Hunt NH, Jinn J, Jacobs LF, Full RJ (2021) Acrobatic squirrels learn to leap and land on tree branches without falling. Science. https://doi.org/10.1126/science.abe5753
Summary by the journal
Every day, there are acrobatic extravaganzas going on above our heads. Squirrels navigate remarkably complex and unpredictable environments as they leap from branch to branch, and mistakes can be fatal. These feats require a complex combination of evolved biomechanical adaptations and learned behaviors. Hunt et al. characterized the integration of these features in a series of experiments with free-living fox squirrels (see the Perspective by Adolph and Young). They found that the squirrels’ remarkable and consistent success was due to a combination of learned impulse generation when assessing the balance between distance and branch flexibility and the addition of innovative leaps and landings in the face of increasingly difficult challenges.
Arboreal animals often leap through complex canopies to travel and avoid predators. Their success at making split-second, potentially life-threatening decisions of biomechanical capability depends on their skillful use of acrobatic maneuvers and learning from past efforts. Here, we found that free-ranging fox squirrels (Sciurus niger) leaping across unfamiliar, simulated branches decided where to launch by balancing a trade-off between gap distance and branch-bending compliance. Squirrels quickly learned to modify impulse generation upon repeated leaps from unfamiliar, compliant beams. A repertoire of agile landing maneuvers enabled targeted leaping without falling. Unanticipated adaptive landing and leaping “parkour” behavior revealed an innovative solution for particularly challenging leaps. Squirrels deciding and learning how to launch and land demonstrates the synergistic roles of biomechanics and cognition in robust gap-crossing strategies.
Jinn, J., E. Conner and Jacobs, L.F. (2020). How ambient environment influences olfactory orientation in search and rescue dogs. Chemical Senses.
Under natural conditions, an animal orienting to an air-borne odor plume must contend with the
shifting influence of meteorological variables, such as air temperature, humidity and wind speed,
on the location and the detectability of the plume. Despite their importance, the natural statistics
of such variables are difficult to reproduce in the laboratory and hence few studies have
investigated strategies of olfactory orientation by mobile animals under different meteorological
conditions. Using trained search and rescue dogs, we quantified the olfactory orientation
behaviors of dogs searching for a trail (aged 1-3 hours) of a hidden human subject in a natural
landscape, under a range of meteorological conditions. Dogs were highly successful in locating
the human target hidden 800 m from the start location (93% success). Humidity and air
temperature had a significant effect on search strategy: as air conditions became cooler and more
humid, dogs searched significantly closer to the original trail. Dogs also modified their speed and
head position according to their search location distance from the original trail. When close to
the trail, dogs searched with their head up and ran quickly but when their search took them
farther from the trail, they were more likely to search with their nose to the ground, moving more
slowly. To our knowledge, this is the first study of a mammalian species responding to localized
shifts in ambient conditions and it lays the foundation for future studies of olfactory orientation,
and the development of a highly tractable mammalian species for such research.
Jacobs, Lucia F. (2019) The navigational nose: a new hypothesis for the function of the human external pyramid. Journal of Experimental Biology.
There is currently only one hypothesis for the evolution of this structure, based on its role in respiration, yet the nose also has a sensory function. This paper proposes that the human external nose may also have evolved to enhance stereo olfaction during spatial orientation.
PDF: 2019 JEB Jacobs
Delgado, M. M, and L. F Jacobs. How squirrels protect their caches: location,
conspicuousness during caching, and proximity to kin influence cache lifespan. BioRxiv 6
(August 16, 2019): 338–45. https://www.biorxiv.org/content/10.1101/738237v1
By genotyping a subpopulation of Berkeley squirrels, Mikel showed that that scatter hoarding fox squirrels placed caches closer to caches made by their close relatives. This suggests that foraging decisions are influenced by kin selection, as the loss of caches to pilfering relatives would be offset by inclusive fitness. Her study also identified key strategic choices squirrels make while caching and how this influences how long the cache remains hidden before it is retrieved or pilfered.
Delgado, M.M. & Jacobs, L.F., 2017. Caching for where and what: evidence for a mnemonic strategy in a scatter-hoarder. Royal Society Open Science, 4(9), pp.170958–6.
Squirrels organize their caches spatially by the species of nut. Such ‘spatial chunking’ increases the accuracy of memory recall in other species and probably reduces the cognitive load of building and managing an optimal cache map.
Delgado, M.M. and Jacobs, L.F. (2016). Inaccessibility of reinforcement increases persistence and signaling behavior in the fox squirrel, Sciurus niger. Journal of Comparative Psychology. 130(2): 128-137.
