new study has led archaeologists to believe that  world's first war was in Sudan. Researchers from France and  UK have re-examined 61 human skeletons from  site at Jebel Sahaba in  Nile Valley in Northern Sudan. The skeletons are 13,400 years old and were uncovered in  1960s. For decades, scientists believed  millennia-old humans were killed in  one-off massacre. New research on injuries sustained by  early humans revealed that they were killed during a longer war that took place over several years.  skeletons are now regarded as evidence of the earliest example of organized warfare between humans. Furthermore,  war was probably triggered by climate change.
 researchers conducted  deeper investigation into injuries on  skeletons found at Jebel Sahaba. The scientists said the injuries were as  result of weapons such as arrows and spears. They were likely sustained during  series of conflicts or battles over several decades. The researchers believe conflicts arose as rival tribes competed  food and water that were in limited supply because of dramatic changes in climate 11,000 to 20,000 years ago. At this time, ice covered  lot of the Northern Hemisphere. This caused flooding and major changes to  availability of farmland.  researcher said: "These changes were not gradual at all. People had to survive these changes, which were brutal."