To help feed billions of people, scientists braved the snake-infested and croc-filled swamps of northern Australia in search of rice. ... Musgrave is one of a few pit stops along the rutted, mostly dirt road that traverses Cape York, Australia, and ends at the northeasternmost tip of the continent, just 100 miles from Papua New Guinea. The peninsula is part of the world’s greatest concentration of free-flowing rivers and its most extensive network of intact tropical savannas, which stretches across the country’s north for hundreds of miles. Even in a country where open spaces rule the landscape, this place looms in the national mind as an uncharted, prehistoric mystery. This year alone, scientists discovered 13 new spider species on the peninsula. Cape York is roughly the size of Nebraska but with only 17,000 residents, most of whom are indigenous and clustered in a few towns along the coast. ... Grown on six continents and in 117 countries, rice is the world’s most important food. There are 144 million farms that grow rice, more than for any other crop. The vast majority of these are in developing countries, and virtually all of them are small, averaging just over 2 acres apiece. Simply put, the crop is the daily sustenance of the world’s poor. The primary reason is its remarkable biology. Rice is naturally prolific, each plant generating perhaps 25 times as many grains as a single wheat plant. When grown in water, its microbiome regenerates the soil’s nutrition, making fertilizer unnecessary. ... In recent decades, an increasing number of geneticists and plant breeders have realized that crops’ wild relatives hold immense value because they have not been domesticated. Instead of being narrowed and homogenized by humans, these crops have produced immeasurable genetic diversity as a result of their natural adaptation to pests, diseases, and climatic fluctuation. Their genes have already begun to help agriculture tackle the enormous challenges it faces today.

For most of my life, if I’ve thought at all about the bacteria living on my skin, it has been while trying to scrub them away. But recently I spent four weeks rubbing them in. I was Subject 26 in testing a living bacterial skin tonic, developed by AOBiome, a biotech start-up in Cambridge, Mass. The tonic looks, feels and tastes like water, but each spray bottle of AO+ Refreshing Cosmetic Mist contains billions of cultivated Nitrosomonas eutropha, an ammonia-oxidizing bacteria (AOB) that is most commonly found in dirt and untreated water. AOBiome scientists hypothesize that it once lived happily on us too — before we started washing it away with soap and shampoo — acting as a built-in cleanser, deodorant, anti-inflammatory and immune booster by feeding on the ammonia in our sweat and converting it into nitrite and nitric oxide. ... While most microbiome studies have focused on the health implications of what’s found deep in the gut, companies like AOBiome are interested in how we can manipulate the hidden universe of organisms (bacteria, viruses and fungi) teeming throughout our glands, hair follicles and epidermis. ... AOBiome does not market its product as an alternative to conventional cleansers, but it notes that some regular users may find themselves less reliant on soaps, moisturizers and deodorants after as little as a month. Jamas, a quiet, serial entrepreneur with a doctorate in biotechnology, incorporated N. eutropha into his hygiene routine years ago; today he uses soap just twice a week. The chairman of the company’s board of directors, Jamie Heywood, lathers up once or twice a month and shampoos just three times a year. The most extreme case is David Whitlock, the M.I.T.-trained chemical engineer who invented AO+. He has not showered for the past 12 years. ... I got close enough to shake their hands, engage in casual conversation and note that they in no way conveyed a sense of being “unclean” in either the visual or olfactory sense.

Burgers and fries have nearly killed our ancestral microbiome. ... A group of Italian microbiologists had compared the intestinal microbes of young villagers in Burkina Faso with those of children in Florence, Italy. The villagers, who subsisted on a diet of mostly millet and sorghum, harbored far more microbial diversity than the Florentines, who ate a variant of the refined, Western diet. Where the Florentine microbial community was adapted to protein, fats, and simple sugars, the Burkina Faso microbiome was oriented toward degrading the complex plant carbohydrates we call fiber. ... Scientists suspect our intestinal community of microbes, the human microbiota, calibrates our immune and metabolic function, and that its corruption or depletion can increase the risk of chronic diseases, ranging from asthma to obesity. ... Numerous factors are implicated in these disappearances. Antibiotics, available after World War II, can work like napalm, indiscriminately flattening our internal ecosystems. Modern sanitary amenities, which began in the late 19th century, may limit sharing of disease- and health-promoting microbes alike. Today’s houses in today’s cities seal us away from many of the soil, plant, and animal microbes that rained down on us during our evolution, possibly limiting an important source of novelty. ... But what the Sonnenburgs’ experiment suggests is that by failing to adequately nourish key microbes, the Western diet may also be starving them out of existence.

Calories consumed minus calories burned: it’s the simple formula for weight loss or gain. But dieters often find that it doesn’t work. ... more than two-thirds of American adults are overweight or obese. For many of them, the cure is diet: one in three are attempting to lose weight in this way at any given moment. Yet there is ample evidence that diets rarely lead to sustained weight loss. These are expensive failures. This inability to curb the extraordinary prevalence of obesity costs the United States more than $147 billion in healthcare, as well as $4.3 billion in job absenteeism and yet more in lost productivity. ... part of the problem goes way beyond individual self-control. The numbers logged in Nash’s Fitbit, or printed on the food labels that Haelle reads religiously, are at best good guesses. Worse yet, as scientists are increasingly finding, some of those calorie counts are flat-out wrong – off by more than enough, for instance, to wipe out the calories Haelle burns by running an extra mile on a treadmill. A calorie isn’t just a calorie. And our mistaken faith in the power of this seemingly simple measurement may be hindering the fight against obesity.