Evolution: teleology and stability (Introduction)

by David Turell , Saturday, September 09, 2017, 22:54 (2630 days ago) @ David Turell

A philosophic essay about the stability of life and how biology has not been approached by science as chemistry and physics are:

https://aeon.co/essays/paradoxes-of-stability-how-life-began-and-why-it-can-t-rest?utm_...

"Living things might be made of the same fundamental stuff as the rest of the material world – ‘dead’ atoms and molecules – but they do not behave in the same way at all. In fact, they seem so purposeful as to defy the materialist philosophy on which the rest of modern science was built.

"how did life on Earth actually come about? Both at the abstract level and in the particular story of our world, there seems to be a chasm between the animate and inanimate realms.

***

"The name we give to the process by which simple life emerged from inanimate matter is ‘abiogenesis’. Evolution, on the other hand, is the biological mechanism by which life branched out into Darwin’s ‘endless forms most beautiful’. Traditionally, these are viewed as quite different things: the former, one of nature’s greatest mysteries; the latter, broadly understood, thanks to Darwin. Through systems chemistry, however, they stand revealed as a single continuous progression. (my bold)

***

"Evolution exhibits an identifiable driving force, a direction if you like, and this ‘teleological’ tendency acts at both the chemical and biological stages; that is, it operates both during, as well as after, what we think of as abiogenesis. Thus the purpose-driven character of life, the very thing that seemed to distinguish biology from the rest of nature, turns out not to be unique to life after all. Its beginnings are already discernible in certain inanimate systems, provided they are replicative and able to evolve. And this driving force can be described in strictly physical terms.

"Put simply, it is nature’s drive towards greater stability – a drive that is as ubiquitous in physics as it is in biology.

***

"High entropy and low energy, however, are just one manifestation of stability. Does nature offer others? It does. It turns out that stuff can be highly persistent even when it is highly unstable energetically. Indeed, that’s precisely what we find in the world of replicators.

"Living things are low-entropy and energy-consuming, so they are unstable in the thermodynamic sense. Nevertheless, they can still be remarkably stable in the sense of persisting over time. Some replicating populations (certain bacterial strains, for example) have maintained themselves with little change over astonishing periods – millions, even a billion, years.

***

"Why do replicating molecules give rise to replicating cells? In a word: evolution. Or, in four more: replication, variation, competition, selection.

***

"In the replicative world, stability can be unrelated to energy content. Provided there is a source of metabolic energy to keep the thermodynamic books balanced, anything goes. So this is genuinely a different kind of stability.

***

" Some replicators are indeed astonishingly durable, but, crucially, DKS always remains circumstantial. Change the environmental conditions and the winner of the replicative race can change. In fact, that’s exactly what makes life so capricious and the evolutionary path largely unpredictable: the mathematics of replication forces it into a paradoxically restless search for rest.

"Why are living things so complex? Here’s another seemingly eternal riddle that we’re now in a position to answer. As many a systems chemist has learnt to his or her sorrow, the simplest molecular replicators can be quite finicky. You need fancy labs, specialised equipment and dedicated researchers to get them to replicate and, even then, it can be hit or miss. By contrast, biological replicators – living things – are extraordinarily robust.

"Consider some of the simplest life forms, bacteria. These highly complex entities can survive and prosper pretty well anywhere – some deep within the Earth, some high in the atmosphere, some in boiling water, some in nuclear reactors, no labs, equipment or human assistance required. The inordinate complexity of all living things has emerged for one reason alone – to facilitate the replicative function, thereby enhancing the stability of the replicating system.

***

"So complexity and function go hand in hand. Joyce’s RNA experiment demonstrated the first (conceptual) step on a thousand-mile journey – toward that stupendously effective (and inordinately complex) replicator, the bacterial cell.

***

"Nature’s most fundamental drive, dictated by logic itself, is toward greater stability. That drive has a thermodynamic manifestation, as expressed through the ubiquitous Second Law, but it also has a kinetic manifestation – the drive toward increasingly persistent replicators. Two mathematics, two material forms. This distinction does not trace the dividing line between living and dead matter precisely – but it does explain it, and many of the other riddles of life into the bargain."

Comment: Read the whole article. I think it is ridiculous reasoning, but he makes some reasonable observations. Highly complex bacteria are stable because of the unexplained source of the complexity they exhibit. Note my bold: origin of life and evolution are one continuous system.