For a long time, scientists have been studying extra concerning the diets of early hominins, notably their reliance on vegetation. Yet we nonetheless don’t know when these ancestors of people began consuming meat.
This is a irritating hole in our understanding of human evolution. We suppose common meat consumption was one of many major drivers of mind progress and evolution in hominins, as a result of animal merchandise are calorie-dense and simpler to digest than unprocessed plant meals. They additionally comprise all of the important amino acids and are wealthy in biologically vital vitamins, minerals and nutritional vitamins.
What we do know is that by the point our genus, Homo, emerged over two million years in the past, hominins had been recurrently consuming meat. This is evident from their elevated reliance at this level on stone instruments to butcher and course of meat merchandise. We’ve additionally discovered fossil bones with minimize marks that point out butchering.
But that doesn’t clarify when and the place common meat consuming began and which species of our ancestors made that essential shift.
Now, thanks to fossilised tooth enamel, we’re a step nearer to a solution. In a examine with a number of different co-authors, we measured nitrogen isotopes within the enamel from fossilised tooth belonging to the hominin genus Australopithecus, found in South Africa’s Sterkfontein Caves. This is among the oldest recognized human ancestor species.
Atoms of the identical factor can have completely different variations, known as isotopes, which have the identical variety of protons however completely different numbers of neutrons. This makes them barely heavier or lighter however chemically related. For instance, nitrogen has two steady isotopes: nitrogen-14 (¹⁴N) and nitrogen-15 (¹⁵N). These happen naturally, however their ratio varies in nature. In meals webs, nitrogen isotopes grow to be enriched as you progress up the chain, which means predators have greater ¹⁴N/¹⁵N ratios than herbivores.
Identifying these isotopes is a manner to reconstruct historical diets and ecosystems, serving to scientists perceive how previous environments formed the survival of species – together with early people.
We additionally examined the isotopic signature of animals that lived within the ecosystem on the identical time. We noticed that the isotopic signature of Australopithecus was low – related to that of herbivores.
Our findings counsel that these ape-like, small-brained early hominins had been consuming largely vegetation. There was little to no proof of meat consumption. They could have snacked on the occasional egg or insect however they weren’t recurrently searching massive mammals like Neanderthals did tens of millions of years later.
A toothy strategy
One of us (Dr Lüdecke) started working with fossilised tooth enamel throughout her PhD. The focus was on measuring steady carbon isotopes within the enamel as a manner to uncover the plant-based a part of an extant or extinct animal’s food regimen.
This strategy reveals whether or not a species relied on lush, leafy vegetation or hardy, grass-like vegetation in African savanna ecosystems. But there was at all times that small, unsatisfying sentence within the dialogue part of her tutorial papers: “This dataset cannot inform about the meat portion of the diet.”
Then inspiration struck. The co-authors of the newest examine, Alfredo Martínez-García and Daniel Sigman, had developed a technique with their groups to measure nitrogen isotopes in marine microfossils – tiny creatures that, like fossilised tooth enamel, comprise nearly no natural materials.
We questioned whether or not the identical method may work for historical tooth and at last present a date marker for early hominins’ meat consuming behaviour.
We began small by testing the tactic on rodent tooth enamel from animals with managed diets in a specialised feeding experiment. It labored. From there, we moved on to the enamel of untamed mammals from museum collections and different animals that had lived naturally in African ecosystems.
When these outcomes aligned with what we anticipated by way of their recognized diets, we knew we had a dependable instrument. After extra laboratory testing, methodology tweaking and checking, we felt prepared to analyse the fossilised tooth enamel of non-primate fauna present in one of many oldest fossil-bearing deposits of South Africa’s Sterkfontein Caves. This deposit, Member 4, shaped about 3.4 million years in the past, in the course of the Late Pliocene interval.
Again, these analyses gave us the anticipated outcomes: it was clear on the isotopic degree whether or not we had been coping with the tooth of a herbivore or a carnivore.
Then we lastly sampled seven Australopithecus molars from Member 4 to uncover whether or not these historical hominins, which lived and died across the Sterkfontein Caves about 3.4 million years in the past, had been sinking their tooth into meat or sticking to a largely vegetarian menu.
By evaluating the nitrogen isotope ratios of those early hominins with these of different animals from the identical ecosystem – like antelopes, monkeys and carnivores – we discovered that the isotopic signature of Australopithecus was low, related to that of herbivores.
Future plans
This discovery is only the start. We’re now increasing our analysis to different fossil websites throughout Africa and Asia, hoping to reply greater questions. When did meat really enter the hominin food regimen? Which species of hominins by way of our evolution consumed meat? Did the behaviour emerge a number of occasions and did it coincide with the rise of bigger brains, or marked modifications in behaviour, like new stone instrument know-how? And what does this imply for a way we perceive the evolutionary path that led to our species?
Tina Lüdecke is Leader of the Emmy Noether Group for Hominin Meat Consumption (HoMeCo), Max Planck Institute For Chemistry. Dominic Stratford is an affiliate professor of archaeology on the University of the Witwatersrand and specialist in palaeoanthropology and geoarchaeology. This article is republished from The Conversation.
Published – March 05, 2025 03:22 pm IST
