125 billion people in 4,000 years?

[Surroundx]

[p]There was some discussion in my thread on macroevolution, as to whether 4,000 years was a sufficient amount of time for 125 billion people to have been born and died (or still alive). I thought I would lay out what I thought was the easiest way to try to answer the question:[/p]

Assumption #1: There were 8 founders. Assumption #2: A consistent generation time of 25 years. Assumption #3: The sex ratio is 50/50. Assumption #4: Everybody has three children.

[p]Based upon the above assumption, every couple would have three children. This would mean that the population increases by 1.5 every single generation, as follows:[/p]

width="500" style="width: 500px"
|-
| Generation(years)
| Population
|-
| 0(0)
| 8
|-
| 1(25)
| 12
|-
| 2(50)
| 18
|-
| 3(75)
| 27
|-
| 4(100)
| 40.55
|-
| 5(125)
| 60.75
|-
| ...........................
| ...........................
|-
| 160(4,000)
| 1.195890555 x 10^29
|-

I'm no mathematician, so I don't know what the 1.1958..... number actually works out to be. I don't have a special formula since I can't figure out any pattern to the 1.5ing every generation (can anybody help?). But if we could get a nice formula, then we could tweak each variable to make it more realistic, and hence give a more accurate figure. However, we would also need to take into account death by disease, wars, murder etc. I don't know how you would do that, but perhaps we could get around it by assuming the slowest growth rate possible. If it is still possible to get 125 billion people in 4,000 years with a much slower birth rate than 1.5, then it becomes quite probable that it could actually happen. Thoughts?

 

[richoman_3]

im no mathmetician either but im pretty sure this is more than 1.195890555 people lol

 

[Surroundx]

im no mathmetician either but im pretty sure this is more than 1.195890555 people lol

Haha, yeah sorry. I thought I formatted it all properly, but it just lumped everything into one giant paragraph. So you couldn't see that the number I came up with was actually 1.195890555 x 10^29.

 

[Just_Plain_Nuts]

well brendan you have seen my calculation in the other thread... haha
1.195890555....x 10^29 means that it's
119,589,055,500,000,000,000,000,000,000 where 125 billion is
125,000,000,000

there is plenty of room for movement there with lower birth rates I think....exponential growth is an amazing thing, starts slow then starts to explode incomprehensively

 

[Radar]

Feel free to throw a few good famines and trenchwars in there

 

[Just_Plain_Nuts]

Using a Malthusian growth model

Xt=Xo(1+g)^t
where
Xt is the total number born
Xo is the original number you started with
g is the growth rate % per year
and t is the total number of years

from here you could get real tricky and work on a variable growth rate that changes over the ages, but that would make my head hurt

 

[grannieannie]

LOL....damn it, I'll be dead in less than 50 yrs, and that's fine by me...so what happens after that I don't really care about, that's for the next generations to work out. Small minded little person that I am....

 

[Just_Plain_Nuts]

Feel free to throw a few good famines and trenchwars in there

This model doesnt take into account populations, life expectancy etc. Just the number of people ever born. To try to work it out accurately would be near impossible and require a lot of guess work and assumptions

 

[Surroundx]

There is plenty of room for movement there with lower birth rates I think....exponential growth is an amazing thing, starts slow then starts to explode incomprehensively

Exponential growth certainly is an amazing thing. But the death rate would be much higher than what I have calculated in my equation above, which is completely unrealistic. So I'm not sure exactly how much that affects the final figure, but I suspect it does very dramatically. Various wars have killed thousands or even hundred of thousands of people, which also affects the birth rate as well.

 

[JungleManSam]

1+1 = 3 is my limit on math.

 

[slim6y]

One thing that stumps the lot of ya is you've taken the exponential growth to be constant - we know that this isn't true.

We also know birth and death rates are important.

The real factor then, if JPN's magnificent calculation was so significantly over the top - then why is our CURRENT population only 7 billion.

Instantly you must see thousands (if not billions) of flaws in your calculation.

Just that shear ratio would consider we'd have around 300 billion at the very least on earth - right now.

We also know, that that's not true nor is it possible.

Therefore - your maths isn't correct - nor is it remotely correct if you think about it.

At that rate you'd hope that the life expectancy was around 32.... SECONDS!!!

It's ridiculous JPN and you know it! But... the math could be solid - but the theory, like creationism, is far from!

 

[Surroundx]

One thing that stumps the lot of ya is you've taken the exponential growth to be constant - we know that this isn't true.

I'm well aware of that. That's why I said as one of my assumptions a constant birth and death rate. My equation is extraordinarily rough. The real equation, if we could come up with one, would be extraordinarily complex. But not only that, all the different rates, birth rate, death rate, sex ratio, all change over time. It was just a basic equation so that we could tinker with it to make it more realistic.

EDIT: Sorry, I only stated a consistent generation time, so there may have been some confusion as to my understanding that the growth is not consistently exponential.

 

[Just_Plain_Nuts]

One thing that stumps the lot of ya is you've taken the exponential growth to be constant - we know that this isn't true.

We also know birth and death rates are important.

The real factor then, if JPN's magnificent calculation was so significantly over the top - then why is our CURRENT population only 7 billion.

Instantly you must see thousands (if not billions) of flaws in your calculation.

Just that shear ratio would consider we'd have around 300 billion at the very least on earth - right now.

We also know, that that's not true nor is it possible.

Therefore - your maths isn't correct - nor is it remotely correct if you think about it.

At that rate you'd hope that the life expectancy was around 32.... SECONDS!!!

It's ridiculous JPN and you know it! But... the math could be solid - but the theory, like creationism, is far from!

The reason why we only have 7 billion now is that my formula was only estimating the number of people ever born , obviously most of these would be dead over the 4000 years, just maybe...

If I have some more time I may make a formula which takes into account death rates and approximate populations, however I still don't know how to get around the problem of variable growth rates, not to mention trying to figure out life expectancies for different periods etc etc etc

 

[slim6y]

JPN - that's why people like Carl Haub work on this problem for YEARS! It's rather complex - and your calculation, though rough, just begins to show how many intricate details that could be required to perform such an equation.

I understand that you're only saying the number of people ever born - but my point was clearly, if they had a life expectancy of 30 - 50 years then our population would be HUGE!!! Not 7 billion, but maybe 700 billion!

So clearly something isn't right (you got x 10^29 or something ridiculous like that in 4,000 years, you must realise that's impossible and therefore you've over cooked your equation considerably).

 

[Just_Plain_Nuts]

id if i get a chance alone i will see what i can do about a more accurate equation...I much prefer doing my own investigations and deductions over trusting other's opinions..

 

[disintegratus]

Whatever the number is, it's too many. We should start culling and enforced sterilisation NOW.

 

[Surroundx]

I worked out the number assuming a population growth rate of 1.1 every 25 years this time. The number is much, much smaller: 15,659,509. This is a far more realistic number, and I think calls into question the possibility of 125 billion people being born in as little 4,000 years.

 

[slim6y]

Carl Haub suggested 50,000 years for that many....

 

[Surroundx]

Carl Haub suggested 50,000 years for that many....

I wouldn't be surprised if the growth rate was basically static for most of our history. The death rate would have been vastly higher for neolithic cavemen and women.

 

[Erebos]

I don't see the point in this! do you think we will be here in 4000 years?

I dont


Cheers Brenton