Wednesday, September 28, 2005

Biology and Culture : An interactive co-evolution.

Two recent papers published in Science point to a rapid evolution in Humans of two developmental genes known to regulate brain size (2005, vol. 309, p.1717-1722). This rapid evolution, which is different between ecogeographical regions, seems to be initiated along with radical and historical changes in the Human environment, migrations and agriculture. Researchers don't want to speculate about this because, as impressive as they can be, these are preliminary data. They must be confirmed by more investigations focusing on the precise phenotype of these genes, their physiology and more importantly, in my opinion, there must be quantification, with MRI techniques, of the differences these genes introduce in the phenotype of the brain . Moreover, these genes are probably not the only ones involved in regulating brain size. A year ago, researchers published a finding concerning a Myosin gene mutation in the jaw. This mutation relaxes the jaw muscles. It was speculated that this fact might have contributed to the expansion of the cranium and consequently to a larger brain (Nature 428, 415–418, 2004).

These findings are fascinating. They point to a new direction in many research areas in the brain and mind sciences. Indeed, some beliefs related to these sciences will have to adapt to the new findings. One is that there is one direction to evolution, from genes to phenotypes, and that it is reproductive success which ultimately give a direction to evolution. Another is that the structure of the brain is the product of a random gene selection and a third is that genes are selected on the basis of their behavioral outcomes as ultimate phenotypes. These three assumptions are often part of the ideological arsenal of what is usually called evolutionnary psychology which is a radical version of adaptationist thinking. According to evolutionary psychology, the explanation of the rapid evolution of genes controlling brain size during development can go like this: an allele is selected randomly and it becomes dominant in a population because it gives his owner more fitness - based on the outcome of the gene on the behavioral level - accompanied by reproductive advantage.

This kind of thinking, however powerful (and I am not saying true), does not apply to genes involved in developmental regulation of the phenotype. Why ? Because development is a construction based on interactions between genes and environment. Depending on the developmental stage, these interactions have different pathways . In the evolutionary psychology paradigm, they are carried out mainly by the behavioral outcomes of the gene - note that, most of the time, behavioral outcome is not fully displayed in species with a very slow development like Humans. During development, pre and early post natal, interactions between genes and environment are more likely to be carried out by structural constraints related to the whole organism. Starting at the level of the interface of the organism and its environment, they are transmitted to lower levels of structural organisation in the organism. In humans, the body, its sensations, motions and affects are the primary interface for genes/environment interactions. These interactions are mainly translated, in early development, into constraints on the construction of the organism which go down to the structure of genes.
Phenotype regulation during development acts on forms and not on behavioral outcomes since these outcomes are determined later at maturity. This kind of selection is exerted at the level of an individual organism, it is not populational.

The findings above point to a possibility that the environment - including the one that is our own making like migrations and agriculture - introduces structural constraints on the expression of genes in the construction of the organism, playing an active role in the phenotypic outcome at the structural level and thus directing the evolution. The term 'positive selection' used by the researchers to describe the process of the rapid evolution of genes controlling brain size is nothing else than directed - and not random - selection. Selection directed by the environment. Indeed, positive selection occurs when selection favors only one allele increasing its frequency in a population, where random selection operates on more than one allele.

Arguments against directional selection claim that directional selection is actually an instruction and not a selection. This kind of thinking is erroneous since it assumes that the environment 'knows' what it is doing. There is no 'anticipation' of adaptation in the process, there is only a joint effect on the construction of organisms during a developmental period in which organisms are dependant on their environment for their survival, as in the case of slow human brain development. This slow development is even magnified by an increase in the size of the brain which extends the duration of the maturation process.

What does this mean for us as Humans and as a society ? It means that the environment we are changing continually with our cultural artifacts and products and with our social expertises - which are passed on across generations - is contributing to our biological evolution. It means that Culture is irreversibly grounded in Biology. It means also that radical environmental changes of any kind, being physical, cultural or social, have an impact on our destiny as species for generations to come.

However, in the case of Human brain environment, instruction - as knowledge transfer - is an essential part of the interactions between the organism and its environment. But even though it is directional for the behavioral outcome, it 'knows' what to expect, it is not directional when it comes to structural constraints it may place on the organism and the brain at different organisational levels. At the structural level, instruction is a blind and a neutral process, value free. It has however an unanticipated advantage: it produces additional variations in the phenotype, induced by the environment and not included in the initial genetic program inherited from other species. These value free variations are specified in a social context. We are then responsible for the values that will be attached to these variations.

There is a big challenge here. As Humans, we have the knowledge and the moral capacity to judge behavioural outcomes of gene/environement interactions during development. From these behavioural outcomes we must anticipate and construct an ethic of harmony and agreement between Nature - biological nature of Humans - and Nurture in which every generation must take lessons from the past - the impact of past expertises on present behavioral and environmental outcomes (including man made social and ecological changes) - to build a better future for the generation to come. This is a great responsibility that falls upon us, a responsibility in which every man and woman have to become their own god.

