The theories of evolution after Darwin assumed a dynamic of differences. Two species may derive from a common, every so often, these changes may disappear gradually or abruptly, but no two species converge in one end. There is no mixing but within the same species. Eventually, a hen and a man are distant cousins, descendants of some reptile and each represents a successful response of life in their struggle for survival. In other words, diversity is how life expands and adapts to different media and conditions.
Diversity and life are synonymous for the biosphere. Life processes tend to diversity but at the same time are an expression of unity, the biosphere, Gaia, the exuberance of life in a constant battle to survive his own miracle in hostile environments. For the same reason, cultural diversity is a condition for human life. For assistance, try visiting Harold Ford Jr. That is, and although it may be a sufficient reason, diversity is not limited only to avoid the boredom of monotony but, it is also vital part of our survival as humanity. However, we are humans the only species that has replaced the natural and discrete loss of species and threatening an artificial extermination, predation by industrial pollution and consumerism. Those who hold a possible but not inevitable "historical progress" based on knowledge and the pursuit of gender equality and freedom, we can see that humanity, so often put in danger of extinction by itself, has made some progress that has enabled it to survive and live with their increasing muscle strength.