Methodological Challenges of Psychohistory and Reflections on Aliens

Traditionally, the natural sciences such as physics, chemistry, and biology are built on a combination of theory and experiment (or observation). By repeating an experiment under the same conditions a sufficient number of times, we can verify the behavior of the system and theorize about the reasons for such behavior.

Several centuries after the beginning of the scientific revolution, we increasingly encounter research objects and systems that are difficult or impossible to study in this manner. Firstly, some systems are so complex that it is practically impossible to conduct repeated experiments under the same conditions. These systems have a multi-level internal structure, a rich interface for interacting with the external environment, and a memory of their past states. The most relevant example of a science that has undertaken the study of such objects, yet has achieved limited results, is cognitive science.

Secondly, there are systems we observe in only a single instance. For example, cosmology studies the properties of the universe, but how can we confidently answer questions about the general properties of different universes, why we live in this particular universe and not another, and why at this particular moment in time and not another?

Psychohistory, as the science of the development of human society, suffers from both of these difficulties: its subject of study is extremely complex and exists in a single instance. Similarly, the science of the origin and evolution of life is in the same position. Therefore, it might be interesting to discuss the book "Zoologist's Guide to the Galaxy," in which Arik Kershenbaum speculates on what intelligent aliens might look like and how we can reasonably approach this question.

If we agree that among the trillions of planets in our galaxy, there is at least one that has produced life, how can we predict what it looks like? The entertainment industry has created many variations of aliens, mostly either threatening in appearance (like the aliens), resembling humans in appearance and behavior (most races from sci-fi TV series like Star Trek), or entirely beyond human comprehension (e.g., Solaris). Most of these images do not withstand scientific scrutiny, but what can they offer instead?

When we try to describe conditions existing in the Earth's depths, on the Sun's surface, or a billion years ago, we assume that the physical laws governing nature are unchanged in both space and time. This principle of mediocrity, also known as the Copernican principle (Copernicus rejected the geocentric view of the world and "moved" the Earth from the center of the universe to an unremarkable position), implies that the entire universe is arranged approximately the same, and since we are in a random place (and time) within it, it is very likely that this place (and time) is typical, ordinary. Although this principle is not proven and likely cannot be unequivocally proven, there is a large body of observational evidence supporting it. More importantly, any alternative to this principle undermines, at least to some extent, the very possibility of understanding the universe.

So, if in physics, without being able to directly visit distant planets, we can still convincingly discuss the conditions on them thanks to the universality of physical laws, can we do the same in biology? Kershenbaum suggests doing just that, proposing natural selection as the driving force of evolution as the universal biological law, where less adapted individuals give way to more adapted ones. Alternative explanations for the diversity of living beings and their evolution, such as divine creation or the containment of all possible forms of life within a single cell, do not withstand reasonable criticism.

For evolution based on natural selection to "work," living beings (regardless of the precise definition of life we choose) must possess variability and heredity. Importantly, these two properties do not necessarily have to be implemented in the form of familiar Darwinian genetics, where organisms have (almost) unchanging carriers of information that dictate the properties of the organism. In the Darwinian world, the appearance of your children is predetermined at your birth (and the birth of your partner), and selection occurs through encounters or lack thereof with this partner. In contrast, Lamarck, a biologist who lived a few decades before Darwin, suggested that living beings could pass on acquired traits to their offspring, meaning the appearance of the children depends on when you produced them.

Consider, for example, giraffes and their long necks. According to Lamarck, giraffes spend their lives stretching their neck muscles to reach the upper branches of trees with juicy leaves. By reproducing, they pass on this trained trait to their offspring, and over time, giraffes as a species acquire long necks. According to Darwin, giraffes can give birth to offspring with varying neck lengths, but the short-necked ones die from not getting enough food. Over many generations, the average neck length grows, as short-necked giraffes die before reproducing. Weismann conducted experiments by cutting off the tails of mice and convincingly showed that Lamarckism does not work in our world (mice continued to be born with tails), which nevertheless does not mean that Lamarckian life cannot exist in principle.

It is also possible to transmit hereditary information through external carriers, such as environmental changes or what we call culture.

An indirect confirmation of the hypothesis about the universality of the law of natural selection is the phenomenon of convergent evolution. In living beings on Earth, there is a close connection between form and function. If a living being encounters a new task, the chosen solution will most likely resemble those found by its cousins in the past. For example, in the last billion years, flight has been independently mastered by living beings four times, eyes six times, bioelectricity six times, photosynthesis 31 times, and live birth at least 100 times.

The remainder of Kershenbaum's book is devoted to attempting to reconstruct how natural selection could act on alien life. Contrary to the clever initial hypothesis, this part is more speculative and vulnerable to criticism, as probably should be expected. He concludes that aliens ready for contact must be mobile, have a complex social structure, possess advanced communication methods, intelligence, language, and their technology must be based on abstract mathematics. If we depict such aliens using AI, we get something suspiciously similar to humans...