Reviving extinct animal species through techniques like cloning or genetic engineering raises ethical concerns and practical challenges. While it may be exciting to see species like the woolly mammoth or passenger pigeon back on Earth, there are questions about the impact on current ecosystems and whether these revived species would truly thrive. It is important to consider the potential consequences and prioritize conservation efforts for currently endangered species before attempting to bring back extinct ones. **

Pain did not revive Jiraiya because he believed that Jiraiya's death served a greater purpose in the cycle of hatred and war. Pain's ultimate goal was to bring about peace by showing the world the pain and suffering caused by conflict. Reviving Jiraiya, who was a powerful and influential figure, would have undermined Pain's message and the impact of his actions. Additionally, reviving Jiraiya would have also potentially disrupted the balance of power that Pain was trying to establish. **

Reviving someone who has experienced death does not provide direct insight into what happens after death. Revival techniques such as CPR or defibrillation are aimed at restoring the body's vital functions, but they do not provide any information about the individual's experience during the time they were clinically dead. The concept of death and what happens after it is a complex and philosophical question that goes beyond the scope of medical revival techniques. **