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Sharpen Your General Knowledge
Shamim Ansary:
When did humans appear on Earth?
This is not an easy question to answer. Debates rage over which fossils can be called truly hominoid (humanlike), or hominid (human).
The development of human characteristics took place over millions of years. The earliest primate (an order of mammals that includes humans, apes, and monkeys), no bigger than a rat, appeared 60 million years ago.
About 10 million years ago, the Ramapithecus showed remarkable hominoid attributes. But there is no further evidence until 6 million years later.
The first generally accepted hominoid is called Australopithecus, and some believe they are actually the most primitive of the human lineage.
Homo habilis, dating back at least 2 million years in modern-day Africa, is undisputedly human. Less than a half-million years later, Homo erectus lived in Africa as well as in Asia and Europe.
A fossil skull fragment discovered in England is the oldest known example of modern-day humans: a 300,000-year-old Homo sapien.
Shamim Ansary:
Did Dinosaurs and Humans Ever Coexist On Earth?
Dinosaurs and humans did not coexist on earth.
Dinosaurs first appeared in the Triassic period, about 220 million years ago, and disappeared at the end of the Cretaceous period, about 65 million years ago.
Modern humans (Homo sapiens) appeared only about 25,000 years ago.
Movies that show humans and dinosaurs existing together are only Hollywood fantasies.
Shamim Ansary:
What stops Earth from crashing into the Sun if the Sun’s gravitational force is so strong?
When Earth formed, it created its own gravitational force, enhanced by spinning, or rotating.
This kept the collected material together. Without the Sun’s gravity, Earth would go spinning off into space, but without Earth’s own gravity in conjunction with the gravitational force from other planets, it would be drawn into the Sun.
So, while the Sun pulls Earth toward it, the cumulative gravity of Earth and the other planets keeps it in its orbit around the Sun. Think of it as a multiple tug-of-war.
Shamim Ansary:
How do we know how dinosaurs lived when all we have are fossils?
It is amazing how much can be deciphered from a fossil.
For instance, scientists can often tell what dinosaurs ate by studying their fossil remains. If a fossil of a dinosaur shows that it had sharp teeth and claws, scientists can figure that it was a meat-eating dinosaur.
Meat-eating dinosaurs were bipedal, which allowed them to run swiftly after prey. If a fossil seems to show that the living creature walked on two legs, that might also indicate that it ate other animals.
Plant-eaters had teeth suitable for grinding vegetation. Many were quadrupeds, meaning they walked on four legs. Fossils with these characteristics are of plant-eating dinosaurs.
The depth of fossilized footprints can be used to calculate the weight of dinosaurs. Some of the most impressive fossils are those of dinosaur tracks. Footprints also confirm that many dinosaurs traveled in groups, with younger dinosaurs in the middle of the herd where they would be protected.
These were herbivorous dinosaurs, their social structure resembling herd animals (such as water buffalo) of today.
Shamim Ansary:
Why Is Africa Called the “Birthplace of the Human Raceâ€
Africa is called the birthplace of the human race because scientists have found fossilized bones of human ancestors in eastern and southern Africa that are the oldest of any in the world.
They believe that humans gradually moved out of Africa to populate the rest of the world.
The earliest Homo sapiens, or modern human, found in Ethiopia can be dated back to about 200,000 years ago.
Most scientists believe that the human species originated from the African continent.
Fossil remains of several species of early apelike humans believed to have evolved into modern man, such as Australopithecus afarensis from about 3 million years B.C. have been discovered.
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