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September 16th, 2020 
Awake Goy A study of some of the oldest remains associated with early humans from the Olduvai Gorge in Tanzania has produced some intriguing results. A microbial study of sediments from 1.7-1.8 million years ago has revealed details of the environment that our ancestors lived in. It also indicates that they may have used hot springs to cook their food, which could be a breakthrough find when it comes to understanding human evolution.
A team led by Ainara Sistiaga, an MIT fellow who works at the University of Copenhagen, examined sediments that were taken from the Olduvai Gorge in Tanzania, where fossils of early humans from 1.8 million years ago have been unearthed. Collected in 2016 when Sistiaga joined an archaeological expedition in Tanzania, the sediments were taken from a layer that is dated back 1.7 million years. The geological layer has intrigued experts because it is noticeably darker than other layers and this may indicate changes in the environment. Sistiaga is quoted by Phys.Org as saying: “Something was changing in the environment, so we wanted to understand what happened and how that impacted humans.”
Ainara Sistiaga took samples of sediment at Olduvai Gorge, in northern Tanzania, where fossils of early humans from 1.8 million years ago have been unearthed. (Ainara Sistiaga / MIT)
Ancient Environment of Early Humans
The sediments were then studied by a multinational team of experts and some lipids were found in the material. In PNAS the researchers explain that “fossil lipid biomarkers from ancient plants and microbes encode information about their surroundings via their molecular structures and composition.” The lipids provided insights into the environment of Olduvai Gorge, where some of the earliest human fossils have been found as well as evidence of stone tools. The results showed that the local landscape was “a mosaic ecosystem with great biodiversity, rivers, edible resources, and hydrothermal features,” according to the article in PNAS. These environmental changes were possibly a result of a drier climate that led to the valley becoming a savanna.
Researchers focused on evidence of the presence of hydrothermal features, such as hot springs , in Olduvai Valley which was something new. The team found evidence for a type of bacteria, known as Thermocrinis ruber , that only live in very hot waters and which they have studied before in the context of thermal springs in Yellowstone Park , in North America. This was unambiguous evidence that there were geothermal features in the ancient valley when it was inhabited by early humans. “It’s not a crazy idea that, with all this tectonic activity in the middle of the rift system, there could have been extrusion of hydrothermal fluids,” explains Sistiaga on MIT News . It is known that the Olduvai Gorge is in a geologically active region which has witnessed a great deal of volcanic activity in the past and this could have created hot springs in the valley.
The team, seen here during the dig, took samples from the Olduvai Gorge in Tanzania. (Fernando Diez-Martin / MIT)
Cooking Kills in Hot Springs
Experts know that the valley was once settled by early humans, because of the local archaeological record, and they have theorized that they had deliberately settled in the area to be near these hot springs. Roger Summons, a professor of geobiology, is quoted by MIT News as explaining that the “proximity of these hydrothermal features raises the possibility that early humans could have used hot springs as a cooking resource.” They could have placed the flesh of their kills into the hot and bubbling water of the springs in order to cook it. This is an important theory as it shows that humans could have been cooking their food long before they could manage fire.
Richard Pancost, who teaches biogeochemistry at the University of Bristol, told MIT News that the research project “introduces the fascinating possibility that such springs could have been used by early hominins to cook food .” How the hominins possibly cooked the food is unknown. It is also possible that animals that fell into the hot water were retrieved by early humans. “If there was a wildebeest that fell into the water and was cooked, why wouldn’t you eat it?” Sistiaga told MIT News .
Ainara Sistiaga in her lab. (Image: Angel Mojarro / MIT)
Cooked Food and Bigger Brains
After this exciting archaeological discovery from the Olduvai Gorge in Tanzania, the team are looking to study other sites for evidence of thermal springs. If certain lipids are found, this would help to prove their thesis that early humans cooked their kills in pools of hot water. If they can show a pattern, then this may indicate that early humans did indeed cook their food in thermal reservoirs. Such evidence would be important as it would indicate that early hominids were capable of complex behaviors and were able to use the resources in their environment. Moreover, if early humans consumed cooked meat it could have important implications for human evolution. Cooked meat resulted in our ancestors having bigger brains and other physiological changes, which profoundly changed our species.
Top image: The location of early settlements to hot springs has led researchers to wonder if early humans used them as a cooking resource long before they discovered fire. A research team has analyzed samples from Olduvai Gorge in Tanzania and believes to have found the answer. Source: Tom Björklund / MIT
By Ed Whelan
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