The article "Evolutionarily Conserved Elements in Vertebrate, Insect, Worm, and Yeast Genomes" by Adam Siepel et al. presents a comprehensive search for conserved elements across multiple alignments of genomes from five vertebrate species, four insect species, two species of *Caenorhabditis*, and seven species of *Saccharomyces*. The authors used a computer program called phastCons, which is based on a two-state phylogenetic hidden Markov model (phylo-HMM). This method identifies conserved elements by fitting the phylo-HMM to the data using maximum likelihood, considering the phylogeny of the species and the rate of substitution in conserved regions. The predicted conserved elements cover a significant fraction of the genomes, with higher fractions in more compact genomes like *Drosophila melanogaster* (37%–53%), *Caenorhabditis elegans* (18%–37%), and *Saccharomyces cerevisiae* (47%–68%). These elements are found to lie outside of known protein-coding genes, suggesting the importance of regulatory and noncoding sequences in complex eukaryotes. The study also highlights that highly conserved elements (HCEs) in vertebrates are associated with 3′ UTRs of regulatory genes, stable gene deserts, and megabase-sized regions rich in moderately conserved noncoding sequences. HCEs in vertebrate 3′ UTRs show strong evidence of RNA secondary structure, indicating a role in post-transcriptional regulation. The results provide insights into the functional landscape of genomes and the evolution of regulatory mechanisms.The article "Evolutionarily Conserved Elements in Vertebrate, Insect, Worm, and Yeast Genomes" by Adam Siepel et al. presents a comprehensive search for conserved elements across multiple alignments of genomes from five vertebrate species, four insect species, two species of *Caenorhabditis*, and seven species of *Saccharomyces*. The authors used a computer program called phastCons, which is based on a two-state phylogenetic hidden Markov model (phylo-HMM). This method identifies conserved elements by fitting the phylo-HMM to the data using maximum likelihood, considering the phylogeny of the species and the rate of substitution in conserved regions. The predicted conserved elements cover a significant fraction of the genomes, with higher fractions in more compact genomes like *Drosophila melanogaster* (37%–53%), *Caenorhabditis elegans* (18%–37%), and *Saccharomyces cerevisiae* (47%–68%). These elements are found to lie outside of known protein-coding genes, suggesting the importance of regulatory and noncoding sequences in complex eukaryotes. The study also highlights that highly conserved elements (HCEs) in vertebrates are associated with 3′ UTRs of regulatory genes, stable gene deserts, and megabase-sized regions rich in moderately conserved noncoding sequences. HCEs in vertebrate 3′ UTRs show strong evidence of RNA secondary structure, indicating a role in post-transcriptional regulation. The results provide insights into the functional landscape of genomes and the evolution of regulatory mechanisms.