Evolution of Chromosomes (IMAGE) University of Chicago Caption University of Chicago physicist Riccardo Levi-Setti in his high-resolution scanning microprobe laboratory. Levi-Setti and his associates have used the microprobe to study the evolution of chromosomes in eukaryotic organisms. Eukaryotes, which include humans, mammals, and single-celled organisms called dinoflagellates, all pack their genetic material in a cellular nucleus. Eukaryotes may have evolved more than one way to pack large quantities of DNA into the smaller volume of a chromosome. Credit Dan Dry Usage Restrictions This image may be used by news organizations in reports describing the research of Riccardo Levi-Setti. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.