What's the deal with tongues?

Episode Summary

Executive Summary: This BBC Crowd Science episode explains why animal tongues vary so much, using zoo visits and expert interviews to show that tongue form reflects diet, feeding method, and environment. From macaws’ bony, finger-like tongues to snakes’ split smell-sensing tongues and humans’ muscular swallowing tools, the episode traces how tongues evolved from aquatic ancestors into highly specialized structures.

Main Topics: Macaw tongues and food manipulation (Priority: 5/5): At London Zoo, parrots are used to demonstrate how macaws have a bone in the tongue, giving it finger-like dexterity to crack, peel, and manipulate nuts and seeds. Origins of tongues in evolution (Priority: 5/5): Evolutionary biology explains that tongues likely emerged as land vertebrates adapted from water-based suction feeding to manipulating food in air and on land. Snake tongues as sensory organs (Priority: 4/5): King cobras use forked tongues to sample chemical cues in stereo, with the tongue working alongside the Jacobson's organ to detect smells rather than taste. Mammalian tongues as muscular hydrostats (Priority: 5/5): Most mammals have muscular, bone-free tongues that can change shape dramatically for precise movement, food placement, and swallowing. Specialized tongues in herbivores and giraffes (Priority: 4/5): Herbivores such as cows and giraffes have adapted tongues for cropping vegetation; giraffes also use long, dark, saliva-coated tongues to strip leaves and avoid sun damage. Tongue mechanics and human health (Priority: 4/5): The episode links tongue movement to safe swallowing and notes that better understanding of tongue mechanics could improve treatment for dysphagia and post-stroke patients.

Key Arguments: Tongue shape is strongly shaped by function: feeding style, prey capture, food manipulation, and sensory needs drive anatomical differences across species. Animal tongues evolved from musculature in aquatic ancestors as vertebrates moved onto land and had to replace water’s role in food capture and transport. Macaws benefit from a bony tongue that acts like a finger, helping them process nuts and seeds efficiently. Snake forked tongues split scent sampling across two sides, enabling directional chemical sensing rather than taste. Human and other mammalian tongues are primarily muscular, allowing complex internal deformation that helps position food, chew, and swallow safely. Tongue function is medically important because impaired swallowing can lead to pneumonia and other serious complications.

Data Points: Macaw tongue anatomy: 1 bone inside the tongue - Jessica Ray explains that all parrots, including macaws, have a bone in the tongue. Giraffe tongue length: about 45 centimetres - The hoofstock keeper describes giraffe tongues as roughly 45 cm long. Snake species: male king cobra - The reptile expert introduces Arthur, a king cobra, as an example of a forked tongue used for sensing. Evolutionary timescale: hundreds of millions of years - The narrator notes tongues have existed for hundreds of millions of years since early vertebrate evolution.

Pivotal Quotes: "like all parrots, they have a bone inside of their tongue" — Jessica Ray: Explaining why macaw tongues look finger-like and are unusually dexterous "the tongue became elaborated from musculature that was already present in the fish to take the place of water" — Kurt Schwenk: Describing the evolutionary origin of tongues as vertebrates moved from water to land "they've got antiseptic saliva, so helps it heal quicker" — Nick Garrett: Explaining why giraffe tongues can handle thorny acacia browsing

Implications: The episode highlights tongues as a key evolutionary innovation and a medical priority: understanding tongue mechanics can improve care for swallowing disorders, while animal tongue diversity reveals how anatomy adapts to diet and sensing needs.