In two back-to-back symposia at the annual meeting of the American Association for the Advancement of Science in Washington, D.C., on Sunday, Feb. 17 at 1:30 and 3:30 PM respectively, a cross-disciplinary cohort of scientists will present the first comprehensive investigations of how humans interacted with plant and animal species in different cultures worldwide through time. By compiling and comparing detailed data from pre-industrial and modern societies, the researchers are sketching a picture of humans' roles and impacts in sustainable and unsustainable socio-ecological systems. "Almost all food webs that have been compiled and studied have been put together without including humans," says Jennifer Dunne (Santa Fe Institute), an ecologist and complex systems scientist who is leading the project with archaeologist Stefani Crabtree (Santa Fe Institute and Center for Research and Interdisciplinarity). "It takes a lot of time and effort to put these kinds of detailed data together. So even though ecologists have been studying food webs for decades, we're only now in a position where we can start to rigorously compare human roles and impacts across different systems to understand sustainability in new kinds of ways," says Dunne. What do we learn when we do include humans? As part of her presentation during the second symposium, Dunne will reveal initial results from a comparison of food webs that explicitly include humans across several socioecological systems. Three are pre-industrial systems -- the Aleutian Islands of Alaska, the Pueblo U.S. Southwest, and the Western Desert of Australia, and one is modern -- the Tagus Estuary of Portugal. Given the diversity of cultures, ecologies, climates, and time periods represented in the data, Dunne suggests that we can start to learn "something more general about human roles in, and impacts on, ecosystems" by comparing these systems. For example, humans are often super-generalists compared to other predators -- they feed on a huge variety of different species. In some systems, humans as super-generalist predators can fit into ecosystems without causing extinctions or major environmental degradation. For example, according to Dunne's pioneering analysis published in Scientific Reports in 2016, the Sanak Island (Alaska) Aleut fed on a whopping 122 of 513 taxa in the nearshore marine ecosystem. However, like other predators, they switched from their favorite prey -- sea lions -- to shellfish, kelp, or whatever was readily available when the weather did not allow them to hunt in open water. "Prey-switching is very stabilizing for food webs," Dunne explains, "because it allows prey taxa populations to recover from exploitation, as the predator's focus shifts to other prey that are easier to forage or hunt given current conditions." That, plus limited use of hunting technology and other factors helped to minimize potential negative impacts of humans on the Sanak ecosystem -- during approximately 7,000 years of human habitation, there is no evidence for any long-term local extinctions.