Is frustration adaptive? See the experiment here in this short film by KQED http://”Watch Those Frustrated Squirrels”
Jacobs, L. F., Arter, J., Cook, A., & Sulloway, F. J. (2015). Olfactory orientation and navigation in humans. PLoS ONE, 10(6), e0129387. http://doi.org/10.1371/journal.pone.0129387.s001
PDF: PLoS ONE 2015 Jacobs
Given only one minute to sniff a location, humans will be able to return to that location, using only their sense of smell. This first study of olfactory mapping by humans suggests that olfaction is an under appreciated navigational device in our species spatial toolkit.
Jacobs, L. F., & Menzel, R. (2014). Navigation outside of the box: what the lab can learn from the field and what the field can learn from the lab. Movement Ecology, 2(1), 1–22. http://doi.org/10.1186/2051-3933-2-3
Delgado, M. M., Nicholas, M., Petrie, D. J., & Jacobs, L. F. (2014). Fox squirrels match food assessment and cache effort to value and scarcity. PLoS ONE, 9(3), e92892. http://doi.org/10.1371/journal.pone.0092892.s003
Evan L. MacLean, Brian A. Hare, Charles L. Nunn, Elsa Addessi, Federica Amici, Rindy C. Anderson, Filippo Aureli, Joseph M. Baker, Amanda E. Bania, Allison M. Barnard, Neeltje J. Boogert, Elizabeth M. Brannon, Emily E. Bray, Joel Bray, Lauren J. N. Brent, Judith M. Burkart, Josep Call, Jessica F. Cantlon, Lucy G. Cheke, Nicola S. Clayton, Mikel M. Delgado, Louis J. DiVincenti, Kazuo Fujita, Chihiro Hiramatsu, Lucia F. Jacobs, Kerry E. Jordan, Jennifer R. Laude, Kristin L. Leimgruber, Emily J. E. Messer, Antonio C. de A. Moura, Ljerka Ostojić, Alejandra Picard, Michael L. Platt, Joshua M. Plotnik, Friederike Range, Simon M. Reader, Rachna B. Reddy, Aaron A. Sandel, Laurie R. Santos, Katrin Schumann, Amanda M. Seed, Kendra B. Sewall, Rachael C. Shaw, Katie E Slocombe, Yanjie Su, Ayaka Takimoto, Jingzhi Tan, Ruoting Tao, Carel P. van Schaik, Zsófia Virányi, Elisabetta Visalberghi, Jordan C. Wade, Arii Watanabe, Jane Widness, Thomas R. Zentall, Yini Zhao. (2014) The evolution of self-control. Proceedings of the National Academy of Sciences, 111(20), E2140–8. doi:10.1073/pnas.1323533111.
Cook, A., Arter, J., & Jacobs, L. F. (2013). My owner, right or wrong: the effect of familiarity on the domestic dog’s behavior in a food-choice task. Animal Cognition, 17(2), 461–470. http://doi.org/10.1007/s10071-013-0677-0
PDF: Anim Cogn 2013 Cook
Waismeyer, A. S., & Jacobs, L. F. (2013). The emergence of flexible spatial strategies in young children. Developmental Psychology, 49(2), 232–242. http://doi.org/10.1037/a0028334
Jacobs, L. F. (2012). From chemotaxis to the cognitive map: the function of olfaction. Proc Natl Acad Sci, 109, 10693–10700. http://doi.org/10.1073/pnas.1201880109
Bettis, T., & Jacobs, L. F. (2012). Sex differences in object recognition are modulated by object similarity. Behavioural Brain Research, 233(2), 288–292. http://doi.org/10.1016/j.bbr.2012.04.028
Chai, X. J., & Jacobs, L. F. (2012). Digit ratio predicts sense of direction in women. PLoS ONE, 7(2), e32816. http://doi.org/10.1371/journal.pone.0032816
PDF: PLoS ONE 2012 Chai
Kleschevnikov, A. M., Belichenko, P. V., Faizi, M., Jacobs, L. F., Htun, K., Shamloo, M., & Mobley, W. C. (2012). Deficits in cognition and synaptic plasticity in a mouse model of Down Syndrome ameliorated by GABAB receptor antagonists. Journal of Neuroscience, 32(27), 9217–9227. http://doi.org/10.1523/JNEUROSCI.1673-12.2012
MacLean, E.L., Matthews, L.J., Hare, B.A., Nunn, C.L., Anderson, R.C., Aureli, F., Brannon, E.M., Call, J., Drea, C.M., Emery, N.J., Haun, D.B., Herrmann, E., Jacobs, L.F., Platt, M.L., Rosati, A.G., Sandel, A.A., Schroepfer, K.K., Seed, A.M., Tan, J., van Schaik, C.P., and Wobber, V. (2012). How does cognition evolve? Phylogenetic comparative psychology. Animal Cognition 15, 223-238.
