Non-gaussian Bell Curves in Alien Civilizations

Numerate people are familiar with the bell curve. It is a simple result that crops up in elementary probability and in the translation of its results to some simplified genetics. If you have some quantitative attribute, like height, and have a number of genes that contribute to it, each with their own amount, and then you have a gene lottery in which these genes are selected randomly, the population will have a distribution of heights that looks like a bell. There will be a median height, and heights above and below it will drop off according to the gaussian curve. This has its limitations, as obviously there would be no aliens with heights ten times the median, but it is a good approximation.

If aliens on some planet reproduce bisexually, as do all higher organisms here on Earth, then there may be a complication which arises if there are genes which both affect the external quality, such as height, and also the success of a haploid cell in the fertilization process. If there is a positive correlation, such as between height and haploid success, then there will be more embryos with genes that contribute to more height, and the resulting bell curve will bend toward taller individuals. The opposite result happens if there is a negative correlation between the attribute and haploid success of cells containing genes which increase that attribute. If there has been convergent evolution between the alien planet and Earth so that the alien species there reproduce with sperm-egg meiosis, any genes which contribute to the viability and fusion success of either the sperm or the egg will have some evolutionary advantage, and also those related to motility of the sperm. If these genes also affect an attribute, such as height, there might not be a gaussian bell curve, but instead a bell curve following a different formula.

These results are an effect of a double function of a particular gene, and double functioning genes that affect two attributes can also result in a distorted bell curve. Thus, even before environmental effects are considered, there can be non-gaussian bell curves for some attributes.

The external environment can have an early or late effect on the success of a particular gene or combination of genes. These effects are part and parcel of the fitness tests that evolution provides to each planet to improve its gene pools, or better said, to adapt its gene pool to a particular local environment on the planet where some species inhabits. The attribute distribution curve after each particular test will be affected by the results of test on survival. If height improves survival of infants and toddlers, it will be selected early, and after this test there will no longer be a bell curve of the exact gaussian variety, but a distorted one. For example, if very short individuals do not survive the litter of a species which produces large litters at each birth, the curve of heights will be clipped at the bottom. Similarly, if height is a disadvantage, for example because of increased caloric requirements, the curve will be clipped at the top.

The more interesting phenomena is when an attribute, in an individual’s interaction with the environment, affects itself in a kind of feedback loop. Consider height of juveniles of a species on some alien planet, where there is competition for food, and consider that height assists in the competition for food. But also consider that an increase in food intake in a juvenile individual results in more growth. Then what we have is the upper tail of the bell curve stretching itself out toward even taller individuals. If an infant of the species has won the genetic height lottery, it is then more capable of out-competing others who did not, and it becomes even taller because it has obtained more food, which in turn has increased height all the way to adulthood.

There cannot be too many examples of attributes which can interact with the environment to increase themselves, but perhaps there are some important ones. Consider an alien immune system which becomes capable of resisting more infectious organisms by some means if it is successful in doing so. To be more clear, consider an alien species which has several immune responses to infections. One of them grows more capable each time it conquers an infection, but the others do not. An individual with a better set of genes for the first type of immune system will conquer more infections with it, and that system will grow stronger and more capable each time. If it were possible to measure immune system overall capability, the distribution curve would be stretched out on the high side because of this feedback effect.

What might make a tremendous effect on whether an alien civilization climbs to the pinnacle of technology, giving it interstellar interests and possibly capability, is the attribute of intelligence, specifically not literacy or numeracy but problem-solving. This variety of intelligence is what drives a civilization toward heights of technology, while the others play a supporting role. Suppose that the environment of an alien civilization, in its primitive stage, is such that intelligent individuals with higher problem-solving skills can be trained or can train themselves to have even greater problem-solving skills. One might imagine a civilization in which bright individuals, meaning ones which solve problems in a displayable manner in front of their parents or mentors or whatever they use, and is therefore rewarded by being given the opportunity to learn more tricks and techniques for solving problems. Alternatively, just imagine that doing problem-solving is a inherent learned skill in the higher levels, but is genetically based at the lower levels, and an individual with a high lottery score in the genetic basis of problem-solving has opportunities to learn and improve on his or her or its own. Then, with this feedback loop in place, the civilization will have a continual supply of individuals who can advance technology at different eras in the civilization’s history.

This concept, of environment providing positive feedback to intelligence genes, may be a deciding factor in whether a civilization progresses continually or does not. For example, it will be worth considering if a society at different stages of its progress will support such feedback actions or will dissuade them, perhaps totally inadvertently, before it understands the importance of what it is doing. In other words, can a civilization kill its own progress before it understands the requirements for continued progress?