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C O U R S E 
A Brief History of Humankind
Dr. Yuval Noah Harari, The Hebrew University of Jerusalem
C O U R S E   L E C T U R E 
45,000 Years Ago: Human's Decimation of Australia's Large Mammals
Notes taken on September 9, 2013 by Edward Tanguay
ways in which humans related to other animals and plants and became the most important factor in the ecology of planet earth long before the agricultural revolution
until the rise of Homo sapiens, all other human species lived on the Afroasian land mass
no other human species has the ability to cross the open sea or large expanses
plants evolved in each of these places in each of the areas of the earth, thus planet earth was divided into separate ecosystems
Homo sapiens were the ones who began to form connections between these ecosystems shortly after the cognitive revolution
45,000 years ago in Australia
how did Homo sapiens cross over from Indonesia to Australia
some stretches of open sea of 100 or 150 kilometers wide
how did they manage to adapt themselves to the conditions of Australia, since knowing the world or animals and plants is critical to survive
if you knew how to hunt elephants in Asia, you may not know how to hunt kangaroos
theory: 45,000 years ago, humans in Indonesia built the first seafaring cultures and settled Australia
if true, this was an unprecedented in human history since just 30,000 years earlier pre-cognitive humans were living in Africa making simple tools
the journey of the first Homo sapiens from the Eurasia land mass to Australia is one of the most important events in human history, at least as important as the journey of Christopher Columbus to America or the journey of the Apollo 11 expedition to the moon. The journey of the first sapiens to Australia was the first time that any human species managed to leave the Afro Asian ecological system and to settle a new ecological system. Of greater importance than the actual crossing was what the human pioneers in Australia began to do when they arrived in this new world. The moment the first Homo sapiens set foot on the beach of Australia was the moment when humans climbed from the middle to the top rung of the food chain and became the deadliest species of animal in the annals of plant earth. Up until their landing in Australia, humans showed a remarkable ability to adapt themselves to different environments but their impact on the environment was negligible. They had migrated from deserts into fertile and coastal areas and into Siberian winter landscapes, but they had done so without really changing their habitat, they changed the way they behaved, but they did not change the environment. Humans who landed in Australia not only began to change their own behavior in order to adapt, but they began to change the Australian ecosystem. Australia of 50,000 years ago was very different than the Australia that we know today, full of large and strange creatures, including the giant Kangaroo which reached heights of 10 feet tall, the genyornis, a flightless bird, the megalania, a large lizard, and the marsupial lion, the largest meat-eating mammal known to exist in Australia related not to the lion but to kangaroos and wombats. Within a few thousands years of the arrival of the first humans in Australia around 50,000 years ago, almost all of these giant animals became extinct. 50,000 years ago there were 24 Australian animal species that weighed an average of more than 50 kilograms. Within 10,000 years, 23 of these 24 species became extinct. The only large animal in Australia that managed to survive the arrival of sapiens is the red kangaroo
a large number of smaller species also disappeared
ecosystems were completely changed and rearranged
if you look at the annals of Australian history, you see continuity for millions of years, and then a big break, a catastrophe 45,000 years ago
how did this mass destruction and upheaval of animal species and ecosystems happen
theory #1: climate change
theory #2: humans caused these changes
how did a relatively small number of hunter-gatherers bring about the ecological disaster in Australia 45,000 years ago, by using only technology of the Stone Age, not with guns, rockets and tanks, but with spear points and other tools?
reason #1: slow breeding
large animals, who were the primary victims, breed slowly
number of offspring is low
there are long breaks between pregnancies
contrast rabbits which breed frequently, e.g. litters of up to seven about 4 or 5 times a year
even if humans killed only one Diprotodon a month, it would be enough to outnumber the rate of birth and drive them to extinction
reason #2: the element of surprise
animals in Africa and Asia gradually evolved to be afraid of humans
in contrast, the animals in Australia had no evolutionary time to develop a healthy fear of humans, and taken at sight value, humans don't come cross as particularly dangerous, they were smaller than most of these larger animals, were comparatively slow, and did not have big teeth or sharp nails, so the giant koalas would take a look at humans, see that they are different but not particularly dangerous looking, and go back to munching leaves
reason #3: fire agriculture
using fire to reshape the environment to fit your needs better
when they landed 50,000 years ago, they were already experts in using fire
they burned down vast areas of thickets and dense forest in which they had difficult moving and hunting
open grasslands attracted more easily hunted game
up to 45,000 years go, eucalyptus tree were quite rare in Australia, but became more numerous as humans began to burn down forests
they are more resistant to fire than most other trees and tended to survive in larger numbers after forests lands were burned
absence of great rivers or mountain chains meant that there were no geographic barriers to check the spread of fires
reason #4: climate change
destabilized ecological system and made it particularly vulnerable
it could have recovered from these changes as it had many times previously
e.g. the Diprotodon existed in Australia for millions of years and during these millions of years there were numerous climate changes but it existed through them each time
the combination of the weak ecological system and human's new threat made it extremely difficult for many types of animals to find a way to survive
lacking further evidence, it's hard to decide which one of these factors was the most important
yet we have enough evidence to be quite convinced that if humans had never reached Australia, the climate change by itself would not have been enough to cause such a mass extinction event
the extinction of Australia's large animals was the first significant mark that our species Homo sapiens left on planet earth
"These wandering bands of story-telling sapiens turned out to be the most destructive force that the animal kingdom every produced."
"The extinction of Australia's large animals was the first significant mark that Homo sapiens left on planet earth."