In the genetic diaspora of an epidemic, there is ferocious competition between strains of virus to get to the next victim first. That leads to apparently purposeful outcomes, as if the virus had a mind. One of the things people find hardest to grasp about evolution is that it appears purposeful but the mutations on which it feeds are random. How come dolphins evolved to swim if all they had to work with were random changes in genes? Viruses also mutate at random but most people talk as though the rise and fall of these mutant versions is mainly down to chance or luck. Its not.
Mutations occur all the time in RNA viruses; what matters is which ones find favour in natural selection. The champions of Darwinian medicine have been calling for their colleagues to take evolution and adaptation more into account for years, and one of them, Paul Ewald of the University of Louisville, has something very relevant to say about this pandemic. Years ago, Ewald came up with a theory of why some diseases are lethal and others are mild. He argues it is all about the mode of transmission. Infections that you catch from coughs and sneezes are mostly mild; we get more than 200 different kinds of common cold virus and on the whole none of them puts you in bed, let alone kills you. Yet insect-borne diseases such as malaria, plague and yellow fever, and water-borne diseases such as cholera and typhoid, seem quite content to kill you.
The reason, says Ewald, is that in direct-contact diseases such as colds, mild strains will do better than nasty ones, because they send you out to work and to parties, coughing and sneezing. Insect-borne or water-borne diseases, meanwhile, may actually spread better if they confine you delirious to a deathbed with a high pathogen load, the better to attract mosquitoes or (sorry) maximise your contribution to local sewers.
There are two other categories of transmission: sexually transmitted diseases, such as syphilis, herpes and Aids, which may or may not kill you in the end but are good at lurking hidden so you have a chance to move to a new partner; and durable, sit-and-wait diseases such as tuberculosis and to some extent smallpox, caught from surfaces, which can afford to be lethal because they can be passed on after you are dead.
Every virus uses mutation and selection to find a compromise between maximising its offspring while killing the host, or moderating its effect and keeping the host active. Yet there was always one epidemic that didnt seem to fit Ewalds theory: the 1918 flu, which grew more deadly in the second wave, despite being spread by coughs and sneezes. In 2011, Ewald had a crack at explaining this exception in a way that neatly tests the rule. See if you find it convincing.
The 1918 flu was first noticed in US army training camps in Kansas in early March. Throughout the spring and summer it was about as lethal as most flus: dangerous to the very young and very old but mild in everybody else. It was in August, on the Western Front, that army doctors started noticing that the flu was turning deadly, regularly killing fit young adults. Influenza increasing and becoming more fatal, wrote a senior US army surgeon in his diary on 17 August.
Ewald thinks that this was because the lethal strains were spreading better than mild ones. Imagine that a mild case would
There is a worrying parallel with Covid-19. In the early wave a lot of cases were spread by attendants in hospitals and care homes. One South African hospital traced how a single outpatient seeded an epidemic that spread from ward to ward, infecting 39 patients and 80 staff. The virus had a means to get from victim to victim even if they stayed put: it was attendant-borne, like the 1918 flu. Did that encourage the virus to be more lethal? An estimate published this week by Public Health England finds that the B117 (Kent) mutant is roughly 65 per cent more fatal than previous strains.
By contrast, because of lockdown, a mild case of Covid kept you isolated at home. Last week the Financial Times carried an article about the huge but surprisingly mild epidemic of Covid that India is suffering. It quoted one doctor as saying that we are seeing a lot less severe disease than the rest of the world, and a lot more asymptomatic infections and another that its pretty generally accepted that in India, we have a very mild form of the virus. There are lots of possible explanations, but because lockdowns have been mostly ineffective in India, could it be that mild variants have done well and an attendant-borne evolution to greater virulence has not happened?
Yet for every Mumbai, there is a Manaus a city in Brazil that had a huge first wave with little or no lockdown and saw a lot of people die. Some thought Manaus had reached the herd immunity threshold, but it is now seeing a bad second wave. Remember, however, that the deadly strain of 1918 flu started in the trenches, but soon spread everywhere. Its the global average strategy that we use against the virus that counts, not the local one: Manauss new strains seem to have arrived in the city from elsewhere.
