Comment on Sex and Fertility in the Post-Petroleum Age

Blog comment in response to Sex and Fertility in the Post-Petroleum Age by Jan Lundberg,  
27 July 2010

Look at Historical Evidence 
   
Developed societies like ours, with sanitation, medical care, artificial contraception, and optional bottle feeding of infants, are a recent exception in the history of humanity. The prevailing patterns over the history of our species have involved females becoming fertile at a somewhat later age (16-18 years old), due to less adequate food supply; prolonged breast feeding of infants, which suppresses fertility and ensures a longer inter-pregnancy interval; higher infant and maternal mortality; less investment of effort and calories in infants that have a poor chance of survival or less social utility (e.g., the Greeks abandoning deformed infants at birth); a certain amount of infanticide, usually by men, who kill a woman's children by a former male partner; etc, etc.

According to demographers, the controls over human fertility fall into four main categories: 
1. Who can have sexual intercourse with whom, and with what frequency and regularity--as determined by gender, age, tribal customs, behavioral controls; it's worth noting that assisted reproductive technologies, such as in vitro fertilization, have allowed modern humans to bypass actual sexual intercourse by having the equivalent take place in a petri dish--an option that will not be available under more primitive circumstances;
2. The chance that intercourse will result in pregnancy--as determined by factors such as when intercourse takes place (relative to the fertility cycle), who is doing it with whom (gender), their fertility (related to nutrition, health, age, and whether the female is not ovulating due to full-time nursing of an infant), sexual techniques (intravaginal ejaculation versus withdrawal, oral or anal intercourse, or masturbation), and use of contraceptive methods;
3. The chance that a fertilized ovum will result in a viable birth--which relates to health and nutrition factors (dependent in turn on the amount of investment the individuals and the society put into maternal feeding and care), specific diseases, childbirth and delivery practices, and both spontaneous abortion (i.e. "miscarriage") and induced abortion; and
4. "Becoming a person"--neonatal death rates, and the specific practices and social investment in post-natal care, not only of the newborn, but the infant and toddler, which may or may not result in its survival to the age at which it can reasonably feed itself and participate meaningfully in the human community.

Human societies have always regulated their numbers by the combination of these factors they employ, however purposefully or unwittingly. Historically, the stable societies with the highest ongoing fertility rates have averaged 8-9 children per woman. This is achieved by fairly early onset of intercourse (mid- to late teens), marriage at an early age, very low divorce rates, good modern medical care for women, and high value placed on having children and caring for them.

It's also interesting to note some of the social controls societies have exercized through the four factors: delayed marriage (e.g., until the man can afford to own property); prohibition of pre- and extra-marital sex; a man having to marry his dead brother's widow; battering (to death) of a single woman's child by a previous partner; prohibition of homosexual relationships; abandonment of nursing infants as well as the elderly in times of famine (it being more valuable to preserve a self-sufficient, lactating female than a dependent infant); prohibition of abortion and/or contraception; permission of extramarital sexual relations; etc. Some of these practices favor population growth, others counter it. Often these various practices were adopted for what were considered religious, spiritual, economic, or cultural reasons, without their impact on fertility being considered explicitly--but they still have a net effect on population size.

In imagining what kind of society one would like to have in an overheated, post-collapse world, it is worth thinking through such factors to decide on the mix that would be reasonably likely to yield the desired population size and its stability under varying environmental circumstances.  

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