Why dodo birds can't fly

In 1598 Dutch sailors first discovered the dodo bird on the island of Mauritius in the Indian Ocean.  The bird was so unusual that it attracted a lot of attention; it was very large (3-4 feet tall and as heavy as 50 lbs) and had such small wings that it was unable to fly.  The sailors apparently weren't impressed by it's disposition, because  the word "dodo" comes from the Dutch word "dodoor" which means "sluggard."

The dodo's bizarre features were a result of an evolutionary process called island gigantism, where animals on an island grow much larger than their mainland counterparts.  The reason is that islands usually lack large predators, so in their absence the prey can grow larger and larger.  The dodo also probably lost the ability to fly because without any clear threat to evade, wings became unnecessary.

The Dutch also noticed that the birds had no fear of humans.  The sailors could walk right up to them and the dodo would just stand there with a dumb look on it's face.  The birds had never been introduced to humans or any other large predator, so they had no reason to see them as a threat.  Basically, life had been easy on this quiet, little island in the middle of the Indian Ocean, and over thousands of years the dodo grew fat, slow, and flightless.

As you can imagine, they were an easy target for hungry sailors who had been too long at sea.  The sailors didn't even like taste of the meat, but they were big and simple to hunt.  By 1681, 83 years after their discovery, they were extinct.

The dodo's years of easy life had done them no favors; they were weak and vulnerable, and all it took was one new predator to completely wipe them out.  We are like the dodos, because when life is easy and carefree, we don't benefit.  What makes us strong is challenge, adversity, struggle, pain.  This is one reason I love endurance sports, because in addition to being fun, they make you stronger, faster, more patient, more wise.  They make you ready for the next big thing coming, unlike our long extinct friend, the dodo.