Around 13.8 billion years ago, things began to happen. All of matter, space, energy, and time existed prior to this in a compressed state known as a quantum singularity. 13.8 billion years ago, than singularity entered a state commonly referred to as the Big Bang. Time and space expanded at an exponential rate and began to be filled by the remaining matter and energy. 13.7 billion years ago, the first stars began to shine in the heavens. 4.4 billion years ago, matter accretes to form a metallic planet about 1 AU away from its sun, which we affectionately call Earth.
Around 3 billion years ago, the first primitive cells begin to appear, and around 2.8 billion years ago, the first multicellular colonies of cyanobacteria appear in the fossil record. 1.2 billion years ago, we see the beginning of plants and animals, with the development of mitochondria and chloroplasts. 530 million years ago sees the start of the Cambrian Explosion, one of the most dramatic examples of speciation in earth's history. By the time it ended 450 million years ago, Earth had seen the first of the vertebrates, and the first of the terrestrial plants.
370 Million years ago, the very first land vertebrates slither out of the oceans. They are called tetrapod, the ancestors to every other vertebrate living on land. 330 million years ago, the first species of amniotes appear, the first to be able to lay their eggs on dry land and have them survive. 67 million years later, the first synapsids appear, the first precursors to the theraspids, who, 200 million years ago, gave rise to the very first mammals... who were probably Hadrocodium.
14 million years ago, we saw the rise of the most recent common ancestor of all the apes, ourselves included. And between 5 and 6 million years ago, we saw the Australopithecines diverge between genus Homo, our own, and Genus Pan, the chimpanzees.
195,000 years ago or so, the first anatomically modern examples of Homo sapiens sapiens appear in Africa, and 145,000 years later, they show the first examples of the modern thought process. 7300 years ago, the first urban society is formed in Mesopotamia. Within the last 6000 years, recorded history begins as writing becomes commonplace among the learned. 2350 years ago, Aristotle is making his contributions to western thinking, including the foundations of the scientific method, upon which our modern society's marvellous technologies, medicine, and understanding are based. 1100 years ago, the first examples of early English appear. 144 years ago, Canada confederates. Within those 144 years, two world wars begin and conclude, mankind learns to fly, walks on the moon, maps the human genome, develops the simple computer, builds the internet, launches a cloud of artificial satellites in concert with radio towers (also developed in that time period) making it possible for any of 5 billion people in 212 different countries to contact any of their number remotely, instantaneously. We learn to split the atom, leading to revelations both good and bad; to send entire libraries, almost instantaneously, along strands of glass the width of a hair. We've seen outside our own solar system and mapped planet mars.
The sum of recorded human history makes up, quite roughly, four billionths of the sum total of the time passed since, well, time started passing. And the modern era, depending on your definition, makes up about 2.4% of all of recorded history. In that time, we've gone from the age of the monolithic train to the ubiquitous automobile, from the first, clumsy powered flight to putting men and machines on other worlds. What used to fill an entire room in terms of processing power now fits on the radius of a human blood-cell, and 5 billion of us hold in our pockets a processing power greater than the moon landers had in their entire vessels.
Some would look at these time-scales and argue that humanity is an insignificant player in the overall scheme, and that argument is correct. However, in the scale of the human experience, the frame of reference that one argues matters most, we are significant. We, the temporal 2.4% of history, have done things our ancestors could only dream, and in some cases, could not even conceive. And of those things we have done, we have only opened more questions than are answered.