The Murchison meteorite was found to be 4.5 billion years old, and it was studded with amino acids—seventy-four types in all, eight of which are involved in the formation of earthly proteins. In late 2001, more than thirty years after it crashed, a team at the Ames Research Center in California announced that the Murchison rock also contained complex strings of sugars called polyols, which had not been found off the Earth before.
人们发现，默奇森陨石的年代已达45亿年，上面星星点点地布满着氨基酸——总共有74种之多，其中8种跟地球上的蛋白质有关。2001年底，在陨石坠落30多年以后，加利福尼亚的埃姆斯研究中心宣布，默奇森陨石里还含有一系列复杂的糖，名叫多羟基化合物。这类糖以前在地球之外是没有发现过的。
A few other carbonaceous chondrites have strayed into Earth's path since—one that landed near Tagish Lake in Canada's Yukon in January 2000 was seen over large parts of North America—and they have likewise confirmed that the universe is actually rich in organic compounds. Halley's comet, it is now thought, is about 25 percent organic molecules. Get enough of those crashing into a suitable place—Earth, for instance—and you have the basic elements you need for life.
自1969年以来，又有几块碳质球粒陨石进入地球轨道——有一块于2000年1月坠落在加拿大育空地区的塔吉什湖附近，北美许多地方的人都亲眼目睹了那个景象——它同样证明，宇宙里实际上存在丰富的有机化合物。现在认为，哈雷彗星大约25%是有机分子。要是这类陨石经常坠落在一个合适地方——比如地球，你就有了生命所需的基本元素。

There are two problems with notions of panspermia, as extraterrestrial theories are known. The first is that it doesn't answer any questions about how life arose, but merely moves responsibility for it elsewhere. The other is that panspermia sometimes excites even the most respectable adherents to levels of speculation that can be safely called imprudent. Francis Crick, codiscoverer of the structure of DNA, and his colleague Leslie Orgel have suggested that Earth was "deliberately seeded with life by intelligent aliens," an idea that Gribbin calls "at the very fringe of scientific respectability"—or, put another way, a notion that would be considered wildly lunatic if not voiced by a Nobel laureate.
胚种说——即生命源来天外的理论——的观点有两个问题。第一，它没有回答生命是如何产生的这个问题，只是把责任推给了别的地方。第二，连胚种说的最受人尊敬的支持者有时候也到了猜测的地步。肯定可以说，这是很轻率的。DNA结构的两个发现者之一弗朗西斯·克里克和他的同事莱斯利·奥格尔认为“聪明的外星人故意把生命物种子”播在了地球。格里宾称这个观点“处于科学地位的最边缘”——换句话说，假如这个观点不是一位诺贝尔奖获得者提出的，人家会认为它简直荒唐透顶。