Crocodile and Hippopotamus Served as 'Brain Food' for Early Human Ancestors ScienceDaily (June 10, 2010) — Your mother was right: Fish really is "brain food." And it seems that even pre-humans living as far back as 2 million years ago somehow knew it. A team of researchers that included Johns Hopkins University geologist Naomi Levin has found that early hominids living in what is now northern Kenya ate a wider variety of foods than previously thought, including fish and aquatic animals such as turtles and crocodiles. Rich in protein and nutrients, these foods may have played a key role in the development of a larger, more human-like brain in our early forebears, which some anthropologists believe happened around 2 million years ago, according to the researchers' study. "Considering that growing a bigger brain requires many nutrients and calories, anthropologists have posited that adding meat to their diet was key to the development of a larger brain," said Levin, an assistant professor in the Morton K. Blaustein Department of Earth and Planetary Sciences at Johns Hopkins' Krieger School of Arts and Sciences. "Before now, we have never had such a wealth of data that actually demonstrates the wide variety of animal resources that early humans accessed." Levin served as the main geologist on the team, which included scientists from the United States, South Africa, Kenya, Australia and the United Kingdom. A paper on the study was published recently in Proceedings of the National Academy of Sciences and offers first-ever evidence of such dietary variety among early pre-humans. In 2004, the team discovered a 1.95 million-year-old site in northern Kenya and spent four years excavating it, yielding thousands of fossilized tools and bones. According to paper's lead author David Braun of the University of Cape Town (South Africa), the site provided the right conditions to preserve those valuable artifacts. "At sites of this age, we often consider ourselves lucky if we find any bone associated with stone tools. But here, we found everything from small bird bones to hippopotamus leg bones," Braun said. The preservation of the artifacts was so remarkable, in fact, that it allowed the team to meticulously and accurately reconstruct the environment, identifying numerous fossilized plant remains and extinct species that seem to be a sign that these early humans lived in a wet -- and possibly even a marshy -- environment. "Results from stable isotopic analysis of the fossil teeth helped refine our picture of the paleoenvironment of the site, telling us that the majority of mammals at the site subsisted on grassy, well-watered resources," Levin said. "Today, the Turkana region in northern Kenya is an extremely dry and harsh environment. So, clearly, the environment of this butchery site was very different 1.95 million years ago -- this spot was much wetter and lush." Using a variety of techniques, the team was able to conclude that the hominids butchered at least 10 individual animals -- including turtles, fish, crocodiles and antelopes -- on the site for use as meals. Cut marks found on the bones indicate that the hominids use simple, sharp-edged stone tools to butcher their prey. "It's not clear to us how early humans acquired or processed the butchered meat, but it's likely that it was eaten raw," Levin said. The team theorizes that the wet and marshy environment gave early pre-humans a way to increase the protein in their diets (and grow larger brains!) while possibly avoiding contact with larger carnivores, such as hyenas and lions. Email or share this story: | More Story Source: The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Johns Hopkins University, via EurekAlert!, a service of AAAS. Journal Reference: 1. B. H. Passey, N. E. Levin, T. E. Cerling, F. H. Brown, J. M. Eiler. High-temperature environments of human evolution in East Africa based on bond ordering in paleosol carbonates. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1001824107 -- 原始网址（有鳄鱼图 0rz）： http://www.sciencedaily.com/releases/2010/06/100609122857.htm 其实我觉得这个标题取的并不恰当。 原文大意是说，在肯亚北部发现了一个不同於以往的聚落，以往总是为了发现一堆骨头和 石器而欢喜。然而，这次找到的约是两百万年前的聚落，是有着一堆鸟的骨头和鳄鱼的腿 骨。这个发现让研究者相信这是一个早期人类具有广泛食物种类的摄取的第一个实证，而 他也认为实用这些乌龟或者是鳄鱼是有丰富的营养，而人类学家认为肉类的摄取是造成大 脑快速成长的重要原因。 --

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