Three conclusions that can be drawn after discussing the reasons for differences between people in the color of their skin. Column for Kompyuterra #123

{"author":"Dmytro Shabanov","title":"And more about skin color: why we are white and why we tan","subtitle":"Three conclusions that can be drawn after discussing the reasons for differences between people in the color of their skin\nHow to take rational control of our innate tendency to xenophobia?","columns":"Column for Kompyuterra #122\nColumn for Kompyuterra #123\nColumn for Kompyuterra #124","content":"The two previous columns were devoted to analysis of one, in general, quite simple trait of humans — the color of their skin. Do not think that I have exhausted the entire diversity of factors influencing this trait. Nevertheless, in this column I will no longer detail the example that I discussed in the last two times, but will calmly (and, I hope, not too confusingly) attempt to discuss what, in my view, follows from this.\n\nFirst conclusion. We discussed which ecological factors affect human skin color. Recall how ecological factors are classified.\n\nAll people who studied in secondary school in the late USSR, as well as in the new Russia and new Ukraine (if they actually studied and did not merely simulate learning), when asked about which groups ecological factors are divided into, confidently answer: abiotic, biotic, and anthropogenic. This wisdom has been migrating from textbook to textbook for quite some time. Let us try to understand its meaning.\n\nAbiotic — related to inanimate nature; biotic — generated by living nature. It is accepted that biotic factors can be divided into phytogenic (of plant origin), zoogenic (related to animals), and so on. Placing \"-genic\" and \"-ic\" factors in the same row is, in general, illogical. It would be more consistent to divide factors into abiotic, biotic, and anthropic (and the latter, in turn, divided into \"-genic\" groups, including among them anthropogenic factors, as done in this textbook). But the main collision does not consist in this. The given classification of factors is simply not ecological!\n\nIn the post-Soviet space, confusion continues regarding the meaning of the word \"ecology.\" Haeckel, who invented this term in 1866, gave this science an unambiguous definition:\n\n\"By ecology we understand the general science of the relations of organisms with the environment, where we include in a broad sense all 'conditions of existence'. They are partly of organic, partly of inorganic nature\" (Ernst Haeckel, 1866).\n\nOf course, Haeckel did not pull ecology out of his head like a frog princess from a sleeve. By that time, many scientists had already changed who were engaged in ecological, in the modern sense of this word, research. There was no word, no \"brand,\" and Haeckel provided it. Starting from Haeckel's time, there has been an unbroken continuity of researchers who study the connections of organisms (and systems of a higher level) with the environment. If you wish — here are several modern definitions of ecology (more detail — here).\n\nEcology is the science studying the interaction of organisms and supraspecific systems with the environment.\n\nEcology is a biological science that investigates the structure and functioning of supraspecific-level systems in space and time, under natural and human-modified conditions (international definition; the organism level is lost).\n\nEcology is the science about the interrelations ensuring the existence of organisms (including humans) and supraspecific systems: populations, ecosystems, and the biosphere.\n\nThe science that describes the environment has a completely different name in the developed world — \"environmentology\" (from environment — surrounding environment), which differs from the word \"ecology.\" Sometimes in Russian they use the tooth-breaking calque of this concept, the word \"envi­ron­men­to­lo­gy.\" I am convinced that one should use the simple and understandable word \"environmental studies.\" Alas, in the post-Soviet space they do not choose between \"environmentology\" and \"environmental studies,\" but inappropriately decline the long-suffering \"ecology.\"\n\nAs an example, I can cite the university where I work (which is, after all, in its third century of history). It has six people with academic degrees in ecology: four at the biology department (one of them is me), two at the research institute of biology. And the university also has an ecology faculty, where there is not a single (not a single!) person with a degree in ecology. And this is because the ecology faculty deals not with ecology, but with environmental studies.\n\nAnd so — everywhere…\n\nSo, the division of factors into abiotic, biotic, and anthropic is not ecological, but environmental. The very principle by which factors are divided into groups is determined not by how they affect the organisms and supraspecific systems we study, but by how they arise.\n\nAnd what approach to factor classification will be truly ecological? One in which factors are classified by their action on the system we study. However primitive the division of factors into favorable and unfavorable may be, it is constructed precisely from the viewpoint of the object on which they act. And the classification of factors by the mechanisms of their origin describes the environment in which organisms with very different requirements may find themselves.\n\nWhich classifications of factors will be ecological? For example, the subdivision into conditions and resources. Organisms consume and expend resources, but not conditions. Sunlight is a resource for plants and a condition for humans. There is no single correct ecological classification; from the viewpoint of the system being studied, many different approaches can be developed.\n\nSecond conclusion. One and the same environmental factor may correspond to several ecological factors that are significant for the biosystem we are considering.\n\nThe first example is given in the column itself. Ultraviolet irradiation (environmental factor; a set of quanta of electromagnetic radiation with identical properties) acts on the same person as several ecological factors simultaneously:\n\n— a source of energy for photochemical reactions, the result of which is the synthesis of an important regulator of calcium metabolism;\n— a cause of changes in the activity of folic acid, which influences reproductive activity;\n— a cause of somatic mutations that can potentially lead to skin cancer;\n— a regulator of melanin synthesis in the skin as a result of tanning.