Can you hear the Silent Spring?

30 Jan 2019

Can you hear the Silent Spring?

Rachel Carson wrote Silent Spring in 1962 to highlight the destruction of the environment from chemicals, especially pesticides [1].

Through the irresponsible and widespread use of pesticide, we’ve annihilated populations of insects, crustaceans molluscs, fish, birds and mammals. Insects and aquatic life were directly killed by the poisons while birds and mammals died from consuming poisoned critters. Genetic mutations and infertility were also caused by pesticides leaving the season of spring silent – depleted of the usual bird song.

Soil destroying

Although Rachel focussed on animals, she also noted the destruction of microbes from industrial chemicals. Her book highlights the importance of soil microbes for their role in decay and nutrient cycling. These are critical processes which can be interrupted by the use of chemicals which can prove toxic to microbes.

 

While there’s more control over pesticides today, we're still destroying the planet and many of our fellow co-inhabitants. Soaps and cleaning solutions boast of their ability to ‘kill 99.9% of bacteria’. While their claims are based on a tiny fraction of ‘tested’ bacteria, the destruction seems worryingly indiscriminate.

 
Fear of the future

 

It's hard not to fear the future outlined by H.G. Wells in Time Machine [2]. He imagined a scene in year 802701 where diseases no longer occurred, but this came at a cost, which prevented decay. He described a future devoid of life except for the human descendants and the species they selected for their value. How many microbes do we value? Will we only appreciate them once they are gone?

 

The tiny world of microbes and their complex interactions with the living and non-living means we are only starting to appreciate their importance. Yes, some cause disease, but they're vital to us and the planet for: our health [3], insect control [4], nutrient cycling [5] and even the production of rain [6].

 

Clean machines

 

We reduce microbes with our cleaning measures, but have we made any extinct? Specific bacteria gradually have become extinct over the Earth’s history but avoided mass extinction events, unlike the dinosaurs [7]. These microbial extinctions seem to have occurred before our time or without our notice.

 

The extinction of microbes by humanity has not been charted, but we are likely to wilfully eradicate pathogens including the smallpox virus, leprosy bacterium and tuberculosis bacterium [8]. Preventing disease is important, but what might we be losing along the way, and will we notice a lack of microbes in the future?

 

Road to extinction?

 

I've had a motorbike for 7 years and I used to get covered in insect splatter between the months of April and October. Although I travel the same  routes, I’ve seldom been covered in bug goo during the past three years. The reduction in insects is evident and unexplained, and the same may also apply to microbes.

 

Dr Pickett was quoted by Rachel Carson for saying, “We move from crisis to crisis merely trading one problem for another”. Once bacterial infections were brought under control, attention diverted to controlling insects, but now – we face the potential of a post-antibiotic era.

 

Boom and bust


Rachel Carson outlines how pesticides usually caused a boom in the ‘pest’ insect, by also killing off harmless competing insects and their predators. The pest insects also quickly developed resistance to the chemicals designed to eradicate them. Our carelessness with antibiotics and other antimicrobials has led to microbes which are harder to treat upon infection, including the multi-drug resistant nosocomial bacteria [9].

 

The events in Silent Spring occurred during my grandparent’s generation, leaving my parent’s generation to impose controls and better testing of pesticides. 

 

The wider public often fear bacteria, tainting them with the same reputation as the few that cause disease. 

 

If microbes outnumber our human cells, surely our priority should be to understand them better, not eradicate them entirely.

 

Further reading

[1] Carson, R. (1962). Silent Spring. A Fawcett Crest Book, New York. 

 

[2] Wells H.G. (1895). Time Machine. 2005 edition, Penguin Classic, London.

 

[3] Wang, B., Yao, M., Lv, L., Ling, Z., Li, L. (2017). The human microbiota in health and disease. Engineering, 3: 71-82.

 

[4] Arora, A.K., Douglas, A.E. (2017) Hype or opportunity? Using microbial symbionts in novel strategies for insect pest control. Journal of Insect Physiology, 103: 10-17.

 

[5] The Ohio State University (2019) Understanding Soil Microbes and Nutrient Recycling

 

[6] Schiermeier, Q. (2008) Rain-making’ bacteria found around the world

 

[7] Louca, S, Shih, P.M., Pennell, M.W., Fischer, W.W., Parfrey, L.W., Doebeli (2018). Bacterial diversification through geological time. Nature Ecology & Evolution, 2: 1458-1467. 

 

[8] Armand-Frappier Museum (2008). Species that are extinct of are on the verge of extinction. Available from:

 

[9] Levy, S.B., Marshall, B. (2004). Antibacterial resistance worldwide: causes, challenges and responses. Nature Medicine, 10: S122-S129.