#3. AviApics 101 [population, engineering, evolutionary psychology]

PO     EN     EP     

Red, theory; black, fact.

Here, I go into detail about the human population controller introduced in the previous post.

I assume that, like everything in the natural (i.e., evolved) world, it is a masterful piece of engineering, as Leonardo Da Vinci declared.

The way to build an ideal controller is the inverse plant method, where the controller contains the mathematical inverse of a mathematical model of the system to be controlled.  To derive the model, you take the Laplace transform of the system's impulse response function. For populations, a suitable impulse would be the instantaneous introduction of the smallest viable breeding population into an ideal habitat.

What happens then is well known, as least in microbial life forms too simple to already have a controller: unrestrained, exponential population growth as per Malthus, with no end in sight.

This exponential curve is then the impulse response function we need, and its Laplace transform is simple: 1/(S - r), where S is complex frequency and r is the Malthusian constant, that is, percent population growth rate per year. The mathematical inverse is even simpler: S - r, which is calculated as set point X minus controlled variable Y. The result is summed with perturbation P and made equal to Y. The result is usually simplified to permit predictions about controller performance, but that is not needed in this discussion.

The control effort is E(S - r), which can be multiplied out as ES - Er. Remember that everything has been Laplace transformed in these expressions, and that ES becomes the time differential of e when transformed back into the real world. Multiplication by a constant such as r stays multiplication, however. Control effort in the real world is then rate of change of e minus r times e. (Lowercase variables are the un-transformed versions.) Since e = x - y, and since x is constant, x becomes zero when differentiated, and drops out of the expression. Control effort is then -dy/dt - er. <Corrected 5 Jun '16.>

I theorize that women calculate -dy/dt, and men calculate er. When they get together, the complete population control effort is exerted, resulting in stability, which the world rewards. However, on average, the men and the women will be pulling in opposite directions exactly 50% of the time, if we model population variation as a sine wave centered on the set point.

A prediction is that women unconsciously react to evidence of increased birth rate or decreased death rate by wanting fewer children. Men react to excess absolute population relative to set point by violence, and to breathing room under the set point by partying.

That negative sign in front of the male contribution was puzzling at first, until I realized that it must derive from the married state itself, and not from the base male response to population error. This could be the origin of statements such as: "Marriage is the exact opposite of the way you think it will be." 

The level of the noise produced so copiously by small children is probably the signal that women unconsciously integrate to estimate birth rate, and the wailing and long faces following a death probably serve the same purpose for estimating death rate, aided by reading the tabloids. [My (married) older brother once showed me the developmental time course of child noise in the air with his hand, and it looked like an EPSP, the response of a neuron to an incoming action potential. The EPSP is the convolution kernel by which a neuron decodes a rate code.] The men have to calculate absolutes, not rates, however. The male proprietary instinct causes them to divvy up the limiting resource for breeding (jobs in our present society) into quanta that can be paired off with people like pairs of beads on adjacent wires of an abacus. Excess people left over at the end of this operation spells trouble. Politicians are right to worry about jobless rates.

#2. The Iatrogenic Conflicts of the Twentieth Century [population, engineering]

The Edwardian era (1901-1911) in small-town Ontario, and La Belle Epoque will soon be over. (From a photo owned by Constance M. Mooney of Ottawa, Canada)

PO     EN     

Red, theory; black, fact.

Medical advances during a turbulent century

In 1911, the anti-syphilis drug salvarsan, invented by Paul Ehrlich, became widely available to the public, at a time when this disease was cutting a wide swath of morbidity and mortality. Three years later, World War I broke out.

In 1937, sulfa drugs, the first effective treatment for tuberculosis, became available to the public. Two years later, World War II broke out.

In 1945, both penicillin and streptomycin became available to the public, followed in short order by the first mass vaccinations, notably against smallpox. In that decade (1945-1955), the Cold War between the United States and the Soviet Union began. That one nearly finished us in 1962, the year of the Cuba Missile Crisis, when a nuclear WW III was narrowly averted.

