msb@dciem.UUCP (Mark Brader) (07/18/86)
To Mike Maxwell's query: > Something I've always wondered: of all the people who've ever lived, > what percentage are alive today? I suspect it's a rather large > percentage, and it makes me wonder why there aren't more people like > Plato, Galileo, Michaelangelo, Bach, Einstein. ... We see responses like: ] Anyway, since it is exponential growth, roughly 1/2 of all people ] who have ever lived, are currently living. and even: } I once read that there are more people alive than dead. In other words, } there are more people walking around today than all the people who } lived previously. Good grief, doesn't anyone have an almanac? Patrick Stirling gets it a lot closer: # I remember reading about 10 years ago, when the world population was around # 4bn, that the dead outnumbered the living about 30 to one. Actually it # shouldn't be too hard to come up with an estimate ... No, it shouldn't. My 1985 edition of the World Almanac gives these figures: YEAR 10000BC 1 1650 1700 1750 1800 MILLIONS POP. 10 300 510 625 710 910 YEAR 1850 1900 1950 1970 1982 MILLIONS POP. 1130 1600 2510 3575 4600 Now, of course, these ARE only estimates. Another widely distributed book with another set of estimates is the Guinness Book of World Records. My 1984 edition has these figures: YEAR 10000BC 1 1000 1250 1500 1650 1700 1800 MILLIONS POP. ~5 ~200 275 375 420 550-600 615 900 YEAR 1900 1920 1930 1940 1950 1960 1970 1975 MILLIONS POP. 1625 1862 2070 2295 2513 3049 3704 4033 YEAR 1976 1977 1978 1979 1980 1981 1982 1983 MILLIONS POP. 4107 4182 4258 4336 4432 4508 4580 4650 Now make the simplifying assumption that the population increased linearly from each data point to the next. Where the two estimates disagree, just take the average of the two. If we combine all the data from both lists, from the year 1 to 1983, we get an average world population of 482 million over that interval. For most of history, the human life expectancy has been about 30 years. (Guinness gives some figures on this too. It was still under 50 years just a few decades ago.) But if the average population is 482 million and if (another simplifying assumption) the average life expectancy is 30 years over the 1983-year interval, then the total number of people who have lived during that time must be (1983/30)*482 million, or a bit under 32 billion. Since the population and life expectancy have been rising together, this is somewhat of an overestimate, and we should probably knock off a couple of billion. If we take it at 30 billion, then we can conclude that: JUST ABOUT 1/6 OF THE PEOPLE WHO HAVE LIVED SINCE THE YEAR 1 ARE ALIVE NOW. The original question concerned the total number of people who have EVER lived. If we continue the assumption of linear increase from the 5-10 million at 10000 BC to the 200-300 million 10000 years later, then the average population during the interval would be 102.5-155 million, and with a life expectancy of 30 years, there would have been 34-52 billion more people during that interval. This is probably rather an overestimate; I don't expect the increase really was linear. On the other hand, there have also been humans for maybe a couple of million years before that. I have no idea what the average population was over that interval. If it was 300,000, that would be 20 billion more for the total, still assuming 30 years life expectancy. I once read (I forget where) a remark by Arthur C. Clarke to the effect that the total number of humans that had ever lived, and the total number of stars in the galaxy, were coincidentally equal at 100 billion. In view of the above computations, this remark seems justifiable. So it is probably fair to say that: PERHAPS 1/20 OF THE PEOPLE WHO HAVE EVER LIVED ARE ALIVE NOW. So, are our times suffering from a shortage of great people? In order for us to have heard of someone, they pretty well have to have lived during historic times. Of course history goes back different lengths of time in different places, but I would think it a good guess that 1/8 of the people who have lived during historic times are alive today. But, then, people don't tend to become recognized as great until late in their lives, or even after they are dead. Consequently, as a first approximation we can exclude anyone born since, say, 1940 from consideration. But in 1940 the population was a bit under 1/2 what it is today, so we have only about 1/17 of the total of the people who have ever lived to consider. And do we have, among those who are over 45 today, as many great people as 1/17 of those that there have ever been? I suggest that we do. Mark Brader "Don't be silly -- send it to Canada" Toronto -- British postal worker