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Estimating World GDP, One Million B.C. - Present

J. Bradford DeLong

Department of Economics, U.C. Berkeley

delong@econ.berkeley.edu

http://www.j-bradford-delong.net/


I construct estimates of world GDP over the very long run by combining estimates of total human populations with estimates of levels of real GDP per capita.

 

Population

I take my estimates of human population from Kremer (1993), but it would not matter if I had chosen some other authority. All long-run estimates of human population that I have found are quite close together (with the exception of estimates of population around 5000 BC, where Blaxter (1986) (cited in Cohen (1995)) estimates a population some eight times that of other authorities). Note that this does not mean that the estimates are correct--just that they are the same.

Kremer (1993) sees human populations as growing at an increasing proportional rate from perhaps 125,000 in one million B.C. to 6 billion today. Population reached approximately 4 million by 10000 BC, 50 million by 1000 BC, and 170 million by the year 1. Population then reached 265 million by the year 1000, 425 million by 1500, and 720 million by 1750 before exploding to 1.2 billion by 1850, 1.8 billion by 1900, 2.5 billion by 1950, and 6 billion today. Up until 1950 Kremer calculates that the rate of growth of human populations was roughly proportional to their total level.

 

GDP per Capita

Angus Maddison (1995) has constructed estimates of real GDP per capita for the world from 1820 to 1992. His estimates are best thought of as Laspeyres purchasing power parity estimates in 1990 international dollars. That is, they:

All of these save the last is reasonabl--is in fact a way of proceeding vastly preferable to the alternatives. I will return to the last of these later. But first I want to extend Maddison's estimates backward before 1820.

If you plot the rates of world population growth against Maddison's estimates of world GDP per capita, you find a very high and significant correlation between the two from the early nineteenth century until roughly World War II. After World War II the demographic transition has begun to take hold in large parts of the world, but before World War II the higher is world GDP per capita, the faster is population growth--with a 1 percentage point per year increase in population growth associated with an increase in average world GDP per capita of $1,165 (with a t-statistic of 7.4 and an adjusted-R2 of 0.84).

If you are enough of a Malthusian to believe that this tight relationship before World War II is not coincidence but instead reflects a near-linear dependence of the rate of human population growth on the margin between actual production and bio-cultural subsistence, then you can use the fitted relationship between population growth and Maddison-concept GDP per capita to backcast estimates of world GDP per capita before 1820.

An alternative (preferred by Maddison) is to assume that GDP per capita was constant in Asia and Africa from 1500-1820, grew at 0.1 percent per year from 1500-1820 in Latin America and Eastern Europe, and grew at 0.2 percent per year from 1500-1820 in Western Europe (an estimate that Maddison attributes to Simon Kuznets (1973)); this alternative could then be backcast further by assuming that pre-1500 GDP per capita was constant at near-Malthusian bio-cultural subsistence.

I prefer the first alternative (and have used it). But I also report estimates using the second.

 

New Goods

A large proportion of our high standard of living today derives not just from our ability to more cheaply and productively manufacture the commodities of 1800, but from our ability to manufacture whole new types of commodities, some of which do a better job of meeting needs that we knew we had back in 1800, and some of which meet needs that were unimagined back in 1800.

How much has this change--the fact that we make not just the same goods, but new goods and new types of goods--enhanced our material prosperity? Nordhaus (1997) provides perhaps the most eloquent and sophisticated argument that standard measures--like those of Maddison--that do not take explicit account of these factors grossly understate the rate of economic growth over the past two centuries.

I know that I at least would be extremely unhappy if I were handed my current income, told that I could spend it on goods at current prices, but that I was prohibited from buying anything that was not made before 1800. Yet Maddison's procedures would implicitly take such a reduction in the range of goods I could purchase as having no effect on my real income or real material standard of living.

But by how much has our power to make new things--not just the same things more efficiently--amplified our material prosperity?

In at least some models of growth in which the set of goods that can be produced expands, the correct measure of real output is proportional to the product of purchasing power (income divided by the average price of a good) and the number of goods that can be produced. As best as I can determine, about three-quarters of world expenditure today is spent on commodities that simply did not exist back in 1800. So I (somewhat arbitrarily) use this to assign an additional fourfold multiplication to output per capita since 1800 in addition to the increases in output per capita calculated by Maddison.