11 comments:

Najmeh Khalili said...

" God is a conjecture: but I should like your conjecturing restricted to conceivable. Could ye conceive a God?--But thet this mean Will to truth unto you, that everything be transformed into the humanly conceivable, the humanly visible, the humanly sensible! Your own discriminant shall ye follow out to the end! And what ye have called the wold shall be created by you: your reason, your likeness, your will, your love, shall it itself become! And verily for your bliss, ye discerning one. ... thus spake Zarathustra."

Nietzche saw the relationship between culture and nature in terms of a dielectic. Every epoch in the history of human evolution, by which Man transforms nature by technology, is also a period in which the nature of Man is transformed. Each period then gives rise to a (physical) ideal of Man, a special category which is also and simultaneously a new body. [However,] Neitzsche rejected Darwinism as false scientific optimism. For Nietzsche, modern society had brought about, not the survival of the fittest, but the survival of the most degenerate ...

I'm quoting something that I was reading coincidentally at the same time I came across this blog [Recent developments in the theory of the body, Bryan S. Turner]. Somehow, this posting and the one a little further down "bad media and bad science" inspired me to share a my little grin with others ... "the survival of the most degenerate?"

Sonia Mansour-Robaey said...

The theory of evolution does not imply progress but merely continual change. The idea of change as differentiation from the homogenous to the more heterogenous was probably borrowed from Karl Ernst Von Baer, a baltic-german developmental biologist http://www.zbi.ee/baer/laws.htm
But the Harvard biologist Richard Lewontin recognizes that some interpretations of the theory of evolution, like sociobiology and evolutionary psychology, hint at the idea of progress: http://www.nybooks.com/articles/18363

''Darwin himself avoided implications of general progress or of directionality. It should be noted that his great work is unideologically titled On the Origin of Species, not On Evolution, and the word "evolution" nowhere appears in the first edition of that work, which thus neatly avoids, by intent or not, any implication of an unfolding of a progressive program. Equally revealing is the title of his work on human evolution, a field in which its more recent practitioners find notions of progress and directionality all too tempting. Darwin's title is The Descent of Man.[3] The theory of evolution was not a product of a commitment to progress but a reaction to a consciousness of the instability of the social structures that characterized the bourgeois revolutions and the radical changes in them...Despite Darwin's caution, notions of progress and directionality have indeed reappeared from time to time in evolutionary theory, especially in discussions of human physical and cultural change. However, the modern empirical science of evolutionary biology and the mathematical apparatus that has been developed to make a coherent account of changes that result from the underlying biological processes of inheritance and natural selection do not make use of a priori ideas of progress. It is true, as Ruse points out, that two of the originators of the mathematical formulation of evolutionary dynamics were ideologically committed to some form of meliorism, if not perfection. Ronald Fisher in England was an advocate of eugenics, and both he and Sewall Wright in America formulated the principle of natural selection as a process of increasing, from generation to generation, the average fitness of members of a breeding population. Yet these formulations make no predictions about a general progress of species.
This may seem odd, since the process of natural selection is supposed to make organisms more fit for their environment. So why does evolution not result in a general increase of the fitness of life to the external world? Wouldn't that be progress? The reason that there is no general progress is that the environments in which particular species live are themselves changing and, relative to the organisms, are usually getting worse. So most of natural selection is concerned with keeping up...Judging from the fossil record a typical mammalian species lasts roughly ten million years, so we might expect to last another nine million unless, as a consequence of our immense ability to manipulate the physical world, we either extinguish ourselves a good deal sooner or invent some extraordinary way to significantly postpone the inevitable.''

As for Nietzche, he formulated his opposition to the theory of evolution at a time when sociobiology was a dominant interpretation of the theory and sociobiology is committed to a certain form of meliorism, the survival of the fittiest. Behind the ideas of the survival of the fittiest or the most degenerate is a commitment to a certain form of idealism which we can call, in the case of Nietzche, the idealism of the origins and in the case of sociobiology, the idealism of the future. But as Lewontin points out, the environment seem to become less and less welcome to a certain species during evolution. So the idealism of the origins on Nietzche's part could well be the idealisation of the original environment of the first moral human being, while that of sociobiology could well be the idealisation of the process of elimination and adaptation to the worse, the future of a given species.
In many regards, Nietzche's views constitute a real challenge to sociobiology and evolutionary psychology but not to evolutionary theory itself. They stand only as long as there is an idea of progress in evolutionary theory.

Philippe said...

"In humans, the body, its sensations, motions and affects are the primary interface for genes/environment interactions. These interactions are mainly translated, in early development, into constraints on the construction of the organism from the interface to the structure of the gene.
Phenotype regulation during development acts on the form of organisms and not on their behavioral outcome since this behavioural outcome is determined later at maturity. This kind of selection is exerted at the level of an individual organism, it is not populational"

You are putting a lot of emphasis on the body as the interface between genes and environment. I would be enclined to put the emphasis on the social building of human specific competences. These competences are embodied of course, but the most important is that the slow developing brain allow for durable and iterative interactions with the environment which have the potential to amplify or reorient dramatically phenotypes driven initially by genes. As these interactions are iterative, they are more and more driven away from the original phenotype. In fact, genes are never interacting with the environment, what interact with the environment in the genotypic value, meaning the phenotype change determined by a gene change. This phenotypic value can be dramatically changed during its interaction with the environment. A simple example of that is the fact that having an oral anatomy suitable for language does not give a human phenotype unless the child has a long and iterative exposure to adult language and communication.

