Human Self-Domestication

...the hypothesis of human self-domestication has recently been revived as a possible explanation of changes of human physical traits since the late Pleistocene. These changes include the reduction of body size and decrease in skeletal robusticity, modifications in cranial and dental features including reduction in cranial capacity, shortening of the facial region of the skull and maleruption of teeth, and reduction in sexual dimorphism. In contrast to earlier biological writings, other domes...

 Back-of-the-Envelope Calculation

It was from Kuiper that I first got a feeling for what is called a back-of-the-envelope calculation: a possible explanation to a problem occurs to you, you pull out an old envelope, appeal to your knowledge of fundamental physics, scribble a few approximate equations on the envelope, substitute in likely numerical values, and see if your answer comes anywhere near explaining your problem. If not, you look for a different explanation. It cut through nonsense like a knife through butter.