I was watching some videos today and was thinking about young earth creationism. It was easily absurd to me to even consider it as true. I thought about an easy way to falsify the claim.

Most YEC's are bible literalistic. If the bible true and they place Adam and Eve as the first two people from which all human life is formed, then we have gone from 2 people to 7 billion in a matter of (at most) 10,000 years.

I'm hoping someone can point me to an essay or a mathematical formula to show the absurdity of the claim. I haven't been able to find one myself, and as a person with a degree in math, feel kind of silly that I'm not sure how to even formulate the equation. (However I think it must be a fairly complex equation and I can't even comprehend where to begin, given that life expectancy rates rise over time, as birth rates (generally) decrease over time, at least in some cultures) If possible can someone use a general formula to determine the birth rates needed to go from 2 to 7 billion people in 10,000 years, or a general formula to solve for time to see how long it would take to go from 7 billion people back to 2, using random but realistic birth and mortality rates?


As I write this and continue to browse various sites I came across this photo, which conveniently enough dates back to 10,000 BC (which given the time frame I'd let the YEC's slide on a mere 2000 years). Still has the world population around 4 million.



http://en.wikipedia.org/wiki/File:Wo...g_scale%29.png


I'm going to x-post this in SMP because someone there might have an answer, but the religious aspect is what made me think of the problem to begin with and I have never seen anyone discuss it, so it was posted here first.

If you accept YEC then you also need to accept that life expectancy used to be a lot better than now. After all Methuselah lived 969 years. So YEC believers can plug in any birth and mortality rate they want.

That is a good point. But I still want to see the math using reasonable estimations. I really dont think it would be to hard to do. People breed like rabbits.

I am not familiar with Christian mythology so I have to ask - who did Adam and Eve's children have sex with to procreate? Their siblings or did God create extra people for that purpose?

They went to the land of Nod. Luckily there were somehow people already there

i did not know that. i guess if you can procreate for 969 years it help you get around my posed population problem

Not really. Whether one man can keep making babies forever or if a slew of young males does it is beside the point. The female population is the limiting factor.

The machine - look at your chart. The claim is not absurd based on any math formula or limits on growth rates or life spans. Apply the same growth rate shown on the chart from 2,000 BCE to 4,000 BCE to the period before that, and you can get to a single couple in the 8,000 BCE range, or even later. We didn't, but not because it was mathematically absurd.

yes it is mathematically absurd.

you cant just take an area and say well if we continue with that growth rate we would hit 0 around 8000BC.

your argument has the same validity as me saying take the growth rate from 1900 to 2000 and we could hit 2 people around 1700 or so. doesnt work that way. because population growth is determinant on the size of the previous population (and in real terms other factors too, but im trying to focus on the mathematical perfectly exponential growth)

If we assume 2 people to 7 billion, and constant growth, we get .22% population growth pr. year.
I assumed it would be orders of magnitude higher.
Perhaps Jesus did ride into Bethlehem on a velociraptor after all.

YEC can't be disproved by scientific reasoning. DUCY?

yes, not to disprove it, more to just see the mathematical absurdity of the claim. i didnt know their ancestors lived for 969 years though

it is not really mathematically absurd

to get from two to over 7 billion you "only" have to double the population every generation (say 20 years) for 660 years (2^33= 8,589,934,592)

unrealistic but not mathematically absurd

i just played around with my calc a bit:
1 generation = 20 years: to get from 2 to over 7bn in 5500 years you only need a growth rate per generation of 8.35% (2 x 1.0835^275)

thats not even that much. it has been higher the last 150 years

So in this world of yours is everyone immortal?

no, why?

I think by 'growth rate' it is assumed that it is the net population increase, not the # of babies born.

http://en.wikipedia.org/wiki/Populat..****eneck#Humans

Evolutionary biologist Richard Dawkins has postulated that human mitochondrial DNA (inherited only from one's mother) and Y chromosome DNA (from one's father) show coalescence at around 140,000 and 60,000 years ago, respectively. In other words, all living humans' female line ancestry can be traced back to a single female (Mitochondrial Eve) at around 140,000 years ago. Via the male line, all humans can trace their ancestry back to a single male (Y-chromosomal Adam) at around 60,000 to 90,000 years ago.

This is consistent with the Toba catastrophe theory that suggests that a bottleneck of the human population occurred c. 70,000 years ago, proposing that the human population was reduced to perhaps 15,000 individuals when the Toba supervolcano in Indonesia erupted and triggered a major environmental change. The theory is based on geological evidences of sudden climate change and on coalescence evidences of some genes (including mitochondrial DNA, Y-chromosome and some nuclear genes) and the relatively low level of genetic variation with humans.

nice link, but can you explain what this has to do with the thread? im not really following the direct usefulness...

A Population Bottleneck would provide one start date for population growth.

The YEC and this theory might produce similar current populations. There were some huge plagues along the way that would partially reset the clocks.

No, it's not.

Why not? What's so extraordinary about the growth rate from 4,000 BCE to 2,000 BCE that it couldn't have been the same for the previous few thousand years?

I disagree. The growth rate from 1900 to 2000 has been affected by many developments that would not have applied in 6,000 BCE, but they didn't apply in 3,000 BCE either. That's why I didn't suggest extrapolating recent growth rates. Though I'm not sure I would even characterize that as absurd.

To be clear - population growth depends on the previous population. Population growth rate doesn't. As others have posted, a growth rate of less than a quarter of one percent per year will grow a population from 2 individuals to 7 billion in 10,000 years. Since rates have been much higher recently, the historical rate could be even lower. No absurdity here.

Except, that in addition to the problem of death rates knef posted, this also means there were only about 1000 people alive in 2500 BCE, when we know, to a high degree of certainty, that there was a thriving civilization in Egypt. Even if we give Egypt an incredibly generous 1/4 of the world's population, this means that 250 people built the Pyramids of Giza. That's a problem.

Additionally, we know that population growth has not been steady. In the 6th and 14th centuries, bubonic plague wiped out a significant portion of Eurasia's population. The Columbian Exchange resulted in the death of 95% of the indigenous population of the Americas. That's another problem.

Mitochondrial Eve was not the 'first and only woman' that we descended from. She's just a close common ancestor that the human species has a direct unbroken FEMALE line to, since the Y chromosome is passed unbroken from female to female.

Nuclear DNA has proven that the human population has never dipped below 10 000.

There were thousands of 'women' alive when she was alive that might all have descendants today, but the chain was broken somewhere along the way.

of course it does. a population of 2 people has one child. whats the population growth rate?

population of 10000 people has one child, whats the growth rate

If you're a Biblical literalist, you have to start the population calculation over after the flood, not at Adam and Eve.