From FogCityJournal.com:
Suppose that an alien comes into orbit around our planet, and requests that a single human come aboard and in less than one hour brief the alien about the human history of planet earth. Here is Human History in a Hurry…
5×10^9 (about 5 billion years ago) – a supernova explosion just 1 light year away from the solar nebula sends a massive shockwave into the solar/planetary disc, resulting in a large number of planets (about 10, more at first in unstable orbits). Shortly thereafter one of these protoplanets crashes into the early earth, and like a billiard ball hit on its side, the collision produces a rapidly spinning earth, setting the stage for the evolution of a biphasic (waking and sleeping) system of learning, two time zones ahead.
5×10^8 (about 500 million years ago) – the first fish, our veterbrate ancestors.
5×10^7 (about 50 million years ago) – the first monkeys, beginning the brainbranch of evolution with a prominent cerebral cortex equipped with a biphasic/circadian system with its continuous interaction of learning from the waking state, reorganized during sleep. (LB now gives the alien a copy of the theory of learning, published by the University of Chicago Press, in 1969, when the first humans were landing on the moon. The moon is the result of collision described at 5×10^9.)
5×10^6 (about 5 million years ago) – the first humans, the big brained biped.
5×10^5 (about 500,000 years ago) – the first helpless offspring, for at least 5 years. The pelvic outlet within the hips of the human female can get no bigger, due to biomechanical restrictions for walking and especially for running. For the first time in evolution, there is huge brain growth after birth, inside the cranium of the helpless neonate/infant/toddler.
More here.