Woodgate, J. L.; Buchanan, K. L.; Bennett, A. T. D.; Catchpole, C. K.; Brighton, R.; Leitner, S.: Environmental and genetic control of brain and song structure in the zebra finch. Evolution: International journal of organic evolution 68 (1), pp. 230 - 240 (2014)
Scientists studying a rare population of tool-using chimpanzees have found that aging can have a profound impact on their abilities—but not all chimps decline equally.