You might conclude from this logic that we have made a mistake by locking down, ensuring that the virus remains deadly or becomes more so. I hesitate to agree with that, because I have been wrong about a lot during this pandemic. And there is one crucial way in which Covid-19 differs from flu: it spares the young and clobbers the old. That might be enough to ensure that nasty strains remain competitive with mild ones even in the absence of lockdowns. A strain that causes only very mild symptoms in most people, so they go out spreading it, but occasionally kills the vulnerable, might thrive.
I dont know if Britain would have seen more than 100,000 deaths or fewer if we had pursued a less draconian strategy like India, Sweden or Florida. But I do know that evolution is about more than mutation.
See the original post here:
Stresses and strains: the evolution of Covid is not random - Spectator.co.uk
- History of Evolution | Internet Encyclopedia of Philosophy - December 9th, 2016 [December 9th, 2016]
- Evolution - Bulbapedia, the community-driven Pokmon encyclopedia - December 12th, 2016 [December 12th, 2016]
- What is Evolution - explanation and definitions - December 21st, 2016 [December 21st, 2016]
- Evolution (2001 film) - Wikipedia - January 28th, 2017 [January 28th, 2017]
- EvolutionM.net - Mitsubishi Lancer Evolution | Reviews, News ... - February 1st, 2017 [February 1st, 2017]
- YMCA evolution continues at lake - Gaston Gazette - February 7th, 2017 [February 7th, 2017]
- Ivanka Trump's Beauty Evolution, From 1998 to Today Watch - Us Weekly - February 7th, 2017 [February 7th, 2017]
- Lumpy, hairy, toe-like fossil could reveal the evolution of molluscs - The Guardian - February 7th, 2017 [February 7th, 2017]
- How Evolution Alters Biological Invasions - ScienceBlog.com (blog) - February 7th, 2017 [February 7th, 2017]
- Cultural evolution and the mutilation of women - The Economist - February 7th, 2017 [February 7th, 2017]
- Late-night hosts on the evolution of Trump: 'Dickish to dictatorish' - The Guardian - February 7th, 2017 [February 7th, 2017]
- Gold's Gym Regina rebrands to become Evolution Fitness - Regina Leader-Post - February 7th, 2017 [February 7th, 2017]
- Incremental Versus Radical Innovation: A Response to Josh Swamidass on Evolution and Cancer - Discovery Institute - February 7th, 2017 [February 7th, 2017]
- Blockchain: Investment (R)Evolution For Developing Markets - Forbes - February 7th, 2017 [February 7th, 2017]
- See the Evolution of the Famed Porsche 911 in 7 Photos - WIRED - February 7th, 2017 [February 7th, 2017]
- Exhibition charts 500 years of evolution of robots - Phys.Org - February 7th, 2017 [February 7th, 2017]
- How evolution turned ordinary plants into ravenous meat-eaters - Wired.co.uk - February 7th, 2017 [February 7th, 2017]
- Are Evolution Fresh Drinks 'Poison'? - snopes.com - February 7th, 2017 [February 7th, 2017]
- Non-Chromosomal DNA Drives Tumor Evolution - The Scientist - February 8th, 2017 [February 8th, 2017]
- Chimpanzee feet allow scientists a new grasp on human foot evolution - Phys.Org - February 8th, 2017 [February 8th, 2017]
- 'Goldilocks' genes that tell the tale of human evolution hold clues to variety of diseases - Science Daily - February 8th, 2017 [February 8th, 2017]
- Pac-Man is Coming to 'The Sandbox Evolution' Next Week - Touch Arcade - February 9th, 2017 [February 9th, 2017]
- Chimpanzee feet allow scientists a new grasp on human foot ... - Science Daily - February 9th, 2017 [February 9th, 2017]
