NASA researchers have uncovered evidence that gravity, or
the lack thereof, may play an important role in the
development and evolution of life. The study suggests
fertilization is gravity-sensitive and works differently in
the near-weightless environment of space than it does here on

Using sperm from tiny sea urchins, the research team conducted
both ground- and space-based experiments to examine the impact
gravity has on the reproduction process.

According to a paper authored by Dr. Joseph Tash, a NASA
researcher and professor at the University of Kansas Medical
Center in Kansas City, scientists found gravitational changes
may influence a species’ ability to reproduce. His team’s
findings were published in a recent issue of Biology of

  • October 2001: “Fertilization of Sea Urchin Eggs and Sperm Motility Are Negatively Impacted under Low Hypergravitational Forces Significant to Space Flight”; Joseph S. Tash, Shane Kim, Marianne Schuber, Dieter Seibt, and William H. Kinsey; Biol Reprod 2001 65: 1224-1231. [Abstract] [Full Text – fee required]

“This research shows that fertilization is altered in a
microgravity environment,” said Tash. “Such alterations have
implications for reproduction of plant and animal food and for
long-term space habitation by humans.”

The experiments were conducted under a grant from NASA’s
Office of Biological and Physical Research in Washington. The
research program provides investigators with the opportunity
to use microgravity or low-gravity environments to investigate
the role this fundamental physical force and other space-
flight factors have on biological and ecological systems.

“All life is influenced by the pull of Earth’s gravity. NASA
scientists are conducting research to explore the role of
gravity at all levels of biological processing,” said Dr.
Kathie Olsen, Acting Associate Administrator for Biological
and Physical Research at NASA Headquarters. “Without the
presence of Earth’s gravity, we are able to pursue answers to
questions of how living organisms develop.”

The research team used semen and eggs from the tiny marine
creatures to study motility and interaction during periods of
increased gravity and near weightlessness.

Studies conducted during space shuttle missions showed changes
in cell proteins, which stimulated and increased the activity
of the sperm cells. However, by spinning the cells in a slow-
speed centrifuge to increase gravity, sperm activity was
decreased, suggesting fertilization may be inhibited by
exposure to increased levels of gravity.

Other members of the team included Shane Kim and William
Kinsey from the University of Kansas Medical Center, and
Marianne Schuber and Dieter Seibt from the German Aerospace
Center, Koln, Germany.

Related Links

  • NASA’s Biological and Physical Research Program
  • Sea Urchin Eggs under Microgravity Conditions, ESA
  • Sea Urchin Fertilization and Development During Spaceflight and Effects on Calcium- and Cytoskeleton-mediated Events, NASA ARC
  • Evo Devo Learns a Larval Lesson, NASA Astrobiology Institute