The document discusses several topics related to history: 1) How genetics has allowed scientists to trace human ancestry back to "Eurasian Adam" who lived in Africa between 31,000-79,000 years ago. 2) The effects of the 536 CE eruption of Krakatoa volcano including global cooling, destroyed crops, spread of diseases, and weakening of empires like Rome and southern China. 3) The major cultural and physical exchanges that occurred between Europeans and Native Americans following Columbus' voyage, such as the introduction of new crops, livestock, and deadly diseases which decimated Native American populations.

1. Tommy Beasley 796352 History 30 Online Mr. Arguello What is History?

2. The secrets about our ancestors are hidden in our genetic code. Spencer Wells explains how genetics have made it possible to create a family tree for the whole of humanity. We now know where our ancestors have lived, who they fought, and influenced. The Journey of Man

3. We learned how the male Y-chromosome has been used to trace the stretch of humanity from Africa to Eurasia. The film has taught us that the Neanderthals are not our ancestors. It has also explained to us that the entire genetic diversity of Native Americans can be accounted for, by just ten individuals. The Journey of Man

4. After researching males genetics, Wells finds the key ingredient in a man he named, "Eurasian Adam," who lived in Africa between 31,000 and 79,000 years ago. The Journey of Man

5. In the film Catastrophe, David Keys traces the effects of an explosion in Krakatoa in 536. The volcano caused cooling throughout the planet, and major political changes in areas such as Western Europe China, and the Americas. Catastrophe

6. The volcanic cloud blocked sunlight everywhere and destroyed crops. It spread many diseases (especially rat-borne plague), killed much of the human race and left social and political institutions throughout the world vulnerable and displaced. Catastrophe

7. The spreading diseases weekend empires and left them vulnerable. The Roman lost half its territory following the catastrophe. During the same time, the ancient southern Chinese state surrendered to invaders from the north. Enemies noticed a weakness in the system and gave everything they had to take over these defenseless empires. Catastrophe

8. In the Columbian Exchange, explorers created contact between Europe and the Americas. The interaction with Native Americans led to large culture changes. Their was also exchanging of important physical elements. The Columbian Exchange

9. During the Exchange, Europeans brought horses, pigs, cattle and sheep. They also brought cash crops to the Americas such as; sugar, rice, wheat, coffee, bananas and grapes. The Columbian Exchange

10. Many deadly diseases were also transferred during the exchange. Smallpox, measles and whooping cough were some of the most common diseases exchanged. The Native Americans had no resistance to the diseases so they were deeply affected and lost a large amount of their population. The Columbian Exchange