1-Did our ancestors work their stabilizers to this degree? And if so how? And they worked them through every day activities, like carrying things and walking/running then
Yes, they would have worked them through every day activities like carrying things or any of the manual labour they did.
2-Wouldn't this mean we work our stabilizers in the same fashion, while moving through the natural world of the modern jungle, and therefor we do not need to overly recruit them at the gym?
In our day to day life we are not lifting things that are as heavy as the things we lift in the gym. You would only strengthen your stabilisers enough to carry shopping or open doors etc.
Gym machines artificially isolate muscles so that only that muscle is worked. You are unlikely to injure yourself using the machine because the whole point of the machine is it does the job of your stabilisers for you, effectively making your muscles work in only one direction of movement. However, it makes you prone to injury because you're increasing the strength of a muscle without the surrounding muscles and supporting stabilisers also being strengthened. This means when you later come to lift something you are prone to injury because the stabilisers aren't able to do the job they're supposed to. Your big strong muscle might be able to contract with enough strength to lift the thing, but it's missing the support in rotational directions that help you to balance the thing you're lifting and support the arm correctly. Injury becomes likely, particularly if you also have a degree of hypermobility in your joints.
When you lift with free weights and compound exercises, you engage the whole muscle groups and stabilisers in the way your body intended them to be used, so injury is less likely provided that you start with a weight you can manage comfortably and build up. The whole interconnected system gets stronger as a group, instead of just one muscle.
Why would you want to use machines, tho? Because they're easier?
For me it was because they're easier and less prone to embarrassment. The machines are easy to use, often with little diagrams on the machine so you don't need instruction from a trainer or have to worry about people looking at you doing it wrong the first few times. You can also lift higher weights and feel like you're making bigger progress. Of course, one day it will catch up to you, and that happened to me. I was out of action for nearly 6 months due to a rotator cuff injury. I strongly encourage people to use free weights and compound lifts, with machines only in moderation. People tried to warn me about machines but I ignored them. They're useful for increasing strength, but don't use them exclusively. It's not how our bodies were designed to work.
Edited by Debaser, 04 May 2014 - 07:13 PM.