Dunno about that. Armor would have been far more useful earlier, when we were jabbing each other with sharp sticks. Yet sharp sticks still work. And steel manmade armor, presumably harder than anything biological, was very cumbersome and ineffective against even the crudest firearms.

 

Actually, biological armor can be remarkably effective against firearms - crocodiles are notorious for deflecting small-arms fire via their dorsal osteoderms (plates of bone under the large back scales). Remember, bone is a composite material with exceptional strength, resistance to fracture, and durability (not to mention healing).

 

However, biological armor is also very heavy, limits flexibility, and does not seem to be "easy" to evolve in lineages without scales.

Wouldn't the abundance of food available remove selection pressures against putting less energy into growth?

Well, it would reduce them - reduced growth can also be due to other factors such as the need to move fast and fit into small spaces, or simply lack of necessity (after all, how big does a male spider really have to be if he's just going to mate and get eaten?)

Hi i am new to this Forum, But I have always believed that if mankind is to survive

then the population must be reduced in size bye stature, if mans size was reduced by 2/3

then the world size would increased 2/3. We have the Technology to go forward and remain in Status Que