Neanderthals: How a carnivore diet may have led to their demise

Imagine having an unhealthy interest in the lives of your neighbors. Unable to ask them directly, you go through their trash cans. You find the bones of cooked chickens and try to figure out what else they eat.

This is a bit like how archaeologists study the diets of extinct humans such as Neanderthals and early homo sapiens. This is more than satisfying curiosity. Understanding our ancestors’ diets can reveal critical clues to their evolutionary success or failure.

A recent study that analyzed zinc from a Neanderthal tooth from Spain reveals that they were mostly carnivores, wherever they lived. This discovery explains why they disappeared.

Neanderthals dominated Europe and western Asia during the last 200,000 years of the Ice Age, while homo sapiens developed in Africa. Their remains and characteristic stone tools are abundant throughout Europe and the Near East, and in smaller numbers as far away as Tajikistan (which shares a border with China).

Neanderthals lived in the heart of the Eurasian steppes (the largest grassland in the world, stretching from Hungary to China), an area not rich in nutritious vegetables. However, surveys of their campsites revealed that they ate nuts, fruits, mushrooms, shellfish and other easily gathered foods.

Neanderthals were a constantly on-the-go species that needed a high-calorie diet. The butchered remains of horses, reindeer, bison and mammoths left by Neanderthals at their campsites reveal that they hunted the most dangerous animals in their world. But that doesn’t tell us whether their diets varied from group to group across their vast range.

Low carb diet

Over the past two decades, advances in molecular biology have deepened archaeologists’ understanding of early human diets. Cool conditions in northern Europe, such as France and Germany, help preserve collagen in fossilized bones. With a technique called stable isotope analysis we can recover minute amounts of carbon and nitrogen from the collagen in early human bones and learn where the protein they ate came from. Isotopes are groups of atoms that belong to the same element but have different masses. Isotope studies of these bones have shown that Neanderthals in northern Europe got 80-90% of their protein from animals. This is up there with wolves and hyenas. In the arid southern parts of Europe we are not so lucky. The collagen in the fossilized bones breaks down easily in warmer climates, taking with it clues to the southern Neanderthal diet.

But in the last year archaeologists have discovered that traces of zinc in Neanderthal bones also preserve information about the diet of the ancient individual they belong to.

Studies in recent years of zinc isotopes show that they hold enormous potential for unlocking clues to the evolution of life, such as the rise of eukaryotes, a group of organisms to which humans belong, and the complexity of marine food webs.

Special hunters

Zinc levels in the bones of carnivores are lower than those of their prey. The difference is not affected by age, gender or wear and tear over time. Zinc ratios can be measured from bone samples as small as 1 mg. Even these tiny amounts allow an accurate estimate of an animal’s place in the food chain when it was alive.

The recent study’s analysis of zinc from the tooth enamel of a Neanderthal, who lived and died about 150,000 years ago in the Spanish Pyrenees, gives new insights into the diet of ancient humans. Zinc isotopes were analyzed from 43 teeth of 12 animal species living in a grassland around the Los Moros I cave in Catalonia, Spain. These included carnivores such as the wolf, hyena, and hole (also known as the mountain wolf), omnivorous cave bears, and herbivores such as the ibex, red deer, horse, and rabbit. The results brought to life a Pleistocene steppe food web, a system of interconnected food chains from plants to top carnivores. The zinc in the Neanderthal tooth had by far the lowest value of zinc in the food web, revealing that it was a top-level carnivore.

Bone piles at Neanderthal campsites show that they hunted large animals in large numbers. These piles even occur in areas of the landscape where humans would be at a disadvantage, such as at the edges of watercourses. Imagine trying to spear a full-grown bison or horse. Both weigh almost a ton. The new isotope study reveals that Neanderthals’ main survival strategy was to hunt whatever animals could be found wherever they were in the world. Small animals and vegetables were probably little more than accompaniments. Their game plan was to shoot first and answer questions later.

Broader diets have made us more resilient

Isotopes obtained from sites across Europe from his remains Homo sapiens groups that inherited Pleistocene Eurasia from the Neanderthals reveal that they had a wider dietary range. Plants, birds and fish were the main dishes for these early people. The Pleistocene was a grassland-steppe ecosystem that dominated Siberia during the Pleistocene and disappeared 10,000 years ago. It had a remarkably unstable climate and changed from dry grasslands and wet tundras to coniferous forests, constantly shaking up the variety and number of large herbivores that graze there.

Thus, an omnivorous diet would have made these people much more resilient than those who relied on hunting large game. We don’t know much about what happened to the Neanderthals when the big game populations collapsed. If the reindeer didn’t show, what could they do? But with rapid advances in biomolecular science, I doubt we’ll have to wait long to find out.

This article is republished from The Conversation under a Creative Commons license. Read the original article.