Evolution

How the Evolution of Man Changed Planet Earth



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"How the Evolution of Man Changed Planet Earth"
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When the first hominids made their appearance on the continent of Africa four or five million years ago, they were part of the food chain, just like any other animal. They ate plants and were eaten by large predators. Two or three million years later, Homo habilis appeared on the scene, with a taste for meat. They became predators as well as prey. The "hunting hypothesis" of human evolution speculates that those early ancestors developed both cognitive and social skills through the practice of communal hunting.

The next generation, homo erectus, was a tool-maker and may have been the first species to use and control fire. Once this hairless ape had the means to keep warm, he could survive in colder climates, and migrated to Europe and Asia. Animals had to watch out for a new predator, whose camp fires scarred the earth and poured carbon emissions into the air. Those early humans were probably responsible for a few forest fires as well.

Approximately 300,000 to 400,000 years ago, the transition of from Homo erectus to Homo sapiens occurred. "Sapiens" is the Latin word for "wise, shrewd, sensible, and knowledgeable". The scientists who named him were probably thinking of his hunting and tool-making skills. The tough and adaptable Neanderthal version appeared, survived the Ice Age, and disappeared. Finally, homo sapiens sapiens, our "doubly smart" direct ancestors, came on the scene around 130,000, and started making major changes in the planet. They learned how to use metal and wood for tools and jewelry, drew graffiti on the rocks, and started tearing up the earth for cultivation. They domesticated animals, and learned the science of selective breeding. Not only were they changing the face of the earth, but also the characteristics of its flora and fauna.

Maybe "Homo sapiens sapiens" should be translated as "too smart for his own good." The species survived, thrived, made love and war, and found new ways to change its environment and remove itself from the food chain. A thousand years before the Christian era, the estimated human population was 50 million. At the beginning of the next millennium, the number had increased to 200 million. In the year 1,000, there were 310 million. Many expected to world to end that year, but it didn't. In 1900, the number of humans had leaped to over 1.6 billion. A hundred years later, the tally was an unbelievable 6,070,581,000. If you want to know the current human population of our planet, visit the World Population Clock at http://math.berkeley.edu/~galen/popclk.html. Don't blink! New people are being added to our population every second.

The results of this phenomenal population increase are bemoaned daily. Humans have damaged or destroyed much of their habitat, sometimes out of ignorance and greed, and sometimes out of the simple desire to survive. Science keeps looking for new ways to keep us alive, and we keep fighting for more elbow room, more control, more pleasure, more freedom from human limitations.

Erosion from agriculture, dams, road-building and urban development have made humans the dominant force behind changes in sedimentation. Human activity has pushed carbon dioxide levels one-third higher than 200 years ago, higher than they have been in the past 900,000 years. The oceans are noticeably more acidic, and the water levels are rising. Native plant and animal species are being replaced by those favoured by humans. Increasingly, man is tampering with DNA, creating instant mutations.

Some species have been forced into extinction, and others have been forced to evolve into tougher, more adaptable versions who may some day get the better of us. Nature, who was once our benevolent mother who gave us everything, may become our deadly enemy. An increasing number of people are seeing humans as an infestation of the planet. When a new superbug threatens us, or a hurricane flattens human habitations, they nod wisely. "Gaia is fighting back."

In February 2008, David Suzuki announced:
"Well, it seems we've finally done it. Humanity has finally made its mark - our own little place in history."

Since the last ice age 10,000 to 12,000 years ago, we have been living in the Holocene epoch. Now, scientists suggest that we have entered a new epoch, in which almost every natural process bears a human signature.

"Changing epochs is not like changing your socks," Suzuki wrote. "In scientific terms, this is a big deal. Epochs tend to be delineated by periods of upheaval. Think ice ages and mass extinctions. When Nobel-prize winning chemist Dr. Paul Krutzen brought up the idea back in 2000 and again in 2002, it was still considered pretty radical and somewhat impetuous for our little species to have its own epoch.

"But a team of scientists writing in a new paper in the journal GSA Today, published by the Geological Society of America, now argues that it's becoming increasingly difficult to deny humanity's growing influence on a planetary scale. In their paper, they examine the case for change and conclude that it's time to accept the obvious - we are in the Anthropocene."

Will the name stick? Stay tuned. We'll know the answer in a few thousand years.

For the full text of Suzuki's article, surf to:
http://www.davidsuzuki.org/about_us/Dr_David_Suzuki/Article_Archives/weekly02150801.asp

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