An Effort to Explain the Process of Body Formation
| Scientific Paper | |
|---|---|
| Title | An Effort to Explain the Process of Body Formation |
| Read in full | Link to paper |
| Author(s) | Per Jonson |
| Keywords | slime molds, cells, altruism, evolution, body formation |
| Published | 2009 |
| No. of pages | 30 |
Read the full paper here
Abstract
ABOUT THE ABSTRACT
Please note: The abstract is not originally written by the author of the paper, but consists of an effort to condensate the content in a shape common to scientific abstracts, performed by a son of his. He himself was due to his unprecedented decease unable to fulfil the publication of the paper.
ABSTRACT
In this paper a model for body formation is proposed, to a large extent founded upon a biologically extended concept of 'altruism', as contrasted to 'selfishness'. Though originally selfish, cells seem to be able to act, as if were there an altruistic option, available at events of deep crisis concerning the very survival of a society, as its destruction seems inevitable.
In the paper a special focus is put upon the properties of slime molds, but initially the situation for prisoners in a concentration camp during a night formation in a severe cold weather is described. Facing the common threat to freeze to death, they begin to unify as a group, paradoxically feeling joy and strength being together, in spite of the killing cold. External threats, that disable the individuals of a population from functioning, seem to release supreme, thus far hidden, functions of the individual cells, which enable them to together form a new body, on a higher existential level. However, once formed, these in turn begin to exert selfishness. Hence, it is possible to draw the conclusion that there exists a balance of forces between properties defined as altruistic and properties defined as selfish.
In connection with the process, during which cells under outer pressure unify with other cells, thereby attaining a higher state, they lose their selfishness and begin obeying the orders given by the new body. This is thoroughly being analysed in the paper.
Overview
This is a thirty-page essay written in Swedish in 1996 by Per Olof Jonson of Bandhagen (under the title Ett försök till lösning av kroppsbildningens problem), translated into English and posted in a September 2008 version. Jonson states plainly that he is not a biologist and will not use technical vocabulary he cannot master; the paper is an argued philosophical hypothesis rather than a research report, and it contains no experiments, measurements or calculations of its own. Its subject is a single question: what are the necessary preconditions for cells to form a body? Jonson holds that the standard evolutionary literature does not answer this question but merely names it — a colony of cells "becomes" a multicellular organism — and that the naming conceals a real discontinuity.
His proposal is that multicellularity is produced by a level rise: a sudden, non-gradual transition in which the individual cells of a population lose their selfishness, become "altruistic", and pass under the control of a newly existing "superior function" belonging to a body one level above them. The trigger is not selection pressure of the ordinary kind but a catastrophe situation from which escape is impossible. This departs from the Darwinian account in a specific way: Jonson accepts that selfishness is the fundamental property of every free-living organism, but denies that a population of selfish individuals can, by its own resources, produce an unselfish co-operating body. Something must be added, and that addition is not itself Darwinian. He therefore proposes to restrict the doctrine of evolution "to biological individuals, directly subjected to the environmental pressure", and to treat the level rise as an appendix to it.
The argument
Three cases: prisoners, pilots, slime molds
The essay opens autobiographically. Jonson reports reading Bruno Bettelheim's The Informed Heart, in which Bettelheim describes a night roll-call in a concentration camp during severe cold. After twenty prisoners froze to death the ordinary order of the formation broke down; the individual prisoner "had to disappear within the mass", the guards' threats lost their effect, and the men reported an "almost orgiastic feeling of happiness", free of personal fear and able to help others. After fifty deaths the ordeal was stopped, the euphoria vanished and individual fear returned. Jonson's decisive observation is that the prisoners had, for a time, acted as one "body".
He connects this to two other memories: the fighter pilots of Richard Hillary's The Last Enemy, who described an inseparable fellowship the survivors could not leave behind, and the cellular slime molds (Myxomycetes) described by Robert Ardrey in The Territorial Imperative. The slime mold life cycle supplies the paper's central model. The amoeboid cells feed on soil bacteria and divide every three or four hours; when the food within the territory is exhausted, they cluster around a founder cell, cling together into a "sausage-shaped slug visible to the naked eye", move toward heat or light, raise a stiffened peduncle and form a spore sphere at its top. Jonson notes Ardrey's further reported facts: a gas that repels neighbouring groups while attracting the clan, a signal that the whole population obeys at once, and the observation that the number of fruiting societies in a given area depends on the space, not on the number of cells — a thousand cells and ten thousand cells both give about ten groups.
