Trends in Evolution

 Trends in evolution can happen in many different ways but the most important thing is that the changes of trends happen over a long period, which makes it a trend not just a random flux of changes. For example, if several generations of a lineage experience the same type of change over a long time period, then it can be categorized as a trend. Many times, the cause of the trend is not obvious as it could have been caused by a variety of reasons. Evolutionary trends also don't happen to every species. While many could acquire a trend such as getting larger, many species do not. Finally, it is not easy to answer the question if evolution is progressive due to humans' need to categorize progress like steps up a ladder, whereas evolution is more shown as a tree with the changes going out like branches.