Study of manual actions during tool use among wild primates is essential for understanding the evolution of the manual dexterity and flexibility that underlie these skilled behaviors.We describe how chimpanzees in the Goualougo Triangle use herbaceous probes to fish for termites from labyrinthine, epigeal nests.Using remote video footage (30 fps), we coded the fishing techniques of seven female chimpanzees (five adults and two sub-adults).With a coding scheme of 20 actions and 70 modifiers, we analyzed frame by frame 16 clips lasting approximately two minutes each.We recorded hand position, grips and readjustments, oscillations of the inserted tool, the location of the insertion point with respect to eye level, and the form of feeding actions for 410 attempted insertions, of which 334 succeeded.All the chimpanzees used a wide variety of actions, and we did not detect clear individual patterning or differences in success rates.Insertions at eye level (vs.above or below eye level) were more numerous (M = 29 vs. 15, NS, Wilcoxon signed ranks).Chimpanzees occasionally aided insertion with a second hand (M = 28%, range 5-50%) and occasionally failed to insert the probe (M = 24%, range 12 -37%).Our findings indicate that experienced chimpanzees manage the fishing task flexibly, often using complementary bimanual actions, and suggest that insertions at eye level are preferred.
Motivated by the question of computing the probability of successful power domination by placing k monitors uniformly at random, in this paper we give a recursive formula to count the number of power domination sets of size k in a labeled complete m-ary tree. As a corollary we show that the desired probability can be computed in exponential with linear exponent time.
Motivated by the question of computing the probability of successful power domination by placing k monitors uniformly at random, in this paper we give a recursive formula to count the number of power domination sets of size k in a labeled complete m-ary tree. As a corollary we show that the desired probability can be computed in exponential with linear exponent time.
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