Mathematical model of animal growth suggests life is defined by biology, not physics

Mathematical model of animal growth suggests life is defined by biology, not physics

Juvenile lobster roach Nauphoeta cinerea. Lobster cockroaches weigh about 5 milligrams when they hatch, and as they grow to adult size, their weight increases by two orders of magnitude to 0.5 grams.Credit: Monash University

Monash University scientists have challenged the conventional notion that biological patterns can be explained by physical constraints.


In a study published today sciencethe researchers demonstrated their mathematical model of animal growth, which describes how animals use energy for growth and reproduction as they age and increase in size.

“While organisms cannot break the laws of physics, evolution has proven itself to be very good at finding loopholes,” said lead study author Professor Craig White, from Monash University’s School of Biological Sciences and Centre for Geometric Biology.

An unexplained problem in biology involves the non-proportional (allometric) relationship between energy metabolism and size.

“Finding that metabolism in animals can be explained without invoking physical constraints means we’ve been looking in the wrong place in our search for answers to why this general pattern occurs,” Professor White said.

“We believe that physical constraints are not driving the biology we observe as previously assumed, and that evolutionary selection is broader than previously thought,” he said.

During development or evolution, increases in body size are often accompanied by disproportionate increases in energy requirements, so larger animals burn less energy and require less food than grams.

For example, small mammals like shrews may need to eat three times their body weight in food each day, while the largest whales – only 5-30% of their body weight in krill per day.

“Our study counters the conventional view that biological patterns such as allometric growth occur due to physical constraints,” Professor White said.

“We devised a mathematical model of animal growth that describes how animals shift energy allocation from growth to reproduction as they age and size, and show that lifetime reproduction is maximized when metabolism is disproportionate to size,” he said. .

“Many models proposed since the early 19th century use physical or geometric constraints to explain this pattern, but ours doesn’t. Simply put, the classical theory says that animals have the metabolism they have because they must, and we found that they have The metabolism they have because it’s the best.”

Professor White said the study showed that allometric growth was not necessarily the result of physical or geometric constraints. Instead, natural selection, not physics, favors allometric growth.


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More information:
Craig R. White et al, Metabolic scaling is a product of life history optimization, science (2022). DOI: 10.1126/science.abm7649

Courtesy of Monash University

Citation: Mathematical model of animal growth shows life is defined by biology, not physics (19 Aug 2022) Retrieved 20 Aug 2022 from https://phys.org/news/2022-08- mathematical-animal-growth-life-biology. html

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