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Brain size matters for primates
Bigger brain means larger frontal cortext, study finds
Updated: 5:00 p.m. ET March 09, 2004WASHINGTON -
A study of primates' brains ranging from tiny bush babies
to humans and apes
shows that size really may matter, researchers said on Monday.
All primates have an unusually large frontal cortex, a part of the brain used by humans for higher thought and reasoning, they found.
From lemurs to chimpanzees, that part of the brain is especially large compared with overall brain size, the California Institut
of Technology team found.
"In primates, having a bigger brain means you have a disproportionately larger frontal cortex," said Eliot Bush, a PhD candidate at Caltech who worked on the stud
y.<b
r>
While the study does not offer any deep insight into what separates humans from
other mammals, it does show that much of what makes people and our cousins the apes different may lie in our primate heritage.
A comparison to carnivores --the order that includes lions, tigers and dogs --shows they do not have the same disproportionately large frontal cortex.
This may explain why a 5-pound (2-kg) house cat is every bit as intelligent as a 100-pound (40-kg) lion.
Bush said the finding, published in this week's issue of the Proceedings of the National Academy of Sciences, disputed theories that suggested human behavior could be traced in part to a disproportionately large frontal cortex compared to the rest of the brain.
It turns out that smaller primates such as lemu
rs and bush babies actually devote a larger proportion of their brains to the frontal cortex. But because they are small overall, this area is small.
What makes us unique
Humans and apes a
re b
ig and have
big brains, so while the proportion is not as big, the frontal cortex ends up being hug
e, comparatively.
This could explain some behavioral differences that make humans, apes and monkeys --the large primates --unique.
"Primates are able to understand abstractions --maybe understanding those two monkeys over there are a mother and a daughter, whereas maybe other mammals don't have that ability," Bush said in a telephone interview.
"In humans, the frontal cortex is involved in a lot of interesting things such as social relationships. I think that quite possibly is what it is about."
For their study, Bush and his professor, John Allman, compared 43 mammals, including 25 primates and 15 carnivores.
They found that in primates, the ratio of fr
ontal cortex to the rest of the cortex was about three times higher in a large primate than in a small one.
The ratio does not change in carnivores.
They did not look at other
notably
big-brained animals
such as cetaceans --the group that includes whales and dolphins.
Copyright 2004 Reuters Limited. All
rights reserved. Republication or redistribution of Reuters content is expressly prohibited without the prior written consent of Reuters.
http://msnbc.msn.com/id/4488656/
Brain size matters for primates
Bigger brain means larger frontal cortext, study finds
Updated: 5:00 p.m. ET March 09, 2004WASHINGTON -
A study of primates' brains ranging from tiny bush babies
to humans and apes
shows that size really may matter, researchers said on Monday.
All primates have an unusually large frontal cortex, a part of the brain used by humans for higher thought and reasoning, they found.
From lemurs to chimpanzees, that part of the brain is especially large compared with overall brain size, the California Institut
of Technology team found.
"In primates, having a bigger brain means you have a disproportionately larger frontal cortex," said Eliot Bush, a PhD candidate at Caltech who worked on the stud
y.<b
r>
While the study does not offer any deep insight into what separates humans from
other mammals, it does show that much of what makes people and our cousins the apes different may lie in our primate heritage.
A comparison to carnivores --the order that includes lions, tigers and dogs --shows they do not have the same disproportionately large frontal cortex.
This may explain why a 5-pound (2-kg) house cat is every bit as intelligent as a 100-pound (40-kg) lion.
Bush said the finding, published in this week's issue of the Proceedings of the National Academy of Sciences, disputed theories that suggested human behavior could be traced in part to a disproportionately large frontal cortex compared to the rest of the brain.
It turns out that smaller primates such as lemu
rs and bush babies actually devote a larger proportion of their brains to the frontal cortex. But because they are small overall, this area is small.
What makes us unique
Humans and apes a
re b
ig and have
big brains, so while the proportion is not as big, the frontal cortex ends up being hug
e, comparatively.
This could explain some behavioral differences that make humans, apes and monkeys --the large primates --unique.
"Primates are able to understand abstractions --maybe understanding those two monkeys over there are a mother and a daughter, whereas maybe other mammals don't have that ability," Bush said in a telephone interview.
"In humans, the frontal cortex is involved in a lot of interesting things such as social relationships. I think that quite possibly is what it is about."
For their study, Bush and his professor, John Allman, compared 43 mammals, including 25 primates and 15 carnivores.
They found that in primates, the ratio of fr
ontal cortex to the rest of the cortex was about three times higher in a large primate than in a small one.
The ratio does not change in carnivores.
They did not look at other
notably
big-brained animals
such as cetaceans --the group that includes whales and dolphins.
Copyright 2004 Reuters Limited. All
rights reserved. Republication or redistribution of Reuters content is expressly prohibited without the prior written consent of Reuters.