Modern biology has a tremendous potential to use the new DNA sequencing technology to sequence genomes of all the species that surround us. We have already obtained genome sequence data for over 100 000 species, including humans. However, in order for our knowledge of these genome sequences to “come to life”, we need to understand the message encoded in the DNA. For a large portion of genes in these sequenced genomes we do not know their role or function. In this project we are testing an exciting idea that the evolutionary age of genes can be used to predict their function. Biologists know how to make evolutionary trees. Based on genome sequence data, we can reconstruct the tree of life starting with the first unicellular living organisms, all the way to presently living species. Our method, called genomic phylostratigraphy, can assign the origin of all genes to some point on the evolutionary tree. For example, we can show that all cancer-related genes appeared at the same time when multicellular animals appeared. That makes sense, since single cell animals cannot have cancer. In the same way, from the evolutionary age of genes of unknown function, we can predict what functions or processes they are involved in. If successful, this means we can bring the “dark matter” of genomic DNA sequences to light. By doing so we will be able to better understand various diseases, discover new antimicrobials, and better understand the complex phenomenon of life.