James Neill, The Origins and Role of Same-Sex Relations in Human Societies, McFarland & Co., 2011.

Hitonaru Nishie and Michio Nakamura, A newborn infant chimpanzee snatched and cannibalized immediately after birth: Implications for «maternity leave» in wild chimpanzee, American Journal of Physical Anthropology 165: 194–9 (January 2018).

Sue O’Connor et al., Fishing in life and death: Pleistocene fish-hooks from a burial context on Alor Island, Indonesia, Antiquity 91 (360): 1451–68 (6 December 2017).

H. Freyja Ólafsdóttir et al., Hippocampal place cells construct reward related sequences through unexplored space, Elife 4: e06063 (26 June 2015).

Seweryn Olkowicz et al., Birds have primate-like numbers of neurons in the forebrain, PNAS 113 (26): 7255–60 (28 June 2016).

C. Organ et al., Phylogenetic rate shifts in feeding time during the evolution of Homo, PNAS 108 (35): 14555–9 (30 August 2011).

A. Powell, S. Shennan and M. G. Thomas, Late Pleistocene demography and the appearance of modern human behavior, Science 324 (5932): 1298–1301 (5 June 2009).

Shyam Prabhakar, Accelerated evolution of conserved noncoding sequences in humans, Science 314 (5800): 786 (3 November 2006).

Shyam Prabhakar et al., Human-specific gain of function in a developmental enhancer, Science 321 (5894): 1346–50 (5 September 2008).

D. M. Pratt and V. H. Anderson, Population, distribution and behavior of giraffe in the Arusha National Park, Tanzania, Journal of Natural History 16 (4): 481–9 (1982).

D. M. Pratt and V. H. Anderson, Giraffe social behavior, Journal of Natural History 19 (4): 771–81 (1985).

Helmut Prior et al., Mirror-induced behavior in the magpie (Pica pica): Evidence of self-recognition, PLoS Biology 6 (8): e202 (19 August 2008).

Jill D. Pruetz et al., Savanna chimpanzees, Pan troglodytes verus, hunt with tools, Current Biology 17 (5): 412–17 (6 March 2007).

Jill D. Pruetz and Nicole M. Herzog, Savanna chimpanzees at Fongoli, Senegal, navigate a fire landscape, Current Anthropology 58 (S16): S337–S350 (August 2017).

Jill D. Pruetz and Thomas C. LaDuke, Reaction to fire by savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal: Conceptualization of «fire behavior» and the case for a chimpanzee model, American Journal of Physical Anthropology 141 (14): 646–50 (April 2010).

Kay Prüfer et al., The bonobo genome compared with the chimpanzee and human genomes, Nature 486: 527–31 (28 June 2012).

Anita Quiles et al., A high-precision chronological model for the decorated Upper Paleolithic cave of Chauvet-Pont d’Arc, Ardèche, France, PNAS 113 (17): 4670–75 (26 April 2016).

Joaquín Rodríguez-Vidal et al., A rock engraving made by Neanderthals in Gibraltar, PNAS 111 (37): 13301–6 (16 September 2014).

Douglas G. D. Russell et al., Dr. George Murray Levick (1876–1956): Unpublished notes on the sexual habits of the Adélie penguin, Polar Record 48 (4): 387–93 (January 2012).

Anne E. Russon et al., Orangutan fish eating, primate aquatic fauna eating, and their implications for the origins of ancestral hominin fish eating, Journal of Human Evolution 77: 50–63 (December 2014).

Graeme D. Ruxton and Martin Stevens, The evolutionary ecology of decorating behaviour, Biology Letters 11 (6) (3 June 2015).

Angela Saini, Inferior: How Science Got Women Wrong, Fourth Estate, 2017.

Ivan Sazima, Corpse bride irresistible: A dead female tegu lizard (Salvator merianae) courted by males for two days at an urban park in south-eastern Brazil, Herpetology Notes 8: 15–18 (25 January 2015).