Phase one, phase two and the level rise
Jonson distinguishes phase one — a territory of free, selfish cells reacting directly to environmental pressure — from phase two, the slug. Ardrey classifies the slime mold territory as "a society of outward antagonism, isolated and unified by the defense of a social territory", but Jonson insists this covers only the period up to the signal. What follows is not a territory at all: "a body-like society is something completely else than a territory", and the difference between the phases is specific, not gradual.
He models phase one with a four-arrow diagram: environmental pressure acts on the gene set, the gene set on the cell, the cell only exceptionally back on the environment. The catastrophe arrives when the gas barriers of neighbouring groups have become too strong to break and the food is gone. The cell "is forced towards a collapse and is unable to react upon the environmental pressure"; its selfish routes to survival and reproduction are eliminated. When the collapse is total — when cellular selfishness "has been set to zero" — a momentary reaction transfers the cells into the altruistic state, the slug appears, and it is now the slug, not the cell, that is the biological individual exposed to environmental pressure.
The balance of selfishness and altruism
From this Jonson draws the paper's most general claim, an equilibrium principle: the selfishness of every biological individual balances the altruism of all its parts. The selfish cells of the territory are replaced by one selfish slug, so "the sum of selfishness during that level rise is constant"; altruism without a corresponding selfishness cannot exist, and vice versa. He concedes at once the obvious difficulty — "it is difficult to think of any method to quantitatively measure selfishness respectively altruism". He also proposes that as latent altruism accumulates in the territory population, latent selfishness accumulates simultaneously in the not-yet-existing higher identity.
He offers definitions to match: selfishness is a necessary property of biological individuals at every level; altruism, or its equivalent, is the necessary property of non-biological individuals — parts that belong to a biological individual of higher order, ruled by its superior function and reached by environmental pressure only through that higher individual.
Relations between the levels
The two phases are held to be causally sealed from each other. The superior function governs only the slug's cells; it does not reach back into the free cells of phase one, or the balance between the phases would be disturbed. The contact between slug and cell is strictly one-way. A cell inside a body — Jonson's example is a cell in an eye — has a purely local task, perceives the body's directives as instincts, "incomprehensible but absolutely imperative", and cannot form any conception of the body, of the outer world, or even that an outer world exists. Were such a cell to lose its altruism by mutation, the whole structure of the body would appear to it meaningless or hostile.
Because the slug's cells do not divide after the level rise and cannot be physically changed without DNA-directed division, only behaviour can develop in the slug. Jonson therefore requires that every cell carry the whole behavioural programme — an "inner plan" — and activate whichever part corresponds to the position it happens to occupy. This is why the slug forms "rapidly and without roundabouts".
Extension to normal bodies
Jonson then transfers the model to ordinary embryogenesis. A population is a prerequisite for a level rise, so a fertilised cell must divide a few times first; citing Bonner on the equipotentiality of early embryonic parts, and Lennart Nilsson and Lars Hamberger's remark that the great mystery is how each early cell knows what it will become, he proposes that eight (he notes the figure has since been revised to sixteen) identical cells each carrying the complete programme constitute the phase-one population. His answer to Nilsson's question is: "Before the level rise the cell does not know what it shall become. That is being decided after the level rise." The catastrophe that triggers the transition, he speculates, is the confinement of the dividing cells within the enclosing membrane, which after a few divisions makes the situation "precarious". A lasting body formation requires that the catastrophe be repeatable in every generation — an unavoidable link "built in to the system of lasting bodies".
Criticism of the received accounts
Chapter 9 surveys what Jonson found in the literature available to him. From Gould's The Panda's Thumb he takes the two standard scenarios — cells aggregating into a colony that develops a division of labour, and compartmentalisation within a single protist — and says he cannot judge them but doubts they solve the problem. Bonner's answer, that multicellularity was driven by the advantages of larger size, he treats as describing an incentive rather than a mechanism. Bonner's "continuum between the two extremes", with every intergradation on display among living algae and protozoa, is exactly the gradualism he rejects. Against Dawkins he argues that "cell colony" and "gene colony" are labels, not explanations: "it is impossible to derive sufficiently strong forces from the colony concept"; a colony lacks an identity of its own; and it is the cells, not the genes, that actually perform the level rise, since "genes are unable to act".
