People these days are greedy. They are ready to do anything to be rich. People kill animals for the tiger's skin,elephants teeth etc. The selfish and cruel attitude by humans have led to the endangering of species like tiger etc. The extincted dodo bird is an example for this. It is said that some of the people who travelled the the middle of the sea saw an island where most of these dodos live. They decided to settle there for a few days. Due to their starvation they caught some dodos and killed it,Cooked it. The dodos flesh flashed tremendous taste in those people. They started to kill a big number of dodos and ate it. More people came to discover the island and as a result the dodos came to an extinction. So from this we can understand Selfish and cruel attitude if man has led to the extinction of some animals. The number of species created by god has been reduced to almost 40% less than the duration when god created them. In,short No. of species in earth has decreased due to the selfish and cruel attitudes of man.