seven minutes after birth, due to defects in its lungs. Other cloned animals have been observed to have similar lung defects. There are many species that have gone extinct as a direct result of human activity. Some examples include the dodo, the great auk, the Tasmanian tiger, the Chinese river dolphin, and the passenger pigeon. An extinct species can be revived by using allelic replacement of a closely related species that is still living. By only having to replace a few genes within an organism, instead of having to build the extinct species' genome from scratch, it could be possible to bring back several species in this way, even Neanderthals. The ethics surrounding the re-introduction of extinct species are very controversial. Critics of bringing extinct species back to life contend that it would divert limited money and resources from protecting the world's current biodiversity problems. With current extinction rates approximated to be 100 to 1,000 times the background extinction rate, it is feared that a de-extinction program might lessen public concerns over the current mass extinction crisis, if it is believed that these species can simply be brought back to life. As the editors of a Scientific American article on de-extinction pose: Should we bring back the woolly mammoth only to let elephants become extinct in the meantime? The main driving factor for the extinction of most species in this era (post 10,000 BC) is the loss of habitat, and temporarily bringing back an extinct species will not recreate the environment they once inhabited. Proponents of de-extinction, such as George Church, speak of many potential benefits. Reintroducing an extinct keystone species, such as the woolly mammoth, could help re-balance the ecosystems that once depended on them. Some extinct species could create broad benefits for the environments they once inhabited, if returned. For example, woolly mammoths may be able to slow the melting of the Russian and Arctic tundra in several ways such as eating dead grass so that new grass can grow and take root, and periodically breaking up the snow, subjecting the ground below to the arctic air. These techniques could also be used to reintroduce genetic diversity in a threatened species, or even introduce new genes and traits to allow the animals to compete better in a changing environment. Research and technology When a new potential specimen is found, scientists normally first analyze for cell and tissue preservation