FreeLists / tn-bird / [TN-Bird] Article about birds having "minds of their own."

[Dthomp2669@xxxxxxx]

Here is an interesting "birdy" article that I hope you will all enjoy and, 
hopefully, will not think it to be too "off message" for me to have posted.  

Dee Thompson
Nashville, TN
 
February 1, 2005

Minds of Their Own: Birds Gain Respect

By SANDRA BLAKESLEE 
    
irdbrain has long been a colloquial term of ridicule. The common notion is 
that birds' brains are simple, or so scientists thought and taught for many 
years. But that notion has increasingly been called into question as crows and 
parrots, among other birds, have shown what appears to be behavior as 
intelligent 
as that of chimpanzees.

The clash of simple brain and complex behavior has led some neuroscientists 
to create a new map of the avian brain. 

Today, in the journal Nature Neuroscience Reviews, an international group of 
avian experts is issuing what amounts to a manifesto. Nearly everything 
written in anatomy textbooks about the brains of birds is wrong, they say. The 
avian 
brain is as complex, flexible and inventive as any mammalian brain, they 
argue, and it is time to adopt a more accurate nomenclature that reflects a new 
understanding of the anatomies of bird and mammal brains. 

"Names have a powerful influence on the experiments we do and the way we 
think," said Dr. Erich D. Jarvis, a neuroscientist at Duke University and a 
leader 
of the Avian Brain Nomenclature Consortium. "Old terminology has hindered 
scientific progress."

The consortium of 29 scientists from six countries met for seven years to 
develop new, more accurate names for structures in both avian and mammalian 
brains. For example, the bird's seat of intelligence or its higher brain is now 
termed the pallium. 

"The correction of terms is a great advance," said Dr. Jon Kaas, a leading 
expert in neuroanatomy at Vanderbilt University in Nashville who did not 
participate in the consortium. "It's hard to get scientists to agree about 
anything." 


Scientists have come to agree that birds are indeed smart, but those who 
study avian intelligence differ on how birds got that way. Experts, including 
those in the consortium, are split into two warring camps. One holds that 
birds' 
brains make the same kinds of internal connections as do mammalian brains and 
that intelligence in both groups arises from these connections. The other holds 
that bird intelligence evolved through expanding an old part of the mammal 
brain and using it in new ways, and it questions how developed that 
intelligence 
is.

"There are still puzzles to be solved," said Dr. Peter Marler, a leading 
authority on bird behavior at the University of California, Davis, who is not 
part 
of the consortium. But the realization that one can study mammal brains by 
using bird brains, he said, "is a revolution."

"I think that birds are going to replace the white rat as the favored subject 
for studying functional neuroanatomy," he added. 

The reanalysis of avian brains gives new credibility to many behaviors that 
seem odd coming from presumably dumb birds. Crows not only make hooks and 
spears of small sticks to carry on foraging expeditions, some have learned to 
put 
walnuts on roads for cars to crack. African gray parrots not only talk, they 
have a sense of humor and make up new words. Baby songbirds babble like human 
infants, using the left sides of their brains.

Avian brains got their bad reputation a century ago from the German 
neurobiologist Ludwig Edinger, known as the father of comparative anatomy. 
Edinger 
believed that evolution was linear, Dr. Jarvis said. Brains evolved like 
geologic 
strata. Layer upon layer, the brains evolved from old to new, from fish to 
amphibians to reptiles to birds to mammals. By Edinger's standards, fish were 
the 
least intelligent. Humans, created in God's image, were the most intelligent. 
Edinger cut up all kinds of vertebrate brains, noting similarities and 
differences, Dr. Jarvis said. 

In mammals, the bottom third of the brain contained neurons organized in 
clusters. The top two-thirds of the brain, called the neocortex, consisted of a 
flat sheet of cells with six layers. This new brain, the seat of higher 
intelligence, lay over the old brain, the seat of instinctual behaviors.

In humans, the neocortex grew so immense that it was forced to assume folds 
and fissures, so as to fit inside the skull. 

Birds' brains, in contrast, were composed entirely of clusters. Edinger 
concluded that without a six-layered cortex, birds could not possibly be 
intelligent. Rather, their brains were fully dedicated to instinctual 
behaviors. 

This view persisted through the 20th century and is still found in most 
biology textbooks, said Dr. Harvey Karten, a neuroscientist at the University 
of 
California, San Diego, and a member of the consortium, whose research has long 
challenged the classic view. 

