HUMAN SPATIAL EVOLUTION
Humans make an interesting comparison species, with significant advantages for cognitive biology: a well-studied, easily trained, mildly polygynous (advantage for sex difference studies), olfactory navigating and food-storing species, all traits found in rodents and other vertebrate species. We study sex differences in spatial coding as a model system for testing the parallel map theory of hippocampal function and spatial navigation [HIPPOCAMPAL MAPS], which offers an evolutionary framework for thinking about female- and male-specific spatial cognitive traits.
We began to use humans to test the olfactory spatial hypothesis [OLFACTION AND SPACE]when we found that humans also map locations using odor. We then moved on to the question of plume orientation, funded by the NSF Ideas Lab consortium grant on olfactory navigation. Using the statistics of actual plumes from John Crimaldi’s team, we created a virtual navigation task. Using sound as a proxy for odor, this task produces a large male advantage in plume orientation, as predicted from the parallel map theory (Jinn, McHugh, Crimaldi & Jacobs, in prep). Using real odor in an indoor space, we find, as in the virtual environment, that stereo olfaction enhances orientation accuracy (Jinn & Jacobs, in prep). Recently, Véronique Bohbot’s group has provided new evidence in support of the olfactory spatial hypothesis, demonstrating a correlation between olfactory ability, virtual navigational ability and hippocampal size in humans (Dahmani et al. 2018, Nature Communications).
Humans have also been a valuable species to test the PROUST hypothesis [OLFACTION AND SPACE], a new formulation of the impact of olfaction on vertebrate sensory evolution (Jacobs, in prep.) Extending the PROUST hypothesis to primates offers a new hypothesis for a uniquely human trait: the external pyramid (nose), that is only found in the genus Homo. We are now working on the navigational nose hypothesis, proposing that this structure evolved to enhance stereo olfaction and hence long-distance movements in Homo erectus (Jacobs, in press, Journal of Experimental Biology).
(In press) Jacobs, L. F. (2018) The navigational nose: a new hypothesis for the function of the human external pyramid. Journal of Experimental Biology.
Jacobs, L. F., Arter, J., Cook, A., & Sulloway, F. J. (2015). Olfactory orientation and navigation in humans. PLoS ONE, 10(6), e0129387. doi:10.1371/journal.pone.0129387.s001
Chai, X. , and Jacobs, L.F. 2012. Digit ratio predicts sense of direction in women. PLoS ONE 7, 2 (e32816).
Chai, X.J. , Ofen, N., Jacobs, L.F., and Gabrieli, J.D. (2010). Scene complexity: influence on perception, memory, and development in the medial temporal lobe. Frontiers in Human neuroscience 4, 21 (21-10).
Chai, X.J. , and Jacobs, L.F. (2010). Effects of cue types on sex differences in human spatial memory. Behavioural Brain Research 208, 336-342.
Chai, X.J. , and Jacobs, L.F. (2009). Sex differences in directional cue use in a virtual landscape. Behavioral Neuroscience 123, 276-283.
Jacobs, L.F. (1996b). Sexual selection and the brain. Trends in Ecology and Evolution 11, 82-86.