Our world sure is amazing. The Earth came into existence a long time ago. I know I’ve mentioned it before, but Earth is approximately 4.54 billion years old. How is this true?
Well. Scientists determined this age through radiometric dating of meteorites. It is very accurate. Here is how it goes.
Some rocks contain tiny amounts of special atoms called radioactive atoms. These atoms are naturally unstable. Over time, they slowly change. The change into different, stable atoms. Scientists call the original atoms the parent atoms and the new ones the daughter atoms.
Here is the important part.
They always change at the same speed. AND. Nothing can make them speed up or slow down. So scientists simply measure how much of the parent atom is left. Then they measure how much of the daughter atom has formed.
To understand this. I have an example.
Imagine a magic bag with 100 marbles.
Every 10 years:
Half of the blue marbles magically turn into red marbles.
After 10 years:
50 blue
50 red
After 20 years:
25 blue
75 red
After 30 years:
About 12 blue
88 red
If you found the bag and counted only 25 BLUE marbles left, you’d know about 20 years had passed.
And there it is. Radioactive atoms behave in almost exactly this way.
So the scientists test our rocks and figure out how old the Earth is by that good old marble method.
Anyway, those meteorites they analyzed were formed at the same time as the rest of the solar system. They also tested some of the oldest known rocks on Earth and the Moon.
Why am I telling you all of this?
Because I just found out that sharks have existed longer than trees on this good Earth.
The first sharks appeared in Earth’s oceans about 450 million years ago, during the Ordovician Period. At that time, life was almost entirely in the sea. There were no forests, no birds, no mammals, no dinosaurs, no flowers. Nadda.
The first true trees didn’t appear until about 385 million years ago, during the Devonian Period. That means sharks had already been swimming in the oceans for roughly 65 million years before the first forests took root.
Sharks are older than trees.
Sharks are older than the rings of Saturn.
Sharks are older than the Atlantic Ocean.
Sharks are much older than dinosaurs.
Sharks have several advantages that have helped them endure. For one thing, they are efficient predators. Their skeletons are made of lightweight cartilage rather than bone. And. They evolved into hundreds of different species occupying many ecological niches.
During their long history, sharks have lived through five mass extinctions.
People don’t like sharks. Most people. I think they are incredibly cool. But I sure don’t ever want to meet one.
Except for Bruce. Maybe I would want to meet Bruce.
From Finding Nemo. “Hello. Name’s Bruce.”
I wonder how old he is? He moves pretty well, whatever his age might be.
Just remember today. If you don’t feel like moving, remember: Age is just a number.
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“The Earth has music for those who listen.” — George Santayana
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“Look deep into nature, and then you will understand everything better.” — Albert Einstein
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“Time is the wisest counselor of all.” — Pericles
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“Life finds a way.” — Michael Crichton
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