"Species Preservation Instinct"? Column in KomputerraOnline #62

Humans are capable of acting in the interests of humanity, and therefore it may seem to us that a wolf acts for the good of all wolves (wolfdom?), a starling — in the name of starlingdom, and a shark — for the sake of sharkdom. Is such anthropomorphism justified?
Some yoga website blithely asserts: "A human being, like any other creature on Earth, appears in order to ensure the prosperity and development of its species." Vasily Shchepetnev is more cautious: "There is a hypothesis that in every population there exists a group of individuals who unconsciously sacrifice themselves for the good of the species as a whole." Professional patriots, nationalists, Nazis, and other disreputable figures call upon people to self-sacrifice in the name of hypothetical supra-individual entities, insisting that this self-denial is biologically predetermined.
I will not discuss here the fact that people who invoke lofty ideals usually pursue purely selfish interests. More interesting is another question — does what is called the "species preservation instinct" actually exist?
What is written about this instinct on the internet! Sometimes it is considered the most fundamental of all, though it then includes the drive toward one's own reproduction. With reproduction everything is clear — it is easier to explain by concern not for the species, but for the spread of one's own genes. To understand whether concern for the species exists in its own right, one must look for examples of conflict between the interests of one's own reproduction and the "interests of the species."
My internet searches revealed much that was unexpected. I will share the most striking specimen (I will not give the link — it is not a site I would direct my students to; I will even change the wording). A medical doctor, a professor with a doctoral degree, argues for a style of marital relationship in which a wife, with her husband's approval, has an affair with another man and even becomes pregnant by him. After discussing evolution through gene selection, the author asserts that men instinctively strive, for the progress of the species, to have their wives impregnated by carriers of the best genes. This, he claims, is the source of the cuckold husband's pleasure.
Now imagine a gene that nudges a man to offer his woman to a superior sire. Will this gene pass to the next generation? The offspring will inherit the genes of men who did not think about the progress of the species but reproduced themselves.
How then to explain the existence of men who live by such rules, create special websites, and apparently are genuinely prepared to delegate the fertilization of their wife to someone else? By the complexity of our psychology. Genes are genes, but our behavior is governed by a unique personality that develops through the complex interaction of genes, culture, and experience. It is well known that sign reversals in such development (the transition from love to hate, from rejection to acceptance, and vice versa) are not uncommon. Genes influence these phenomena but are not their cause.
Is the altruism I have already written about here and here an expression of "concern for the species"? I maintained that it is a consequence of group selection, not species selection. Altruism appears in the form of parochial altruism or parochialism: a combination of love for "one's own" and hatred of "outsiders." Concern for the interests of humanity is provided by reason, not by biologically predetermined altruism.
Let us examine this carefully and establish the principal levels of selection. Fair warning: this topic is electrified by disputes among irreconcilable opponents.
In Darwin's time everything seemed clear: selection acts on individuals. Some survive and leave descendants resembling themselves; others do not. Darwin also allowed for competition between groups, connecting it, for example, with the evolution of altruism. The disputes began in the second half of the twentieth century. Let me quote the prominent American evolutionist Stephen Jay Gould:
"From above came the Scottish biologist V.C. Wynne-Edwards, assaulting orthodoxy… claiming that not individuals but groups are the units of selection, at least in the evolution of social behavior. From below... came the English biologist Richard Dawkins, declaring that genes themselves are the units of selection, and individuals are merely their temporary vessels."
Do you know, for example, why starlings gather in large flocks in autumn? According to Wynne-Edwards, they observe one another, assess the size of the population, and determine how much offspring to produce the following year. To understand how to evaluate this hypothesis, let me examine a simpler case. One biologist tried to convince me that cockroaches in one's apartment must not be swatted with a slipper. When a cockroach is crushed, a substance is supposedly released that stimulates the reproduction of other cockroaches.
Regarding cockroaches, I do not believe that explanation. It contains an implicit claim that in the absence of crushed individuals, cockroaches restrain their reproduction (presumably devoting more time to philosophy and music). In the case of starlings, I have no certainty whether Wynne-Edwards's hypothesis is true or false. I admit that such a mechanism might operate, yet it can be explained by the starlings' "concern" not for the species, but for their own offspring.
Recall what I wrote about grey toads. Depending on the phase of their population's development, it is (as I hypothesize) advantageous for them either to maximize the number of their offspring in the coming years or the number of offspring over a long lifetime. Switching from one program to the other is beneficial for the transmission of genes by individual organisms, but this switching also promotes the flourishing of populations!
By hypothesizing the wide prevalence of group selection, Wynne-Edwards provoked his opponents. Matt Ridley writes about this as follows:
"Wynne-Edwards did biology an enormous service by revealing a gigantic fallacy that had systematically infected the very heart of evolutionary theory since Darwin's time. He exposed the fallacy not in order to destroy it, but because he believed it was true and important."
