[Paleopsych] Eureka: Emory scientist finds different paths lead to similar cognitive abilities

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Emory scientist finds different paths lead to similar cognitive

Despite the divergent evolutionary paths of dolphins and primates -- and
their vastly different brains -- both have developed similar high-level
cognitive abilities, says Emory University neuroscientist and behavioral
biologist Lori Marino. She presented her latest findings on the
evolution of and differences in brain structure between cetaceans (ocean
mammals like whales and dolphins) and primates April 5 during the 14th
annual Experimental Biology 2005 meeting in San Diego.

Marino's presentation examined the diverse evolutionary patterns through
which dolphins and primates acquired their large brains, how those
brains differ, and how sensory information can be processed in different
ways and still result in the same cognitive abilities.

"Eventually, a better understanding of how other species process
information might be useful in helping people impaired in "human" ways
of processing information. Perhaps there are alternative ways to sort
out information in our own brains," says Marino, whose talk was part of
the scientific sessions of the American Association of Anatomists.

Recent research by Marino and her colleagues has traced the changing
encephalization, or relative brain size, of cetaceans during the past 47
million years by using magnetic resonance imaging and histological
studies of the fossil record. While modern humans have brains that are
seven times bigger than would be expected for our body size, giving us
an encephalization level of seven, some modern dolphins and whales have
an encephalization level close to five -- not a huge difference, says
Marino. For example, Homo sapiens' closest relatives, the great apes,
have encephalization levels of only two to two-and-a-half.

"While humans are the most encephalized -- the brainiest -- creatures on
earth, we are relative newcomers to that status," says Marino. "The
cetaceans enjoyed a tremendous increase in brain size and organization
about 35 million years ago, whereas humans got their big brains much
more recently during the past one to two million years."

Marino's earlier research has shown how dolphins have the capacity for
mirror self-recognition, a feat of intelligence previously thought to be
reserved only for Homo sapiens and their closest primate cousins. Marino
is a professor of neuroscience and behavioral biology at Emory and a
research associate at the Yerkes National Primate Research Center. Her
work has been funded by the National Science Foundation, The SETI
Institute, The Smithsonian Institution, and Emory University.

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