(see Appendix C). However, they share in mating with oestrous females. And in their
territorial behaviour they act together on behalf of the community. At Sonso we have
some evidence of patrolling by adult males, and of territorial defence (see below). So,
while maternal kinship functions as a critically important nurturing and social learning
device, paternal kinship functions to protect the community in its home range and to kill
young infants of non-community males if their mothers bring them in, thus returning
their mothers to reproductive condition.
Because males remain resident in the community, they are a close-knit group and
have an extremely detailed working knowledge of their range, its food sources and
dangers. They groom each other with high frequency and intensity (see next chapter).
Their genetic relatedness is, however, less close than might be imagined because their
mothers have come from a number of other communities and their sexual partners
likewise. Thus there is a constant influx of genes from outside, ensuring genetic variety
down the generations (see Appendix C).
The median birth interval for known births at Sonso is 66.05.0 months (Emery
Thompsonet al. in press). The first recorded birth (Bahati) took place in 1994, so the
kinship structure of this community lacks depth at the present time. Of our adult
females, only one (Zimba) is knownto be a grandparent (daughter Kewaya, grand-
daughter Katia), others may be but we cannot be sure. The maternal kinship relation-
ships we know of from births observed during our study period, and from our genetic
studies, are shown in Table 5.7.
102 Social organization
Table 5.7: Maternal kinship in the Sonso community. Offspring are designated by codes in the
table; those in parentheses were born outside the community and immigrated with their mothers
(see text). Birth years are estimated before 1995.
Year of Before 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
birth 1990
Mother
Banura ZF SH BT BE
Clea CT
Flora (FD) (FK)
Harriet (HW) HL
Janie JT
Kalema BH KM
Kewaya KA
Kigere KD KE KI
Kutu KT KN KS
Kwera KZ KR
Melissa (MR) MN
Mukwano MD
Nambi AY MS NR NT
Polly (PS)
Ruda BO RE
Ruhara NK GT RS RM
Sabrina (SA)
Wilma (WS)
Zana ZL ZD
Zimba KY GZ ZG ZK