PATH TO A SUSTAINABLE EARTH

Life evolution    

 

Life starts around 3.5By years ago with bacteria in the form of Stromatolites that absorb carbon dioxide and seed the earth with oxygen.

 

 

 

 

 

 

 

 

Marine life evolves through series of extinctions.

 

 

 

The first land based species emerged.

 

 

Another extinction 205My ago, probably caused by volcanic activity,  allows  the dinosaurs to emerge. The fabulously diverse dinosaurs dominated for over 200My.  The  meteor 66My ago finished them off, forming the K-T boundary changed the trajectory of evolution  and allowed mammals to flourish and humans to evolve. The dinosaurs have roughly 80% of DNA in common with humans, which accounts for the recognizable "architecture" of dinosaur skeletons. 

 

The K-T meteor 66My ago changed the trajectory of evolution.

 

 

 

 

 

Shrews survive the meteor,  mammal species explode, and birds   evolved as the survivors of the dinosaur line.

The ancestral mammals, led to Monotremes as egg layers who suckle their young, and marsupials who give birth to a "fetus" that suckles and develops in a protected pouch. The most successful were the Eutherans who are placental mammals who develop inside the mothers body directly fed using mother blood through a  placenta.

 

 

The role of extinctions can be seen in diversity, measured as the count of different "families" changing overtime.  

 

 

 

 

 

Around 7My ago,  Hominids split from Great Apes and by 200Ky ago humans appeared with 99.5% of the DNA of the common Great Ape ancestor.   Humans have been around 40Ky. 


It took 3By for Stromatolites to evolve to  Dinosaurs (80% human DNA), who then lasted for 200My. It took 60My for Shrews (93% human DNA)  to evolve to Apes (99.5% human DNA). It took 7M years for Apes to evolve to Humans.  Mutation rate around 10M years for 1% DNA change, 5M years for a significant new species . 

The increasing size of the brain case is one of the most notable changes in the evolving humans as seen in these skulls at the "cradle of humanity" in South Africa.

The early humans were hunter - gatherers who spent their travelling around following food sources.

The ice ages impacted the migration of humans

During the last ice age, from 70Ky to 15Ky ago, hunter gatherers leave Africa and populate all the major land masses using land bridges formed by ice and low sea levels.

 

 

 

 

 

 

 

 

 

 

Cave paintings in Chauvet France date from 30Ky ago.

 

The end of the last ice age around 10Ky ago, uncovered the Fertile Crescent which became one the first centers of settled farming.  Once people could grow more than they needed, cities and  a ruling class emerged in Babylon. 

As soon as ruling classes emerge with wealth and resources, fights between rulers to increase their wealth and influence became the norm that has lasted to this day - unfortunately. Over 3000 years, the Egypt of the Pharoes was invaded by the Persians, Greeks, and Romans without disturbing the religious establishment. 

 

 

 

 

By 500BC, trans-continental trade over the Silk Road to the far east and India, and the Incense Route to Africa and Arabia brought exotic goods. Petra stood at a crossroads of these routes and brought wealth to the Nabateans, a semi nomadic Arabian tribe that ran many of the trans Arabia routes. 

Food availability allowed populations to grow, while urbanization increased the mortality from disease.  The Black death  700y ago (1300's) killed around 50% of city dwellers. 

The competition between European powers changed to empire building through exploration. Discovery by Columbus, Magellan, and  Drake followed by invasions by Cortes, Cartier, the Pilgrims and others led to slavery and mass genocide of native populations in the name of commerce and religious conversion. The voyages of discovery and empire building by the Europeans  naval powers in the 500-600y ago (1400-1500's), brought new contacts with the indigenous hunter gatherers and resulted in genocide of 90% of the indigenous people from diseases that they had no immunity for. 

The scientific revolution changed the trajectory of life on earth through modern medicine and nutrition.

 

 

 

Pre industrial revolution the population increased at 0.15% a year, post it has increased to 1.7% a year equivalent to 3 children per couple per generation. This has lead to  the massive consumption of land for food and fossil fuels. 

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