Evolution: Part One of Two
I'm Daniel, the Editor of Junior Skeptic. Welcome to Part One of our two-part look at the exhilarating subject of evolution, and Darwin's idea of natural selection, which explains how evolution happens.
A lot of people have questions about evolution. The history of life is very complicated, but as we'll see, Darwin's discovery was almost unbelievably simple. To some, the idea that the entire tapestry of life could be woven by simple, easy-to-understand natural processes seems too good to be true.
Chances are you've wondered about some of this stuff yourself. How did life begin? How did it develop? Why do bats and pterodactyls look so similar, even though one is a living mammal and the other an extinct reptile? Why do tigers and whales look so different, even though they're both mammals?
And why are people still arguing about evolution, more than 150 years after Darwin revealed his discovery? Find out.
Let's Find out.
THE BIG QUESTIONS
For as long as humans have had language for storytelling and minds to wonder, they've had big questions about the world around them:
Was the world always here, or was there a time before there was a world? Were the world and living creatures always just like they are now, or has there been change over time?
Human civilizations came up with all sorts of answers to these puzzles. Some people (the Cherokees) figured there was a time before there was solid ground, until the original water beetle brought mud from the bottom of the ocean as the seed for the land. Some people thought the world was born from primordial chaos (the Greeks), or that it was made from the shells of ducks eggs (the ancient people of Finland). Others thought the world was made from the body of a dragon (the Babylonians), or even made from vomit of a giant (the Boshongo people of Africa). Or, others thought that it was born from the mingling of fire and ice (the Norse). Meanwhile, still others thought the world was created out of nothing whatsoever--or that it had always been here.
A lot of different ideas (a whole lot!) but very few answers ...
AN ANCIENT ANCIENT TIME
Ancient Greece strikes us as an almost imaginary time: an age of legends where history and story merged; where mortals had adventures with gods and mythological creatures. Yet, for the ancient Greeks, "ancient" Greece was just everyday reality. They were (obviously) just people, who had jobs and got sunburns and stubbed their toes and chatted with friends, all just the same as today. "And, just as we imagine ancient Greece as a heroic age, the ancient Greeks imagined that their distant ancestors were "heroes"--literally "larger than life" giant humans who lived when the world was young and reality mingled with magic. They had good reason for supposing people were giants in the distant past--they sometimes found their enormous bones!
Most fossils are found at places like seaside cliffs or riverbanks, where weather and water carve away rocks and reveal the fossils within. In ancient Greece, erosion sometimes revealed the fossil bones of mammoths and other species of prehistoric elephants. The Greeks mistook the nose opening in the fossil skulls of elephants for an eyesocket, and assumed they were looking at a one-eyed cyclops, and thought that the bones of giant cave bears were ancient heroes.
Greek mythology taught people that the world had been created in the ancient past, and that it had changed a great deal since then. Giant fossil bones confirmed these ideas: men and animals were very different in the distant past.
Philosophers had little faith in mythology, but it was clear to them that the natural world changed over time. Philosophers worked out, correctly, that fossils were mineralized remains of living creatures. They also realized fossils were embedded within rocks that had once been soft mud--that fossil-bearing rocks were basically fossilized mud. …