CNN Senior Executive Producer
As soon as I read today’s environmental headline, that nearly a third of America’s 800 bird species are in danger, I thought of the great sparrow massacre in China.
On May 18, 1958, the Chinese dictator, Mao, erroneously convinced that sparrows were eating large portions of China’s grain crop, ordered: “The whole people, including 5 year old children, be mobilized” to eliminate the sparrows. A former Chinese elementary school student, quoted in Judith Shapiro’s memorable book “Mao’s War Against Nature,” describes the slaughter. “The whole school went to kill sparrows. We climbed ladders to knock down their nests, and beat gongs in the evenings when they were coming home to roost.”
This coordinated effort, by millions of Chinese children and adults, killing sparrows, beating gongs at a specific designated hour all over the countryside, day after day, to exhaust the birds, basically wiped out the sparrow population. The next year locusts and other pests that were the primary food sources for sparrows, devoured the grain crop. The sparrows had been their predators. Without the sparrows, the pests took over. A famine ensued. Millions of Chinese died. The next year Mao was informed that the campaign against the sparrows backfired. He issued a new order: “Forget it.”
That’s what can happen when an ecosystem gets out of whack - when a single keystone species is lost. That’s why the first U.S. government report out this week on “The State of the Birds” is essential. Hundreds of bird species across America are in danger. Habitat loss is a major reason. With enough money and enough planning, various measures outlined in the report could save those species.
BIRD BRAINS AND US
It’s not only the health of our environment at stake. Every bird, every species, for that matter, may contain mysteries that could lead to a better understanding of ourselves. Harvard Physician Aaron Bernstein, co-author with Dr. Eric Chivian of the award winning new book “Sustaining Life: How Human Health Depends on Biodiversity,” relays what just one bird species helped teach us about the human brain.
“It was believed up until very recently that humans were born with all the brain cells they would ever have. “This,” explains Dr. Bernstein, “was the dogma taught in medical education for decades and was one explanation for why humans don't recover from injury to the central nervous system.” Then, we got some surprising news from a canary which killed the dogma.
In the late 1970s, Dr.Bernstein points out, a research group at Rockefeller University “noticed that the regions of the brain that made up the song system of canaries were larger in males than in females” and that those regions of the brain grew larger at the start of each breeding season. Not only that. According to Laura Erickson, of the Cornell Ornithology Lab, every breeding season male canaries make up new songs. Female canaries like that. But how do those little canary brains make room for all that new music. It took years to find out. It turns out, says Erickson, that they “erase the files containing their old memories, their useless old songs, from their hard drive.” In other words, old neurons containing old memories die, and are replaced by new neurons that can remember new songs.
Could it be, wondered leading scientists, that if birds can grow new brain cells, so can humans? Brain researchers got further motivation from the black-capped chickadee.
Laura Erickson remembers when the temperature in northern Minnesota once dropped to a record low of 60 below 0. Despite the cold, when the morning arrived, the calls of the naked chickadees could be heard. In order to survive under such harsh conditions, the chickadee’s tiny brains must enable them to find food first thing on those cold mornings, food they’ve hidden in thousands of tree crevices. When the food runs out in those hiding places, the chickadees, like the canaries, must erase those old neurons which contain memories of useless empty food cupboards, and create new neurons to store memories of new food hiding places.
And so, now, after years of taking their cue from these two birds, the medical establishment has discovered that human beings do grow new brain cells well into adulthood. And researchers continue to study birds for further insights into the mechanisms of the human brain. “The implications of this work for human medicine,” says Dr. Bernstein of Harvard, “cannot be overstated. It has changed the way we think about learning and memory and raised the possibility of halting or even reversing some of the devastating effects of some degenerative conditions, such as Alzheimer’s.” It has also, adds Dr. Bernstein, in Sustaining Life, given us new leads on how to repair damage from strokes and head injuries.
And it all started with a bird that sings.
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