But since this--large--extra adjustment is not to everyone's taste, I also report the "ex-Nordhaus" series without the "new kinds of goods" adjustment.

 

Conclusion

The outcome of this set of calculations is thus seven series: Kremer's (1993) estimates of population; three estimates of GDP per capita (my preferred estimate, the constant-before-1500 estimate, and the ex-Nordhaus estimate); and three estimates of total world real GDP (capita (my preferred estimate, the constant-before-1500 estimate, and the ex-Nordhaus estimate).

They are reported in the table below:

 

Average World GDP per Capita

 

(1990 International Dollars)

 

 

 

 

Year

 

 

 

 

Preferred

 

 

 

Ex-Nordhaus

 

Constant Pre-1500 GDP per Capita

 

-1000000

 

92

 

340

 

115

 

-300000

 

92

 

341

 

115

 

-25000

 

92

 

343

 

115

 

-10000

 

93

 

344

 

115

 

-8000

 

96

 

357

 

115

 

-5000

 

103

 

381

 

115

 

-4000

 

109

 

406

 

115

 

-3000

 

113

 

420

 

115

 

-2000

 

112

 

415

 

115

 

-1600

 

121

 

449

 

115

 

-1000

 

127

 

471

 

115

 

-800

 

143

 

530

 

115

 

-500

 

137

 

509

 

115

 

-400

 

130

 

483

 

115

 

-200

 

113

 

420

 

115

 

1

 

109

 

404

 

115

 

14

 

102

 

380

 

115

 

200

 

98

 

362

 

115

 

350

 

94

 

350

 

115

 

400

 

97

 

360

 

115

 

500

 

102

 

379

 

115

 

600

 

104

 

387

 

115

 

700

 

112

 

414

 

115

 

800

 

116

 

430

 

115

 

900

 

131

 

486

 

115

 

1000

 

133

 

494

 

115

 

1100

 

124

 

459

 

115

 

1200

 

104

 

386

 

115

 

1250

 

99

 

367

 

115

 

1300

 

89

 

331

 

115

 

1340

 

109

 

406

 

115

 

1400

 

128

 

476

 

115

 

1500

 

138

 

512

 

115

 

1600

 

141

 

524

 

140

 

1650

 

150

 

556

 

155

 

1700

 

164

 

607

 

172

 

1750

 

178

 

662

 

190

 

1800

 

195

 

722

 

210

 

1850

 

300

 

788

 

300

 

1875

 

429

 

948

 

429

 

1900

 

679

 

1263

 

679

 

1920

 

956

 

1550

 

956

 

1925

 

1108

 

1735

 

1108

 

1930

 

1134

 

1716

 

1134

 

1940

 

1356

 

1915

 

1356

 

1950

 

1622

 

2138

 

1622

 

1955

 

1968

 

2505

 

1968

 

1960

 

2270

 

2792

 

2270

 

1965

 

2736

 

3251

 

2736

 

1970

 

3282

 

3768

 

3282

 

1975

 

3714

 

4119

 

3714

 

1980

 

4231

 

4533

 

4231

 

1985

 

4634

 

4797

 

4634

 

1990

 

5204

 

5204

 

5204

 

1995

 

5840

 

5641

 

5840

 

2000

 

6539

 

6103

 

6539

 

 

 

 

Total World Real GDP

(Billions of 1990 International Dollars)

 

 

 

 

Year

 

 

 

 

Preferred

 

 

 

Ex-Nordhaus

 

Constant Pre-1500 GDP per Capita

 

-1000000

 

0.01

 

0.04

 

0.01

 

-300000

 

0.09

 

0.34

 

0.11

 

-25000

 

0.31

 

1.15

 

0.38

 

-10000

 

0.37

 

1.38

 

0.46

 

-8000

 

0.43

 

1.61

 

0.52

 

-5000

 

0.51

 

1.91

 

0.57

 

-4000

 

0.77

 

2.84

 

0.80

 

-3000

 

1.59

 

5.89

 

1.60

 

-2000

 

3.02

 

11.20

 

3.09

 

-1600

 

4.36

 

16.16

 

4.12

 

-1000

 

6.35

 

23.55

 

5.73

 

-800

 

9.72

 

36.05

 

7.79

 

-500

 

13.72

 

50.90

 

11.46

 

-400

 

16.02

 

59.44

 

14.09

 

-200

 

17.00

 

63.05

 

17.19

 

1

 

18.50

 

