Enlarge (credit: Nathan Devery)

Cellulose is the primary component of the cell walls of plants, making it the most common polymer on Earth. It's responsible for the properties of materials like wood and cotton and is the primary component of dietary fiber, so it's hard to overstate its importance to humanity.

Given its ubiquity and the fact that it's composed of a bunch of sugar molecules linked together, its toughness makes it very difficult to use as a food source. The animals that manage to extract significant calories from cellulose typically do so via specialized digestive tracts that provide a home for symbiotic bacteria—think of the extra stomachs of cows and other ruminants.

Amazingly, humans also play host to bacteria that can break down cellulose—something that wasn't confirmed until 2003 (long after I'd wrapped up my education). Now, a new study indicates that we're host to a mix of cellulose-eating bacteria, some via our primate ancestry, and others through our domestication of herbivores such as cows. But urban living has caused the number of these bacteria to shrink dramatically.

Enlarge / In this photo illustration, melatonin gummies are displayed on April 26, 2023, in Miami, Florida. (credit: Getty | Joe Raedle)

Federal regulators have long decried drug-containing products that appeal to kids—like nicotine-containing e-cigarette products with fruity and dessert-themed flavors or edible cannabis products sold to look exactly like name-brand candies.

But a less-expected candy-like product is sending thousands of kids to emergency departments in the US in recent years: melatonin, particularly in gummy form. According to a new report from researchers at the Centers for Disease Control and Prevention, use of the over-the-counter sleep-aid supplement has skyrocketed in recent years—and so have calls to poison control centers and visits to emergency departments.

Melatonin, a neurohormone that regulates the sleep-wake cycle, has become very popular for self-managing conditions like sleep disorders and jet lag—even in children. Use of melatonin in adults rose from 0.4 percent in 1999–2000 to 2.1 percent in 2017–2018. But the more people have these tempting, often candy-like supplements in their homes, the more risk that children will get ahold of them unsupervised. Indeed, the rise in use led to a 530 percent increase in poison control center calls and a 420 percent increase in emergency department visits for accidental melatonin ingestion in infants and kids between 2009 and 2020.