７８万年前の人類、焼き魚食べていた　イスラエル研究論文

【パリＡＦＰ＝時事】７８万年前の人類の祖先は、火をしっかりと通した魚を好んで食べていたする研究論文が１４日、公開された。調理に火が使われたことを示す最も古い証拠だと説明している。（写真はイスラエル・テルアビブ大学のスタインハルト自然史博物館に展示されたコイの頭の骨。同大提供）
　論文は、学術誌「ネイチャー・エコロジー・アンド・エボリューション」に掲載された。筆頭著者はテルアビブ大学スタインハルト自然史博物館の考古学者、イリット・ゾーハル氏。
　火が暖を取るためではなく調理に使われていたことを証明するのは難しく、調理が始まった時期をめぐっては考古学者の間で議論されてきた。論文によると、これまでは１７万年前のネアンデルタール人と初期現生人類（ホモ・サピエンス）による調理痕が最も古い「決定的な証拠」とされていた。
　しかし、ゾーハル氏はイスラエル北部にあるヨルダン川近くのゲシャー・ベノット・ヤーコブ遺跡で、大量の魚の歯を見つけた。「骨はほぼ残っていなかった」という。遺跡の近くにはかつて湖があった。
　魚の骨は５００度以下の温度で熱せられると柔らかくなり分解するが、歯は残る。このことから発見は、魚が調理されていた可能性を示唆していた。同じ場所からは火をおこすために使ったとみられる焦げた火打ち石なども見つかった。
　歯はほとんどが２種類の大型のコイのもので、「ジューシーな」魚が好まれたようだ。コイは大きいもので体長が２メートル以上あった。
　ゾーハル氏によると、「決定的な」証拠となったのは歯のエナメル質だった。
　大英自然史博物館でＸ線粉末回折によってエナメル質を構成する結晶構造の熱による変化を調べた結果、２００～５００度の熱にさらされたことが分かった。これは魚をしっかりと調理するのに適した温度だ。調理には、土でできた窯が使われていた可能性がある。
　論文を読んだ仏国立自然史博物館の考古学者アナイス・マラスト氏は、「死んだ魚を処分するためなのか、それとも調理するためなのか、火にさらした理由が疑問点だ」と指摘した。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2022/11/17-13:14）

Early human ancestors living 780,000 years ago liked their fish well-done, Israeli researchers revealed Monday, in what they said was the earliest evidence of fire being used to cook.
Exactly when our ancestors started cooking has been a matter of controversy among archaeologists because it is difficult to prove that an ancient fireplace was used to prepare food, and not just for warmth.
But the birth of the culinary arts marks an important turning point in human history, because by making food easier to chew and digest it is believed to have greatly contributed to our eventual expansion across the world.
Previously, the first definitive evidence of cooking was by Neanderthals and early Homo sapiens 170,000 years ago, according to a new study published in the journal Nature Ecology and Evolution.
The study, which pushes that date back by more than 600,000 years, is the result of 16 years of work by its first author Irit Zohar, an archaeologist at Tel Aviv University's Steinhardt Museum of Natural History.
During that time she has catalogued thousands of fish remains found at a site called Gesher Benot Ya'aqov in northern Israel.
The site near the banks of the Jordan River was once home to a lake, where a treasure trove of ancient fish fossils helped the team of researchers investigate exactly when the first cooks started getting inventive in the kitchen.
It was like facing a puzzle, with more and more information until we could make a story about human evolution, Zohar told AFP.
- 'Desire to cook'? -
The first clue came in an area that contained nearly no fish bones but lots of teeth, she said.
This could point towards cooking because fish bones soften and disintegrate at temperatures under 500 degrees Celsius (930 Fahrenheit) -- but their teeth remain.
In the same area, a colleague of Zohar's found burnt flints and other evidence that it had previously been used as a fireplace.
And most of the teeth belonged to just two particularly large species of carp, suggesting they had been selected for their succulent meat, the study said. Some of the carp were over two metres (6.5 feet) long.
The decisive proof came by studying the teeth's enamel, Zohar said.
The researchers used a technique called X-ray powder diffraction at the Natural History Museum in London to find out how heating changes the structure of the crystals which make up enamel.
Comparing the results with other fish fossils, they found that the teeth from the key area of the lake were subjected to a temperature of between 200?500 degrees Celsius (400-930 Fahrenheit).
That is just the right range for well-cooked fish.
Whether our forerunners baked, grilled, poached or sauted their fish remains unknown, though the study suggested they may have used some kind of earth oven.
Fire is thought to have first been mastered by Homo erectus some 1.7 million years ago.
But because you can control fire for warming, that does not mean you control it for cooking -- they could have eaten the fish next to the fire, Zohar said.
Then the human ancestors might have thrown the bones in the fire, said Anais Marrast, an archaeozoologist at France's National Museum of Natural History not involved in the study.
The whole question about exposure to fire is whether it is about getting rid of remains or a desire to cook, she said.