• Dirk

Living on a Petri dish called Earth

Updated: Dec 14, 2019

Antony Leeuwenhoek lived in the 17th century and was the first one to detect single living cells, he called animalcules, which we now term bacteria. A German bacteriologist, called Julius Petri, invented a while later a dish to culture bacteria. In these small dishes you can grow bacteria (and other microorganisms) and observe them under the microscope.

Usually, bacteria take a while to start growing, adapting to the media in that Petri dish. After a while, the growth rate is exponentially increasing to then reach a stationary phase. Once all the resources on that Petri dish have been used, death phase starts (Figure 1).

In the year 200, a few million humans lived on Earth, with a density of 1.45 persons per square kilometer. That largely remained so for many hundreds of years more. In the Arab world, the first agricultural revolution occurred between the years 800 and 1300. During that time, irrigation of plantations were developed, and animal husbandry improved rendering agriculture more productive than it has been before. It may have triggered increased human growth, but the human population remained far below the 1 billion mark. 400 years later, new improvements in agriculture occurred by, for example, crop rotation, increasing agricultural productivity further. In the year 1800, the human population reached 1 billion. So, the early 19th century has seen 1 billion people on the planet, which is not so long ago, as for example my great great grandparents were likely born at that time. It was also the time Charles R. Darwin (1809), the Charles Darwin was born, an English naturalist, geologist and biologist, best known for his contributions to understanding evolution. Darwin was born at the start of industrialisation and in the midst of the 2nd agricultural revolution. When Darwin died in 1882, aged 73, the human population already scratched the 2 billion mark, which was reached by 1920.

Hence, at the start of the 2nd agricultural revolution, the human lag phase was definitely over and exponential growth has started. Our planets resources were increasingly exploited, coming along with pollution, land use and resource depletion, which Earth was not able to regrow or buffer anymore. In 1962, Rachel Carson (1907 – 1964) was publishing her observations of our degrading planet in her book Silent Spring. Her major concern was with the future of our planet and all life on Earth. Chemical pollution, she predicted, has the potential to destroy insects, and to kill insect-eaters at the same time, resulting in a spring deprived of cricket chirps, bee buzzes, frog croaks and bird songs. In her book, she suggested a needed change in how democracies and liberal societies operated so that individuals and groups could question what their governments allowed others to put into the environment. During the same time, scientist’s warnings became louder that rising CO2 levels triggered a change in our planet’s climate.

Today, 59.3 people live on a square meter, 41 times more than 1819 years ago, and since industrialisation a mere 200 years ago, 7 billion more people share the dwindling resources of our planet. There are projections on a stationary phase with roughly 11 billion people living on the Petri dish Earth. After a stationary phase, bacteria enter the final phase, the death phase. This phase is blended out by most, especially politicians.

A Swedish teenager called Greta Thunberg has achieved what thousands of scientists have not over many decades - to mobilize the masses. We live in a Petri-dish called Earth.

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