Evolution of Plants: The Basis for Human Foods and Animal Feeds
For at least 400 million years before humans appeared on earth, plants were producing food consisting of leaves, stems, seeds, nuts, berries, fruits, tubers, etc., that made life possible for humans and animals when they evolved. Early plant evolution was essential not only for food but also for producing an oxygen environment necessary for animal and human survival. Plants introduced a very effective way of using the sun's radiation to transform carbon dioxide into food materials, such as sugars, starches, and cellulose, through the green pigment chlorophyll and the organelle that serves as the site for photosynthesis, the chloroplast. Both plants and animals evolved in a microbial environment, where the microbes were ready and able to recycle organic matter. Plants and animals had to develop ways of resisting microbial invasion. Plants did this in part by developing a lignocellulosic body resistant to microbial breakdown. Humans also evolved in a sea of microorganisms and have a tough skin over their bodies resistant to microbial invasion. They had to develop internal immune systems against invasion by microorganisms. Human blood contains phagocytes similar to and probably derived from free-living amoebas, which search out and consume invading bacteria. Then as now, some microorganisms could invade the live animal or human, causing disease. Microbes enter our bodies in the air we breathe into our noses and lungs, into our mouths and throats, stomachs, and intestinal tracts via the water and foods we swallow, through our eye sockets, through our skin via abrasions and punctures, and through our genitals and other mucous membranes. This intimate contact with microbes begins at birth and continues through life. Some microorganisms become regular inhabitants, parasites of our bodies; they become what can be described as our normal flora. Some microorganisms are virulent, invading our bodies and upsetting our metabolic activities and causing disease; these are the pathogenic microbes. Other microbes are normal microbial flora or pathogens on plants. Still other microbes are continuously invading plant food materials and recycling the organic matter. If this activity is controlled and stopped at the proper levels, these become our fermented foods, which include alcoholic foods and beverages; vinegars; lactic-acidfermented cabbage and other vegetables (that is, sauerkraut and pickles); lactic-acid-fermented milks and cheeses; sourdough breads; Indian idli (from rice); Ethiopian enjera (a bread made from teff, an indigenous cereal grass); textured-vegetable-protein meat-substitutes, such as Indonesian tempeh (from soybeans or, sometimes, peanuts) and ontjom (from peanuts or, sometimes, soy fiber); high-salt meat-flavored amino acid/peptide soy sauces and pastes; African alkaline-fermented foods such as dawadawa, soumbara, and iru (all from locust beans [Parkia biglobosa] or soybeans); Indian kenima, Japanese natto, and Thai thua-nao (all from soybeans); and leavened yeast breads.