A number of brilliant opponents of Wynne-Edwards — among them George Williams, William Hamilton, John Maynard Smith, and Richard Dawkins — argued against group selection. Williams demonstrated that if a given form of behavior can be explained both by individual selection and by group selection, the former explanation should be accepted as the more parsimonious. In my previous column I expressed skepticism about faith in the parsimony of evolution, but my skepticism does not extend to Williams's arguments.
Other opponents of group selection went even further. Dawkins expressed their credo most vividly in The Selfish Gene. The primary (or sole) level of selection is gene selection. Individuals are epiphenomena, secondary entities. Their purpose is to serve as vehicles for genes. Dawkins's main argument is that changes that occur in organisms — and even more so in their groups — are not transmitted to subsequent generations (or are transmitted inefficiently). By contrast, changes in the genes of germ-line cells (sex cells — fertilized zygote — cells from which sex cells will develop — sex cells, and so on, potentially to infinity) are directly reflected in future generations. Consequently, only germ-line genes truly evolve; everything else is superficial.
The proponents of supra-individual selection were not idle either. The American palaeontologist Steven Stanley put forward the hypothesis of species selection, which was supported by other founders of the concept of punctuated equilibrium — Stephen Jay Gould and Niles Eldredge.
Although the set of levels of evolution claiming universality includes genes, individuals, groups, and species, many modern molecular orthodoxists maintain (usually citing Dawkins) that selection operates exclusively at the level of genes.
I have already had occasion both to cite research demonstrating high-level selection and to note that Dawkins himself acknowledged its possibility (if you are skeptical, read the sixth chapter of The Extended Phenotype, especially its final section). Dawkins merely argues that selection at the gene level is the most efficient, and therefore complex organismal adaptations should be explained by its action. In delineating the units of selection (replicators, in his terminology), Dawkins includes genes, the genomes of asexual organisms (as well as the semi-clonal hybrids of green frogs), the gene pools of species or other reproductively isolated groups, and memes (units of cultural inheritance). The question to be answered is not whether selection exists at levels higher than the genetic, but what effects it can produce and what it cannot.
In speaking of levels of selection, I am approaching a topic that strikes me as extraordinarily interesting. Do you remember the column about the Invisible Foot? When will selection in superordinate systems "prevail," and when in subordinate ones? In which situations will the selection of subsystems within a system produce the action of the Invisible Hand, and in which the Invisible Foot?
This topic calls for an unhurried discussion, and I will leave it for another time. For now I will describe how opponents of high-level selection implicitly invoke it in their own reasoning.
The same Ridley who calls group selection a gigantic fallacy, in his magnificent (without a trace of irony!) The Red Queen, presents an explanation belonging to Laurence Hurst of Oxford for why a spermatozoon contributes to the fertilized egg only its nucleus with genes, and nothing else. Follow closely.
In the cells of animals, plants, fungi, and protists, genes are contained, first, in the nucleus, and second, in organelles of symbiotic origin — mitochondria (in all) and plastids (in those capable of photosynthesis). These organelles reproduce by division, forming intracellular clones.
Imagine an organism in which mitochondria (or plastids) are transmitted along both maternal and paternal lines. Selection would favor those clonal lineages of organelles that enter sex cells more frequently and are thus transmitted more successfully to descendants. This would lead to competition among clones racing in speed of reproduction and in the secretion of substances that suppress competitors.
This is not a speculative conjecture. In the alga Chlamydomonas, plastids are inherited along both maternal and paternal lines. Ninety-five percent of them are destroyed in the course of a war between maternal and paternal clones that exhausts the entire cell! And therefore, as Ridley writes,
"...the nuclear genes of both father and mother conspire to kill the male organelles. The advantage (for the male nucleus, not for the male organelles) lies in belonging to a type that allows its organelles to be killed in order to have viable offspring as a result."
We observe a conflict of "interests" (vectors of selection) between the nuclear and mitochondrial genes of the male. Selection of mitochondrial genes promotes their entry into spermatozoa and endless tug-of-war with maternal mitochondria. Selection of nuclear genes supports those that will ensure the formation of spermatozoa that do not transmit mitochondria, thereby putting an end to the organelle wars. Perhaps in some cases the nucleus wins this conflict, and in others the organelles? No. Ridley emphasizes that the transmission of paternal organelles, as in Chlamydomonas, is an exceptional phenomenon. But why does the nucleus almost always win, even though selection presses more strongly on the organelles?
Ridley did not answer this question, but I will. Species in which the nucleus prevailed prove more stable than those in which the organelles prevailed. Species selection settles the outcome of the competition among different gene groups.
Thus, the "species preservation instinct" is a fairy tale not worth wasting time refuting. The problem of the relationship between selection at different levels, however, is of unquestionable interest. We will return to it.