The definition. Biological evolution, simply put, is descent with modification. This definition encompasses small-scale evolution (changes in gene frequency in a population from one generation to the next) and large-scale evolution (the descent of different species from a common ancestor over many generations). Evolution helps us to understand the history of life. The explanation Biological evolution is not simply a matter of change over time. Lots of things change over time: trees lose their leaves, mountain ranges rise and erode, but they aren't examples of biological evolution because they don't involve descent through genetic inheritance.
Southpaw is a boxing term that designates the stance where the boxer has his right hand and right foot forward, leading with right jabs, and following with a left cross right hook. Southpaw is the normal stance for a left-handed boxer.
The right hand signifies strength, perhaps because most people are right-handed and that is the hand that normally has their greatest strength. Most people write with their right hand, they do the most difficult things with their right hand, and it is the hand where the strength typically occurs.