Why is Wi-Fi free at cheap hotels, but $14 a night at expensive ones?

There's one thing that shows up on all of the lists of what makes us human: language. Our ability to share our thoughts and complex information with others far surpasses all the barks, squeaks and growls of our animal friends.

Walking is a skill that took millions of years for us to develop... If you wanted to design a robot that could walk as well as a person, this would be fantastically complicated software. It would have to be doing billions of calculations with every step.

Today, there are over 7,000 languages spoken throughout the world. They may sound different, but in every case, they're drawing on the same regions of the brain. If you had told me that stone-tool-making had something to do with our ability to speak, I would have said you've got rocks in your head, but the latest studies indicate that once Homo erectus got creative with stone, our brains were on the way to inventing the most powerful tool of all: language.

One day robots may even babysit our kids, a job that has always required a human touch.

Just as words in their proper places form sentences, each individual strike must be done in the proper order to get the desired result: a flat stone blade.

If you continue to improve a product enough, you'll eventually ruin it.