A thought which emerged from the article:
Science Has Wonderful News for Young People Who Don't Want Kids You're not alone. MIC.COM|BY MIC
In working on the POTUS genealogy connection, I noticed some lines progressively die off.
Allowing for Homosexual males (NOT gay females who can continue to reproduce), and other factors, we get the question: could a multi-generational or multi-sibling progressive decline in children represent a genetic factor ... one which represents itself as depression, or unhappiness? Not just the hormonal one already identified in some women, but also in males?
Maybe manifesting early in sibling rivalry that takes extended duration. The opposing manifestation would be observed closeness of siblings from birth ... inferring those who would themselves have multiple children.
If so, then there might also be beneficial genetic traits in those who are close to siblings, exhibit no unhealthy rivalry, and so represent an element of natural selection which effectively halts the continued progression of negative traits.
If that were true, than it could allow for calculation of a "critical mass" in population which would result in a sharp and predictable decline in reproduction -- a trait observable to those focused on animal husbandry in restricted pastoral populations. If so, that would explain the apparent global shift in population growth.
In the case of the continued up move in Africa, the hardship level related emotions would mask the reproductive depression ones and allow, or promote, continued high reproduction rates. Disease response, like HIV IMMUNITY observed in Nigeria, might also be a factor ... the positive trait needing to reach critical "universal" levels before the population can eradicate the negative traits through a reproductive decline. In some ways, this would also add to population bottleneck occurrences or characteristics ... one of which appears to explain the POTUS connections.
NOW, if we used a weird calculation, we might find for many animal species: A population of three offspring, each of whom produced three offspring, would – excluding accident and death via some external force (war/murder/etc) – grow at an exponential rate limited only by the availability of non-related mates.
The years marked by each generation need not be those marked by observational data for humans – the key is the number of generations required to achieve the environmental (or global) resource limit that would support that population (so it can be a bacteria, virus, or any species). If we assume three per generation, raw math extrapolation yields the current human population in 21 generations.
Naturally such raw math needs to be refined to allow for reintegration of the same genetic line due to a limited external resource line. But, only for the sake of discussion, we will use 21 generations. (we will also hold to the ancient and recently proven idea that the adult is established by age 8).
To ensure the pattern is maintained, the parent would need to live (in human terms) until their grandchild is 8 years old and has been fully trained in the basic traits they will demonstrate as adults.
If the first child is produced when mom & dad are age 16, and the first grandchild when they are 32, then they need only live to be age 40. If the first child is produced at the female outer limit of 40 – with grandchild 40 years after that -- then they need live to 88.
Assuming an outer limit of 50 for child production by a female, the upper age of a parent would be 108 … if we take the Biblical 120, then can assert the grandparent status at age 112 and parent status at 66 (which fits the male pattern and adjusts for children killed in accidents, or by war/murder, or prove to be homosexual).
If we utilize the Biblical “Sins of father unto third generation” assertion … than the 120 minus 8 yields the great-grandchild, and the math adjusts to an average which has the three children per generation define a generation as a child every 37-years and 3-months.
Thus, consistent with the encoded math system revealed in GENESIS OF GENESIS – the Bible formula infers a human generation every 35-years and 8-months (based on adulthood at age 13); and every 33 years if, per both the Hebrew and western custom, a man should marry at 21.
We therefore have basis for a formula which might yield the critical mass limitation on population for any species or organism on the planet. Thus allowing a maximization of resources and revealing how the prophecy in the David and the Revelation forecasts were made. (Davidic called for 50% die off, Revelation reduced that to 33% and introduced a time frame which falls in the current Climate Change & Global Warming era.)