Life on earth can be extremely complex where different parts function together for the survival and reproductive success of the organism as a whole. Evolution of complexity required several small steps known as major transitions. Among such transitions during the evolution of life, certain events are unique (for example; evolution of genetic code), whereas other transitions might have happened multiple times through the history of evolution of life on earth.

There are obvious difficulties associated with discussing rare events such as evolution of genetic code, evolution of eukaryotic cells, and origin of life. However, we have an advantage while making prediction about how life must have originated on earth. This is because our predictions about the origin of life should adhere to the well-accepted laws of chemistry and mechanisms of natural selection. Since, most living organisms contain self-sustaining chemical system- dependent on external source of energy, and properties such as heredity, reproduction and differential reproduction. It is predicted that early life on earth must have exhibited these properties. Furthermore, growing body of evidence suggests that RNA molecules must have served as a replicating molecule responsible for heredity and also for coding metabolism inside primitive cells.

For evolution of metabolism and maintenance of RNA, both template and replicase activity is needed to be enclosed in some form of a physical compartment. Additionally, compartmentalization will lead to concentration of molecules, provide protection from environmental conditions, and allow evolution of cooperative network between replicating molecules. Given the significance of compartmentalization, I will discuss how simple lipid vesicles – protocells - might have functioned as an early barrier between extracellular and intracellular environment. However, without complex machinery used by modern cells for growth and division, simple vesicle-like early cells must have exhibited properties of spontaneous duplication and growth. I will discuss how the mechanism of spontaneous duplication and growth might have resulted in competition between vesicles. Overall, in this seminar, we will review properties of the early cell-like structure that until recently was a complete black box, and how the information gained from recent empirical evidence has helped us better understand the early evolution of life on earth.