So far in the series, we’ve gotten a range for N, the number of detectable civilizations in the galaxy, to [5e-7 to 8e-6] * f_c * L. Today’s post will estimate the value of f_c, the fraction of intelligent species that go on to develop a civilization detectable (through electromagnetic transmissions and/or probes travelling at a sizable fraction of lightspeed) across interstellar distances.
A common assumption in science fiction is that intelligent life forms will inevitably build high-tech civilizations. Similarly to the typical view of inevitable evolutionary progress toward intelligence which I demolished previously, this common assumption smacks of whig history. Of course progress is a law of nature. It gave rise to the pinnacle of existence: us.
To the contrary, there’s nothing inevitable about the rise of high-tech civilizations. Douglas Tainter in The Collapse of Complex Societies (New Studies in Archaeology) points out that among hunter-gatherers and slash-and-burn agriculturalists, social complexity only forms on the Big Man model. A Big Man only gains and keeps followers by offering them rewards they could not get on their own. (For “rewards” read booty plundered from outsiders). When the rewards per follower shrinks–when the outsiders fight back or flee, and/or when the number of followers grows, it becomes tougher and tougher for the Big Man to keep lashed together his rickety coalition of self-interested followers. So the followers abandon the Big Man, and the cycle renews itself.
Examination of human history shows that a drive towards ever more advanced technological civilizations is the exception. The norm? Every every increase in agricultural productivity leads to an increase in population. The vast majority of societies are trapped on an ever-accelerating Malthusian treadmill. It is only rare exceptions that allow a society to jump off the treadmill by reinvesting their agricultural surplus in technological prowess, rather than more mouths to feed. In our world, it began only in northwestern Europe, and has been flowing out in fits and starts for only a few centuries.
What was special about northwestern Europe? The takeoff in European civilization starting in the high Middle Ages, and accelerating with the age of exploration and the scientific and industrial revolutions, is correlated with a number of rare features of human societies.
- Some sociologists want you to believe the nuclear family and unequal inheritance are recent and aberrant inventions. In reality, nuclear families, as well as families where unequal inheritance of the parents’ estate is not only permissible, but common, originated centuries ago in the Celtic and Germanic fringes of Europe. England was the first society to adopt these traits, and was also the society that brought about the Industrial Revolution. Coincidence?
- Northwest Europeans also developed patterns of late marriage and small families. Perhaps as a response to the cool summers and long winters of their homelands. As should be apparent, social structures encouraging small families disrupt the Malthusian ratchet of more food -> more children, in favor of a dynamic of more food -> fewer farmers -> more workmen, artisans, technologists, and scientists.
- Geography may not be destiny, but it can have beneficial impacts on societies. The English Channel and the North Sea gave Britain natural defenses, reducing the risk of invasion, thereby allowing smaller standing armies. Both those features are conducive to peace, order, and good government, which in turn helps a society develop science, mathematics, and engineering, as the English did up to and through the Industrial Revolution. (Note also, Japan has the same geographic advantage, and was the first Asian society to adopt Western advances in science, mathematics, engineering, and industrial productivity.)
- We can’t underestimate the effect of historical accident. The Chinese invented movable type. However, in Europe, the movable type printing press, coupled with the Latin alphabet and the Protestant reformers’ insistence on the priesthood of all believers and each person’s right to read the Bible for himself, gave rise to the historically aberrant mass literacy prevailing in Protestant Europe by the 1800s, and spreading to Catholic Europe by the early 1900s. It should be clear that mass literacy improves the spread of knowledge, from cutting-edge physics to basic skills.
- Did domestication of livestock play a role? From early times, Europeans used horses and oxen to do work that in China required massive armies of people. This may have allowed Europeans to free up human capital for more skill intensive work then farming or porting products. Europeans also benefited from the caloric boost provided by the combination of cows and lactase persistence.
Which of these factors (or some others) were necessary or sufficient for northwestern Europeans to start on the path toward high technology civilization? Whatever the answer to that question, the important point for us is that high technology civilization is an uncommon occurrence. (Consider that China, where movable type, gunpowder, and numerous other technologies first appeared, failed to start on that path).
Time to put a value on f_c. Any value will be imprecise. But given the contingencies, as well as my contrarian desire to poke a finger in the eye of believers in whig history, I’ll say only 1% of intelligent species develop high technology civilization. That sets the value of f_c at 0.01.
Our value for N, the number of detectable civilizations in the galaxy, is now [5e-9 to 8e-8] * L, where L is the longevity of the civilization’s ability to send across interstellar space either messages or probes traveling at a sizable fraction of the speed of light.
What then is the value of L? Find out in our next post in the series.