- Bacteria sleep, then rapidly evolve, to survive antibiotic treatments - Phys.Org - February 9th, 2017 [February 9th, 2017]
- Orangutan squeaks reveal language evolution, says study - BBC ... - BBC News - February 9th, 2017 [February 9th, 2017]
- Evolution gives rhyme its reason - Aurora News Register - February 9th, 2017 [February 9th, 2017]
- Deeper origin of gill evolution suggests 'active lifestyle' link in early vertebrates - Science Daily - February 9th, 2017 [February 9th, 2017]
- From Tara Palmer-Tomkinson to Cara Delevingne: the evolution of the It girl - The Guardian - February 10th, 2017 [February 10th, 2017]
- Banned TED Talk: Rupert Sheldrake The Science Delusion - Collective Evolution - February 10th, 2017 [February 10th, 2017]
- VOTD: Watch the Evolution of Keanu Reeves' Acting Career - /FILM - February 10th, 2017 [February 10th, 2017]
- Pokmon Go Eevee evolution: How to evolve Eevee into Vaporeon, Jolteon and Flareon with new names - Eurogamer.net - February 10th, 2017 [February 10th, 2017]
- Horse evolution bucks evolutionary theory - Science News - February 10th, 2017 [February 10th, 2017]
- Samsung's Chromebook Pro highlights the category's continued evolution - TechCrunch - February 10th, 2017 [February 10th, 2017]
- Scientists solve fish evolution mystery - Phys.Org - February 10th, 2017 [February 10th, 2017]
- Wildfire evolution forces Forest Service into new thinking - The Daily Progress - February 11th, 2017 [February 11th, 2017]
- How the horse can help us answer one of evolution's biggest questions - Raw Story - February 11th, 2017 [February 11th, 2017]
- A primer on Darwin Day: Some religious groups embrace 'Theistic evolution' - LancasterOnline - February 11th, 2017 [February 11th, 2017]
- Apple: Evolution of in-car audio tech moving at 'speed of sound ... - Times of India - February 11th, 2017 [February 11th, 2017]
- Mariska Hargitay's Evolution from '80s Glam to Law & Order: Special Victims Unit - TVOvermind - February 12th, 2017 [February 12th, 2017]
- Evolution of baseball from power to speed has left SBs behind ... - Chicago Sun-Times - February 12th, 2017 [February 12th, 2017]
- More order with less judgment: An optimal theory of the evolution of cooperation - Science Daily - February 12th, 2017 [February 12th, 2017]
- J. Albert C. Uy speaks on evolution, biodiversity in bellied flycatcher population - The College Reporter - February 12th, 2017 [February 12th, 2017]
- See the Evolution of Movie Magic With Every Oscar Winner for Visual Effects in History - Gizmodo - February 12th, 2017 [February 12th, 2017]
- Numerology: Here's What Your Name Says About You - Collective Evolution - February 13th, 2017 [February 13th, 2017]
- The Evolution of Valentine's Day - Inside Science News Service - February 13th, 2017 [February 13th, 2017]
- Why evolution may be tech billionaires' biggest enemy - The Week Magazine - February 13th, 2017 [February 13th, 2017]
- Community Viewpoint: Evolution, like gravity, is much more than theory it is a fact - Kdminer - February 13th, 2017 [February 13th, 2017]
- How the horse can help us answer one of evolution's biggest questions - Phys.Org - February 13th, 2017 [February 13th, 2017]
- How evolution alters biological invasions - Science Daily - February 13th, 2017 [February 13th, 2017]
- Cockeyed squid shines light on deep sea evolution - Christian Science Monitor - February 13th, 2017 [February 13th, 2017]
- Eye Evolution: A Closer Look - Discovery Institute - February 14th, 2017 [February 14th, 2017]
- Evolution always wins: University of Idaho video game uses mutating aliens to teach science concepts - The Spokesman-Review - February 14th, 2017 [February 14th, 2017]
