Q: How many people are living today and how many have lived in the past?
A: Today (that's the easy part) there are about 5.5 billion people. Counting how many preceded them is a little trickier. Esimates rely on a number of dubious assumptions, including which of our ancestors count as "people" and what their birth and death rates were over time. But a few educated guesses have been made. Take your pick:The respected demographer Nathan Keyfitz estimated that 110 billion will be the total world population over all time to the year 2000. Carl Haub, a demographer at the Population Reference Bureau, arrived at a similar estimate, 100 billion, counting from 200,000 B.C. to the present. And using estimates made by the French demographer J.N. Biraben and others, A.R. Thatcher, former director of the British Office of Population Censusees and Surveys, calculated that the number of people who died from 40,000 B.C. to A.D. 1990 was almost 60 billion.
Q. How many sunken ships are there in the ocean?
A. No one knows how many sunken ships there are in the world. But some experts estimate that there are at least 40,000 ships at the bottom of U.S. coastal waters. Some of the ships go back to the arrival of the first settlers from Europe in the early 1600s Also, during World War II, about 600 American ships were sunk, not all in American waters, however. Iron Bottom Sound near Guadalcanal in the Southwest Pacific has about 80 sunken ships, experts say. That's because there werre big battles fought there during World War II. Also, in and arouund the Carribbean Islands, there are many sunken ships, as these waters include the trading routes of explorers from Europe.