17Over the past millennium,world population rose 22 fold.Per capita income increased 13 fold, world GDP nearly 300 fold.This contrasts sharply with the preceding millennium,when world population grew by only a sixth,and there was no advance in per capita income.
From the year 1000 to 1820 the advance in per capita income was a slow crawl the world average rose about 50 per cent.Most of the growth went to accommodate a fourfold increase in population.Since 1820,world development has been much more dynamic.Per capita income rose more than eightfold,population more than fivefold.
Per capita income growth is not the only indicator of welfare.Over the long run,there has been a dramatic increase in life expectation.In the year 1000,the average infant could expect to live about 24 years.A third would die in the first year of life,hunger and epidemic disease would ravage the survivors.There was an almost imperceptible rise up to 1820,mainly in Western Europe.Most of the improvement has occurred since then.Now the average infant can expect to survive 66 years.
The growth process was uneven in space as well as time.The rise in life expectation and income has been most rapid in Western Europe,North America,Australasia and Japan.By 1820,this group had forged ahead to an income level twice that in the rest of the world.By 1998,the gap was 7:1. Between the United States (the present world leader)and Africa (the poorest region)the gap is now 20:1.This gap is still widening.Divergence is dominant but not inexorable.In the past half century, resurgent Asian countries have demonstrated that an important degree of catch up is feasible. Nevertheless world economic growth has slowed substantially since 1973,and the Asian advance has been offset by stagnation or retrogression elsewhere.
The purpose of this book is to quantify these long term changes in world income and population in a comprehensive way;identify the forces which explain the success of the rich countries;explore the obstacles which hindered advance in regions which lagged behind;scrutinise the interaction between the rich countries and the rest to assess the degree to which their backwardness may have been due to Western policy.
There is nothing new about long term surveys of economic performance.Adam Smith had a very broad perspective in his pioneering work in 1776.Others have had an equally ambitious vision. There has been spectacular progress in recent years in historical demography. What is new in this study is systematic quantification of comparative economic performance.
In the past,quantitative research in economic history has been heavily concentrated on the nineteenth and twentieth centuries when growth was fastest.To go back earlier involves use of weaker evidence,greater reliance on clues and conjecture.Nevertheless it is a meaningful,useful and necessary exercise because differences in the pace and pattern of change in major parts of the world economy have deep roots in the past.
Quantification clarifies issues which qualitative analysis leaves fuzzy.It is more readily contestable and likely to be contested.It sharpens scholarly discussion,sparks off rival hypotheses,and contributes to the dynamics of the research process.It can only do this if the quantitative evidence and the nature of proxy procedures is described transparently so that the dissenting reader can augment or reject parts of the evidence or introduce alternative hypotheses.The analysis of Chapters 1,2 and 3 is underpinned by six appendices which are intended to supply the necessary degree of transparency.
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