Humanity serves as a carrier for the Earth's purposes. Not humanities own. The dominating aspect of DNA is the bases or sugars used to encode and error check the information carried by the DNA molecule. These sugars are Adenine, Thymine, Guanine and Cytosine. This is Earths Genotype.
Genes carry a mechanism with which to self regulate and self perpetuate.
These two axioms are consistent for all complex systems. From viruses to single cell bacteria to mammals to planetary ecosystems to the universe. In all cases the means of perpetuation or breeding maintains a certain order that is intrinsic and inherent in the parent. The order the Earth seeks to perpetuate is it's genotype. To maintain and transport this genotype, the Earth requires a means by which to break the gravity well in an efficient manner which is least damaging to it as a host.