Units of Inheritance.

The classic selfish gene of Dawkin's fame I think, is defunct. As a focus for inheritance it is too small, too narrow. The are of course examples of phenotypic expression that rely on single genes but they are by far in the minority. Genetisists were most puzzled when they conducted experiments that 'knocked out' certain genes, preventing them from expressing, to scrutinize the effects and so ascertain their function. They found out that a lot of the time, nothing happened at all. The body kept on trucking without any major lapses in biochemical function.

Something compensated for these artificially imposed abscences.

If you've ever studied models of internet pathways you get a monstrously bushy, hyper-connected network, something like this, but on a much more massive scale:



The American military pioneered reseach into the robustness of distributed networks - knocking out specific nodes - to see how much loss a network can sustain of physical hardware, before such a network ceases to be of use as a vehicle for communication. The answers they got is that networks are amazingly robust - there of course remain specific nodes that always carry more traffic, are more vital for overall function - but on the whole, a network can sustain massive damage without major impairment of function. There is a critical threshold, which once crossed causes a sudden massive failure, but prior to that functionality remains almost negligibly effected.


The above is an illustration of a "Waddington epigenetic landscape" the nodes below the upper sheet are single genes. The upper sheet itself corresponds to the phenotypic expression - the bodytype - associated with the genes in the network below. You've been to the circus - remember the big-top..? Imagine such a tent but with millions of different interwoven guy-ropes beneath, giving the big-top its distinctive shape, not through singular efforts on the part of any particular gene or rope-stay - but through the whole network of interactions, each new rope, each new connection altering the tension in all the others.

I would offer a new unit of inheritance, a less physical one, a more emergent consequence of evolution improving the robustness of its genotype-phenotype linkages - the network.

...Continued...