Newtonian Metaphors For Darwinian Processes

It's the secret thing that connects the wrongness of economics and the wrongness of the left/right spectrum model of politics: using Newtonian metaphors for Darwinian processes. 

But what does that mean?

Ed Yong, in the Atlantic, on cancer cells evolving: 

In the classical view of cancer, a cell picks up mutations until it shakes off the checks and balances that restrain its growth, allowing it to divide uncontrollably and turn into a tumor. This linear process is a macabre version of that famous image where a chimp walks to the right and gradually morphs into a human hunter. And both visuals are wrong.