Re: Colors of alien plants -- Scientific American

Bryan Derksen skreiv:
> Eivind Kjorstad wrote:
>> Typical vegetation convert at best 1% of the incoming photons to 
>> usable energy. This compares pretty poorly with even todays crude 
>> solar-cells which can easily do 10% and we've got designs that in 
>> principle should be able to go to 30-50% 

> On the other hand, how easy is it for those solar cells to be 
> synthesized by protein-based cellular mechanisms from raw materials that

> are readily present in an aqueous solution?

Not easy. And indeed that may be the reason, "you can't get there from 
here" kind of problem where the end-result may be desirable but there's 
no easy evolutionary pathway.

> Does the increased energy efficiency of the new photosystem make up 
 > for the increased energy cost of making the new photosystem in the
first
 > place?

It certainly does. The entire energy-cost of making them is made up for 
in aproximately 10% of the lifespan of the modules. They're not easily 
accessible for the kind of life we have here on earth, other than human 
beings.

Indeed, if you take a large view on things, you may argue that humanity 
have evolved to the point where we can do photosynthesis, and outdo 
plants at it. Plants aren't about to be obsolete anytime soon, but it's 
imaginable to synthesize food from solar-derived-energy and basic
elements.

> For something that evolution's been noodling over for so long and that 
> has such a major impact on organism fitness I think it's a good default 
> assumption that the current design balances the tradeoffs in a 
> near-optimum manner given the environment the organisms are dealing 
> with.

OR that it's a strong local maximum. If there is a better way, but 
getting there requires crossing a large area of poor fitness, then that 
is something that is tricky for evolution to handle.

	Eivind Kjørstad