Remains of consumed shellfish were discovered by archaeologists excavating the Gruta da Figueira Brava dig site, which is around 20 miles (32 kilometers) south of Lisbon. Amongst the midden were limpets, mussels, and clams, but also remains of brown crab, which is still frequently consumed in Portugal, Spain, Italy, and France. In fact, the site was mostly made of shell and pincer fragments from brown crabs. The results were published Tuesday in the journal Frontiers in Environmental Archaeology

According to the study, Neanderthals mostly hunted the larger adult crabs, suggesting that these particular crabs had been chosen for their size, with a shell or carapace of about 16 centimeters (6.3 inches) broad. The amount of crabmeat from each crab would have been about 200 grams (7 ounces).

Crabs are difficult to catch by hand, but the study concluded that it was likely that they were collected in shallow, low-tide rock pools close to the cave, possibly with the help of spears to knock them out. The study made notice of the recorded use of this method of crab collecting by Indigenous people throughout North America. The study concluded that patterns of crab shell and pincer damage ruled out the presence of other predators, such as birds or rodents.

The crabs were likely roasted on hot coals to temperatures between 300 and 500 degrees Celsius (572 and 932 degrees Fahrenheit), and then their shells were cracked apart to access the cooked flesh. The study also revealed that the crack marks on the archaeological site specimens were strikingly comparable to the ones made today when eating crabs, despite the fact that Neanderthals would have used stone tools rather than modern metal hammers and cutlery to open the mollusk.

The discovery is important because it supports evidence that refutes the widely-held belief that our species, Homo sapiens, was uniquely smarter than other, now-extinct prehistoric humans, such as Neanderthals, due to our preference for seafood, which is rich in omega-3 fatty acids that are crucial for brain development. The study emphasized that Neanderthals were able to adapt to many environments, hunt a variety of species, and use a variety of foods.