative assessments from Frederick

Adams Woods’s “The Influence of Monarchs”. Scored from -1 to +1

before comparison with country averages ‡Probability that both

copies of any given gene are identical (offspring of siblings=25%),

%-point difference from country average §Change in natural log

Source: “The effect of European monarchs on state performance”,

by S. Ottinger & N. Voigtländer, NBER working paper, 2020

→ The Habsburg noble family were the kings and queens of much of Europe—and of inbreeding

The ancestry of Charles II of Spain Amount of inbreeding v subjective assessment

of ruler ability†, relative to country average, 990-1795

Amount of inbreeding v change in European land

area controlled by ruler§, relative to country average

1100-1795

First cousins marry

Marriage

Siblings

Second cousins marry

Uncle/niece marry

Habsburg rulers

Charles II Spain

Charles II

Spain (^) -0.1
-0.2
0
0.1
0.2
-5 0 5 10
Amount of inbreeding‡
Maria Theresa Austria
Maria
Theresa
Austria
Henry II France
Henry II
France
Adolphus Frederick
Sweden
Adolphus Frederick
Sweden
Henry VIII England
Henry VIII England
-1.0
-1.5
-0.5
0
0.5
1.0
-5 0 5 10 15 20
15 20
Amount of inbreeding‡
Change in area ruled §
Ruler ability†
Averaged values
Selected individual rulers