266 Chert 16’32
P1: some prehistoric creatures proof their existence. More ancient more obscure
P2: microscopic cells A period nearly indistinguishable. Very few fossilized cells to be accessible to the earth surface today.
P3: high-empowered microscopes make geologists to detect 3.456 billion years old fossils(when simple inorganic molecules first self-replicated). 1996 new tech solidify life existed 365 million years ago. Meteorite found in A 3.9 billion year old biosignatures announced.
P4: only one life sign still clamors(持续的叫喊,持续有影响力吧?). cast doubt on earth;s two oldest geologic records of life in G&A through 1.rocks formed where no life live 2. whether lifeless chemistry be able to be biosignatures.
P5: debate: how can anyone be sure about identification about primitive life. “no life on earth, no life on Mars”
主题:史前生物的identification
结构:史前生物存在——史前生物的介绍——现代科技的发现——专家对发现的质疑——开发性结尾,留存问题
主要内容
P1
prehistoric creatures好像留了无数的线索证明它们存在。monstrous thighbone变成sandy stone;jagged fronds变成jet-black layers of coal;worm burrows变成limestone。
the more ancient the creatures, the mroe obscure Its Grave.
P2
在其他更高级动物出现之前,没有东西像微生物一样遍布全球。据说它们存货在25亿年前,他们的traces变得难以分辨了。几百年以来的burial和resurface让一些fossilized cells存活在地球表面的岩石中。通常地质学家会依赖其他signs of life———生物特有的化学物质。
P3
十年前高准度显微镜侦察到34。65亿年前的微生物fossils,接近于出现能够和环境反应,自我繁殖的微生物的时期。
1996年新科技找到生命存在于36.5千万年前的线索。
同年有科学家检测到39亿年前火星上的生物信号。
P4
未经证实的glory没持续太长时间。
在火星的信号中,只有一个是比较可信的。
2002年,一个为人所接受的confidence也遭遇了质疑。研究对地球在格陵兰和澳洲两种life的记录提出质疑。一些新研究发现rock上可能没有出现过生物。其他人则质疑lifeless 化学物质是不是代表生物的存在。
P4
重新审视的分析促进了在这一话题上的debate———没有人能够确定earth或者是solar system 最早的生命起源。
无法定位地球的生物起源,就不会准确的定位火星的!
266. Chert
P1 - Prehistoric creatures left proof of their existence in rocks.
P2 - All traces of lifes lived 2.5B years ago are indistinguishable. Geologists must rely on other signs of life.
P3 - A decade ago high-powered microscopes enabled geologists to detect fossils in earthly rocks as 3.4B years old. E.g. meteorite was found carrying biosignatures from Mars.
P4 - Research has cast doubt on interpretations of the earth's two oldest geologic records of life.
P5 -The revisionist analyses are debating over how anyone can be sure of correctly identifying primitive life of earth.