Explaining Natural Selection

#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.

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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) 

 See also: Delayed Success - Evolution (April 2023)

Updated 26 January 2021

Is this really as nature intended?

@AsNatIntended (As Nature Intended) is an excellent health food chain in London. I visit the Ealing branch regularly, but I can't help thinking that the name is a bit misleading, based on a romanticized idea of Nature.

Because some of us might think Nature intended apples to create apple trees, not apple pies. Surely fruit is "designed" to attract insects and birds rather than humans? And for that matter, didn't Nature intend men and women to smell of honest sweat, rather than organic lavender soap and fennel toothpaste?

Upmarket health food is based on a rather strange notion of authenticity. As @stephenpoole writes

"It is widely assumed that food sold as organic is purer and closer to an assumedly benign Nature, although no food is made from inorganic matter and organic farming standards sanction the use of neurotoxic fertilisers." Stephen Poole, Why are we so obsessed with the pursuit of authenticity? (New Statesman March 2013)

But the idea that Nature's purpose is to serve mankind is an old one. We can find it in the Bible and in Ralph Waldo Emerson.

• "Every moving thing that liveth shall be meat for you; even as the green herb have I given you all things." (Genesis 9:3)

• "Nature, in its ministry to man, is not only the material, but is also the process and the result. All the parts incessantly work into each other's hands for the profit of man. The wind sows the seed; the sun evaporates the sea; the wind blows the vapor to the field; the ice, on the other side of the planet, condenses rain on this; the rain feeds the plant; the plant feeds the animal; and thus the endless circulations of the divine charity nourish man." (Emerson "On Nature", Chapter 2 Commodity)

And the idea that mankind has subverted Nature's purpose is also an old one. @DaveZinczenko suggests that "Whereas our sweet tooth was once nature’s way of protecting us from disease, now it’s the food industry’s way of tricking us into it." (Origins of the Sweet Tooth, Mens Health July 2004) via @br1anv. See also The Extraordinary Science of Addictive Junk Food (New York Times Feb 2013) via @EllenNaylor.

Meanwhile, there are endless ideas about restoring Nature's purpose - from naked cooking to public nudity. There was a 1961 film by Harrison Marks called Naked as Nature Intended (Link Not Safe For Work), and there are several militant naturists around these days, including Vincent Bethell and Stephen Gough. There are also some rather alarming ideas for Restoring Nature's Homeostasis (Link Not Safe For Mealtimes).

But is letting nature decide such a good idea (asks @stephenpoole)? 'After all, he reminds us, nature tried to kill us all with the Black Death. Nature is currently experimenting feverishly to find just the right strain of avian flu to cause a global pandemic. "Nature," as the young microbiologist points out in the zombie film World War Z, "is a serial killer." ' Is our love of nature writing bourgeois escapism? (Guardian July 2013)

It could be dangerous to regard nature as benign. The only consistent intention nature seems to have for us it is that we should get old and die. Et in Arcadia Ego.

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See also Madeleine Somerville, Natural's not in it: just because a product calls itself 'natural' doesn't make it good (Guardian 8 March 2016). (I'm guessing the headline was a Guardian subeditor's tribute to the Gang of Four song "Natural's not in it".)

@MadeleineSix "Natural is not in it your relations are of power We all have good intentions but all with strings attached" @gangof4official

— Richard Veryard (@richardveryard) March 8, 2016

“@MadeleineSix: @richardveryard that what the title is from?? The reference was lost on me!”- our ideas are not "natural"; humans make them

— GANG OF FOUR (@gangof4official) March 8, 2016

Finally, @HadleyFreeman writes that "perhaps the most striking thing about the natural trend is how much it reinforces gender stereotypes". If the cavemen did it or ate it, it’s got to be good for you. Right? (Guardian 16 April 2016)


Related posts: Viral Pandemic (April 2005) Arguments from Nature (December 2010) The Purpose of Baldness (Jan 2011). Related category: Death
(Links Not Safe For Romantics)

Updated 17 April 2016

Arguments from Nature

#entarch @G_Doherty of @theopengroup (via @tetradian ) suggests that we can get advice from Mother Nature.

