BY DENICE PEREZ

The Journey of History

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Spencer Wells has concluded that all humans alive today are came from a single man who lived in Africa around 60,000 years ago.

Every piece of DNA in our bodies can be traced back to an African source. The Y-chromosome traces back to eastern or southern Africa, around 60,000 years ago.

The Journey of Man

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Anthropologists agree that human culture, imagination and ingenuity suddenly flowered around 45,000 years ago.

The evidence ranges from fantastic cave paintings

Elaborate graves to the first fishing equipment and sturdy huts

Continued

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The Journey of Man

"As often happens in science," he said,

"technology has opened up a field to new ways of

answering old questions—often providing startling

answers."

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The Catastrophe

535 AD the worlds climate changed drastically

Rain poured redDarknessIce Cold for two yearsClouds enveloped the

Earth

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The Catastrophe

Tree ringsKrakatoa, volcano

believed to have erupted.

Largest volcanic eruption of the last half million years

The atomic bomb

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Catastrophe

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The Colombian Exchange

The plants and animals of the tropical continents of Africa and South America differed sharply from each other and from those in any other parts of the world

One of geographical divergence announced by the simple fact of the separateness of the continents.

A large tome would not provide enough space to list the plant, animal, and micro-organism exchanges

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The Colombian Exchange

For tens of millions of years the dominant pattern of biological evolution on this planet has been one of geographical divergence dictated by the simple fact of the separateness of the continents.

Even where climates have been similar, as in the Amazon and Congo basins, organisms have tended to get more different rather than more alike because they had little or no contact with each other.

The Amazon has jaguars, the Congo leopards.

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The Colombian Exchange

"We are world-travelers, trekkers of deserts and crossers of oceans. . . . Humans have in the very

last tick of time reversed the ancient trend of geographical biodiversification."