Scientists discover a universal law that limits the growth of life

Living organisms need nutrients to grow. However, there comes a time when growth slows down even with abundant food. This phenomenon is known as the “law of diminishing returns.”

Researchers at the Tokyo Institute of Science in Japan have discovered a universal law that explains why this happens. The work, published in the Proceedings of the National Academy of Sciences on October 3, could boost agricultural productivity and biomanufacturing efficiency.

Law of diminishing returns

Although nutritional factors are known to influence the development of organisms, previous research has focused on studying nutrients individually or specific biochemical pathways. Figuring out how all the processes work together inside the cell to control growth has been a mystery.

To solve the problem, Japanese scientists proposed a model of how several factors influence living cells in managing the expansion of organisms, rather than just a single element, as in previous theories.

Since 1940, microbiologists have relied on the Monod equation. The theory suggests that growth rates increase as nutrients are added until they stabilize. However, the model focuses on only one nutrient as a limiting element, while in the cell there are several processes occurring at the same time, promoting conflict over resources.

According to the new study, growth is limited by several factors that change as conditions change. For example, if the problem of nitrogen deficiency is “solved”, it seems that another weakness will take the place of the problem. In other words, there is always something new that limits an organism’s expansion when it is fully developed, even when there is an abundance of nutrients.

In the tests, computational models were used to simulate the cells’ actions, proving that the theory worked in practice. “The shape of the growth curves arises directly from the physics of resource allocation within cells, rather than relying on any specific biochemical reaction,” explains Tetsuhiro Hatakeyama, one of the paper’s authors, in a statement.

With this discovery, the scientific community has a new way to understand more precisely how life grows.

“Our work lays the foundation for universal laws of growth. By understanding the limits that apply to all living systems, we can better predict how cells, ecosystems and even entire biospheres will respond to environmental changes,” said the study’s lead author, Jumpei Yamagishi.

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