History examines events as they occur in both spaces (places) and times. When expressed in this way we see that the key ‘content’ of history is not just time but space as well, in other words, scale. This is like looking down a microscope. Just as looking down a super microscope might reveal first an insect, then its leg, then the anatomy of the leg, as we narrow the historical focus so the different scales bring different factors, aspects or interpretations into view.
The scale of study we choose depends on what we want to learn. Does history begin with the Big Bang, the emergence of humans from ape-like ancestors, or does the use of written language provide a convenient demarcation between history and pre-history (say, around 3000 BCE and after), or is it the advent of modern science and industrial society (say, from around 1500) . . . what would you choose?
The temporal scale we choose for our history can change the mode of historical analysis. If we consider human history from the time of the Big Bang to the present our periodization will be of wide time frames relating to the long-term history of humans and the universe. We would not look to historians to information of these changes we would look primarily to scientists, essentially physicists and anthropologists. At this scale history is Big History. When we look at history in terms of the full span of human history, again it is not historians that we look to for Enlightenment but archaeologists, palaeogeneticists, evolutionary biologists, and anthropologists. It is only when we consider the shorter time frames that humanitarian insights of traditional historians can be brought to bear.
In general terms, the longer the time frame (millennia) the more important become large impersonal forces like geography: ‘what differs is not people but places’. Over the medium-term, say centuries, we tend to focus on change due to political, economic and cultural factors. Short-term history is inclined towards particular places, events, and people.
Big History is large-scale, covering all time and space, what happened in your life is small-scale. Big history encourages historians to work on many scales; it counters our temptation to focus on human agency and whim that gives history its strong sense of contingency . . . ‘At the very large scales, even in human history, structure begins to trump agency’. It resists the tendency to view all history from the perspective of the present, for example, the view that ‘the Stone Age was a preamble to history, a dystopian era of stasis before the happy onset of civilization, and the arrival of nifty developments like chariot wheels, gunpowder, and Google’ (Wikipedia). The general assumption that history begins with the written word looks parochial today.