There have been 5 major extinction events throughout history, are humans impacting the 6th? Why or why not?

The biologists have been researching and they have been loosing 30,000 species per year. there is little doubt that humans are the direct cause of ecosystem stress and species destruction in the modern world through such activities. The transformation of landscape , overexploration of species, pollution, and the introduction of the alien species are the human activities occuring. Began when the first modern humans began to disperse to different parts of the world about 100,000 years ago. The humans of this world are causes of the sixth extinction because they kill animals that have a large amount species but those species are getting lower and lower. Humans are one of the causes for the extinction becausee the lower the amount of species 30,000 per year.
http://www.actionbioscience.org/newfrontiers/eldredge2.html

describe the three types of selections :directional stabilizing and disruptive and give examples

Disruptive selection is the opposite stabilizing selection. In this case, individuals with an average value of the trait are affected most and individuals with values far from the average are affected least. However, the distribution following selection is much narrower, as particularly individuals with extreme values of the monitored trait and this selection is called stabilizing selection.If the population is present under unchanging conditions, there is usually an optimal value of each quantitative trait, for example optimal body length, this is an example of stabilizing selection. Directional selection leads to a change, not only in the average value of a particular trait, but also a change (decrease or increase in size) in the variability of the given trait in the population. A species gradually changes for example organisms either become bigger or smaller.
http://www.frozenevolution.com/selection-disruptive-stabilizing-and-directional