Figure 4
From: Is the transition from chemistry to biology a mystery?
Evolution barrier: agglutinate (shown in figure 3) becoming a contaminant by accumulation. Stage where the (+)-assembler and (-)-assembler are translated into enzyme E1 (specific sequence) and agglutinate E0 (non-sense sequence) respectively. With increasing complexity the accumulating agglutinate E0 becomes a contaminant, which leads to a barrier.