This the fifth post in an ongoing big history series. It follows the structure of the course developed by historian David Christian. This post will explore the origins of humans and collective learning.
The story so far
(adjusted scale: all of time condensed into 13 years)
About 13 years ago, unknown conditions set off the Big Bang. This produced space, time, energy, and matter (mainly hydrogen and helium). The universe was born.
About 36 days later, cooling and tiny variations in the density of matter allowed gravity to bring together hydrogen and helium into high pressure clumps. Stars were born.
High temperatures within those stars, along with supernova explosions, allowed for the synthesis every other element on the periodic table. Chemistry was born.
As new stars formed around chemically rich clouds, solar systems were born. About 4.3 years ago, the Earth formed.
About 3.5 years ago, unknown conditions led to the first prokaryote. Life was born. About 85 days ago, the first mammals evolved from a branch of reptiles that loosely related birds.
About 65 million years ago, a catastrophe (probably a 10km-wide asteroid impact in Mexico) wiped out the dinosaurs and allowed for the adaptive radiation of mammals. In Australia, marsupials won out (think kangaroo). In the Americas, primates evolved into the new world monkeys (think spider monkey). In Africa, around 30 million years ago, the old world monkeys evolved into apes (think orangutan). Apes had fairly large brains, grasping hands, extended shoulder motion, no tail, eyes in the front of the head for depth perception, and social hierarchies.
Around 7 million years ago, apes were doing pretty well in the dense forests of Africa; escaping predators by climbing up trees. However, climate change transformed the environment into a wide open savannah. In response, some apes developed bipedalism in order to run away from new threats.
Around 4 million years ago, Australopithecines arrived on the scene with their bipedalism. Around 2.3 million years ago, Homo Habilis arrived with their simplistic tool making. Around 1.9 million years ago, Homo Ergaster arrived with their larger brains. Over the next 100 thousand years, Homo Ergaster devolved new tools and possibly even fire. This might have been the first case of technological improvement within a species. Over the next million or so years, branches of apes, like the Neanderthals, developed sophisticated weapons and fire based communities. They were now able to migrate to colder climates. Around 250 thousand years ago, humans arrived.
Everything was going well until about 70 thousand years ago when a super volcanic eruption in Indonesia decimated the human population. This severely limited the diversity of our genetic makeup, which can be seen today. But the survivors carried on an would transform the earth in the centuries to come.
As far as we know, humans are one of the most complex things in the Universe. We are kind of a big deal and we owe that to collective learning.
Collective learning is the ability of a species to retain more information with one generation than is lost by the next. For about 13.8 billion years, new knowledge survived only as long the entity that discovered it. Humans changed this by developing a systematic way to record and pass on knowledge to future generations: language.
Many other intelligent species exist – dolphins, chimpanzees, crows- but only humans developed symbolic language. By writing down and sharing information, humans could exponentially increase the amount of knowledge in a group. Overtime, this knowledge compounded and led to new complexity.
Large brains and a symbolic language allowed humans to be the first species on Earth to develop collective learning. Humans of today aren’t any smarter than they were 200 thousand years ago, but we have the advantage of the compounded knowledge that was passed on from generation to generation. This ability to amass knowledge was about to set off a massive boom in complexity.