When studying energy in biology, students learn that the mitochondria are the powerhouses of the cell; about the many chemical reactions of glycolysis, the Krebs cycle, and the electron transport chain… but less covered is the great mystery of metabolism. We understand our pulse and that our beating hearts move resources around our bodies, but we do not have a fundamental understanding of why we use as much energy as we do. If you’re reading this and are more or less relaxed, your metabolic rate is likely about 50-100 Watts, a measure of energetic flux that can be estimated by a handheld device, or more precisely validated by measuring your heat production or oxygen consumption in a laboratory setting. We understand the underlying metabolic chemistry at the microscopic level and we can measure metabolic rates at the whole-person scale, but we don’t yet have a convincing theory or model to explain how these are connected.
Ant metabolic rates can be measured just like our own, and this is one of the major activities of our research lab at Providence College – to measure the oxygen consumption and carbon dioxide production of ants from different types of colonies, across ranges in size, as they engage in different behaviors. Our work on swarm energetics and efficiency is currently supported by a grant from the National Science Foundation, the federal agency responsible for funding basic science research and community engagement across the country, which just this morning was forced to abruptly let go of almost 200 program officers and staff, without notice or severance. Our grant is funding a full-time postdoctoral scholar, stipends for summer research students, and collaborations with groups across the country all working on solving the metabolic mystery, by using social insect colonies as model systems for physiological integration.
Just like how our metabolic rates are an emergent property that depends on the interactions of trillions of cells within our bodies, the metabolic rates of social insect colonies depend on the interactions among all of the individuals within the colonies. Across ranges in individual body size or across ranges in colony size, we’ve found that metabolic rates increase with size, raised to the ¾-power exponent. This power-law scaling means that larger things, whether individuals or colonies, use relatively less energy pound-for-pound or per-capita, compared to smaller ones. This scaling pattern, though unexplained, has impacts across ecology, evolution, and medicine. Remarkably, cities show very similar patterns. Large cities use more energy than smaller ones, but on a per-capita basis, the average person in New York, Boston, or Providence uses less energy than a person in the suburbs or rural communities. Thinking about the connections begs us to investigate the ways we use public infrastructure and common resources to generate an economy of scale in urban centers, and how our bodies may have been similarly shaped across time by evolutionary pressures.
If we can’t pursue the research that will help us to understand some of the most fundamental aspects of how life works and scales across sizes, from individual cells to collective groups, we will continue to be stuck in ignorance, planning cities and prescribing medicine by guess-checkand-revise, forced to accept myths and lore in place of knowledge, lost in the dark. It’s time to rage against the systematic destruction of our national scientific infrastructure. At stake is nothing less than the pulse of our cities. •
Follow Dr. Jane and her research lab on Instagram @antlabpvd or on the web at lovetheants.org. Illustration by Danika Valentine.
