Earth's crust is made up of huge slabs called plates. The plates move constantly. At times, the plates move away from each other, creating gaps. Earth's surfaces finds it's way out of the gaps. Magma comes out of Earth, creating a heap of lava, ash, and rocks. The heaps grows bigger and bigger as the volcano erupts and, creating q huge mound. The mound cools down over thousands over years to form a mountain.
Water vapor in the air contains heat from waters of the ocean. This heat gets transferred as part of the water cycle.
Your lymph nodes or "thymus" promotes the maturation of t cells.
QUICK ANSWERNatural selection leads to evolution because the traits of those who are able to reproduce influence future generations genetics and gradually lead to these passed on traits becoming the normal state of being, thus causing the species in question to evolve. If a group of people have predominantly brown hair genes and have children, then by way of natural selection the dominant gene will increase with future generations, meaning that slowly in time this group of people will evolve to have mostly brown hair genes
