Our lab has pioneered the use and development of single cell sequencing techniques to study cancer. We use these tools to understand how tumors evolve from single normal cells in somatic tissues. Tumors are akin to ecosystems and obey the Darwinian laws of natural selection. As tumors grow in size, the cells can form distinct lineages and subpopulations as they encounter selective pressures, resulting in intratumor heterogeneity. This salient characteristic of human cancer confounds basic research and clinical diagnosis, because standard tools are unable to resolve complex admixtures of cells.