of developmental biology. Models of how morphogen gradient responses were encoded had previously been proposed but not tested across a set of unrelated enhancers constructed from a shared regulatory grammar and located throughout a genome. Three major unexpected findings resulted from this work. The first finding is that gradient responses in general do not evolve by changes in transcription factor (TF) binding site quality or quantity (site density) as expected, but rather by changes in the precise spacing between binding sites for morphogenic TFs and their partner TFs. The second finding is that homotypic site clustering at such enhancers was largely the result of a complex evolutionary history of selection for different threshold responses in the evolving insect egg. A third-related finding is that frequent selection for different responses also enriches for microsatellite repeat tracts, which are inherently unstable and most responsible for the production of novel indel alleles. Erives' work also showed the existence of inherent spatial-temporal conflict in morphogenic responses and how this is handled in nature via complementary morphogenic gradients. Molecular determinants of the genetic code Using insights gleaned from archaeal genomes, Erives elaborated and described a stereochemical model of "proto-anti-codon RNAs" (pacRNAs). The pacRNA model ascribes a predetermined combined origin for the universal genetic code (i.e., the codon table), the biogenic amino acids, and their exclusive homochirality in life. The model implies that early RNA world was an aminoacylated RNA world and that proteinogenic amino acids arose because of compatible interactions with nucleotide-based polymers. The pacRNA model explicitly lists possible interactions between various anti-codon di-nucleotide and tri-nucleotide sequences and different amino acids. When the nucleotides are D-ribose based, L-amino acids are preferred. In the pacRNA world, codons originate as cis-elements for recruiting self-aminoacylated pacRNAs/proto-tRNAs. Thus, a curious aspect of this model is that the (anti-) codon table is determined in evolutionary history prior to the origin of ribosome-based protein translation. The pacRNA model may explain why extant tRNAs are heavily modified in all three domains of life. Erives first presented the pacRNA model at NASAs 2012 Astrobiology Science Conference and most recently at the 2013 Iowa City Darwin Day festival, which focused on the origins of life on Earth. Like Erives' enhancer studies, which focus on how protein complexes interact with enhancer DNAs, his pacRNA work focuses on how biogenic amino acids would have beneficially interacted with the nucleotide-based molecules of early life. Both areas of