Andrew Knoll is Harvard Fisher Research Professor of Natural History and author of the recent popular science book “A Brief History of Earth: Four Billion Years in Eight Chapters” (The Harvard Gazette)
How much do you know about the Earth? The basics are easy, but there is much about the planet that most people have not heard. In order to create awareness about the importance of protecting natural resources and within the framework of Earth day which was held on April 22, The Harvard Gazette meeting half a dozen lesser known facts with the help of Andrew Knoll, Professor of Historia Natural Fisher Research de Harvard and author of the recent popular science book A Brief History of Earth: Four Billion Years in Eight Chapters.

1. “Earth is a planet that records its own history”

“Layered in the rocks of the planet there are physical, chemical and biological inscriptions that narrate what the world was like at different points in Earth’s history”, said Knollciting the Grand Canyon as an excellent example. For the expert, although it is spectacular to see, it is also it is a giant library. “Each layer of rock has its own story. The rocks at the bottom tell stories of about 800 million years ago, when there was oxygen in the atmosphere but probably not enough to oxygenate the ocean. Above these rocks there are others from 500 million years ago that tell stories about the appearance of terrestrial organisms”, added the expert.

2. “Animals only appear 85% of the way through Earth’s history”

“All the animals, from humans to dinosaurs and trilobites, were late to the party,” joked the specialist. The reason, he said, is that the history of life on Earth is largely microbial. For billions of years, the bacteria and other single-celled organisms were the only life form on earth.

In fact, the time interval from the first dinosaurs to today represents only about 5% of the history of life on Earth. “These microscopic life forms not only dominate the planet, but also we should thank them for transforming the planet. For example, cyanobacteria, which ingest carbon dioxide and release oxygen. A few billion years ago, they began to produce more oxygen than the planet’s natural processes consumed, hence oxygen began to accumulate in the atmosphere, paving the way to make it habitable for the animals,” he explained. Knoll.

For billions of years, bacteria and other single-celled organisms were the only life on Earth (REUTERS)

3. “All possibilities of life, air, oceans and continents were put in position when the Earth was created more than 4,500 million years ago”

Knoll pointed out that Mars and the other planets probably never were like Earth because they didn’t have the right pieces to begin with.

Earth, on the other hand, when our solar system formed, received all the ingredients it would need to transform into a great “blue paradise”.

4. “For almost the first half of our planet’s history, the air and oceans were essentially oxygen-free”

modern life is bathed in an oxygen-rich atmosphere. leads to think that life cannot exist without oxygen, but that line of thinking is incorrect, the paleontologist assured.who noted: “This goes back to microbes: there were many on the early Earth that lived with little or no oxygen for billions of years.”

“Since the 1950s, the amount of carbon dioxide in the atmosphere has increased by almost 30%. This has warmed the planet, made seawater more acidic (affecting many species), and decreased oxygen in deep-sea environments.” (AFP)

5. “The modern Earth is not necessarily representative of our planet as it has existed throughout time”

The earth is a dynamic system and is changing all the time, according to Knoll. The change, however, is geologically measured over billions or millions of years.

“Five hundred million years ago, during the Cambrian period, for example, there was supercontinenteswith North America and Northern Europe side by side and all the southern continents rolled into one. We live in a particular moment in the history of the Earth which is the culmination of all that came before. But here’s the trick: What will the planet be like in 500 million years? Would we recognize it? the expert wondered.

6. “In the history of the Earth, high rates of environmental change commonly coincide with high rates of extinction”

“this clearly not a good omen. Hoy, our planet is changing at a rate rarely seen in the geological record”, he pointed. And he concluded: “Since the 1950s, the amount of carbon dioxide in the atmosphere has increased by almost 30%. This it has warmed the planet, made seawater more acidic (affecting many species), and decreased oxygen in deep-sea environments. Consider this: 252 million years ago, massive volcanism triggered a similarly strong and rapid environmental change that wiped out most animal species on Earth.”

For Knoll, it is up to us whether the 21st century will also end in mass extinction.

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