隐藏在当今活生物的现代基因组中的，是古代生物地化事件留下的印记。Lawrence David 和 Eric Alm建立了用来重构古基因组的一个新算法，该算法将横向基因转移的混淆效应及系统发生上的不确定性考虑了进去。将这个算法应用于来自当今生物的约10万个基因序列，他们发现了地球历史上重大事件的遗传印记，包括开始于距今25亿多年前的氧含量的逐渐升高，以及以前没有报道过的、发生在太古代（在距今超过20亿年前的“寒武纪大爆发”之前）的虽然短暂但却巨大的遗传多样性增加。（生物谷Bioon.com）
生物谷推荐原文出处：
Nature doi:10.1038/nature09649
Rapid evolutionary innovation during an Archaean genetic expansion
Lawrence A. David& Eric J. Alm
The natural history of Precambrian life is still unknown because of the rarity of microbial fossils and biomarkers1, 2. However, the composition of modern-day genomes may bear imprints of ancient biogeochemical events3, 4, 5, 6. Here we use an explicit model of macroevolution including gene birth, transfer, duplication and loss events to map the evolutionary history of 3,983 gene families across the three domains of life onto a geological timeline. Surprisingly, we find that a brief period of genetic innovation during the Archaean eon, which coincides with a rapid diversification of bacterial lineages, gave rise to 27% of major modern gene families. A functional analysis of genes born during this Archaean expansion reveals that they are likely to be involved in electron-transport and respiratory pathways. Genes arising after this expansion show increasing use of molecular oxygen (P = 3.4 × 10?8) and redox-sensitive transition metals and compounds, which is consistent with an increasingly oxygenating biosphere.
