VANCOUVER, BC Canada -- Freshwater fish was a staple diet for humans as early as 40,000 years ago, according to a new study led by UBC anthropologist Michael Richards.
Richards and a team of researchers from China and the U.S. analyzed stable isotope ratios found in the collagen of human and animal bones discovered in 2001 from the Tianyuan Cave near Beijing, China. Their study, to be published in this week’s Proceedings of the National Academy of Sciences, presents the first direct evidence of fish being a substantial part of early human diet.
The 34 human bones – likely from the same individual scientists call Tianyuan 1 – discovered in the Tianyuan Cave are one of the oldest modern human remains found in Eurasia. Bones of deer, monkey, porcupine and wild cat were also discovered on the site.
Stable isotopes such as those of carbon, nitrogen and sulfur are often used by scientists to reconstruct a food web and determine the long-term source of dietary proteins as they are deposited in the bone collagen over time.
“We found similar carbon isotope values in the remains of the Tianyuan 1 human and those of a wild cat, indicating a similar diet of land animals and plants as a source of protein,” says Richards, who led the study while a researcher at the Max Planck Institute in Germany.
“But significantly higher values of nitrogen isotopes in the human suggest an additional source of protein – probably from freshwater fish since aquatic animals generally have higher nitrogen isotope values due to their longer food chains.”
Since no freshwater fish bones were found in Tianyuan Cave, the researchers studied fish remains discovered in the nearby Donghulin site and found consistent sulfur isotope ratios.
“The combination of these findings provides direct evidence that early modern humans in China consumed freshwater fish regularly,” says Richards.
Anthropologists have previously found indirect evidence of humans eating fish in South Africa as early as 50-60 thousand years ago. This new study presents the first direct evidence of fish being an important part of their diet and may help scientists understand how early modern humans adapted to their environments.
“Since this timeframe predates consistent evidence of effective fishing gear, we think the shift to more fish in the diet may reflect greater pressure from an expanding population and the resulting difficulty in accessing small land animals.”
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