Does Physics Drive Evolution?

Does Physics Drive Evolution?

Some recent evolutionary papers appear to make physical laws not just constraints on natural selection, but guiding hands that build optimal designs.

Hydrodynamics and the perfect transporter:  In cell membranes, aquaporins are hourglass-shaped channels that allow water molecules through but block other molecules.  Their “remarkable  selectivity,” coupled with “optimal permeability,” is admired by biophysicists – so much so that authors of a paper in PNAS about aquaporins [AQPs] remarked, “in a biomimetic perspective, these results provide guidelines to design artificial nanopores with optimal performances.”  How, then, did evolution stumble upon such design perfection?  “This suggests that the hourglass shape of aquaporins could be the result of a natural selection process toward optimal hydrodynamic transport.”   This statement could mean that natural selection found the optimal shape through blind search, but more implicitly that the laws of hydrodynamics lured natural selection toward “excellent water selectivity.” 

Most of the paper focused on why the geometrical shape is so effective:

The aim of this work was to determine the effect of geometry and BCs [boundary conditions] on hydrodynamic entrance effects in biconical nanochannels. Using FE [finite-element] calculations, we have shown that compared with a plain cylindrical pipe, a biconical channel of optimal angle can provide a spectacular increase in hydrodynamic permeability. A simplified model based on entrance effects and lubrication approximation rationalizes the observed behavior. Although speculative, this could indicate that the hourglass geometry of AQPs results from a shape optimization, to reduce end effects and maximize water permeability.

They said very little about evolution.