A new study shows that both early humans and Neanderthals had roughly the same kind of diet.

The study conducted by researchers at the University of Tübingen and colleagues challenges the idea that Neanderthals only ate meat of large animals such as horse, bison and mammoths.

Early humans ate a variety of plants and animals and even fish. According to many scholars, dietary flexibility helped humans compete and win against Neanderthals.

The information about dietary differences between Neanderthals and humans comes from research conducted on animal bones found in caves that were occupied by both the hominoids. However, the caves were also occupied by other animals such as bears and lions, leading to confusion about dietary preferences of the inhabitants.

A latest analysis of samples from a cave in the Caucasus Mountains provides an indirect proof that Neanderthals ate fish. Researchers have ruled out the possibility that bears or lions might have eaten the fish at the cave.

A cave located on the northern slopes of the Caucasus Mountains, called Kudaro 3 contains remains of large salmon in the Middle Palaeolithic archaeological layers, dated to around 42 to 48,000 years ago. According to researchers, these fragments might have been deposited by Neanderthals and not other carnivores like bears and lions.

To test their hypothesis, researchers looked at the levels of carbon, nitrogen and sulphur isotopes in bones of predators and compared the isotopic signatures in their prey. The results showed that neither cave bears nor cave lions had fish in their diets. In ancient times, cave bears were strictly vegetarians while cave lions preyed on other herbivores.

"This study provides indirect support to the idea that Middle Palaeolithic Hominins, probably Neandertals, were able to consume fish when it was available, and that therefore, the prey choice of Neandertals and modern humans was not fundamentally different," said Hervé Bocherens, one of the study authors, according to a news release.

The study, "Were bears or lions involved in salmon accumulation in the Middle Palaeolithic of the Caucasus? An isotopic investigation in Kudaro 3 cave," is published in the journal Quaternary International.