Front-loading and Convergent Recruitment

The beauty of the front-loading hypothesis is that it unites the two aspects of evolution that are quite friendly to teleology – deep homology and convergence.  As I just explained:

That is, the globin-fold itself is a preadaptation and it is this preadaptative state that restricts possibilities as evolution is much more likely to tap into and exploit this poised, pre-existing state than stumble upon some other possible solution that would be harder to reach.  In other words, a significant factor to convergence can be attributed to deep homology, where ancient ancestral states effectively “constrain” where evolution goes.

[….]

front-loading expects an intrinsic dimension, where deep homology constrains evolution by functioning as a preadaptation.

This logic is all tied to one of the predictions of front-loading:

3. Evolution would be significantly driven by intrinsic, biotic features. Since the design itself would be biotic, then the more that evolution is likened to a biological process, the more that design can be connected to such evolution. In other words, if evolution was purely a function of random happenstance propagated only because such events happened to elicit greater fitness against the backdrop of haphazard environmental conditions, we would predict that the ability to design the future through the present would be quickly be swamped by noise. But if there is a strong, intrinsic component to evolution, the designs are buffered against such noise.

In fact, back in May 2010, I used an example from social engineering (“nudging”) to explain the logic:

Let’s rephrase this. A choice architecture is a context that has been set up to favor certain choices or outcomes. The choice architecture is the design and it is this design that influences the choices or outcomes later in time.

At this point, we simply ask whether choice architecture/context must necessarily be environmental?

Consider human choice. Do you accept the idea that a person’s genetics can predispose him to make certain choices? There is plenty of evidence that says it does. So the context that influences choice does not necessarily need to be environmental. The choice can be influenced by both environmental and genetic contexts. In principle then, the choice architecture behind the nudge can be internal/genetic.

The manner in which the various pieces and parts of life were hooked up would represent the architecture of life and this, in turn, would amount to a logic that would help guide and facilitate subsequent evolution. The actual pieces and parts of life would represent the composition of life and this, in turn, would amount to various preadaptations that would favor certain evolutionary trajectories over others.

Of course, all of this emanates from the logic of front-loading that was laid out in The Design Matrix:

Front-loading is the investment of a significant amount of information at the initial stage of evolution (the first life forms) whereby this information shapes and constrains subsequent evolution through its dissipation. This is not to say that every aspect of evolution is pre-programmed and determined. It merely means that life was built to evolve with tendencies as a consequence of carefully chosen initial states in combination with the way evolution works.

[…]

Front-loading, by definition, is about designing the future through the present. It is about imposing some kind of constraint on evolution, or more simply put, it is using evolution to carry out design objectives. Since evolution would proceed outward from the originally designed cells, evolution may have been endowed with various sequences and structures to increase the odds that certain future states would be found through a random search stemming outwards from this front-loaded state.

So the idea is that this original state would both constrain and facilitate evolution and deep homology, at work behind the scenes in examples of convergence, represents evidence that my hypothesis of designing evolution is indeed feasible and a serious possibility.  In fact, a paper published a few weeks ago in Trends in Genetics will sound very familiar to readers of this blog and the DM:

The multiple origins of a trait represent exceptional replicates of evolutionary processes and can provide extremely valuable insights into the constraints and opportunities that govern evolution. In particular, comparing the genetic determinants of the independent origins of an adaptive phenotype can shed new light on the role of genomic background in restricting or opening new evolutionary trajectories towards adaptive innovations. In this paper we discuss the potential causes of convergence at the genetic level together with their implications for our understanding of evolutionary biology in general.

In fact, the authors take this dynamic seriously enough to give it its own name:

studies have traced phenotypic convergence to modifications of homologous genes; in this paper such phenomena will be further referred to as convergent recruitment (Glossary).

And their glossary defines it as follows:

Convergent recruitment: the process of homologous gene becoming recurrently responsible for a novel function.

Yep, convergent recruitment is exactly the type of phenomenon front-loading predicts, rendering a plausible hypothesis even more strongly plausible.

——–

Pascal-Antoine Christin, Daniel M. Weinreich and Guillaume Besnard. 2010. Causes and evolutionary significance of genetic convergence. Trends in Genetics 26 (2010) 400–405

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