Dolphin, Humans Share Similar Brain Size

Dolphin, Humans Share Similar Brain Size, Scientists say
Dolphins recognize themselves in mirrors, communicate in symbols

Scientists have determined how brain size has changed in dolphins and their relatives over 47 million years and have found that human and dolphin brain size is similar, according to an October 27 National Science Foundation (NSF) press release.

Dolphin brains are four to five times larger than would be expected for their body size when compared to the average brain size for animals of a similar size. In humans, the measure is seven times larger.

Results of the NSF-funded research were published online this week in the journal The Anatomical Record.

"Essentially, the brains of primates and cetaceans arrived at the same cognitive space while evolving along different paths," said Lori Marino of Emory University in Atlanta. "What the data say to me is that we, as humans, are not that special. Although we are highly encephalized [have large brains], it's not by much compared with cetaceans." Whales, dolphins and porpoises belong to a group of mammals known scientifically as cetaceans.

Dolphins have shown behavioral abilities ascribed in the past only to humans and great apes. The abilities include mirror self-recognition; comprehending artificial, symbol-based communication systems and abstract concepts; and learning and transmitting behaviors described as cultural from one generation to another.

Dolphins' large brains likely enable these capabilities, Marino said.

The study was also funded by the SETI (Search for Extraterrestrial Intelligence) Institute in California, a private, nonprofit organization dedicated to scientific research, education and public outreach.

Text of the NSF press release follows:

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National Science Foundation
Press release, October 27, 2004

Read more: http://www.america.gov/st/washfile-english/2004/October/20041028134023lcnirellep5.062503e-02.html#ixzz0PvGlnJUS