1.   Biologists have not despaired of restoring the universal ancestor with phylogenetic trees, but the unveiling will not take place nearly so soon as expected.

2.   A new and far-reaching theory about the universal ancestor has been developed by Woese.

3.   He argues there might have been many lost branches of the tree of life before the universal ancestor.

4.   Still, many more years of evolution presumably passed before the universal ancestor, a quite sophisticated genetic system, attained its final form.

5.   The horizontal exchange of genes seems to have started before the three kingdoms of life diverged from each other and the universal ancestor.

6.   With three points of triangulation, scientists can start to work backwards to figure out features of the universal ancestor cell of the three kingdoms.

a. + ancestor >>共 186
common 13.57%
human 10.18%
direct 4.79%
ancient 2.99%
distant 2.40%
earliest 2.40%
early 2.20%
wild 1.80%
remote 1.60%
dead 1.40%
universal 1.20%
universal + n. >>共 692
coverage 9.06%
suffrage 4.71%
service 3.11%
appeal 2.84%
access 2.33%
language 2.29%
support 1.65%
health 1.28%
bank 1.24%
truth 1.24%
ancestor 0.27%
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