Scientific Reports 4: Article number: 6239; published online: 01 September 2014; updated: 18 December 2015.

The Acknowledgements section in this Article is incomplete.

“We also thank the Brazilian Agencies CNPq, CAPES, FUNCAP and FINEP, the FUNCAP/CNPq Pronex grant and the National Institute of Science and Technology for Complex Systems in Brazil for financial support. Hernan Makse thanks NIH and ARL for financial support. We thank Prof. César Barreira for valuable discussions during the development of this work.”

should read:

“We also thank the Brazilian Agencies CNPq, CAPES, FUNCAP and FINEP, the FUNCAP/CNPq Pronex grant and the National Institute of Science and Technology for Complex Systems in Brazil for financial support. Hernan Makse thanks NIH and Army Research Laboratory Cooperative Agreement Number W911NF-09-2-0053 (the ARL Network Science CTA) for financial support. We thank Prof. César Barreira for valuable discussions during the development of this work.”