Cerveau d'humain comparé à un cerveau de dauphin
Janvier 2010
Les scientifiques affirment (enfin !) que les dauphins devraient être traités comme des "personnes non-humaines"
Cerveau
d'humain comparé à un cerveau de dauphin
Dotés de conscience de soi, d'une très haute
intelligence, de cultures propres, de langage et d'une vie sociale extrêmement
complexes, les dauphins n'ont évidemment pas leur place dans une prison
aquatique. Pas plus que les Humains, ils ne supportent d'être emprisonnés ou
soumis à la volonté de Grands Singes à des fins mercantiles. C'est ce
qu'affirment également les scientifiques.
Lire ci-dessous l'article complet.
Free
dolphin. Panama City Beach (Florida)
SUNDAY TIMES
http://www.timesonline.co.uk/tol/news/science/article6973994.ece
Scientists say dolphins should be treated as 'non-human
persons'
Dolphins have long been recognised as among the most intelligent of animals
but many researchers had placed them below chimps
Jonathan Leake
January 3, 2010
Dolphins have been declared the world¹s second most intelligent creatures after
humans, with scientists suggesting they are so bright that they should be
treated as "non-human persons".
Studies into dolphin behaviour have highlighted how similar their communications
are to those of humans and that they are brighter than chimpanzees. These have
been backed up by anatomical research showing that dolphin brains have many key
features associated with high intelligence.
The researchers argue that their work shows it is morally unacceptable to
keep such intelligent animals in amusement parks or to kill them for
food or by accident when fishing. Some 300,000 whales, dolphins and porpoises
die in this way each year.
"Many dolphin brains are larger than our own and second in mass only to the
human brain when corrected for body size" said Lori Marino, a zoologist at Emory
University in Atlanta, Georgia, who has used magnetic resonance imaging scans to
map the brains of dolphin species and compare them with those of primates.
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Dolphins have long been recognised as among the most intelligent of animals but
many researchers had placed them below chimps, which some studies have found can
reach the intelligence levels of three-year-old children. Recently, however, a
series of behavioural studies has suggested that dolphins, especially species
such as the bottlenose, could be the brighter of the two. The studies show how
dolphins have distinct personalities, a strong sense of self and can think about
the future.
It has also become clear that they are ³cultural² animals, meaning that new
types of behaviour can quickly be picked up by one dolphin from another.
In one study, Diana Reiss, professor of psychology at Hunter College, City
University of New York, showed that bottlenose dolphins could recognise
themselves in a mirror and use it to inspect various parts of their bodies, an
ability that had been thought limited to humans and great apes.
In another, she found that captive animals also had the ability to learn a
rudimentary symbol-based language.
Other research has shown dolphins can solve difficult problems, while those
living in the wild co-operate in ways that imply complex social structures and a
high level of emotional sophistication.
In one recent case, a dolphin rescued from the wild was taught to tail-walk
while recuperating for three weeks in a dolphinarium in Australia. After
she was released, scientists were astonished to see the trick spreading among
wild dolphins who had learnt it from the former captive.
There are many similar examples, such as the way dolphins living off Western
Australia learnt to hold sponges over their snouts to protect themselves when
searching for spiny fish on the ocean floor.
Such observations, along with others showing, for example, how dolphins could
co-operate with military precision to round up shoals of fish to eat, have
prompted questions about the brain structures that must underlie them.
Size is only one factor. Researchers have found that brain size varies hugely
from around 7oz for smaller cetacean species such as the Ganges River dolphin to
more than 19lb for sperm whales, whose brains are the largest on the planet.
Human brains, by contrast, range from 2lb-4lb, while a chimp¹s brain is about
12oz.
When it comes to intelligence, however, brain size is less important than its
size relative to the body.
What Marino and her colleagues found was that the cerebral cortex and neocortex
of bottlenose dolphins were so large that ³the anatomical ratios that assess
cognitive capacity place it second only to the human brain².
They also found that the brain cortex of dolphins such as
the bottlenose had the same convoluted folds that are strongly linked with human
intelligence.
Such folds increase the volume of the cortex and the ability of brain cells to
interconnect with each other. ³
Despite evolving along a different neuroanatomical trajectory to humans,
cetacean brains have several features
that are correlated with complex intelligence,² Marino said.
Marino and Reiss will present their findings at a conference in San Diego,
California, next month, concluding that the new evidence about dolphin
intelligence makes it morally repugnant to mistreat them.
Thomas White, professor of ethics at Loyola Marymount University, Los Angeles,
who has written a series of academic studies suggesting dolphins should have
rights, will speak at the same conference.
³The scientific research . . . suggests that dolphins are Œnon-human persons¹
who qualify for moral standing as individuals,² he said.
Additional reporting: Helen Brooks