The Four Forces of Nature

1. Gravity. This is the weakest of the four, but it is a long-range force and acts on everything in the universe as an attraction. This means that for large bodies the gravitational forces all add up and can dominate over all other forces. 2. Electromagnetism. This is also long-range and is much stronger than gravity, but it acts only on particles with an electric charge. being repulsive between charges of the same sign and attractive between charges of the opposite sign. This means the ele...

 A lot happens in 100k Years of Evolution

Inside my skull is a brain that was designed to exploit the conditions of an African savanna between 3 million and 100,000 years ago. When my ancestors moved into Europe (I am a white European by descent) about 100,000 years ago, they quickly evolved a set of physiological features to suit the sunless climate of northern latitudes: pale skin to prevent rickets, male beards, and a circulation relatively resistant to frostbite. But little else changed: Skull size, body proportions, and teeth ar...