Neanderthals avoided seafood in summer due to its toxicity

Published on May 24, 2026 | Translated from Spanish

A study from the University of Burgos reveals that Neanderthals in the Cueva de los Aviones planned their shellfish gathering. They did not consume them in summer, as they were aware of the risks of rapid decomposition and toxic red tides. They preferred autumn and winter, when shellfish have more meat and better flavor after their reproductive cycle.

Cueva de los Aviones, Neanderthals at the rocky entrance examining shellfish in winter, a group sorting mussel and limpet shells into fiber baskets, another individual pointing to an empty summer basket next to remains of dried seaweed, demonstrating seasonal planning, stone tools and bone scrapers on a limestone slab, cold winter sunset light entering the cave, rough rock texture and wet sheen of shells, photorealistic cinematic style, technical detail in the arrangement of mollusks and tools, dramatic natural lighting

Harvesting calendar: the first Neanderthal database 🐚

The analysis of archaeological remains shows a deliberate seasonal selection. Neanderthals did not act randomly; their strategy involved knowledge of the biological cycle of mollusks and coastal weather patterns. By avoiding summer, they reduced the risk of poisoning from toxic microalgae and food loss due to decomposition, evidencing a more complex resource management than previously believed.

How Neanderthals avoided spoiled shellfish without a fridge 🧠

While we scan supermarket barcodes, Neanderthals were already applying their own traceability system: if the shellfish smelled like summer, it was not eaten. Without labels or expiration dates, they applied the most basic logic: avoid marine toxins and rotten meat. A lesson some still need to learn at raw fish counters.