1. Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
2. Indiana University Network Science Institute, Indiana University, Bloomington, IN 47405, USA
3. ICREA-Complex Systems Laboratory, Universitat Pompeu Fabra (GRIB), Dr Aiguader 80, 08003 Barcelona, Spain
4. Institut de Biologia Evolutiva, CSIC-UPF, Pg Maritim de la Barceloneta 37, 08003 Barcelona, Spain
5. Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA