Lipids play an essential role in cellular structure, signaling, and energy storage. As nonpolar molecules composed of carbon and hydrogen, lipids form nonsoluable structural units that designate the inter- and extra-cellular spaces where biological activities take place. Critically, omega-3 long-chain polyunsaturated fatty acids (LC-PUFAs), form the main structural constituents of the brain, nervous system, and photoreceptors. While the emergence of higher-order aerobic organisms became possible only after oxygenation of the atmosphere, a mere 600 million years ago, primordial bacteria and archaea had a 2.5 billion year head-start to evolve lipid metabolism genes in an anaerobic marine environment especially enriched in the omega-3 LC-PUFAs. As complex life emerged on land, lipid availability switched to a dominance of omega-6 fatty acids, yet neural and retinal tissue still relied on omega-3 LC-PUFA. Since terrestrial sources of omega-3 LC-PUFAs are rare, the anaerobic polyketide PUFA-synthase complex presents an interesting yet unexplored process by which animals could derive essential fatty acids through their microbiome. The network of lipid coding genes, however, remains vastly under studied. Therefore, this proposal details an investigation on the network arrangements of prokaryote lipid metabolism from animal gut microbiota. The goal is to characterize different microbiomes by their ability to manufacture nutritionally important lipids, with particular attention to the essential omega-3 fatty acids. This research forms the proof of concept for a larger project initiative to resolve the paradox of human brain development in the presence of only terrestrial dietary resources.