Even more interesting, is that the new findings argue that as few as 2,000 humanoid ancestors may have made the first steps out of Africa. The test were done on the mitochondrial DNA, which is passed by the females in their eggs and does not undergo the genetic mixing that occurs with other DNA in reproduction. In chapter three, you will remember, that I made the statement that if our primate forebears switched from a stationery food source, such as fruit trees located in rainforests, to a food source that roamed about on four feet, then if one wanted to survive, one had to follow the food as it moved. This, of course, is not conclusive proof, as their must have been other food sources such as crayfish, fresh water fish, small insects, and of course, yummy plant roots, but four-footed mammals do occupy most of my theory of a moving food source. It is the regular movement of part or all of an animal population from one area to another and then a return to the first area.
Migration is often annual, and thus is closely linked to the planet's seasonal changes.
Emigration, such as what our primal ancestors did, is the movement from one location to another, without the return journey. In North America, the birds we commonly see, such as the robin, wood warblers, and Canadian geese migrate. Most scientists agree that migration is made possible in mammals due to the pituitary gland sending out hormone secretions, which in turn create complex internal messaging. The pituitary influences the reproductive organs, which affect all metabolic mechanisms, which prepare the animal for migration. Part of the preparation could include the build-up of fat tissue as an accumulated internal food source.