Delgado, M.M. (2012).
Jacobs, L. F. (2012). “Do Squirrels Remember Where They Bury Their Nuts?” “What do Honeybees Say When they Dance?” “What Does “Chickadee” Mean to a Chickadee?”
Essays in: M. Lamothe, J. Rothman, & J. Volvovski (Eds.), The Where, the Why and the How: 75 Artists Illustrate the Wondrous Mysteries of Science. San Francisco: Chronicle Books.
Wiener, J., Shettleworth, S., Bingman, V.P., Cheng, K., Healy, S., Jacobs, L.F., Jeffery, K.J., Mallot, H.A., Menzel, R., and Newcombe, N.S. (2011). Animal Navigation – A Synthesis. In Animal Thinking: Contemporary Issues in Comparative Cognition, R. Menzel, and J. Fischer, eds. (Cambridge, MA, MIT Press).
PDF: 2011 Wiener
Waisman, A. S., Lucas, C. G., Griffiths, T. L., & Jacobs, L. F. (2011). A Bayesian model of navigation in squirrels. Presented at the Proc 33rd Annual Conf Cog Sci Society.
PDF: CogSci 2011 Waisman
Chai, X. J., & Jacobs, L. F. (2010). Effects of cue types on sex differences in human spatial memory. Behavioural Brain Research, 208(2), 336–342. http://doi.org/10.1016/j.bbr.2009.11.039
Chai, X. J., Ofen, N., Jacobs, L. F., & Gabrieli, J. D. E. (2010). Scene complexity: influence on perception, memory, and development in the medial temporal lobe. Frontiers in Human Neuroscience, 4, 21–10. http://doi.org/10.3389/fnhum.2010.00021
Chai, X. J., & Jacobs, L. F. (2009). Sex differences in directional cue use in a virtual landscape. Behavioral Neuroscience, 123(2), 276–283. http://doi.org/10.1037/a0014722
Bettis, T. J., & Jacobs, L. F. (2009). Sex-specific strategies in spatial orientation in C57BL/6J mice. Behavioural Processes.
Preston, S. D., & Jacobs, L. F. (2009). Mechanisms of cache decision making in fox squirrels (Sciurus niger). Journal of Mammalogy, 90(4), 787–795.
Jacobs, L. F. (2009). The role of social selection in the evolution of hippocampal specialization. In L. Tommasi, M. A. Peterson, & L. Nadel (Eds.), Cognitive Biology: Evolutionary and Developmental Perspectives on Mind. Cambridge, MA: MIT Press.
Waisman, A. S., & Jacobs, L. F. (2008). Flexibility of cue use in the fox squirrel (Sciurus niger). Animal Cognition, 11(4), 625–636.
Barkley, C., & Jacobs, L. F. (2007). Sex and species differences in spatial memory in food-storing kangaroo rats. Animal Behaviour, 73(2), 321–329. http://doi.org/10.1016/j.anbehav.2006.07.009
Gibbs, S. E. B., Lea, S. E. G., & Jacobs, L. F. (2007). Flexible use of spatial cues in the southern flying squirrel (Glaucomys volans). Animal Cognition, 10(2), 203–209.
PDF: Anim Cogn 2007 Gibbs
Adams-Hunt, M.M., and Jacobs, L.F. (2007). Learning to forage. In: Foraging: Behavior and Ecology, D.W. Stephens, J.S. Brown, and R.C. Ydenberg, eds. (Chicago, IL, University of Chicago), p. 576.
PDF: 2007 Adams-Hunt
Jacobs, L. F. (2006). From movement to transitivity: the role of hippocampal parallel maps in configural learning. Reviews in the Neurosciences, 17(1-2), 99–109.
Hermes, G. L., Jacobs, L. F., & McClintock, M. (2005). The sectored foraging field: A novel design to quantify spatial strategies, learning, memory, and emotion. Neurobiology of Learning and Memory, 84(1), 69–73.
Preston, S. D., & Jacobs, L. F. (2005). Cache decision making: the effects of competition on cache decisions in Merriam’s kangaroo rat (Dipodomys merriami). Journal of Comparative Psychology, 119(2), 187.
Jacobs, L. F. (2003). The evolution of the cognitive map. Brain, Behavior and Evolution, 62(2), 128–139. http://doi.org/10.1159/000072443
Jacobs, L. F., & Schenk, F. (2003). Unpacking the cognitive map: the parallel map theory of hippocampal function. Psychological Review, 110(2), 285–315.
Preston, S. D., & Jacobs, L. F. (2001). Conspecific pilferage but not presence affects Merriam’s kangaroo rat cache strategy. Behavioral Ecology, 12(5), 517–523.
