The biology of smell is a mystery — AI is helping to solve it
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The smell in the laboratory was new. It was, in the language of the business, tenacious: for more than a week, the odour clung to the paper on which it had been blotted.
To researcher Alex Wiltschko, it was the smell of summertime in Texas: watermelon, but more precisely, the boundary where the red flesh transitions into white rind.
“It was a molecule that nobody had ever seen before,” says Wiltschko, who runs a company called Osmo, based in Cambridge, Massachusetts. His team created the compound, called 533, as part of its mission to understand and digitize smell. His goal — to develop a system that can detect, predict or create odours — is a tall order, as molecule 533 shows. “If you looked at the structure, you would never have guessed that it smelled this way.”
That’s one of the problems with understanding smell: the chemical structure of a molecule tells you almost nothing about its odour. Two chemicals with very similar structures can smell wildly different; and two wildly different chemical structures can produce an almost identical odour. And most smells — coffee, Camembert, ripe tomatoes — are mixtures of many tens or hundreds of aroma molecules, intensifying the challenge of understanding how chemistry gives rise to olfactory experience.