There is a bird way and a mammal way to create intelligence, Dr. Karten said. 
One uses clusters. One uses flat sheet cells in six layers. Each exploits the 
basic design of having a lower brain and a higher brain with mutual 
connections. 

In the 1960's, Dr. Karten carried out experiments using new techniques to 
trace brain wiring and identify the paths taken by various brain chemicals. In 
humans, a chemical called dopamine is found mostly in lower brain areas, called 
basal ganglia, which consist of clusters. 

Using the same tracing techniques in birds, Dr. Karten found that dopamine 
also projected primarily to lower clusters and no higher. Later studies show 
numerous similarities between clusters in the mammalian brain and lower 
clusters 
in the avian brain. Experts now agree that the two regions are evolutionarily 
older structures that lie underneath a newer mantle.

Where the experts divide is on the question of the upper clusters in a bird's 
brain. Agreed, they are not primitive basal ganglia. But where did they come 
from? How did they evolve? What is their function? 

Dr. Karten and others in the consortium think these clusters are directly 
analogous to layers in the mammalian brain. They migrate from similar embryonic 
precursors and perform the same functions.

For example, in mammals, sensory information - sights, sounds, touch - flows 
through a lower brain region called the thalamus and enters the cortex at the 
fourth layer in the six-layered cortex. 

In birds, sensory information flows through the thalamus and enters specific 
clusters that are functionally equivalent to the fourth layer. In this view, 
other clusters perform functions done by different layers in the mammal brain. 

A second group, including Dr. Georg Striedter of the University of 
California, Irvine, a consortium member, believes that upper clusters in the 
avian brain 
are an elaboration of two mammalian structures - the claustrum and the 
amygdala. In this view, these structures look alike in bird and mammal embryos. 
But 
in birds they grow to enormous proportions and have evolved entirely new ways 
to support intelligence. 

In mammals, the amygdala is involved in emotional systems, Dr. Striedter 
said. "But birds use it for integrating information," he said. "It's not 
emotional 
anymore." 

Meanwhile, examples of brilliance in birds continue to flow from fields and 
laboratories worldwide. 

Dr. Nathan Emery and Dr. Nicola Clayton at the University of Cambridge in 
England study comparisons between apes and corvids - crows, jays, ravens and 
jackdaws. Relative to its body size, the crow brain is the same size as the 
chimpanzee brain.

Everyone knows apes use simple tools like twigs, Dr. Emery said, selecting 
different ones for different purposes. But New Caledonian crows create more 
complex tools with their beaks and feet. They trim and sculpture twigs to 
fashion 
hooks for fetching food. They make spears out of barbed leaves, probing under 
leaf detritus for prey.

In a laboratory, when a crow named Betty was given metal wires of various 
lengths and a four-inch vertical pipe with food at the bottom, she chose a 
four-inch wire, made a hook and retrieved the food. 

Apes and corvids are highly social. One explanation for intelligence is that 
it evolved to process and use social information - who is allied with whom, 
who is related to whom and how to use this information for deception. They also 
remember.

Clark nutcrackers can hide up to 30,000 seeds and recover them up to six 
months later. 

Nutcrackers also hide and steal. If they see another bird watching them as 
they cache food, they return later, alone, to hide the food again. Some 
scientists believe this shows a rudimentary theory of mind - understanding that 
another bird has intentions and beliefs. 

Magpies, at an earlier age than any other creature tested, develop an 
understanding of the fact that when an object disappears behind a curtain, it 
has not 
vanished. 

At a university campus in Japan, carrion crows line up patiently at the curb 
waiting for a traffic light to turn red. When cars stop, they hop into the 
crosswalk, place walnuts from nearby trees onto the road and hop back to the 
curb. After the light changes and cars run over the nuts, the crows wait until 
it 
is safe and hop back out for the food. 

Pigeons can memorize up to 725 different visual patterns, and are capable of 
what looks like deception. Pigeons will pretend to have found a food source, 
lead other birds to it and then sneak back to the true source. 

Parrots, some researchers report, can converse with humans, invent syntax and 
teach other parrots what they know. Researchers have claimed that Alex, an 
African gray, can grasp important aspects of number, color concepts, the 
difference between presence and absence, and physical properties of objects 
like 
their shapes and materials. He can sound out letters the same way a child does. 

Like mammals, some birds are naturally smarter than others, Dr. Jarvis said. 
But given their range of behaviors, birds are extraordinarily flexible in 
their intelligence quotients. "They're right up there with hominids," he said.

    



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