01:32
Building Blocks: Mass Extinctions
The ultimate example of an environmental change leading to the termination of a species is what's known as a mass extinction.
04:40
Building Blocks: Origins of Life
There are many questions yet to be answered about how, why and where life on Earth began. There are those who believe that DNA protein-based life as we know it may have had its origins in the world of RNA.
03:16
Building Blocks: Role of Evolution in Early Life
The ability to adapt to changing or difficult conditions is clearly necessary if an organism is to be biologically successful.
00:34
Building Blocks: Role of the Ocean in Early Life
Many scientists believe that life on Earth began in the ocean, because continental areas on the early Earth did not offer the kind of conditions that would have been conducive to life.