#evolution #adaptation .
Nature has two largely independent processes: one to produce variation (using mutation and/or sexual reproduction), and one to eliminate unfit variations (known as natural selection). What we observe at any timepoint in natural history is the emergent consequences of the interaction between these two processes. Over millions of years, overall biological complexity has increased, but a vast number of evolutionary paths have ended.
The long-term outcome of natural selection is often referred to as the Survival of the Fittest, the term introduced by Herbert Spencer, but this is at best a massive simplification, if not actually tautological. Darwin happily adopted Spencer's term in the later editions of his book, but Wallace argued that Elimination of the Unfit was a more accurate descriptor.
The actual mechanism of natural selection works in terms of reproductive advantage. Fit individuals (whatever that means) are likely to survive and pass on their genes to the next generation, while unfit individuals won't. Over time, the standards of fitness may gradually shift.
For example, if predators attack a herd of antelopes, the slowest are likely to be caught, while the faster ones will escape. The predators that are not fast enough to catch even the slowest antelopes will starve. Over many generations, thanks to natural selection, the average speed of both the antelopes and the predators will increase. (We're assuming here that the environment remains more or less the same. Obviously if the sea level rises and the plains get flooded, then the rules of the game change, and different variants will start to have the advantage.)
In order to survive, antelopes and predators don't need to be the fastest of their species, they just need to be fast enough. So we shouldn't take
survival of the fittest literally - what this is really about is the survival of the fit.
And as Bateson argued, this term has a double meaning. This is not just about the survival of fit individuals or variants, it is about maintaining the relationship (the fit) between the two species.
During the Covid-19 pandemic, people have become interested in (and sometimes confused by) the way natural selection works among viruses. Professor Rickards spotted a misleading metaphor from the UK Government's Chief Scientific Advisor.
Press conference. Asked about variants, Vallance says ‘the variants are ones liked by the virus’ IMHO, this is bad metaphor, a sort of anthropomorphic thinking.— Tudor Rickards (@Tudortweet) January 15, 2021
And Magnus Nordborg recently challenged a statement made in the Economist.
Misinformation from The Economist: “natural selection favours variants that are more transmissible and less deadly”. The first part is true, the second not. Difficult to predict how virulence evolves, as it mostly changes *because* it affects transmission. https://t.co/al94omMgkJ— Magnus Nordborg (@magnusnordborg) January 4, 2021
I commented that
Natural selection is not about the survival of the fittest but the non-survival of the unfit. A deadly virus might not survive for ever, but don't hold your breath. @gcochran99 insisted that I was mistaken, and added
if a given variant of a particular virus reproduces noticeably faster, it will end up being the one that matters.— Gregory Cochran (@gcochran99) January 5, 2021
I think this is missing the point, for several reasons. Everything will change/mutate many times before anything
ends up anywhere. While there seems to be one particular variant that is currently reproducing itself faster than other variants, new variants may well emerge with significantly different properties. Transmissibility depends on conditions that are not constant and at least partly under human control - including social distancing and wearing masks, as well as vaccines and other medical interventions.
And what I'm mainly arguing against is the idea that we only need to worry about the most efficient viruses because the less efficient ones will eventually disappear. Yes they might, but they might kill a lot of people and animals first. I made a similar point in my post on Viral Pandemic (April 2005). See also Arguments from Nature (December 2010).
In its small way, Gregory Cochran's tweet has
gone viral, receiving more Likes than the rest of the thread put together. But that surely doesn't mean his tweet will end up being the one that matters.
P. den Boer, Natural Selection or the Non-survival of the Non-fit (Acta Biotheor 47, 83–97, 1999)
Dean Keith Simonton, Creative thought as blind-variation and selective-retention: Combinatorial models of exceptional creativity (Physics of Life Reviews 7 (2010) 156–179 - paper recommended by @Tudortweet who writes:
worth linking to the theory of creativity as another metaphor
Charles H. Smith, Natural selection: A concept in need of some evolution? (Complexity, Volume17, Issue3 January/February 2012)
Updated 26 January 2021