Creationist pseudo-scientists have a problem, and not the obvious one of more and more people seeing through their deceptions, working out why they are necessary and realising a rational, scientific explanation is preferable to a magical one which requires lies and misinformation to promote it. The problem they have is, like the problem of the virtual certainty that at some point in the near future, scientists will find evidence of life on another planet, probably in another planetary system, the problem of one of their fundamental arguments being shown to be without any foundation.
I'm talking about the fact that science is getting closer and closer to working out how an early self-replicating molecule arose and gave rise in turn to a self-replicating structure capable of extracting energy and using it to manage entropy - in other words, something we call 'life'.
At that point, of course, creationism's imaginary magic creator will have been evicted from yet another gap and science will have shown there is no need to invoke magic to explain life, either on Earth or on any other planet. The entire thing will have been shown to be the result of a natural process involving nothing more than chemistry and physics obeying fundamental laws and, more importantly, inevitable in the circumstances in which it occurred, just as life's diversification and evolution has been shown to be.
An article by Michael LePage in New Scientist a few days ago hints that science may indeed be getting close to that dreaded day of reckoning for creationism.
The problem they may have explained is how one of the most fundamental processes of living things could have evolved. This is a process that must have been present in the last universal common ancestor (LUCA) - a notional organism from which every living thing is descended - because it is fundamental to every form of life. It is the manufacture of ATP from ADP and phosphate. ATP acts as an energy store which can be used to power metabolic processes by reducing it back to ADP and phosphate, so releasing the stored energy to power the process. Energy being added to the system from outside is why life is an open system and is thus able to bring about greater order (reduced entropy) in full accord with the second law of thermodynamics - despite the creationist pseudo-scientists' lie that this is impossible.
The key to the process is a cell's ability to control the concentration of protons inside the cell by using a proton pump to pump protons from inside the cell to the outside. This sets up a proton concentration gradient which can be utilised by allowing protons to flow back into the cell through a protein embedded in the cell wall which produces ATP in the process. The presence of protons in a solution is what we call it's acidity so what this means, in effect, is that the cell needs to be less acid inside than the liquid medium it lives in.
Michael LePage explains this with a simple analogy:
To understand it in energy terms, think of a double kitchen sink. The small sink represents the inside of the cell and the large one the outside world. Start by filling the large sink with water, leaving the small one empty. The difference in water levels is a potential source of energy: drill a hole in the divider and water will flow into the small sink. The flow could be used to turn a tiny turbine – which is essentially what the ATP-making protein is, a turbine turned by protons and other positive ions.
Michael LePage, Meet your maker: Homing in on the ancestor of all life; New Scientist 2982, 12 August 2014
This, of course, requires a membrane impermeable to protons because, in Michael LePage's analogy, if the water can flow back into the large sink both sinks will eventually reach an equilibrium and there will be no flow through the turbine. It used to be thought that LUCA must have had an impermeable membrane for this process to have evolved but, since the realisation that archaea, whose presence was not appreciated when this model was proposed, have an impermeable membrane alright but one which achieves impermeability in an entirely different way to bacteria. This would mean another impermeable membrane evolved AFTER the proton pump evolved if this evolved in LUCA or before. But, what would be the driver to evolve a different way of doing something that was already being done?
Something here is not adding up. The proton pump is common to both archaea and bacteria yet they have different impermeable membranes neither of which could have evolved from the other. The only conclusion then is that the proton pump evolved BEFORE the impermeable membrane. In which case, how did the cell maintain a proton concentration gradient across the membrane?
This has lead biochemist Nick Lane of University College, London, UK to propose that LUCA did not have a semi-permeable membrane; in fact it must have had a leaky one.
For this to work, Lane argues that living cells must have evolved the proton pump/ATP solution around alkaline hydrothermal vents on the sea floor. This had earlier been proposed to explain why living cells use the proton pump and ATP in the first place. As well as being rich in catalysts like iron and sulphides capable of catalysing the formation of large organic molecules like lipids, proteins and, critically, RNA, there would have been natural proton gradients between the acid sea water and the alkaline water flowing up from the vents and out through the porous 'chimneys' which formed as the minerals precipitated out when the hot solution met the cold sea water.
Lane, and his colleagues Andrew Pomiankowski and Victor Sojo have worked out a scenario and modelled it to show that a leaky membrane in just such an environment could be capable of producing enough energy continuously by exploiting the proton gradient across the cell even IF the cell membrane was leaky. This would mean there was plenty of time for these cells to gradually evolve proton pumps and then impermeable membranes, once in archaea and again in bacteria.
The archaea and bacteria are the deepest branches of the tree of life. The two groups are similar in morphology and share some fundamental biochemistry, including the genetic code, but the differences between them are stark, and rank among the great unsolved problems in biology. The composition of cell membranes and walls is utterly different in the two groups, while the mechanism of DNA replication seems unrelated. We address a specific paradox, giving new insight into this deep evolutionary split: membrane bioenergetics are universal, yet the membranes themselves are not. We resolve this paradox by considering the energetics of a hypothetical last universal common ancestor (LUCA) in geochemically sustained proton gradients. Using a quantitative model, we show that LUCA could have used proton gradients to drive carbon and energy metabolism, but only if the membranes were leaky. This requirement precluded ion pumping and the early evolution of phospholipid membranes. We constrain a pathway leading from LUCA to the deep divergence of archaea and bacteria on the basis of incremental increases in free-energy availability. We support our inferences with comparative biochemistry and phylogenetics, and show why the late evolution of modern membranes forced divergence in other traits such as DNA replication.
In summary then, it's beginning to look as though life developed slowly, not quite in Darwin's "warm little pond" but in the scum forming naturally on a hot little sea bed.
So the day of reckoning for creationists moves a little closer. Somehow between now and then they are going to have to think up a way to explain why a completely natural process is unnatural and why it still requires magic, and they are going to need to start to soften up their victims and prepare the ground for this explanation. I would be astonished to learn that the best brains in the Discovery Institute have not been put to work on this 'problem' already, just as they almost certainly will have been on the impending 'problem' of explaining away life evolving on another planet. Either way, they are going to have to do a lot of creative reinterpretation of the Bible, redefining 'life' and possibly redefining 'intelligent design'.
Either that or they will attack the scientists, lie about the science, deny the evidence and continue as they have till now to rely on the ignorant incredulity and arrogant cultural assumption of their victims that the superstition they were born into simply can't be wrong, and just put up with the inevitable continuing loss of support as more and more people see through their deception and opt for rationalism over Bronze-Age superstition.
*© 2014 Sojo et al. Reproduced under the terms of the Creative Commons Attribution License.