A recent article in The New England Journal of Medicine points out that the human GI tract contains up to 10-million different microbial species. This review of the human intestinal microbiome found bacteria, fungi (yeast), viruses, archaea (specialized bacteria with a resistant cell wall) and algae. More than a billion years of co-evolution of mammals and their gut flora has led to a complex interdependency of the mammal and the microbes, and the microbes with one another. Humans today are dependent on their gut flora for important biologic functions including: development of normal immunity, protection against pathogens, elimination of various toxins, regulation of intestinal function, neurologic signaling, bone-density maintenance, synthesis of essential vitamins and neurotransmitters, plus providing 10% of our daily energy requirements. Studies of abnormal gut flora in humans and mouse models have shown a correlation with a variety of Alist serious health issues: cancer, diabetes, asthma, atherosclerosis and autism. The studies also cited improvement through use of specific probiotics. Two bacteria with long names (Christensenellaceae and methanogenic orchaea) are found in lean people with healthy metabolism, but are absent in obese persons with Type II diabetes and insulin resistance. In a study of genetically predisposed infants for Type I diabetes, the introduction of probiotics in their first month of life reduced their risk of developing diabetes by 60%. In studies of people with atherosclerosis, they were found to have a gut flora that broke down the protein in their diet to a chemical that speeds up plaque deposits in arteries. Research in children of asthmatic parents found that early introduction of probiotics in infancy reduced the risk for developing childhood asthma by 30%. In a mouse model of autism it was found that abnormal gut flora led to an increased production of 4ethylphenylsulfate (4EPS). Improving gut flora with a countering bacteria reduced the 4EPS by 50% and led to a marked improvement in the mouse behavior. Finally, in human cancer studies it was found that taking a probiotic with bifidobacterium improved the response to chemotherapy for melanoma. Also, the probiotic Lactobacillus casei was shown to inhibit progression of colon cancer.