As a senior investigator at the National Cancer Institute, Peter M. Blumberg has devoted his professional life to reducing pain and suffering. Unless you are a squirrel, in which case Blumberg brings the pain.
In 1999, the Harvard-trained biochemical pharmacologist was granted Patent No. 5879696 A, a.k.a. “Treated bird seed preferentially palatable to birds but not to animals.” In other words: hot-pepper birdseed. It burns the tongues of squirrels, not birds.
“The squirrel-proof birdseed was something we stumbled into,” Blumberg said when I visited him on the campus of the National Institutes of Health in Bethesda, Md.
On the windowsill of his small office were five spindly cactuses, some looking a bit shriveled but all boasting rather alarming spikes. They were a clue to Blumberg’s breakthrough, which is employed in such squirrel-thwarting products as Hot Meats birdseed, Blazing Hot birdseed and Cajun Blend birdseed.
The cactuses were from a plant genus known as euphorbia. Spikes aren’t their only protection. They’re related to a plant known as the crown of thorns, the sap of which contains a compound said to be a million times more potent than an habanero pepper: resiniferatoxin or RTX.
Blumberg and his colleagues were interested in RTX because it was thought to be a tumor promoter, a compound that when exposed to a carcinogen encourages the growth of tumors. It turned out that RTX is not a tumor promoter. However, it functions like capsaicin, the chemical that makes chili peppers seem hot. In fact, RTX is 10,000 times more potent than capsaicin.
Using RTX, Blumberg was able to demonstrate that mammals have a nerve receptor that responds to capsaicin, causing a painful sensation.
This is tantalizing to the pharmaceutical industry, which can use RTX to explore new ways to treat pain. For example, a compound might bind with the cellular channel that is activated by capsaicin, preventing it from erupting with a pain response.
“More than a dozen pharmaceutical companies are interested in this as a non-narcotic approach to treating pain,” Blumberg said.
Further research revealed that while this receptor in most mammals responds to capsaicin with pain, the receptor in birds doesn’t. Many species of chili pepper have been spread far afield by birds who have eaten them and pooped out the seeds.
So how did Blumberg come to make a connection between the super-potent sap of a cactus and hordes of greedy squirrels?
“The answer is I live on a farm,” Blumberg said. He and his wife raise horses out of an 1830 farmhouse near the Monocacy National Battlefield in Maryland.
In the country, Blumberg explained, everyone feeds the birds. That usually means feeding the squirrels, too, since the critters seem able to overpower every squirrel-proof mechanism thrown at them.
“This suggested to me that there must be people out there who would object to squirrels eating the birdseed,” Blumberg said. As is required of government employees, he notified NIH’s Office of Technology Transfer so the invention could be patented and licensed, with royalties going to the government.
The patent was licensed to Snyder Seed, a Buffalo, N.Y., company founded by Joseph Dunn, a scientist who had worked with Blumberg while a student at Harvard. Dunn left a job at Eastman Kodak to perfect the product, including how to infuse large quantities of seeds with capsaicin in a way that was safe to humans and economical for manufacturers. (He sourced a highly concentrated cayenne pepper extract from India.)
Dunn’s first product went on the market in 1997, but patent battles with other manufacturers meant no one got rich, he said. The patent on Blumberg’s invention has expired, so any manufacturer is free to make a product based on it.
“Someday I’m going to write a book,” said Dunn, now dean of research at the pharmacy school at D’Youville College in Buffalo. “I’ll call it ‘The Birdseed Wars.’ “
Dunn remains in awe of his mentor. “Dr. Blumberg is one of the scientists this country is lucky to have,” he said, “not because of his birdseed but because of his contribution to cancer biology and pain research.”
Before I left, I asked Blumberg if he used hot-pepper birdseed in any of the bird feeders at his house. “No,” he said. Then he added in a conspiratorial whisper, “After all, I don’t mind the squirrels.”
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Video link: the delicate process of rehabilitating injured squirrels