How many humans have there been?

simu

Does anyone have an estimation of the number of human beings (i.e. homo sapiens) that have existed since the species first appeared to the present day? Or know of any website where I could find information on this topic?

(I've already googled but most sites seem to concentrate on overpopulation or on relatively recent history).

I'm also curious about whether anyone has tried to work out the probability of two human beings having the exact same combination of genes. Any links/info would be appreciated!

Thanks!

GuanYin

You'd need to know the exact starting point of when we became what we now class as humans and the exact population.

Both of these are the most controversial and argued about points in human evolution. So its not surprising you didn't find anything.

But in a way I can answer your question. We all do have the exact same combination of genes (discounting very rare genetic disorders)!

mike65

http://answers.google.com/answers/main?cmd=threadview&id=217634

Mike.

simu

But in a way I can answer your question. We all do have the exact same combination of genes (discounting very rare genetic disorders)!

I meant the probability of 2 different people having the same combination of hereditary chracteristics(both apparent and recessive) - I think you knew what I meant but what's the correct way of describing it? A genotype?

(It's been a while since I did LC biology plus, they tend to simplify stuff at that level).

GuanYin

Originally posted by simu
I meant the probability of 2 different people having the same combination of hereditary chracteristics(both apparent and recessive) - I think you knew what I meant but what's the correct way of describing it? A genotype?

Well yes but it was still wrong

(sorry I should have put a smilie or something at the end of the last post)

There isn't a blue eye gene or a brown eye one, they are alleles of the same gene.

Its an interesting question you have, but I think a best guess estimate is a fairly generous term for any answer that you get.

Arethusa

Originally posted by simu
Does anyone have an estimation of the number of human beings (i.e. homo sapiens) that have existed since the species first appeared to the present day?

Tough question. . . some ideas, though: Have we yet reached the point where the number of humans alive >= the total number who have died? (I doubt it)

Read years ago that at current (1981, year of writing) population growth levels, the weight of human beings would equal the weight of the Earth in only 1800 years' time. I believe the population of the planet 2000 years ago was c.100-125 million. If you are familiar with the "Rule of Sevens", you can work out the growth rate.


Rule of 7s:


69.3

________ = Doubling time in Years

Rate of compound interest


(The 69.3 is usually rounded to 70, thus the name.)

e.g. 5% compound growth -> 14 year doubling time

As sykeirl pointed out, anyone who gives you a positive answer is just guessing, so use some guesses yourself: say 1/2 million years, average generation time 20 years (prob. lower!), mean mortality age 10 years (again, prob. lower). Until relatively recently, most humans never got to 10 years old, never mind reproductive age. Elders were people who reached 30.

I'm sure there's a formula in that lot somewhere. You have to decide on the initial population, etc.

A very interesting question, actually - I've been thinking about this for a good while now.