Olaf Krassnitzky said...

To be adressed more fully later:

"progress" cannot be applied to evolution, scientifically, since it is a value judgement.

But there is 'progression' in evolution:
e.g.
towards more complexity (in the individual and ain the biosphere)
towards more variety (such as through mate selection).

I suspect that the notion/metaphor of "survival of the fittest" (and the implicit value judgement) made it humans to nature first, rather than the other way, and then made it back to humans. An individual organism may be perfectly fitted to survive in a given environment, but still not be selected as a mate. And the less complex (e.g. bacteria)has a better survival record than the complex.

Progression is neither good nor bad.
It just occurs.It is worth thinking about the joint progression of variety and complexity.

Also consider that in mate selection, female brains (or nervous systems may be doing the selecting, i.e. it has intentionality and meaning at some level), whereas the environment is just a selecting contingency (with no meaning or intentionality).

So, progress is out, but not directionality - but directionality without ultimate aim. We are just so gioal bound that we have tgrouble imagining "direction" without goals.
But entropy has direction, doesn't it?

Sonia Mansour-Robaey said...

I agree with you Olaf. Do you know that in an earlier version of ''The origins of species'', published after Darwin's death, there are no mentions of 'fitness', 'adaptation' and 'survival'. Only in the second and official version there is only mention of the survival of the fittiest. What is troubling also is that the theory of evolution borrowed a lot from social theories of its time, when it was first published. Darwin was really hesitant before publishing on some details. On Darwin there is an excellent biography by Peter Bowler (Darwin, 1994 or 1995).
SJ Gould used to say that the theory didn't work quite well for Adam Smith but it worked for Darwin ! Now we are in the opposite situation where social theories borrow from the theory of evolution.

As for Entropy, yes, it has a kind of directionnality and it may charchterise some features of living systems but up to now I am still not convinced by current theoretical applications of the theory of information and entropy related theories to living systems.

Olaf Krassnitzky said...

Still not in the 'rythm'. I hope this one does not get sent twice.

Sonia (the name of my second daughter is Sonja, both derived from Greek Sophia "the wise one", as you probably know...),

Mostly Herbert Spencer.....

Survival only matters as to procreational success: crocodilians surviving, but not the dinosaurs, all the species threatened with extinction......

Mate selection and the involvement of a selecting brain in evolution, which itself is a product of evolution, remains side-stepped...

Of course, life is negentropic, but is it: a river flowing down an incline is an entropic process, but the kinetic energy released in the process can be captured in a power plant, which in turn can be used to build and grow....

This metaphor can used to describe life, which can store energy released in negentropic processes (chemical, light)and convert it into structure, metabolism etc....you can account for both directions (entropy, negentropy), but the latter is a temporary outcome of the former, given the contingencies prevailing on earth.

If you study life at the molecular level, all you have is really information and energy (or just energy, at an even lower level). It is just not information in the form we are using it in every-day life.But it is information of the kind we can observe operating in ecosystems.
Look at the root meaning of information: it "in"-"forms", i.e. it is a physical change of the form of something.
(not very postmodern, I suppose).

This physical change consumes energy,
which has to come from somewhere.....

So, if you don't use energy distributions and information in explaining life, how else would you explain it, and what role would you assign to those two kinds of phenomena? Do you think they can be set aside, once you know about them?

Sonia Mansour-Robaey said...

Two books had a great influence on me and they both consider life at the molecular and the Form levels.
Life as an exchange of energy: Vital Dust by Christian de Duve
Life as an exchange of in-formation: The evolution of individuality by Leo Buss.

olaf krassnitzky said...

The most effective way of my past profs to terminate a discourse was to say: read so-and-so and so-and-so. That way they did not have to declare what they are thinking. We are all products of what we have read, heard and experienced.I am interested in the outcome not in the sources - in other words, not in academic publications. Naj was a bit more accomodating and bloggish in that respect.

Sonia Mansour-Robaey said...

My last comments were not meant to terminate a discourse but to claim my ignorance about such matters and to refer to very few people who attempted to explore these matters. How about that ?

Olaf Krassnitzky said...

Never sure: did not get there or censored by the blogger.I am used to a 'free speech' listserve of humanists. If you reject a comment, there should at least be an off-line communication scilines@on.aibn.com.Or if you must censor,post at least a note: comment from so-and-so moderated.Again, the two books had a great influence on you,in what way?

olaf krassnitzky said...

responsibility without accountability is difficult to conceive.Accountable to whom, for what, by what standards, and why?
Olaf.