Wood (Tree) stores every potential to grow, evolve, hold firmly, and be flexible at the other end, and Earth allowed the penetration of the roots to keep the wood firm. Both these elements within the body are involved in Evolution from the single cell (gamete otherwise) somatic as well as reproductive, from the earlier Primate (monkey) and the Milk drinking ability (all other animal milk) that actually gave the dominance to the Homo Sapien (Human).
Actually, it was the Sunlight element that gave more alertness to the Monkey brains, when the small creature started to use its Thumb and the Index plus middle finger together to hold small stones and learned to throw them at the bigger Animals that came to hunt them. Later the evolved Apes, and the Apemen were wielding the Bamboo or Splinter spears with the Fist more tightly to activate more meridians (Space through the Triple Warmer) and started to fight more fiercely - showing an increase in dominance. They could run more distances (they discovered later) because of the activation of the TW which descends through the GB Meridian (Shaoyang - the opener of the spaces) that controls drainage of sweat and toxins, and therefore lubricator for the Tendons to enable running faster and to more distances.
LI 4 was activated in the first example of the small Monkey. SJ 4, SI 4, LI 5 were activated as they evolved further. As the Apes started running - they could use the Gluteus Maxis (GB 30) to a greater extent - that caused the Human Species to move out from the Denser Jungles towards open Plains, River, and then the Hills.
The most important point notable in _Nei Jing_ : The organ that rules every other Zang and Fu is the Gall Bladder - Dan - Oh No - It may be known as Dan in the Chinese language - In English however, it is the DON - the Boss because It decides everything
People with Healthy Gall Bladder - are more sincere in work, quick in decisions, workaholic, efficient, effective and more.
People with Congestion in the GB are more Irritable, Moody, Procrastinating, sluggish and dull headed. Depending on their DAI Meridian (Belt or Bucket) - the Belt DAI dominant people are too thin.
The Bucket DAI dominant people are Obese with Hanging tummies, Pelvis, Huge Butts and very sluggish. The thin types acquire mental traits like abruptness, mood swings, obsessions and compulsive behaviour.
Dr. Raju C. Krishna