The major evidence that the evolution is still ongoing is mutations that occur. Those changes at gene level happen by chance during the process of copying DNA and change through the populations over time. Individuals who reproduced can pass that mutation to their offspring. When carriers with a specific mutation are better able to survive and reproduce, natural selection will favor them. That is the way of new variant to be passed down and spread through the population.
Since it says all carbon atoms have six electrons, we know that they only have six protons too. The carbon 13 and 14 means they have extra neutrons that increases their atomic mass.