"In nature, complexity abounds; but nothing is ever more complex than it needs to be." EA - Being Fit is Overrated (13 December 2010)

This is circular: the only way we know what nature thinks to be necessary is by observing what exists in nature. (Is the camel necessary?) It is also misleading: nature sometimes takes a very long time to decide what kinds of complexity to keep. (Are humans necessary?)

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.

Garry Doherty supports his argument with a quote often implausibly attributed to Darwin, but which is now thought to have been invented by Leon C. Megginson, a management sociologist who died in February 2010.

“It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.” [See Wikiquote, Darwin Correspondence Project] [@ColinPurrington has some photos of the misuse of this quote in his Darwin on the Floor LHAO]

As a statement of natural history, this is just not true. The horseshoe crab has remained largely unchanged for over 400 million years. Doherty also appears to misunderstand the word "fit", which doesn't mean strongest or most attractive, but is about the alignment between the species and its environment. As Bateson pointed out, the alignment (fit) survives even as the species themselves evolve - which allows us to understand the motto "survival of the fit" at a higher logical level. Nevertheless, Megginson's version of evolution may have been influenced by a misunderstanding of Bateson, who once remarked:

"The fight is not only to the strong or to the well adapted, it is also to the flexible."

Gregory Bateson, 'The New Conceptual Frames for Behavioural Research' Proceedings of the Sixth Annual Psychiatric Institute (Princeton NJ: New Jersey Neuro-Psychiatric Institute, September 17, 1958) reprinted in G. Bateson, A Sacred Unity: Further Steps to an Ecology of Mind (edited R.E. Donaldson, New York: Harper Collins, 1991) pp 93-110

But the facts about adaptability in natural history simply aren't relevant to the question of adaptability in some other domain, such as human organizations. It's just a metaphor, not a source of transferable knowledge.

Doherty thinks there is a real lesson for Enterprise Architects - as if enterprise architects should copy nature and adopt her principles. But even if we could correctly interpret nature's intentions, there is no obvious reason why we should limit ourselves to nature's methods. After all, farmers have been interfering with natural selection for thousands of years, producing plants and animals more suited to human requirements. The resulting ecosystems may sometimes appear more complex than nature alone would have produced, but sometimes they are alarmingly lacking in biodiversity; we can learn from nature but we cannot copy her.

Doherty thinks that "the outcomes of TOGAF™ and evolution are similar". Evolution produced a lot of dinosaurs (and excellent creatures they were too) before it got around to producing us. Be careful about learning from analogy.

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See also Nick Matzke, Survival of the Pithiest (September 2009)

Related posts: The Shelf-Life of Algorithms (October 2016), Explaining Natural Selection (January 2021)

Updated 26 October 2016

Comparing Apples and Pears

I have two pear trees in my garden. In the middle of August, the grass is suddenly covered in rotting pears. Why do pears rot faster than apples? 

People have long observed that pears sink in water, while apples float. The pear is more dense, and has a higher water content. Apples continue to breathe (absorb oxygen) after they are picked, which keeps them fresh, but pears get out of breath (don't absorb much oxygen) and can decay fairly quickly. 

From a human point of view, apples are more well-behaved than pears, and fruit growers and supermarkets would like pears to behave more like apples. Belgian scientists have now discovered differences in the cell structure that explain why apples can breathe better than pears. 

But what does better mean? The apple is more efficient at staying fresh. But the pear is more efficient at rotting. Why is staying fresh better than decaying? The biological purpose of the pear is to grow a new pear tree, not to get wrapped in plastic and put onto a supermarket shelf. For the pear, staying fresh is a bad idea because it delays the fulfilment of its biological purpose. 

Of course, that's not to say that the pear is superior to the apple in terms of producing new trees - it has merely evolved a slightly different method. But both methods seem to work, even in the absence of human intervention. If we try to understand botanical behaviour in terms of human purpose, we may get curious results. 

Jonathan Amos, Apples beat pears on crunch issue, BBC News 11 July 2008

Related posts: Redesigning the Banana (July 2009), Is this really as nature intended? (November 2011)