Climbing the tree of life
It's fun to explore the tree of life at http://www.onezoom.org
It only has amphibians, reptiles, birds and mammals - and only those that are still alive today. But still, it's fun to keep zooming in and see how your favorites are related - along with many others!
One nice feature is that you can see when branches happened. And at first it seemed shocking to how new
so many mammals branches are.
To set the stage, remember that an asteroid hit the Earth and a lot of dinosaurs went extinct 65 million years ago. About 24 million years ago, the Earth cooled enough that Antarctica becomes covered with ice. This cooling trend also created the great grasslands of the world! Humans split off from other apes about 5 million years ago: we are creatures of the grasslands. The glacial cycles began just 2.5 million years ago... and Homo erectus
is first known to have tamed fire 1.4 million years ago.
Now compare this: the cats branched off from hyenas about 40 million years ago. Cheetahs branched off from other cats only 17 million years ago. That makes sense: we couldn't have cheetahs without grasslands! But bobcats and lynxes branched off only 11 million years ago... and tigers just 6 million years ago!
So tigers are almost as new as us! And the modern lion, Panthera leo
, is even newer. It showed up just 1 million years old, after we tamed fire
This changed my views a bit: I tended to think of humanity as the "new kid on the block". And okay, it's true that Homo sapiens
is just 250,000 years old. But we had relatives making stone tools and fires for a lot longer!
Here's another fact that forced me to straighten out my mental chronology: the University of Oxford is older than the Aztec empire! Teaching started in Oxford as early as 1096, and the University was officially founded in 1249. On the other hand, we can say the Aztec empire officially started with the founding in Tenochtitlán in 1325.
And that, in turn, might explain why cell phones don't work very well here in Oxford. But I digress. Check out the tree of life, here:http://www.onezoom.org/