- Geneticists track the evolution of parenting - Phys.Org - February 14th, 2017 [February 14th, 2017]
- How this cockeyed squid shines a light on deep sea evolution - Christian Science Monitor - February 14th, 2017 [February 14th, 2017]
- 4 Possible Roadmaps For macOS and iOS Evolution - The Mac Observer (blog) - February 15th, 2017 [February 15th, 2017]
- The Evolution of the Energy Capital of the World - Texas Monthly - February 15th, 2017 [February 15th, 2017]
- Humons presents an atypical dance evolution - Detroit Metro Times - February 15th, 2017 [February 15th, 2017]
- Pokemon Go Adds 80 Generation 2 Pokemon, New Evolution Items This Week - IGN - February 15th, 2017 [February 15th, 2017]
- Fossil discovery rewrites understanding of reproductive evolution ... - Science Daily - February 15th, 2017 [February 15th, 2017]
- 'X-Men: Evolution' Is the Gateway Drug of Comic Book Shows - Geek - February 16th, 2017 [February 16th, 2017]
- A cultural catch: Evolution of wooden halibut hooks carved by native ... - Science Daily - February 16th, 2017 [February 16th, 2017]
- Bremerton's Fitness Evolution now Planet Fitness - Kitsap Sun (blog) - February 16th, 2017 [February 16th, 2017]
- Eye Evolution: The Waiting Is the Hardest Part - Discovery Institute - February 16th, 2017 [February 16th, 2017]
- Evolution Of The Yeezy: 2009-2017 - HotNewHipHop - February 16th, 2017 [February 16th, 2017]
- Prebiotic evolution: Hairpins help each other out - Science Daily - February 16th, 2017 [February 16th, 2017]
- This 'Live Birth' Fossil Could Change Humanity's Understanding Of Evolution - Daily Caller - February 16th, 2017 [February 16th, 2017]
- Mysterious Ancient Stonehenge-Like Circles Found in Amazon Rainforest - Collective Evolution - February 16th, 2017 [February 16th, 2017]
- 'Pokemon Go': How to Evolve Poliwhirl Into Politoed - Heavy.com - February 17th, 2017 [February 17th, 2017]
- 'Pokemon Go': How to Evolve Slowpoke Into Slowbro or Slowking - Heavy.com - February 17th, 2017 [February 17th, 2017]
- 'Pokemon Go': How to Evolve Gloom Into Bellossom - Heavy.com - February 17th, 2017 [February 17th, 2017]
- Pokmon Go Dragon Scale - how to evolve Seadra into Kingdra and how to get the Dragon Scale - Eurogamer.net - February 17th, 2017 [February 17th, 2017]
- Pokmon Go Eevee evolution: How to evolve Eevee into Umbreon, Espeon, Vaporeon, Jolteon and Flareon with new ... - Eurogamer.net - February 17th, 2017 [February 17th, 2017]
- University of Pittsburgh guest speaker discloses evolution findings - UTA The Shorthorn - February 17th, 2017 [February 17th, 2017]
- 'Pokemon Go' Special Items: Drop Rates for Evolution Items & Berries at Pokestops - Heavy.com - February 17th, 2017 [February 17th, 2017]
- How Vedic Philosophy Influenced Nikola Tesla's Idea of 'Free Energy' - Collective Evolution - February 18th, 2017 [February 18th, 2017]
- Migration to America took long enough for evolution to happen on the way - Ars Technica - February 18th, 2017 [February 18th, 2017]
- How To Choose Your Eevee Evolution In 'Pokmon GO:' Umbreon And Espeon Edition - Forbes - February 18th, 2017 [February 18th, 2017]
- Evolution Items - IGN - February 18th, 2017 [February 18th, 2017]
- Congo River fish evolution shaped by intense rapids: Genomic study ... - Science Daily - February 18th, 2017 [February 18th, 2017]
- Pokmon Go - How to evolve, use Special Items, when to evolve or Power Up your Pokmon - Eurogamer.net - February 18th, 2017 [February 18th, 2017]