how long would it take for population to grow from 2 people to 6.5 billion?
452046
The human population did NOT start out as two (this readily confirmed by analysis of genes found in different groups of humans across the globe).  Also, Earth is some 4.57 billion years old.  Additionally, humans have existed for several million years.\n\n\nOkay...I'll humor you...\n\n-a human generation is 20 years\n-there are only 300 generations in 6000 years\n-before healtcare each generation more or less had enough time to mature and then have offspring\n-human births are risky compared to other animals and can possibly kill the mother\n-average lifespans before healthcare is estimated 20-35\n-sexual maturity generally occurs between 12-14\n-lifespan has only started increasing since 1800 so that is 200 years or 10 generations\n-Therefore to get and maintain 6.5 billion each successive generation had to have an increase of 21,666,666.667 individuals or more per generation to get from 2 to the 6.5 billion in the necessary time AND maintain population size.\n\nTherefore it is NOT possible for humans to have started from a population of 2 and increase up to 6.5 billion considering all factors involved.
623600
6.25 billion people!!!\n\n5.05 billion lives in undeveloped countries.
128442
It's virtually impossible to know the actual population of the earth. Even if you somehow managed to count 6 billion + people, there would be more being born in the process than you could keep up with. Our best method is to do very well-calculated statistics and baset the population on that.
117256
The world population is the total number of humans alive on the planet Earth at a given time. According to estimates published by the United States Census Bureau, the Earth's population hit 6.5 billion on Saturday February 25, 2005
609960
The world's population is following a very standard growth curve, which every population of animal follows.  It begins with a lag phase, then exponential growth, and then, as the species begins to reach equilibrium with what their environment can support, begins to level off.  We are just starting to level off - world population growth is slowing.  It is projected that the world will top out at 9-11 billion people.  This will not be an overcrowded situation - humans currently occupy only a tiny fraction of the planet.  Doubling that will not be a serious problem.\n\nThat being said, obviously there are limits to how many of us earth can sustain.  The biggest problem right now is that the birth rate is way too high in places that cannot support their population.  This problem will correct itself - it has to.
79098
The world population is the total number of humans alive on the planet Earth at a given time. According to estimates published by the United States Census Bureau, the world population in June 2005 was ~6,450,000,000<ref>On January 3, 2006, the population counter read: "World 6,489,102,362 : 13:39 GMT (EST+5) Jan 03, 2006" United States Census Bureau</ref>. In line with population projections, this figure continues to grow at rates that are unprecedented prior to the 20th century. Approximately one fifth of all humans that have existed in the last six thousand years are currently alive. By some estimates, there are now one billion (thousand million) young people in the world between the ages of 15 and 24.
1077917
The population of the earth is 6.25 billion. The population of the U.S. is in excess of 300,000,000. Mud people, quit breeding.
937075
I hope that in 5 billion years. We have somewhat evolved beyond this planet. Besides we won't have enough land or fossil fuels to last the next five hundred. I can hardly imagine five billion years from now.
880173
in 5 billion years which is 5,200,600,000 AD when the sun burns out.
1002066
At the expected rate, about 62.5 days. And they're not all citizens... that's how many people are in the country.
334921
6,5 billion and then some.
622945
World population climbed to 6.2 billion in 2002, up almost 80 million or 1.3 percent from 2001.
431368
6 and a half billion.
873182
about 5 million and growing
15394
6,446,131,400 July 2005 est\nSo nearer 6.5 Billion now
19566
According to the US Census Bureau, as of 1/1/06, world population will be 6,488,578,564.
434315
The world population is the total number of humans alive on the planet Earth at a given time. According to estimates published by the United States Census Bureau,the Earth's population hit 6.5 billion on Saturday, February 25, 2006. In line with population projections, this figure continues to grow at rates that are unprecedented prior to the 20th century. Approximately one fifth of all humans that have existed in the last six thousand years are currently alive. By some estimates, there are now one billion (thousand million) young people in the world between the ages of 15 and 24.