Another possibility: The Great Filter could be the jump from the simple prokaryote cell to the complex eukaryote cell. After prokaryotes came into being, they remained that way for almost two billion years before making the evolutionary jump to being complex and having a nucleus. If this is The Great Filter, it would mean the universe is teeming with simple prokaryote cells and almost nothing beyond that.
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C2`B 另一种可能：原核细胞到真核细胞的跳跃是大筛查。从原核细胞到有细胞核的真核细胞的演化有20亿年。如果这是大筛查，那么宇宙里全是原核细胞了。
q&v~9~^}d There are a number of other possibilities—some even think the most recent leap we’ve made to our current intelligence is a Great Filter candidate. While the leap from semi-intelligent life (chimps) to intelligent life (humans) doesn’t at first seem like a miraculous step, Steven Pinker
rejects the idea
of an inevitable “climb upward” of evolution: “Since evolution does not strive for a goal but just happens, it uses the adaptation most useful for a given ecological niche, and the fact that, on Earth, this led to technological intelligence only once so far may suggest that this outcome of natural selection is rare and hence by no means a certain development of the evolution of a tree of life.”
|au`ph5 还有很多其他猜想，有的人甚至认为最近的大筛选是形成人类智慧。从半智慧大猩猩到智慧人类看起来不像一个奇迹的飞跃，Steven Pinker反对必然性“向上爬”式演化的观点：“因为演化不是为某一目标改变自己而是偶然发生的，如果它以适应性为生命选择生态位，实际上这样就可能会导致至今科技智慧仅仅出现一次，自然选择的这个结果也会是罕见的，并不会有确定的生命树演化发展”。
B?8*-0a'[ Most leaps do not qualify as Great Filter candidates. Any possible Great Filter must be one-in-a-billion type thing where one or more total freak occurrences need to happen to provide a crazy exception—for that reason, something like the jump from single-cell to multi-cellular life is ruled out, because it has occurred as many as [url=http://www-eve.ucdavis.edu/grosberg/Grosberg pdf papers/2007 Grosberg & Strathmann.AREES.pdf]46 times[/url], in isolated incidents, just on this planet alone. For the same reason, if we were to find a fossilized eukaryote cell on Mars, it would rule the above “simple-to-complex cell” leap out as a possible Great Filter (as well as anything before that point on the evolutionary chain)—because if it happened on both Earth and Mars, it’s almost definitely not a one-in-a-billion freak occurrence.
IMqe( 大多数剧变不适合成为大筛选的可能。任何可能的大筛选下，十亿种东西中一个或几个反常的现象就会被称为特例，因此，单细胞到多细胞不算大筛选，因为它在特例中只在地球上就演化了46次。如果我们在火星上找到一块真核生物化石，那将会排除这种以及其演化链时间点之前任何生物的大筛查猜想，以为如果这种大筛查在地球和火星上都发生了，这就不是“十亿种中发生一次”的怪事。
HSG Ln906 If we are indeed rare, it could be because of a fluky biological event, but it also could be attributed to what is called the Rare Earth Hypothesis, which suggests that though there may be many Earth-like planets, the particular conditions on Earth—whether related to the specifics of this solar system, its relationship with the moon (a moon that large is unusual for such a small planet and contributes to our particular weather and ocean conditions), or something about the planet itself—are exceptionally friendly to life.
,Owk;MV@ 如果我们真的是特例，那这可能是一个侥幸型生物学事件，也可能属于“地球殊异假说”：尽管可能还有很多类地行星，但地球上的环境对生命特别友好，这么大的月亮为地球提供了形成气候和海洋环境的条件。
67 Pmnad [ 此帖被命运号角在2016-04-01 20:49重新编辑 ]
