Interchange Between Social Grooming And Infant Handling In Female Tibetan Macaques (Macaca Thibetana)

Infant(0-1 year old)is a basic components in multi-male multi-female nonhuman primates society,it has been considered as a social mechanism to bridge social relationships among group members,it plays an important and unique role in groups.Infants are very attractive to group members,and mothers control group members' access to.them.However,some group members(such as females and adolescent individuals)were still trying to contact with the infant,these creates Infant handling behaviors.Infant handling behaviors included group members(besides mothers)inspect,teeth-chatter,hold,groom and bridge infants.Grooming behavior is widespread among nonhuman primates and promote affinity among group members.For the grooming receiver,the grooming behavior has many benefits such as removing the skin parasite,relieving or reducing stress,stabilizing the heart rate,and improving fitness.Biological market theory suggest that grooming behavior can be regarded as a kind of behavior commodity,and it could be interchanged for different social behaviors,such as support in agonistic encounters,mating opportunities,tolerance,sharing of food and infant handling behavior.However,infant as a limited resource,the degree of exchange between the mother and the non-mother is not clear.This study was conducted during two periods:July 2016 to January 2017,and March to May 2017.We used focal animal sampling method and behavioral sampling to collected the behavior sampling about adult female in tibetan macaques(Macaca thibetana)YA1 group,in order to explore the form of infant handling in female tibetan macaques,and the relationship between grooming and infant handling behavior in macaques group,and how the market force and other factors effect the interaction.The main results are as follows:(1)The highest frequency of infant handling in female tibetan macaques is Bridge(0.68±0.10 times/h(mean±SE)),followed by Inspect(0.67±0.17 times/h(mean ±SE)),and the least frequent occurrence is Hold(0.21 ±0.21 times/h(mean±SE)).For parous females,the highest frequency of infant handling is Bridge(0.90±0.1 times/h(mean±SE)).For nulliparous female,the highest frequency of infant handling is Inspect(0.97±0.11 times/h(mean±SE)).There was no significant difference in the frequency of infant hanlding between the male infant and the female infant.(paired t-test:df=4,t=239,P=0.823).(2)The duration of grooming in which mothers gave to non-mothers before birth was significantly longer than after birth(t= 6.233,df= 5,P= 0.002).The duration of grooming in which mothers received from non-mothers after birth was significantly longer than before birth(t =-4.218,df= 5,P = 0.008).(3)The mean frequency of infant handling was significant higher in PG samples than in focal samples(t = 7.642,df= 10,P = 0.000).The mean frequency of infant handling was significant higher in PG samples than in MC samples(t = 5.858,df= 10,P = 0.000).(4)The duration of grooming was significantly higher in PH samples than in focal samples(t = 7.679,df = 10,P =0.000).The duration of grooming was significantly higher in PH samples than in MC samples(t = 6.475,df = 10,P =0.000).(5)The number of infants per female was negatively correlated with the duration of grooming at which non-mothers gave to mothers during grooming-infant handling interchange(R = 0.624,F = 93.271,P = 0.000).The infant age was negatively correlated with the duration of grooming at which non-mothers gave to mothers during grooming-infant handling interchange(R = 0.634,F = 98.128,P = 0.000).(6)The rank distance between mothers and non-mothers was negatively correlated with the duration of grooming at which non-mothers gave to mothers during grooming-infant handling interchange(R=0.277,F=12.088,P=0.001).There was no significant difference about the duration of grooming non-mothers gave to mothers between kin and non-kin(t = 0.758,df= 4,P =0.491)?These result suggest that there was a interchange between grooming and infant handling in female tibetan macaques.Non-mothers interchange grooming for infant handling,and mothers interchange grooming for infant handling.The biological market theory is further demonstrated,and this study is helpful to understand the role and significance of infant in group relationships.