This is a chart of how many ancestors would have been required to produce someone born in the year 2000 if the ancestors were never related, going back to 10.000 BC. It compares the number required against the estimated world population.

Year

Number of ancestors per generation.

Estimated world population

Year

(Someone born in 2000 would have exactly two parents, four grandparents, eight great-grandparents, etc. Logical---but not practical.)

(lower limit)

2000

2

6 to 8 billion

2000

1970

4

1940

8

2,300,000,000

1940

1910

16

1,750,000,000

1910

1880

32

1850

64

1,128,000,000

1850

1820

128

1790

256

813,000,000

1800

1760

512

629,000,000

1750

1730

1,024

1700

2,048

600,000,000

1700

1670

4,096

1640

8,192

470,000,000

1650

1610

16,384

545,000,000

1600

1580

32,768

1550

65,536

1520

131,072

1490

262,144

425,000,000

1500

1460

524,288

1430

1,048,576

1400

2,097,152

350,000,000

1400

1370

4,194,304

1340

8,388,608

443,000,000

1340

1310

16,777,216

360,000,000

1300

1280

33,554,432

1250

67,108,864

400,000,000

1250

1220

134,217,728

1190

268,435,456

360,000,000

1200

1160

536,870,912

1130

1,073,741,824

1100

2,147,483,648

301,000,000

1100

1070

4,294,967,296

1040

8,589,934,592

1010

17,179,869,184

254,000,000

1000

980

34,359,738,368

950

68,719,476,736

920

137,438,953,472

890

274,877,906,944

226,000,000

900

860

549,755,813,888

830

1,099,511,627,776

800

2,199,023,255,552

220,000,000

800

770

4,398,046,511,104

740

8,796,093,022,208

710

17,592,186,044,416

207,000,000

700

680

35,184,372,088,832

650

70,368,744,177,664

620

140,737,488,355,328

590

281,474,976,710,656

200,000,000

600

560

562,949,953,421,312

530

1,125,899,906,842,620

500

2,251,799,813,685,250

190,000,000

500

470

4,503,599,627,370,500

440

9,007,199,254,740,990

410

18,014,398,509,482,000

190,000,000

400

380

36,028,797,018,964,000

350

72,057,594,037,927,900

320

144,115,188,075,856,000

290

288,230,376,151,712,000

260

576,460,752,303,423,000

230

1,152,921,504,606,850,000

200

2,305,843,009,213,690,000

190,000,000

200

170

4,611,686,018,427,390,000

140

9,223,372,036,854,780,000

110

18,446,744,073,709,600,000

80

36,893,488,147,419,100,000

50

73,786,976,294,838,200,000

20

147,573,952,589,676,000,000

-10

295,147,905,179,353,000,000

170,000,000

1

-190

20,000,000,000,000,000,000,000

150,000,000

-200

-400

2,000,000,000,000,000,000,000,000

162,000,000

-400

-490

20,000,000,000,000,000,000,000,000

100,000,000

-500

-1000

3,000,000,000,000,000,000,000,000,000,000

50,000,000

-1000

-1990

20,000,000,000,000,000,000,000,000,000,000,000,000,000

27,000,000

-2000

-3010

400,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

14,000,000

-3000

-4000

3,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

7,000,000

-4000

-4990

30,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

5,000,000

-5000

-6490

30,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

5,000,000

-6500

-7990

30,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

5,000,000

-8000

-10000

5,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

1,000,000

-10000

Excel worksheet formulas by Gary Hood. Based on a new generation each 30 years.

Estimated census at link below

http://www.census.gov/ipc/www/worldhis.html