My conclusions

In the human brain, there is a wholly unconscious controller for population density with a feedback delay of some two to four years, that answers every sudden downtick in the death rate with a brutal, reflexive uptick. Recently, these downticks in the death rate have been due to advances in medicine, hence my title for this post. "Iatrogenic" means roughly "caused by doctors."

Moreover, last year I noted that the headlines were all about ISIS, an unusually disruptive phenomenon of the Muslim world. I then checked to see what the main preoccupation of the headline-writers had been exactly four years previously. This seemed to be the Arab Spring, when many old governments in the Arab world were being thrown off. I concluded that these regimes had somehow been suppressing population growth.

An engineering model

I began to reason thus: if this controller is real, it should be just as analyzable as Watt's steam-engine governor, using standard engineering approaches. If it has a significant feedback delay, then a perturbation sufficiently rich in high-frequency harmonics (i.e., sufficiently sudden) should drive it briefly into a damped oscillation.

Evidence for the engineering model

In support of these conclusions, I present the US Census Bureau statistics on the percent growth rate of the human population for the 20th century, international yearly figures, aggregated to "World," and extended back to 1900 with decade-wise World data from the historical estimates table. At roughly the end of WW II, we see a huge jump in the growth rate followed by a sharp drop bottoming at 1960, followed by another sharp peak at 1962, followed by a leveling off superimposed on a gradual decline, the latter possibly due to increasing absolute numbers. This time series could be construed as showing a damped oscillation. See below.

The historical global population growth rate scaled to population.

11-07-2018

My surmise that the post-1964 decline in the plot would disappear if corrected for changing absolute numbers is confirmed by calculation based on US Census Bureau data. See below. Furthermore, the plot shown below appears to level off at 78 million new people per year, which is probably the upper trigger level for the controller. There is probably no formal lower trigger level, making this controller asymmetric. Oscillation begins well before this level is reached, however, reflecting the presence of a differential control term, as discussed in the next post. The sharp upstroke in growth rate that occurs at 1980 may be due to the eradication of smallpox over the decade 1967-1977. The downturn after 1988 was probably due to the AIDS pandemic. The data are coarse-grained before 1950 and do not show the upstrokes in 1911-1914 and 1937-1939 that I would have predicted from the two world wars.

World population growth rates in persons per year with no scaling. Note the reaction in 1960.

Center: a centrifugal speed governor familiar in 1914. The Steam Museum, Kingston, Canada, 2012. 

#1. Intro [evolutionary psychology, evolution]

This is the sort of thing I write:

EP       EV      

Red, theory; black, fact.

EP

Religion is the last proto-science (e.g., alchemy, astrology). 
(Parts cut to Deprecated page, Part 2.)

***

EV

The eukaryotic cell arose from a clonal array of prokaryotes that selectively lost some of its internal partition walls while following the colony path to complexity. The remaining partitions gave rise to the internal membrane systems of present-day eukaryotes. Those prokaryote colonists specializing in chemiosmotic processes such as oxidative phosphorylation and photosynthesis could not lose any of their delimiting walls because of the need to maintain concentration gradients, so they remain bacterium-like in morphology to this day. This is an alternative to the phagocytotic theory of the origin of mitochondria and chloroplasts. Modern blue-green algae genetically resemble the DNA in chloroplasts, and modern aerobic bacteria have genetic resemblances to the DNA in mitochondria, but this is not necessarily differential support for the phagocytosis theory. The resemblances can be accounted for by convergent evolution or by the existence of an ancestor common to the modern organisms and the ancient colony formers I suppose here.

11-15-2017

These prokaryote colonies would have originally reproduced by sporulation, not mitosis, which would have come later. The "spores" would be actively-metabolizing prokaryotes and before growing into further colonies, would be subject to natural selection. In the spore phase, the rapid evolvability of typical prokaryotes would have been recovered, allowing the formation of large, slow-growing colonies without sacrifice of the high evolvability of the original solitary prokaryotes. Modern-day eukaryotes often secrete tiny bodies called exosomes containing all the macromolecules of life. Exosomes may be the evolutionary vestige of the sporulation phase of the original eukaryotes.