History Seems to be Missing
It’s interesting that asteroid 163348 (2002 NN4), which is between 150-300m in length, was discovered 18 years ago, arriving in an expected path. They aren’t particularly worrying. What is worrying is something like Oumuamua, which was between 100m and 1 kilometre long and had passed within earths orbit already, went within mercury’s orbit, and was on it’s way out back past earths orbit within 1 month of it being first discovered. How many of these objects are around nobody knows as astronomers are only really starting to look for them.
Human intelligence has probably been at our current level for 300,000 years. Although the first stone tools have been discovered dating back to at least 700,000-950,000 years ago. We have history of maybe 10,000. I’ve always wondered what happened to the other 96.6% of the time, possibly up to 98% if you include Neanderthals and Denisovans, and 99% for stone tools. Just doing nothing, as the unproven assumption is that they were just itinerant primitives, grubbing roots, little more than animals, but they had religion, art, communities, travelled great distances, and were the originators of most of the grains we eat. 6,000 years ago our ancestors were moving giant blocks and creating constructions that would be a problem for most modern engineers. People are now only discovering that some of the chambers were probably used for astronomy around that time. Think who in your local community could do it now with the society we have.
If you trace back the civilizations of the world there is nothing really before 10,000 years ago worth mentioning, then somebody flipped a switch, and simultaneously within 3,000 years all around the world, civilizations started up after doing nothing for hundreds of thousands, possibly up to a million years. It was about the same time as all the megafauna seemed to have disappeared. My view is that they’ve simply been erased by events, not non-existent. Solar Flares, Asteroids, disease, climate change, super volcanoes, polar change, advanced or computer warfare; they are all candidates, perm any 2 from 7 for a bus ticket back to the stone age.