The present world cannot be imagined without human beings. AsapSCIENCE 's video posted on YouTube reveals what could have happened if every human being had been wiped off the face of the earth at once . This video seeks to understand what could happen thousands of years after the disappearance of humans. Once humans are extinct, nuclear power plants will first shut down and gradually collapse. There will be no one to take care of the cattle and poultry. As a result, they would wander about in search of food. Many of them will die without being able to survive in the midst of nature , others will be transformed into food for dogs and cats. Rats and cockroaches will be in danger of not getting food. Human-dependent insects , such as beetles and lice, will soon die. Once the dams in different areas become useless, our roads will be turned into rivers. The subways of the developed countries will be filled with water. The buildings will collapse , surrounded by trees. Wooden and thatched houses in rural areas will be more easily damaged by fire or termites. Without regular painting, all metallic structures like buildings , bridges and various vessels will be eroded . In the absence of humans, the number of different animal species will continue to increase. However, due to humans, many animals will discover themselves in a different area from their natural habitat. For example, a camel will find itself out of a zoo in Australia , or a lion will feel uncomfortable in cold Canada. Even if there are no people, the radio signals made by them will continue to travel in space. Another sign of human presence will remain , and that is garbage. Plastic is a big part of human waste. Different germs and insects will not be able to eat it, so they will remain in the soil for centuries. And after many, many days when alien creatures come to earth , they will be worried when they see these plastics. The environment will also become clean as there will be no man-made pollution. But some contaminants will remain for many, many years.