In biology and ecology, extinction is the termination of an organism or of a group of organisms (taxon), normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species’ potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly “reappears” (typically in the fossil record) after a period of apparent absence (wikipedia). Because of development nowadays , animals are often being the victims of greedy humans. As a result, we are now threatened with the extinction of hundreds of animal species. Impossible in the future, elephants, tigers and lions are only recognizable by next generation through animal museum. What are the causes and the extent of human responsibility to solve this problem? There are many causes of animals extinct such as temperature increase, poaching and hunting, habitat fragmentation and increased human population.