Posture does not matter! Paw usage and grasping paw preference in a small-bodied rooting quadrupedal mammal.
BACKGROUND
Recent results in birds, marsupials, rodents and nonhuman primates suggest that phylogeny and ecological factors such as body size, diet and postural habit of a species influence limb usage and the direction and strength of limb laterality. To examine to which extent these findings can be generalised to small-bodied rooting quadrupedal mammals, we studied trees shrews (Tupaia belangeri).


RESULTS
We established a behavioural test battery for examining paw usage comparable to small-bodied primates and tested 36 Tupaia belangeri. We studied paw usage in a natural foraging situation (simple food grasping task) and measured the influence of varying postural demands (triped, biped, cling, sit) on paw preferences by applying a forced-food grasping task similar to other small-bodied primates. Our findings suggest that rooting tree shrews prefer mouth over paw usage to catch food in a natural foraging situation. Moreover, we demonstrated that despite differences in postural demand, tree shrews show a strong and consistent individual paw preference for grasping across different tasks, but no paw preference at a population level.


CONCLUSIONS
Tree shrews showed less paw usage than small-bodied quadrupedal and arboreal primates, but the same paw preference. Our results confirm that individual paw preferences remain constant irrespective of postural demand in some small-bodied quadrupedal non primate and primate mammals which do not require fine motoric control for manipulating food items. Our findings suggest that the lack of paw/hand preference for grasping food at a population level is a universal pattern among those species and that the influence of postural demand on manual lateralisation in quadrupeds may have evolved in large-bodied species specialised in fine manipulations of food items.
Institute of Zoology, University of Veterinary Medicine Hannover, Hannover, Germany. marine.joly@tiho-hannover.de
Marine
M
Joly
Marina
M
Scheumann
Elke
E
Zimmermann
D000818:Animals; D049628:Body Size; D005121:Extremities / Q000502:physiology*; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D008297:Male; D011187:Posture; D014417:Tupaia / Q000502:physiology*