Jacobs, L.F. (2000). Sexual differentiation and cognitive function. In: Gender and Society: the 1995 Herbert Spencer Lectures, S. Iversen, ed. (Oxford, UK, Oxford University Press).
Lavenex, P., Steele, M. A., & Jacobs, L. F. (2000). Sex differences, but no seasonal variations in the hippocampus of food‐caching squirrels: A stereological study. Journal of Comparative Neurology, 425(1), 152–166.
Lavenex, P., Steele, M. A., & Jacobs, L. F. (2000). The seasonal pattern of cell proliferation and neuron number in the dentate gyrus of wild adult eastern grey squirrels. European Journal of Neuroscience, 12(2), 643–648.
Jacobs, L. F., & Shiflett, M. W. (1999). Spatial orientation on a vertical maze in free-ranging fox squirrels ( Sciurus niger). Journal of Comparative Psychology, 113(2), 116–127.
Barkley, C., & Jacobs, L. F. (1998). Visual environment and delay affect cache retrieval accuracy in a food-storing rodent. Learning & Behavior, 26(4), 439–447.
Lavenex, P., Shiflett, M. W., Lee, R. K., & Jacobs, L. F. (1998). Spatial versus nonspatial relational learning in free-ranging fox squirrels (Sciurus niger). Journal of Comparative Psychology, 112(2), 127–136.
Feener, D. H., Jacobs, L. F., & Schmidt, J. O. (1996). Specialized parasitoid attracted to a pheromone of ants. Animal Behaviour, 51(1), 61–66.
Jacobs, L. F. (1996). Sexual selection and the brain. Trends Ecol Evol, 11(2), 82–86.
Jacobs, L. F. (1996). The economy of winter: phenotypic plasticity in behavior and brain structure. The Biological Bulletin, 191(1), 92–100.
Jacobs, L. F. (1995). The ecology of spatial cognition: adaptive patterns of hippocampal size and space use in wild rodents. In E. Alleva, A. Fasolo, H.-P. Lipp, & L. Nadel (Eds.), (pp. 301–322). Dordrecht: Behavioural Brain Research in Naturalistic and Semi-Naturalistic Setting.
Jacobs, L. F., & Spencer, W. D. (1994). Natural space-use patterns and hippocampal size in kangaroo rats. Brain, Behavior and Evolution, 44(3), 125–132.
Daly, M., Behrends, P., Wilson, M. I., & Jacobs, L. F. (1992). Behavioural modulation of predation risk: moonlight avoidance and crepuscular compensation in a nocturnal desert rodent, Dipodomys merriami. Animal Behaviour, 44(1), 1–9.
PDF: Anim Behav 1992 Daly
Daly, M., Jacobs, L. F., Wilson, M. I., & Behrends, P. (1992). Scatter hoarding by kangaroo rats (Dipodomys merriami) and pilferage from their caches. Behavioral Ecology, 3(2), 102–111.
PDF: Behav Ecol 1992 Daly
Daly, M., Wilson, M. I., Behrends, P., & Jacobs, L. F. (1992). Sexually differentiated effects of radio transmitters on predation risk and behaviour in kangaroo rats (Dipodomys merriami). Canadian Journal of Zoology, 70(9), 1851–1855.
PDF: Can J Zool 1992 Daly
Jacobs, L. F. (1992). Memory for cache locations in Merriam’s kangaroo rats. Animal Behaviour, 43(4), 585–593.
Jacobs, L. F. (1992). The effect of handling time on the decision to cache by grey squirrels. Animal Behaviour, 43, 533–524.
Sherry, D. F., Jacobs, L. F., & Gaulin, S. J. C. (1992). Spatial memory and adaptive specialization of the hippocampus. Trends in Neurosciences, 15(8), 298–303.
Jacobs, L. F., & Liman, E. R. (1991). Grey squirrels remember the locations of buried nuts. Animal Behaviour, 41(1), 103–110.
Jacobs, L. F., Gaulin, S. J. C., Sherry, D. F., & Hoffman, G. E. (1990). Evolution of spatial cognition: sex-specific patterns of spatial behavior predict hippocampal size. Proc Natl Acad Sci USA, 87(16), 6349–6352.
Daly, M., Wilson, M., Behrends, P., & Jacobs, L. F. (1990). Characteristics of kangaroo rats, Dipodomys merriami, associated with differential predation risk. Animal Behaviour, 40(2), 380–389.
PDF: Anim Behav 1990 Daly
Sengelaub, D. R., Jacobs, L. F., & Finlay, B. L. (1985). Regional differences in normally occurring cell death in the developing hamster lateral geniculate nuclei. Neuroscience Letters, 55(2), 103–108.