Most demographers say, the replacement birth rate for most countries is 2.1 children per woman (over her lifetime) just to keep the population stable – neither growing nor shrinking.

This is based on a number of assumptions. They key one of course being that humans are monogamous.

I’m wondering, what if the general population was not monogamous, but that some proportion were polygamous. Or more specifically polygynous i.e. one man having multiple wives.

Anyone willing to have a guess at what the replacement fertility rate would be if:
10 % of the male population had 2 wives
25% …
50%
etc..?

I am not sure how to calculate this number. Assume that there is non-finite number of females to match up with all the males that wanted a second wife, some sort of free immigration policy or such like.

but just as an intellectual exercise, how would polygyny change the birth rate calculations?

I don’t get your point. Polygamy doesn’t change the equation at all.

Are you still assuming roughly 50/50 male/female spilt?
Because if you are, DV has the answer.

dv said:

I don’t get your point. Polygamy doesn’t change the equation at all.

Let me put it another way:

what if you created the situation, through immigration, where the gender ratio became 100:110 males to females in a population. The excess females would in theory be absorbed into polygamous domestic arrangements, so that overall 1 in 10 males would have 2 wives instead of one.

Would the replacement population rate still be 2.1 children per woman under this demographic structure?

becklefreckle said:

Are you still assuming roughly 50/50 male/female spilt?
Because if you are, DV has the answer.

No. I am talking about changing the 50/50 split through immigration.

What can change the replacement fertility level is reducing infant and childhood mortality. With perfect survivorhood through to menopause, theoretically replacement level could be 2.0.

Now that 3rd Worlders have overcome the need
for creating their own private work force…

if the replacement rate remains at 2 per COUPLE
the it should remain the same 1-1 if an added female
gave birth to just 1 replacement for herself.

what would skew the equation is if every extra female
created a replacement for BOTH Herself & Her Hubby.

iow if ideally each person created a single replacement
it shouldn’t matter WHO The Person in Question Marries.

HOWEVER:
WARS & Unexpected Disasters might become problematic.

party_pants said:

Most demographers say, the replacement birth rate for most countries is 2.1 children per woman (over her lifetime) just to keep the population stable – neither growing nor shrinking.

This is based on a number of assumptions. They key one of course being that humans are monogamous.

I’m wondering, what if the general population was not monogamous, but that some proportion were polygamous. Or more specifically polygynous i.e. one man having multiple wives.

Anyone willing to have a guess at what the replacement fertility rate would be if:
10 % of the male population had 2 wives
25% …
50%
etc..?

I am not sure how to calculate this number. Assume that there is non-finite number of females to match up with all the males that wanted a second wife, some sort of free immigration policy or such like.

but just as an intellectual exercise, how would polygyny change the birth rate calculations?

:-)

I asked myself that question a while ago.

That 2.1 is an approximation.
2 children per female of breeding age is replacement.
The approximate 0.1 to to take account of child mortality, females who die before reaching breeding age.
So in countries with high child mortality, it’s higher than 2.1 and in countries with lower child mortality it’s below 2.1.

> how would polygyny change the birth rate calculations?

Not at all.

sure obviously if humans became fully parthenogenetic then the ideal stable replacement reproduction rate would be 1 child for each female

The replacement birth rate for countries is of little importance.

The important number is the replacement rate for the World, which is not affected by men with multiple partners moving to other countries.

Or is it?

SCIENCE said:

sure obviously if humans became fully parthenogenetic then the ideal stable replacement reproduction rate would be 1 child for each female

in each male/female pairing it would be up to her to produce a replacement
for her partner so each female would beholden to have TWO off-spring.

Then theirs me
who managed to live beyond reproductive age without producing a single copy.

To complicte the equation still further
Since every is a decendent to a a line stretching back to slime mold (that’s a joke)
My PARTICULAR FAMILY “LINE” goes extinct when I die, and the family name ends
since my immediate family has only manage 5 copies…and ALL of Them Are FEMALE.

In the fair dinkum department it is not normally considered that males are a rate limiting factor, the earth being awash woth sperm, so the real replacement rate should only consider the average number of girl children a woman produces.

dv said:

In the fair dinkum department it is not normally considered that males are a rate limiting factor, the earth being awash woth sperm, so the real replacement rate should only consider the average number of girl children a woman produces.

Sexist.