Monkey business

Studies show Neuroanatomical correlates of personality in chimpanzees by Robert D. Latzman, Lisa K. Hecht, Hani D. Freeman, Steven J. Schapiro, William D. Hopkins in a way that we are trying to make connections among human psychological and neurobiological traits.

Among such traits, violence comes along.  As long ago back we look, we can see it, as new insights into collective violence in Early Neolithic Central Europe by Christian Meyer, Christian Lohr, Detlef Gronenborn, and Kurt W. Alt tells us.

And among the howlers, what was know about men now is also confirmed in monkeys; the more insecure and worse performing the monkey the louder and more focused in intimidating competitors they are.  Evidence shows an “Evolutionary Trade-Off between Vocal Tract and Testes Dimensions” by Jacob C. Dunn, Lauren B. Halenar, Thomas G. Davies, Jurgi Cristobal-Azkarate, David Reby, Dan Sykes, Sabine Dengg, W. Tecumseh Fitch, Leslie A. Knapp.  Louder howlers apparently work on securing a more captive group of females.  This could compensate for their worse performance in breeding.  Quieter males tend to outperform in less exclusive groups by their reproductive capability.