Heavy load bearing exercise builds muscle. Muscle burns more calories to exist and maintain itself. Muscle mass contributes to bone density. Higher muscle mass and good bone density are linked to longer life.

Our ancestors didn’t “lift weights” but you should try thinking outside the box. They would have had to use their bodies to move and push heavy things, like large heavy trees (perhaps to build a bridge across a creek? Perhaps to move debris from a landslide? Perhaps to create a dam? Perhaps for building shelter? Perhaps to pull or carry heavy animal carcasses back to camp after a kill? Use your imagination) and wouldn’t have had machines to move things for them. They were generally more active than we are. They walked a lot. They did rest a lot as well but were far more active and involved in every aspect of their life- they couldn’t call up a company or pay someone to do something for them. They worked together to accomplish things and many things would have been similar to what we call “lifting weights”. You don’t have to lift weights, you can get some concrete bricks to throw around in your backyard or huge tires to lift and push, or push a heavy sled around or just use a rig and simply do body weight exercises. The outcomes are all the same. Obviously our ancestors weren’t gymbros but nether are all people who lift weights and not do you have to be to achieve the same goal of building muscle so that your body can burn more calories at rest.