68.65

 

19.48

 

14

 

17.50

 

64.91

 

19.59

 

200

 

18.54

 

68.80

 

21.77

 

350

 

17.93

 

66.53

 

21.77

 

400

 

18.44

 

68.40

 

21.77

 

500

 

19.92

 

73.90

 

22.34

 

600

 

20.86

 

77.39

 

22.92

 

700

 

23.44

 

86.97

 

24.06

 

800

 

25.53

 

94.70

 

25.21

 

900

 

31.68

 

117.52

 

27.73

 

1000

 

35.31

 

131.00

 

30.36

 

1100

 

39.60

 

146.91

 

36.67

 

1200

 

37.44

 

138.90

 

41.25

 

1250

 

35.58

 

132.01

 

41.25

 

1300

 

32.09

 

119.06

 

41.25

 

1340

 

40.50

 

150.27

 

42.39

 

1400

 

44.92

 

166.64

 

40.10

 

1500

 

58.67

 

217.64

 

48.70

 

1600

 

77.01

 

285.70

 

76.41

 

1650

 

81.74

 

303.24

 

84.53

 

1700

 

99.80

 

370.26

 

104.67

 

1750

 

128.51

 

476.75

 

136.67

 

1800

 

175.24

 

650.11

 

189.00

 

1850

 

359.90

 

945.60

 

359.90

 

1875

 

568.08

 

1256.10

 

568.08

 

1900

 

1102.96

 

2052.38

 

1102.96

 

1920

 

1733.67

 

2810.15

 

1733.67

 

1925

 

2102.88

 

3293.03

 

2102.88

 

1930

 

2253.81

 

3409.69

 

2253.81

 

1940

 

3001.36

 

4237.90

 

3001.36

 

1950

 

4081.81

 

5379.21

 

4081.81

 

1955

 

5430.44

 

6913.80

 

5430.44

 

1960

 

6855.25

 

8431.84

 

6855.25

 

1965

 

9126.98

 

10845.34

 

9126.98

 

1970

 

12137.94

 

13934.06

 

12137.94

 

1975

 

15149.42

 

16801.40

 

15149.42

 

1980

 

18818.46

 

20162.78

 

18818.46

 

1985

 

22481.11

 

23270.25

 

22481.11

 

1990

 

27539.57

 

27539.57

 

27539.57

 

1995

 

33644.33

 

32503.40

 

33644.33

 

2000

 

41016.69

 

38281.97

 

41016.69



Total World Population

(Millions)

Year   Human Population (Kremer Series; millions)

-1000000 0.125

-300000 1

-25000 3.34

-10000 4

-8000 4.5

-5000 5

-4000 7

-3000 14

-2000 27

-1600 36

-1000 50

-800 68

-500 100

-400 123

-200 150

     1 170

    14 171

 200 190

  350 190

  400 190

  500 195

  600 200

  700 210

  800 220

  900 242

1000 265

1100 320

1200 360

1250 360

1300 360

1340 370

1400 350

1500 425

1600 545

1650 545

1700 610

1750 720

1800 900

1850 1200

1875 1325

1900 1625

1920 1813

1925 1898

1930 1987

1940 2213

1950 2516

1955 2760

1960 3020

1965 3336

1970 3698

1975 4079

1980 4448

1985 4851

1990 5292

1995 5761

2000 6272



References

Michael Kremer (1993), "Population Growth and Technical Change, One Million B.C. to 1990,"Quarterly Journal of Economics 108:3 (August), pp. 681-716.

Joel Cohen (1996), How Many People Can the Earth Support? (New York: W.W. Norton: 0393314952).

Angus Maddison (1995), Monitoring the World Economy, 1820-1992 (Paris: OECD: xxxx).

William Nordhaus (1997), "Do Real Wage and Output Series Capture Reality? The History of Lighting Suggests Not," in Timothy Bresnahan and Robert Gordon, eds., The Economics of New Goods (Chicago: University of Chicago Press: 0226074153).


Professor of Economics J. Bradford DeLong, 601 Evans Hall, #3880
University of California at Berkeley
Berkeley, CA 94720-3880
(510) 643-4027 phone (510) 642-6615 fax
delong@econ.berkeley.edu
http://www.j-bradford-delong.net/

This document: http://www.j-bradford-delong.net/TCEH/1998_Draft/World_GDP/Estimating_World_GDP.html

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