When the climate turns against you, efficiency is the one trait that helps you survive with limited resources. The big heavy dinos didn't have that. Nor did th

When the climate turns against you, efficiency is the one trait that helps you survive with limited resources. The big heavy dinos didn't have that. Nor did the Neanderthals. The problem with efficiency is that when you have more than enough resources, you get obese very quickly. Like chickens and modern humans. :)