A shrew-like primitive mammal that inhabited China 165 million years ago represents a milestone in mammalian evolution, scientists said on July 18, boasting a key anatomical trait in its throat that helped usher in the era of polite table manners.
Scientists described an exquisitely preserved Jurassic Period fossil from Inner Mongolia of a furry critter called Microdocodon gracilis. It was a lightly built, long-tailed, insect-eating tree-dweller roughly 14cm in length that lived in a warm lakeshore environment alongside feathered dinosaurs and flying reptiles called pterosaurs.
Before Microdocodon, land vertebrates including amphibians, reptiles and predecessors to the mammalian lineage had resorted to gulping large chunks of food or swallowing prey whole, as crocodiles do today, relying largely on jaw strength or gravity to guide the meal down the throat. A revolutionary change present in Microdocodon’s throat allowed for more finesse in muscle-powered swallowing and, thus, genteel dining.
Photo: Reuters
照片:路透
Microdocodon is the earliest-known creature whose hyoid bones in the throat are configured as in modern mammals. The delicate hyoids connect the back of the mouth, or pharynx, to the openings of the esophagus, which is the tube connecting the throat to the stomach, and the larynx, the “voice box” that provides an air passage to the lungs.
Unlike its evolutionary predecessors that possessed hyoids in a sturdy rod-like configuration, Microdocodon’s hyoids had mobile joints and were arranged in a “U” shape that let it chew food in the mouth and then swallow it along with liquids one small lump at a time rather than in big, ungainly gulps.
“We, the mammals, distinguish ourselves from other vertebrates by chewing our food into tiny morsels for good digestion,” said University of Chicago paleontologist Zhe-xi Luo, senior author of the research published in the journal Science. “The innovation to chew our food goes hand-in-hand with our sophisticated hyoid apparatus that enables us to swallow the chewed food, to drink water, and also for mammalian babies to suckle milk.”
This apparatus for active swallowing apparently evolved in combination with the advent of complex teeth that let primitive mammals chew and then swallow this predigested food for more efficient energy intake, added University of Bonn paleontologist Thomas Martin, another senior author of the study.
Primitive mammals appeared during the Triassic Period roughly 210 million years ago. Mammals became Earth’s dominant land animals after the dinosaurs were wiped out 66 million years ago by an asteroid impact.
(Reuters)
科學家於七月十八日表示,一億六千五百萬年前棲息於中國、一種貌似鼩鼱的原始哺乳類,代表著哺乳動物演化史上的一項里程碑,原因在於其喉嚨部位具備一項關鍵性的解剖學特徵,迎來「良好餐桌禮儀」的時代。
科學家從一塊出土於內蒙古、保存狀況相當完整的侏儸紀化石中,描繪出一種毛茸茸小動物的樣貌,並取名為「微小柱齒獸」。該物種體型輕巧、有著一條長尾巴,是以昆蟲為主食的樹棲動物,身長約十四公分,和身披羽毛的恐龍以及飛行爬蟲類翼龍,一起生活在溫暖的湖岸環境。
在「微小柱齒獸」出現前,陸上脊椎動物──包括兩棲類、爬蟲類、還有哺乳動物譜系的祖先──進食都要靠大口吞下大塊食物,或是像今日的鱷魚一口氣吞下整隻獵物,仰賴的是上下顎的力氣或地心引力,來引導這頓大餐順著喉嚨向下走。在「微小柱齒獸」喉部出現的這項革命性變化,在肌肉出力的吞嚥動作中加入更細膩的技巧,遂發展出彬彬有禮的用餐方式。
「微小柱齒獸」是目前所知最早在喉嚨內的舌骨配置與現代哺乳類相同的動物。纖細精密的舌骨連結了口腔後方,或稱「咽頭」,和食道與喉頭的開口。食道是連接喉嚨跟胃的管道,而喉頭──也就是「發聲構造」──提供空氣進入肺部的通道。
相異於演化上的祖先,其舌骨呈現結實的棍狀結構,「微小柱齒獸」的舌骨帶有可動關節,而且排列成U字形,讓牠們能夠在嘴巴裡咀嚼食物,再和液體一起一次吞下一小塊,而非不雅地大口吞嚥食物。
這份研究發表於《自然》期刊,主要作者為芝加哥大學的古生物學家羅哲西。他表示:「我們作為哺乳動物,跟其他脊椎動物的區別在於,我們會把食物咀嚼成很小塊以利消化。」羅哲西進一步解釋:「咀嚼食物的革新跟我們複雜的舌骨機制有著緊密關連,它使我們能夠吞嚥咀嚼過的食物、飲水,同時也讓哺乳動物的幼獸可以吸吮奶水。」
此研究的另一位主要作者為波昂大學的古生物學家托瑪斯‧馬汀,他補充說明,這項主動吞嚥的機制顯然是跟複雜的牙齒排列一起演化出現,讓原始的哺乳動物可以嚼食,再吞下那塊化整為零的食物,使能量攝取更有效率。
原始哺乳動物出現於大約兩億一千萬年前的三疊紀。在六千六百萬年前,一起小行星撞擊事件徹底消滅恐龍,從此哺乳類成為支配地球陸地的動物。
(台北時報章厚明譯)
A: Artificial intelligence technology has been causing controversy lately: a student was caught cheating with AI to win the grand prize in an art contest. B: That’s so absurd. Does this mean that AI paints better than humans? A: Maybe. Luckily, the student was later disqualified. B: And more absurdly, it’s becoming more and more popular to use AI technology to “resurrect” people. A: Yeah, some netizens even posted videos featuring the late singer CoCo Lee, who was “resurrected” by them with AI software. A: 人工智慧的爭議不斷,有學生違規使用AI參加美術展,甚至贏得首獎。 B: 真誇張,這是不是代表AI比人類還強大? A: 或許吧,幸好得獎資格被取消。 B: 還有更誇張的︰讓死者重現的「AI復活」技術越來越熱門。 A: 對啊,還有網友製作已故歌后李玟「復活」的影片呢! (By Eddy Chang, Taipei Times/台北時報張聖恩)
It’s no secret that Japanese people have a deep affection for noodles. Like in the rest of East Asia, noodles are an important staple food, second only to rice. Japanese people have enjoyed noodles for over 1,000 years. The first noodles came from China and were introduced around 800 CE. As time passed, noodles in Japan not only became widespread but also developed some unique Japanese characteristics. The three most popular types of noodles in Japan are ramen, soba, and udon. Ramen, typically made from wheat flour, is usually thin and firm. The dough is kneaded and left to
Rice is an essential ingredient in Taiwanese cuisine. Many foods are made of rice, adding more variety to our cooking, such as rice cake, or “gui.” Wagui is made by steaming rice flour batter in a bowl. The term “gui” refers to a type of food made from rice, while “wa” refers to a bowl. The pronunciation of “gui” in Taiwanese Hokkien is similar to the word for “nobility” in Chinese, so it is common for people to prepare various types of gui, including wagui, as offerings to the gods or ancestors,. 米是台灣重要的主食,用米製成的食品十分多元,豐富我們的飲食,如米做成的「粿」。粿的意思是米做成的糕點,碗粿是將在來米漿倒入碗中蒸熟,因而得名。粿因為音同「貴」,因此碗粿等粿食常用作供品祭拜神明和祖先。 nobility (n.) 高貴,高尚;貴族 offering (n.) 供品 While Taiwan may not be
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