Natural selection?: Die poor if you hold that stock

follow-up #8 -- In case anyone wants to talk about Hox-genes ....

Stephen Talbott: Hox genes in motion: who’s moving whom? Back in the days when DNA contained “all the instructions for making a human being”, it was the linear sequence of DNA that somehow carried a “code” for, among other things, the form of organisms — or, to put that last phrase more fittingly, “the forming processes in organisms”. It’s never been easy to see how this code might work. So when particular sequences known as “Hox genes” were eventually discovered playing a role in serially producing the body segments of insects and the vertebrae of (for example) humans, there was great enthusiasm. As these things always go, however, a progressively complex story began to unfold. It might have been expected that countless other factors would be found to be involved; but what is generally not expected — and yet always turns out to be true — is that there is no single locus of control. The Hox genes, far from being at the head of a chain of instructions, are managed in a highly patterned fashion by cellular and organismal processes as a whole. This pattern of activity, in fact, looks very much like the kind of forming activity biologists wanted to explain with Hox genes in the first place, except that it occurs at a finer level of observation. All of which illustrates the general truth that you can never find fixed structures to explain a forming activity. Rather, the structures are what precipitate out of — and subsequently get caught up in and functionally defined by — the activity. Well, none of this is really new, at least for anyone with an eye out for the life of the organism. But I couldn’t help noticing a particular irony in an otherwise not especially noteworthy paper entitled “Hox in Motion: Tracking HoxA Cluster Formation During Differentiation” (Rousseau et al. 2014). The paper amounts to one drop in the flood of current literature dealing with the organization and movement of chromosomes within the three-dimensional space of the cell nucleus. The irony lies in the fact that now — and the paper is one instance of this — researchers are exploring how the Hox loci on the chromosomes must themselves be brought into proper movement and spatial order in order to play their changing roles as cells differentiate. In other words, key DNA “instructional elements” supposedly dictating certain forming processes of the organism cannot even take their limited place within a wider pattern of activity without themselves being brought into proper form according to the needs of the context. It’s about time biologists explicitly acknowledged that their own distinctive understanding, aided as it may be by physical and chemical investigations, is — crucially, and whatever else it may be — an understanding of the play of form.

Box

Ok we don't know what really controls stuff in the cell. DNA has some "control", but is in turn controlled by various epigenetic factors; and so forth. But I'm willing to overlook all that. What I want to know is what could possibly coordinate trillions of cells. Obviously not DNA or epigenetic factors in individual cells, since they are being coordinated. Is there even a concept of something that has the adult form of a complex multicellular organism in 'mind' AND has the capability and power to direct en instruct trillions of cells? Is there even a candidate? Sure there is intercellular communication, but without instruction from a higher level what else than "I'm a muscle cell" can a muscle cell say to other cells? And how is that useful information to other cells? "There is a muscle cell next to me. Well that's good to know, because now I know what to do." No, you don't know what to do mr. Neighbour Cell, because you don't have the map of the adult form in mind and even if you did you wouldn't know what your position is. Box

The almost infinite computing capacity of random mutation was acquired randomly; an elegant conciliation and a most propitious dispensation of random providence. Coordination is random mutation's middle name. I think an initial looks better. Random C Mutation (although not of this parish, as, no doubt, Private Eye would add). Some have greatness thrust upon them. I'm afraid we shall just have to sit this one out. God does indeed has a rival to be reckoned with. Axel

The controllers control the coordinators. Mung

And who coordinates the coordinators? :) Box

The coordinators, obviously. They are a rather secretive cult though. Mung

//off-topic//

Shapiro: During embryonic development, cells make decisions about differentiation based on multiple molecular signals picked up from their environment and from their neighbors by means of surface receptors. These receptors are linked to intercellular molecular cascades called "signal transduction pathways" which integrate the inputs from the receptors to generate appropriate patterns of differential gene expression and morphogenesis of specialized cell structures. Signal transduction is not limited to multicellular development. We are learning that virtually every aspect of cellular function is influenced by chemical messages detected, transmitted, and interpreted by molecular relays. To a remarkable extent, therefore, contemporary biology has become a science of sensitivity, inter- and intra-cellular communication, and control. Given the enormous complexity of living cells and the need to coordinate literally millions of biochemical events, it would be surprising if powerful cellular capacities for information processing did not manifest themselves. [my emphasis]

From whence cometh the coordination? I'm just asking ... "... the need to coordinate literally millions of biochemical events ..." WHAT IS DOING THE COORDINATING? Box

"Humans are assumed to do what they do because they are guided by their instincts" Humans are guided by their prejudices, which is slightly different than their instincts. It is not possible to actually understand most wars until you learn the prejudices of the guys who agreed to order their underlings to start killing each other. That is, both sides need to have leaders with odd understandings of the current reality in order to have a war. If only one of the sides can't deal with real reality, the other side can often figure out some deal short of war. As near as I can tell, politics is the same. It's just harder to find books that explain the odd workings of the minds of men who are merely screwing up a city somewhere instead of getting a million humans killed in a war. Note that the Libertarians point out that the arrival of "government" CAUSES wars and crime. This is because prior to the government exercising the SOLE legal power of armed coercion, the 2 sides sorted things out as equals. Once a territorial governor shows up, there is someone you can bribe to support your position with marshals and judges and such. Armed resistance is then the only alternative to elimination. mahuna

Darwin fretgirl? daveS