You were subjected to someone else’s taste before you can remember. Amniotic fluids in the womb changed with your mother’s diet and it registered. When you were born, your motor skills kicked in immediately to get things into your mouth. This is the reason Nintendo hired a team of flavorists – chemical engineers who ordinarily work in the food, perfume and household products industries – to make their Switch cartridges taste vile. The cartridges are coated in denatonium benzoate, a “bittering agent” used in antifreeze and rat poison, to ward off children and pets. The 100-year-old Gaia theorist James Locklock suggests we could save the rainforest by burying nuclear waste in it. Could we save the planet by making it revolting?

The absence of taste can be a cause for alarm. Trees, flowers, and plants in the Chernobyl Exclusion Zone no longer smell of anything. An early symptom of Covid-19 is the loss of taste and smell. We already live in an era that over-privileges sound and vision. We are enclosed in a digital realm that smells of nothing. It’s no wonder the transition feels like a loss: can we shop, learn or date without smell? Flavorists are unusual among engineers for the way they combine molecular data with auto-experimentation. Their noses and their ability to interpret smells is what makes them so valuable. Humans experience flavors in ways that are contingent, asynchronous, transformed by contexts and bodily states that change over time (as we eat, say, or as we grow accustomed or bored.) We are so far from developing sensors capable of smelling like humans there isn’t even an agreed scientific language, unit of measurement, or technical framework up to the task. Yet the potential for such a field would be immense.

In an interview with Mold (Issue 4), Dr Nongjian Tao, director of the Center for Biosensors and Bioeletronics at Arizona State University, explains the challenge of developing sensors for taste and smell. There are means – molecular sensors and colorimetry – that can do this, but they are far too cumbersome to become accessible at consumer scale. Dr Tao’s department is working towards safety applications such as smoke, air toxicity and pollution in the hopes they will be useful to asthma patients. “I think that chemical sensors need to be designed to be compatible with consumer electronics,” he says. “We’re just not sure how.”

Where force, touch, sound and light can be detected using semiconductors, much of the molecule-level work carried out in industry – primarily the detection of hidden substances, from drugs to secret sauce – is completed using a gas chromatograph-mass spectrometer. The Mars Curiosity Rover contains a complex of sensing devices known as Sample Analysis at Mars, or SAM, to examine carbon compounds, search for biotic or prebiotic organic compounds such as methane, and to develop better evolutionary climate models that may help indicate whether the planet was or may become capable of hosting life.

On earth, where questions of planetary viability are no less valid, lichen have been studied to monitor ecosystem health for around a century. Lichen do not have roots: they are an algae-fungi symbiotic organism that receives nutrients from the air and responds to critical pollutants such as nitrogen and sulfur dioxide. Sensing takes place throughout the food production chain. It happens at a range of scales from microorganism to forest. The current planetary sensing layer is a complex array of technical, cross-modal, and organic indicators. As we continue to discuss below, flavor must be engineered to expand and steer perception.