\n\nSome of these factors may be critically important, some — insignificant; one — favorable, another — threatening. And the quanta that cause these (and other: I did not list all!) reactions remain themselves, the same…\n\nNote that in the first case I listed, UV radiation is a resource, and in others — a condition. This is quite typical. It is often the case that the same environmental factor in the region of low values is a resource, and in greater amounts turns out to be a condition. If you wish, I will give a sinister example.\n\nWhat is borscht for a person? Of course, a resource. In the situation when it is a pot being poured into plates, this conclusion is quite obvious. This resource is obviously exhaustible: if several people eat borscht and one of them eats an extra plate, there will be less for the others.\n\nAfter the first year of university, I was conscripted into the army and ultimately sent to serve in the Pacific Fleet aviation (in Gorbachev's times this was possible). During one of the transfers, I found myself on duty in a huge fleet kitchen (naturally, there it was called the galley). Frightened sailors ran around the enormous hall, the floor of which very often turned out to be greasy (although it was regularly scrubbed). Electric cauldrons were set into the floor, designed, as far as I remember, for several cubic meters of contents. The edges of these cauldrons were below the center of gravity of an average person; running into such a cauldron, one could flip over the edge and end up inside. Supposedly not long before I arrived at this wonderful place, one of the sailors serving his duty fell into a cauldron of borscht and boiled.\n\nBorscht remained borscht both in the plate in front of the sailor and around him in the cauldron. The main thing changed — the mode of interaction. The main essence of ecology.\n\nThird conclusion. Do you remember, I began the first column with the fact that the same phenomenon can be explained at different levels? Depending on specialization and the direction of attention, different people tend toward different explanations. For example, I posted the previous column on my website, and there my colleague praised it. Once he was my graduate student and graduated from the zoology department, and then requalified as a geneticist. His reaction was predictable: \"Interesting, but there is a very lacking discussion of genetic mechanisms.\" When discussing any trait, geneticists first of all try to understand how it is inherited. Skin color, for example — a polygenic trait. Several genes simultaneously affect it, giving approximately the same effect. This leads to a phenomenon that has repeatedly attracted the attention of observant people.\n\nImagine that a typical-typical Negroid and a typical-typical northern Europoid cross. In the first, all genes affecting skin color are represented by alleles (variants) that maximally promote increased synthesis of melanin (dark skin pigment). In the second, on the contrary, all alleles minimize pigment formation. In their first-generation offspring, for each gene there will be one \"+\" allele and one \"-\" allele. By skin color, this offspring will be a typical mulatto. Much more interesting will be the offspring from crossing two mulatos with each other. Since for each gene the \"+\" and \"-\" alleles will be transmitted independently, some of the hybrids purely by chance will accumulate more \"pluses\" and become dark, and others will receive more \"minuses,\" and they will become light. A homebred theorist will begin to discuss that the \"stronger\" heredity of grandparents won over the heredity of parents, weakened by interracial hybridization…\n\nWhen we consider specific genealogies, without studying the inheritance mechanism of the traits that interest us, we cannot manage. However, for understanding why organisms are what they are and not some other way, genetics is almost useless. What state of the trait will be typical for the population we are interested in is determined by ecology (the nature of the connection with the environment) and history (the evolutionary trajectory). If for the survival of organisms in a certain population it is advantageous for them to possess a certain trait (i.e., possessing this trait increases the probable number of offspring they will leave), genetics will find a way to ensure the development of this trait. How? Even as a result of trials and errors!\n\nI will draw your attention to another characteristic difference between STE (the synthetic theory of evolution, which emphasizes population genetics) and ETE (the epigenetic theory, which focuses primarily on the problem of ensuring developmental stability). I have already repeatedly explained the difference between these theories in previous columns, and so will not repeat myself here.\n\nFor STE, the ability of genes to be inherited is the primary characteristic. How to describe the emergence of this ability within STE is not very clear. In the logic of this theory, first genes arise that have the property of causing the formation of certain traits and being inherited, and then a potentially infinite game is launched, in which selection supports more and more \"successful\" genes (selecting organisms depending on the traits that developed under the influence of these genes).\n\nFor ETE, a completely different logic is characteristic. The environment selects organisms possessing adaptive (corresponding to this environment) traits. Such organisms leave offspring with higher probability than their competitors. On the offspring (if the environment has not changed), the same selection acts, which selectively preserves the same traits. As a result, it turns out that organisms that turn out to be similar to their parents have an advantage. Thus, the property of heritability is created by selection.\n\nEvery trait characteristic of some species that we can observe is the result of the tremendous preceding work of natural selection. In it, as in a fragment of a hologram, the entire picture of the evolution of life on Earth is enclosed…\n\nWell, dear readers, from the theoretical discussions is your head not spinning yet? Excuse my teacher's zeal: having reported some fact, to spend a lot of time discussing the instructive conclusions that can be drawn from its comprehension. It's okay, next time I will try to write about something more specific."}