Humans can tolerate only brief bursts of extreme gravitational force. Fighter pilots train to endure high G-loads, but even they struggle beyond 9G. At higher levels, blood drains from the brain, causing blackout within seconds. Sustained exposure remains dangerous and poorly understood, especially during spaceflight and reentry.

Now, new research from the University of California, Riverside suggests biology may be more adaptable than expected. Scientists exposed fruit flies to forces as high as 13G using a centrifuge. Instead of breaking down, the insects survived, reproduced, and eventually recovered normal behavior.

pinning flies to extremes

Researchers used a custom centrifuge to simulate hypergravity. The setup mimicked forces far beyond Earth’s pull. The team tracked movement using infrared sensors and climbing tests.

“The centrifuge is like a merry-go-round,” Arumugam Amogh said. “The faster you go, the more you feel pulled outward. That’s hypergravity.”

The results surprised the researchers. At 4G, flies became highly active after 24 hours. At higher levels like 7G, 10G, and 13G, activity dropped sharply.

“When flies experienced four times Earth’s gravity, or 4G, for 24 hours, they became hyperactive,” said Ysabel Giraldo. “But at higher levels of 7G, 10G, and 13G, the pattern reversed: Instead of becoming hyperactive, the flies became less active, and they didn’t climb as much.”

Behavior shifts, then recovery

The team did not stop at short exposures. They tracked flies across their lifespans and even across generations. After 24 hours at 4G, flies stayed hyperactive for weeks. Eventually, they returned to normal behavior. Flies exposed to higher gravity also recovered over time.

The findings point to a system that adapts under stress rather than failing. The brain may adjust how energy gets used.

“We believe what we’re seeing is that gravity feeds directly into the brain’s decision-making around energy use and movement,” Arumugam Amogh said. “It helps determine whether to act or conserve energy.”

Researchers also observed changes in fat storage and metabolism. Energy use rose and fell alongside movement patterns.

Implications for space travel

The study adds new insight into how gravity shapes biology. Most research has focused on microgravity in space. This work examines the opposite extreme.

The team even raised fruit flies for 10 generations under hypergravity. The insects lived, mated, and reproduced under constant stress. That long-term resilience challenges assumptions about extreme environments.

The findings could help scientists understand how human bodies respond to high-G conditions. That includes fighter pilots and astronauts returning to Earth.

“I think our study is really timely,” Giraldo said. “The link between gravity, physiology, and energy use will only become increasingly important to understand as space travel is poised to become more common in the future.”

As missions like Artemis II push humans deeper into space, understanding gravity’s effects becomes critical. The research suggests that life may adapt better than expected—even under forces that seem extreme.

The study is published in the Journal of Experimental Biology.