Altruism, reward and value neutrality
The last chapters push the argument into ethics. Kin-selected self-sacrifice — dying to save two siblings or eight cousins — is, Jonson says, gene-selfish and so no counter-example; but he adds that an individual will not in fact sacrifice its life without a reward, and that in Bettelheim's camp the reward was the euphoria of the temporary level rise. He posits a second "genuine force", the reproductive force, to explain the mother who dies for even one child, where the gene arithmetic does not add up. Finally he argues that scientific value-neutrality is itself a consequence of assuming a continuum: if life exists only at delimited levels, then at the boundary a genuine choice between a higher and a lower state exists, and the concepts higher and lower, better and worse, acquire validity. Quoting Gould on geologists who "held firm to the dogma that catastrophic causes must never be invoked so long as any gradualist alternative existed", he ends by saying no gradualist alternative will succeed for body formation, and that a level above one's own can neither be observed by natural science nor denied.
Assessment
The essay's attraction is that it takes seriously a question most textbook treatments answer by paraphrase. "A colony became an organism" is not a mechanism, and Jonson is right that the passage from a population of independently reproducing cells to a body whose somatic cells forgo reproduction entirely is a genuine transition requiring explanation, not merely a longer stretch of the same gradient. His choice of the cellular slime molds is well judged: they are the one case in which the whole transition happens in the open, on a laboratory bench, within hours. The insistence that the somatic cell's surrender of its own reproduction is the crux, and the observation that the trigger is a resource catastrophe from which the cells cannot escape, both point at something real — starvation is in fact what initiates aggregation in Dictyostelium. His question to the embryologists — how the identical early blastomeres come to differ — is a fair one, and his refusal of the gene's-eye reduction ("genes are unable to act") is a coherent objection, if not a new one.
The difficulties are correspondingly large. The central mechanism is asserted, never derived. "A momentary reaction will take place, which is setting the cells into an altruistic state" describes the observed aggregation and then renames it; the "superior function" is introduced as an explanation but is given no properties beyond those the slug is already seen to have, and Jonson himself concedes that he cannot say how it communicates with the cells — "it is hopeless for me to try to come any further". The equilibrium principle, that the selfishness of a body equals the summed altruism of its parts, is the paper's boldest claim and is unfalsifiable as stated; Jonson admits there is no way to measure either quantity, which leaves the balance a metaphor rather than a conservation law. The argument also leans throughout on a psychological analogy — prisoners, pilots — that is doing real inferential work: the euphoria of Bettelheim's prisoners is offered as evidence for a "hypothetic euphoria on the molecular level" that serves as the superior function's "reward". Nothing in the paper supports the transfer, and Jonson's own device of granting cells feelings as an "intellectual experiment" quietly becomes an argument.
Against established observation, the model has two specific problems the paper does not address. First, Dictyostelium aggregation is chemotactically driven by cyclic AMP signalling, a mechanism identified in the 1960s and 1970s and not mentioned here; the "signal obeyed by everyone" that Jonson treats as mysterious has a known chemical description, which does not by itself settle his philosophical point but does remove the mystery he builds on. Second, the claim that after aggregation the cells become uniformly altruistic and simply obey is contradicted by the extensive later literature on cheater strains in social amoebae, in which lineages preferentially contribute to spore rather than stalk — precisely the selfishness within the body that Jonson's balance principle forbids. His claim that cell division ceases entirely after aggregation, and his account of embryogenesis as a single momentary level rise at the eight- or sixteen-cell stage, are likewise stated without support and sit awkwardly with continuous, staged, regulative development.
Finally, the paper's rejection of gradualism rests less on evidence than on a felt impossibility: Jonson repeatedly says he "can barely believe" or "cannot conceive" the alternative. The known intermediate forms — Volvox and the volvocine algae above all — are exactly the graded series his argument requires not to exist, and they go unmentioned. Read as what it is, an unfinished philosophical essay by a non-biologist, published posthumously by his son from a manuscript he did not live to complete, the paper is honest about its own limits, careful to mark its speculations as speculations, and worth reading for the sharpness of its question rather than the strength of its answer.