Question: What reduced per capita income prior to the industrial revolution?
About the article "Industrial Revolution", section "Food and nutrition".

Candidate passages:
Some of the most striking evidence for the Great Divergence comes from data on per capita income.
The West's rise to power directly coincides with per capita income in the West surpassing that in the East.
This change can be attributed largely to the mass transit technologies, such as railroads and steamboats, that the West developed in the 19th century.
The construction of large ships, trains, and railroads greatly increased productivity.
These modes of transport made moving large quantities of coal, corn, grain, livestock and other goods across countries more efficient, greatly reducing transportation costs.
These differences allowed Western productivity to exceed that of other regions.
Economic historian Paul Bairoch has estimated the GDP per capita of several major countries in 1960 US dollars after the Industrial Revolution in the early 19th century, as shown below.
His estimates show that the GDP per capita of Western European countries rose rapidly after industrialization. 
Income data from 2005:Average per capita income: 1961.03 złCompared to the average per capita income:  In the Podlaskie Voivodeship: 120.40%  In Poland: 112.20%  
Chronic hunger and malnutrition were the norm for the majority of the population of the world including Britain and France, until the latter part of the 19th century.
Until about 1750, in large part due to malnutrition, life expectancy in France was about 35 years, and only slightly higher in Britain.
The U.S. population of the time was adequately fed, were much taller and had life expectancy of 45–50 years.
In Britain and the Netherlands food supply had been increasing and prices falling before the Industrial Revolution due to better agricultural practices; however, population was increasing as well, as noted by Thomas Malthus.
Prior to the Industrial Revolution, advances in agriculture or technology soon led to an increase in population, which again strained food and other resources, limiting increases in per capita income.
This condition is called the Malthusian trap, and it was finally overcome by industrialization.
Transportation improvements, such as canals and improved roads, also lowered food costs.
Railroads were introduced near the end of the Industrial Revolution.
Under the Islamic Republic, Iran's economy has been dominated by oil and gas exports which constituted 70% of government revenue and 80% of export earnings as of 2008.
It has a large public sector, with an estimated 60% of the economy directly controlled and centrally planned by the state.
A unique feature of Iran's economy is the large size of the religious foundations, or Bonyads, whose combined budgets are said to make up as much as half that of the central government.
Economic problems include the shattering of the Iranian oil sector and consequent loss of output from the revolution and Iran–Iraq War (Iran sustained economic losses estimated at $500 billion), a soaring population over the same period, inefficiency in the state sector, dependence on petroleum exports, and corruption.
The constitution of the Islamic Republic calls for the state sector "to include all large-scale and mother industries, foreign trade", natural resources and communication; and calls on the private sector to "supplement the ... state and cooperative sectors.
"The International Monetary Fund reports that Iran's gross national income per capita almost quadrupled since the revolution despite strong population growth — one year after the revolution it was $2,974 and grew to $11,396 by 2010.
However, complaining about the economy is said to have become "a national pastime" among Iranians.
According to international economic consultant Jahangir Amuzegar, as of 2003:Despite a 100 percent rise in average annual oil income since the revolution, most indicators of economic welfare have steadily deteriorated.
… Average inflation in the years after the revolution has been at least twice as high as during the 1970s, unemployment has been three times higher, and economic growth is two-thirds lower.
As a result, Iran's per capita income has declined by at least 30 percent since 1979.
By official admission, more than 15 percent of the population now lives below the absolute poverty line, and private estimates run as high as 40 percent.
Per capita income declines when the price of oil declines (per capita income reportedly fell at one point (1995) to 1/4 of what it was prior to the revolution); Accumulated assets of the Iranian middle class - carpets, gold, apartments - that were acquired in the four-year boom after the 1973 oil price rise and served to cushion the fall in standards of living, have now reportedly "largely been sold off.
"The poor have also exhibited dissatisfaction.
Absolute poverty rose by nearly 45% during the first 6 years of the Islamic revolution and on several occasions the "mustazafin" have rioted, protesting the demolition of their shantytowns and rising food prices.
Disabled war veterans have demonstrated against mismanagement of the Foundation of the Disinherited.
Hardship has compelled some children to take odd jobs rather than go to school.
A 2002 study leaked from Iran's Interior Ministry, reported nearly 90% of respondents dissatisfied with the present government according to Amuzegar.
Of this total, 28% wanted "fundamental" changes, 66% "gradual reforms."
10% expressed satisfaction with the status quo.
According British-Iranian scholar, Ali M. Ansari, "Iranians joke" that with the world's second or third largest reserves of oil and natural gas, extensive deposits of copper, gold, uranium, as well as an educated and cohesive workforce, "they are blessed with all the facilities to be the industrial engine of the region, except good governance."
Leibenstein has used these 2 terms stimulants and shocks in his theory quite often.
He defines stimulant as any event that changes the value of a variable away from its equilibrium value so that due to this event there is an initial increase in the per capita income.
Shock on the other hand has been defined by Leibenstein as any event external to the system due to which per capita income is reduced initially.
Now in underdeveloped economies shocks are more powerful than stimulants so what should be done in such a scenario is that the levels of incomes should be risen to such an extent that stimulants become stronger than shocks and the growth in incomes becomes self-sustaining.