Birnbaum told Sacks about the vagaries of her cognition, relating strange hallucinatory scents she'd imagined after the accident, like skunk or rotting trash. At one point, she'd been convinced she could smell her own brain. "'It's interesting, said Sacks, 'that the world can change, can be so different, when you no longer have the means to process it like everyone else,' " Birnbaum wrote in Season to Taste.
She found another anosmic in Grant Achatz — the molecular gastronomist who famously lost his taste buds to tongue cancer. Birnbaum's research brought her to Chicago, where she ate at Achatz's restaurant, Alinea. At the start of her dinner, she worried she wouldn't fully appreciate Achatz's notoriously complicated, often subtle balance of taste and scent. Though it was, at times, a struggle, she succeeded.
Achatz granted her an audience, and told Birnbaum about losing his taste buds while undergoing radiation therapy. "During week three, on my way to the hospital, I opened a can of soda," Achatz told her. "It was Dr Pepper. I took a drink and thought, Wow, this Coca-Cola tastes funny." In the aftermath of treatment that would literally burn away his taste buds, Achatz proved that someone without a sense of taste could remain one of the country's greatest chefs.
But for all the people she talked to, Birnbaum has some questions left unanswered.
"Why is smell so emotional? Why is it so tied to the memories we have as a child? When you smell something and, all of a sudden, you're hit by a gut reaction — it's not clear why it moves people so much. On a molecular basis, we don't know how we process smell. We know that scent molecules enter the nose and fire signal patterns to the brain, but how do we read those patterns?"
In spite of having been told by doctors that she would never smell again, Birnbaum smelled rosemary just three months after the accident. "It was pungent, rich, and warm," she wrote. "Like a friend I hadn't seen in years, this scent rang simultaneously familiar and strange. It tingled with possibility."
In the intervening months, in fits and starts, Birnbaum seemed to regain a full complement of olfactory abilities. Four years after the accident, she traveled to perfumer's school in Grasse, France, to see if she had made a full recovery. Birnbaum learned that she could train her nose to differentiate between odors.
"Smell had never been so alive as it was around that table that final week," she wrote. "It changed and grew every day, with every scent, inviting colors and sounds and emotion with each breath." By the end of her tenure in Grasse, Birnbaum was confident she had healed.
I asked Birnbaum to show me what she learned in perfumer's school. She agreed, closing her eyes in total concentration.
"We've been in here for quite a while, so it's kind of dull, but there's coffee — that bitter, slightly sweet, steamy smell." She sniffed again, a satisfied look breaking across her face. "Coffee."
Eugenia Williamson can be reached at firstname.lastname@example.org, or follow her on Twitter @Eugenia_Will.