A Billion, Million and Thousand of Years
A billion of years (1,000,000,000)
4.6 billion years ago earth appear
4.0 billion years ago first continent appear
3.8 billion years ago first life appear
2.5 billion years ago great oxygenation begin (2.1 multicellular life, 1.5 eukaryotes appear)
A million of years (1,000,000)
530 million years ago first fish appear (Cambrian Period Begin)
475 million years ago first land plant appear
380 million years ago first reptile appear, forest appear, (200 mammal, 140 bird, 130 flower, 100 bee)
300 million years ago pangea supercontinent appear, carboniferous rainforest collapse
2.5 million years ago first stone tools appear, plesitocene era (glacial-interglacial cycle), (2.0 homo spread from africa to eurasia)
A thousand of years (1,000)
500 thousand years ago neanderthals appear, (300 fire appear, 200 homo sapiens appear)
100-10 thousand years ago last glacial period (12 agriculture appear, holocene era, end of ice age)
4.2 thousand year ago, Aridification trigger the collapse of Old Egypt (Bond Event 3)
2.8 thousand year ago, Drought, responsible for collapse of Late Bronze Age Cultures (Bond Even 2)
1.5 thousand year ago, Krakatoa volcano erupted, responsible for 535-536 Extreme Weather (Bond Event 1)
0.2 thousand year ago, Tambora volcano erupted, responsible for 1816 Year Without Summer (Bond Event 0), 1 bil population reach in 1820
BBC History of Earth. A number is based from wikipedia, there is a variation for example earth creation between 4.54 or 4.6 billion years, the first life between 3.8 or 3.5. What I am trying to explain is on the sequence aspects. Cyanobacteria (blue algae in the form of stromatolite) appear, which the main byside product is the first oxygen. ref, ref, ref.
So why study history? Unlike physics or economics, history is not a means for making accurate predictions. We study history not to know the future but to widen our horizons, to understand that our present situation is neither natural nor inevitable, and that we consequently have many more possibilities before us than we imagine. Yuval Noah Harari, 2014
How: To reconstruct the series of specific events that led from one point to another. How to make fire, we put a twig, and then wood, and use lighter to burn, an amount of oxygen then put to make fire bigger.
Why: To find causal connections that account for the occurrence of this particular series of events to the exclusion of all others. Why oxygen can make fire bigger?