News

Published: 17 December 2024

Study reveals unique features of human metabolism

A recent study published in the journal PNAS has provided new insights into why humans differ so significantly from other primates. Our ability to develop large brains and live long lives is closely tied to our exceptional metabolism. Researchers from Harvard University have discovered that humans, compared to other primates, process significantly more energy and use it with remarkable efficiency.

Compared to our closest relatives, other primates, humans not only have larger brains but also a longer lifespan. Additionally, humans - at least in their original lifestyle as hunter-gatherers - are physically more active than, for instance, chimpanzees. However, these advantages come at a cost: we require a lot of energy. While other animals often face trade-offs - such as reducing physical activity to conserve energy for survival - humans are different. We manage to remain physically active while maintaining our vital functions.

The biggest differences from other primates

The researchers identified several key differences between humans and other primates. Humans consume up to 85% more energy per day than non-human primates of similar size. This high energy intake is made possible by improved energy acquisition, such as cooking food and cooperative behavior.

To meet their substantial energy needs even during challenging times, humans can store more energy as body fat than their leaner, non-human primate counterparts. These reserves allow humans to endure longer periods of physical activity and reduced energy intake without compromising critical functions like brain development or reproduction. Efficient heat regulation - facilitated by a tenfold increase in sweat glands and reduced body hair - helps humans effectively dissipate heat generated during physical activity.

As a result of these adaptations - enhanced energy intake, storage, and efficient utilization - humans avoid the 'energy trade-offs' faced by other primates. Where non-human primates must choose between physical activity and essential functions like brain metabolism, humans can sustain both. These findings highlight the pivotal role of energy metabolism in human evolution, including the growth of our brain, which requires approximately 200–300 more kcal per day compared to other primates.

Implications for health

The study's findings are also relevant to modern life. In our society, where physical activity is often replaced by a sedentary lifestyle and food is abundantly available at all times, health problems such as obesity and chronic diseases arise. This underscores a crucial insight: our high metabolic rates are designed for a high level of physical activity and require regular physical acticity to maintain health.

Conclusions

The study demonstrates that human metabolism differs significantly from that of other primate species. Humans allocate more energy to support their large brains, physical activity, and overall health without having to compromise between these areas. In contrast, other primates must divide their available energy more strictly. These differences, along with other species-specific distinctions, help explain why findings from animal studies on non-human primates often fail to translate to humans.