title: Eating up the world's food web and the human trophic level.
abstract: Trophic levels are critical for synthesizing species' diets, depicting energy pathways, understanding food web dynamics and ecosystem functioning, and monitoring ecosystem health. Specifically, trophic levels describe the position of species in a food web, from primary producers to apex predators (range, 1-5). Small differences in trophic level can reflect large differences in diet. Although trophic levels are among the most basic information collected for animals in ecosystems, a human trophic level (HTL) has never been defined. Here, we find a global HTL of 2.21, i.e., the trophic level of anchoveta. This value has increased with time, consistent with the global trend toward diets higher in meat. National HTLs ranging between 2.04 and 2.57 reflect a broad diversity of diet, although cluster analysis of countries with similar dietary trends reveals only five major groups. We find significant links between socio-economic and environmental indicators and global dietary trends. We demonstrate that the HTL is a synthetic index to monitor human diets and provides a baseline to compare diets between countries.
authors.affiliation: Institut Français de Recherche pour l'Exploration de la MER, Unité Mixte de Recherche (UMR) Exploited Marine Ecosystems (EME-212), 34203 Sète Cedex, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Bonhommeau
authors.forename: Laurent
authors.initials: L
authors.lastname: Dubroca
authors.forename: Olivier
authors.initials: O
authors.lastname: Le Pape
authors.forename: Julien
authors.initials: J
authors.lastname: Barde
authors.forename: David M
authors.initials: DM
authors.lastname: Kaplan
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Chassot
authors.forename: Anne-Elise
authors.initials: AE
authors.lastname: Nieblas
mesh_terms: D000818:Animals; D020387:Food Chain; D005518:Food Preferences; D006801:Humans; D008460:Meat; D008954:Models, Biological
keywords: human ecology; nutrition transition; trophic ecology