Connecting Global Priorities Biodiversity and Human Health

Case study: plsia alifornia and the human brain
Drugs derived from natural products may perhaps be the most direct and concrete bond that many
may nd between biodiversity and medicine. However, biodiversity holds much broader connections
with human health. In many arenas of biomedical inquiry, biodiversity has beenan invisible linchpin
of discovery. For example, of the 104 Nobel prizes in Medicine awarded since Emil von Behring
received the prizein 1901 for his research on guinea pigs to develop a treatment for diphtheria,
99 were given to scientists who either directly or indirectly made use of other species to do their
research.
In 2000, Eric Kandel shared the Nobel prize in Physiology or Medicine with Arvid Carlsson for his
groundbreaking research on memory. Kandels research established, at a cellular and molecular
level, how our brains learn and form memories. He did not study human brains to do this. Instead,
he studied the nervous system of sea hares from the genus Aplysia. A human brain has about 86
billion neurons whereas Aplysia has, all told, around 20 000, and only about 100 of those neurons
are involved in memory. In addition, Aplysia’s memory cells are also among the largest of their
kind in the animal kingdom and can be visualized with the naked eye. This makes monitoring the
electrical messages that scurry across their membranes, and exploring how these messages may alter
genes and other molecules that control a neurons inner workings, comparatively easy. With these
advantages, Kandel found what was dicult, if not impossible, otherwise. What was gleaned from
Aplysia’s nervous system made possible further research in other species, which has deepened our
understanding not only of learning and memory, but of a host of human ailments, from substance
abuse and Alzheimer disease to the lifelong consequences of early childhood trauma.
For more on research from Aplysia see: Kandel ER. (2007). In search of memory: the emergence of a
new science of mind. New ork, USA: WW Norton & Company.
Aplysia californica releasing ink that not only clouds predators’ view but masks their sense of smell
and taste.
GENEVIEVE ANDERSON
166 Connecting Global Priorities: Biodiversity and Human Health