culture as gene-flow regulator: the arunta

Gerold Firl (
17 Sep 1996 19:35:00 GMT

This post will put forth a hypothesis about some of the cultural
adaptations of the australian arunta as they relate to the problem of
gene-flow regulation in the difficult circumstances of the desert
outback. These ideas were posted here earlier this year, but I thought
it might be interesting to summarize them again, since there is a vocal
opposition to the idea of culture as a functional adaptation currently
active in the newsgroup. I'll try to show how a sociobiological
analysis of arunta kinship and marriage customs leads to falsifiable
predictions about the arunta lifestyle, which in the scientific
tradition is the best test for any theory.

Some salient facts:

In arunta ideology, conception is divorced from copulation. conception
is thought to result from the quickening influence of the local totem
spirit upon the mother. Husbands and wives have sexual relations, but
marital fidelity is not insisted upon, and at the periodic festivals
when large groups of the sparsely populated interior congregate, sexual
licence is encouraged. Arunta men undergo the process of subincision,
where the penis is slit from root to head through the urethra; semen
thus is not ejaculated so much as dribbled.


Given the low population density of the australian desert, gene flow
rates are low; that is, it takes a long time for genes to travel
throughout the population. This can be a problem; it essentially
decreases the genetic variety availible to cope with environmental
changes, leading to lower levels of fitness at the population level. I
propose that the features of arunta culture listed above are functional
adaptations which increase the velocity of genetic diffusion.

Subincision, in this view, would be a method by which the incidence of
marital impregnation would be minimized. Since semen is not ejaculated
against the cervix, birth control can be achieved very reliably. In
female-superior positions, fertilization can be easily avoided.

The idea that children are the offspring of the local totem, rather
than the biological father, would be a means of minimizing jealousy and
avoiding sexual competition between men.

The promiscuous sexual activity at large gatherings would accelerate
genetic mixing, since matings would occur between individuals who were
ordinarily more widely separated than typical marriage partners.


Large-gathering copulations have a higher incidence of male-superior
positions, leading to higher fertilization rates.

Young men on walkabout get laid a lot.


Complex, abstract, spiritual aspects of human culture are intimately
related to the problems of physical adaptation, and are amenable to an
evolutionary analysis. Some of the unusual aspects of arunta culture
should be expected to appear in other low density cultures, such as the
eskimos, where the benefits of enhanced rates of gene-flow have been
found to outweigh the costs of lower paternity-confidence.

Disclaimer claims dat de claims claimed in dis are de claims of meself,
me, and me alone, so sue us god. I won't tell Bill & Dave if you won't.
=-=-=-=-=-=-=-=-=-=-=-=-=-=---- Gerold Firl @ ..hplabs!hp-sdd!geroldf