How Gravity Affects Us On Earth
There’s a reason we’re the size we are. And it has to do with the earth’s gravity. Every creature has to move, and to do that he has to use energy to overcome the force of gravity.
The anatomical structure of an animal depends primarily on 3 things: being able to get around; consuming food for energy; defending itself. The bigger the body, the more difficult it is to get around and the more it must eat. But the bigger the body, the better it is able to capture food and defend itself. There’s always the trade off.
The dinosaurs grew to enormous size because they had easy access to sufficient nutrition without having to move very far. In the wake of the dinosaurs’ demise 65 million years ago, smaller, more agile animals evolved. Eventually that evolution led to homo sapiens—us.
The dinosaurs are not the largest animal ever to have lived. That distinction belongs to the blue whale, which survives today. Whales can grow to large size without having to worry about gravity because they are immersed in water, where they are virtually weightless. They can move very fast—and they need to in order to feed their enormous bodies.