When did people regularly eat meat?

For decades, scientists have been learning more about diet of formerly hominine, in particular their dependence on plants. Nevertheless, we still don't know when they started eating meat. | Photo credit: AFP

For decades, scientists have been learning more about diet of formerly hominine, in particular their dependence on plants. Nevertheless, we still don't know when they started eating meat.

This is a frustrating gap in our understanding of human evolution. We believe that regular meat consumption was one of the main drivers for growth and development of the brain in hominins, since animal products are highly calorie and easier to digest than non -processed vegetable food. They also contain all essential amino acids and are rich in biologically important nutrients, minerals and vitamins.

What we know is that Hominine regularly ate meat when our genus Homo appeared over two million years ago. This shows that from this time the stone tools up to meat products are made from their increasing trust into butchers and processes. We have also found fossil bones with traces of cutting, which refer to battles.

But that doesn't explain when and where regular meat eating started and what types of our ancestors made this decisive change.

Thanks to the petrified tooth enamel, we are now one step closer to an answer. In a study with several other co-authors, we measured nitrogen isotopes in enamel from fossil teeth for hominess AustralopithecusDiscovered in South Africa's Sterkfontin caves. This is one of the oldest known human ancestors.

Atoms of the same element can have different versions called isotopes and have the same number of protons but different number of neutrons. This makes them a little heavier or lighter, but chemically similar. For example, nitrogen has two stable isotopes: nitrogen-14 (¹⁴n) and nitrogen-15 (¹⁵n). Of course, these occur, but their ratio varies in nature. In food networks, nitrogen isotopes are enriched when you move the chain upwards, which means that predators have a higher ¹⁴n/¹⁵N ratio as a herbivore.

Recognizing these isotopes is a way to reconstruct old diets and ecosystems and to understand scientists how past environments have shaped the survival of species – including people in the past.

We also tested the isotopic signature of animals that lived in the ecosystem at the same time. We have seen that the isotopic signature of Australopithecus Was low – similar to herbivores.

Our results suggest that these monkey -like, small early hominins mainly eat plants. There was little to no evidence of meat consumption. They may occasionally have eggs or insects with snacks, but they did not regularly chase large mammals like Neanderthals millions of years later.

A toothy approach

One of us (Dr. Lüdecke) started working with a petrified tooth enamel during her doctoral work. The focus was on the measurement of stable carbon isotopes in enamel in order to uncover the vegetable part of an existing or extinct animal diet.

This approach shows whether a species was based on lush, leafy plants or robust, grass -like vegetation in African savanna ecosystems. But there was always this small, unsatisfactory sentence in the discussion section of her academic papers: “This data record cannot be informed about the meat area of ​​the diet.”

Then inspiration hit. The co-authors of the latest study, Alfredo Martínez-García and Daniel Sigman, had developed a method with their teams in order to contain nitrogen isotopes in marine microfossils on measurement-win-wing creatures that contain almost no organic material like fossilized tooth enamel.

We wondered whether the same technology could work for old teeth and finally provide a date parker for the meat eating behavior of the early hominine.

We started small by testing the method on rodent tooth enamel of animals with controlled diets in a special feeding experiment. It worked. From there we changed from museum collections and other animals, which of course had lived in African ecosystems.

When these results agreed with what we expected in relation to their well -known diet, we knew that we had a reliable tool. After further laboratory tests, methods of methods and checks, we felt ready to analyze the fossilized tooth enamel of the non-primary fauna, which was found in one of the oldest fossil deposits of the South Africa's South Africa. This deposit, member 4, formed about 3.4 million years ago during the late Pliozene.

These analyzes also gave us the expected results: on the isotopic level it was clear whether we dealt with the teeth of a herbivore or a carnivore.

Then we finally tried seven Australopithecus Molars of Member 4 to find out whether these old hominins, who lived and died in the Steric Font caves about 3.4 million years ago, sank their teeth in meat or adhere to a largely vegetarian menu.

By comparing the nitrogen isotope conditions of these early hominine with that of other animals from the same ecosystem – as antelopes, monkeys and carnivors – we found that the isotope signature of Australopithecus Was low, similar to herbivores.

Future plans

This discovery is just the beginning. We are now expanding our research to other fossil locations in Africa and Asia, hoping to answer major questions. When did meat really enter the Hominin diet? Which hominine species consumed meat through our evolution? Did the behavior have appeared several times and combined with the advent of larger brains or significant changes in behavior such as the new Stone Tool technology? And what does that mean how we understand the evolutionary path that led to our species?

Tina Lüdecke is the leader of the Emmy Noether group for Hominin -meat consumption (HomeCo), the Max Planck Institute for Chemistry. Dominic Stratford is an extraordinary professor of archeology at the University of the Witwatersrand and specialist for paleoanthropology and geoarcheology. This article is released The conversation.