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.
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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
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原始網址（有鱷魚圖 0rz）：
http://www.sciencedaily.com/releases/2010/06/100609122857.htm
其實我覺得這個標題取的並不恰當。
原文大意是說，在肯亞北部發現了一個不同於以往的聚落，以往總是為了發現一堆骨頭和
石器而歡喜。然而，這次找到的約是兩百萬年前的聚落，是有著一堆鳥的骨頭和鱷魚的腿
骨。這個發現讓研究者相信這是一個早期人類具有廣泛食物種類的攝取的第一個實證，而
他也認為實用這些烏龜或者是鱷魚是有豐富的營養，而人類學家認為肉類的攝取是造成大
腦快速成長的重要原因。
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※ 編輯: mulkcs 來自: 140.112.174.51 (06/11 11:26)