The Weirdest Thing I Learned This Week · Popular Science

Drunk Monkeys, Heroic Rats, Forehead Teeth

October 8, 2025·46 min·4 clips

Hero rats have cleared over 2 million people from landmine threats by detecting thousands of explosives with their sense of smell.

The episode begins with an exploration of the "Drunken Monkey Hypothesis," which suggests that alcohol consumption has deep evolutionary roots dating back 10 million years to a common ancestor of humans, chimps, and gorillas. Recent research on wild chimpanzees in Uganda and the Ivory Coast found that they consume approximately 14 grams of pure ethanol daily from fermented fruits, equivalent to more than one human drink per day when adjusted for body mass. The chimps preferentially select fruits with higher alcohol content, particularly figs and plums, but don't appear to get intoxicated due to the massive amounts of fiber they must consume alongside the alcohol. This research supports the hypothesis that alcohol detection and consumption provided evolutionary advantages for finding ripe, nutritious fruit in the wild. The study raises questions about whether captive primates miss out on important fermented nutrients and whether human alcohol issues stem from an evolutionary mismatch where we can consume alcohol without the natural limiting factors of fiber and bulk. The second segment introduces African giant pouched rats, three-foot-long rodents being trained for humanitarian work by the organization APOPO. These intelligent animals with exceptional smell capabilities are light enough to walk over landmines without detonating them, making them ideal for detection work. The rats undergo regular weigh-ins to ensure they stay below the trigger weight threshold. According to APOPO's 2024 report, these hero rats have detected over one million landmines and liberated an estimated 2 million people from landmine threats across countries like Tanzania, Cambodia, and Zimbabwe. A rat named Magawa became famous for receiving a gold medal in 2020 - equivalent to the highest human bravery award - for clearing 2.4 million square feet of land and finding 71 landmines. His record was recently broken by a five-year-old rat named Ronin who discovered 100 landmines. Beyond landmine detection, these rats are also trained to identify tuberculosis in human samples, processing 50 samples in eight minutes compared to what a lab technician can test in a full day. Their evaluations increase TB case detection rates by 44% compared to traditional methods. The rats cost $6,000-$8,000 to train but are inexpensive to maintain, making them cost-effective compared to diagnostic equipment that can cost $20,000 per device. New initiatives include training rats to detect illegal wildlife trade and equipping them with high-tech backpacks for search and rescue missions. The final segment examines spotted ratfish, a type of ghost shark or chimera found in deep waters. These relatively cute deep-sea fish have venomous spines that can kill harbor seals and possess electrical sensing abilities for navigation in dark waters. Male ratfish have a unique forehead appendage called a tenaculum - a retractable structure tipped with seven or eight rows of teeth that they use to grasp females during mating. Recent research revealed that these forehead teeth are actually mouth teeth with dental lamina, the same structure that produces teeth in jaws, rather than the skin teeth (dermal denticles) found on sharks. This discovery is particularly strange because ratfish are otherwise smooth-skinned. Fossil evidence shows similar structures existed over 300 million years ago, suggesting this bizarre adaptation has ancient origins. Female ratfish develop the same structure but it remains vestigial, appearing only as a small bump, indicating it may have originally served a different purpose before evolving into a mating tool.

As heard by us

A dry, evidence-minded animal story that ends up asking a surprisingly human question.

The piece treats a strange animal fact with a straight face, and that is what gives it lift. It follows wild chimps drinking alcohol from fermenting fruit into a wider thought about primate behavior and human drinking, then lands on the vivid detail of how much fiber a chimp…

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For when you want one weird science detour that keeps getting weirder.

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