An epoch is a period of time in history or a person’s life, typically one marked by notable events or particular characteristics. Although not officially approved, a working group has proposed that the world entered a new epoch called Anthropocene, or the human epoch. The starting point is still debated, as some believe it started at the beginning of the Agricultural Revolution 12,000–15,000 years ago, and others see it starting as recent as the 1960s. One proposal, based on atmospheric evidence, is to fix the start with the Industrial Revolution circa 1780, with the invention of the steam engine.