Two DNA sequences generated at random must be 25% identical, by virtue of the fact that DNA is a sequence of only four bases. Therefore, all multicellular life, having presumably developed from a single common ancestral form, must be over 25% identical in their DNA sequences.
环境背景还揭示了天平另外一端的秘密。两个任意组合的DNA序列肯定有25%的共同之处，这是由于DNA序列仅仅由4个基数构成。因此，可能由共同祖先进化而来的所有多细胞生命，其DNA序列的相似性肯定会超过25%。