Summary: Kessler et al. (2012)

The evolution of social systems has been largely influenced by kin selection. Within a social group, the ability to recognize paternal kin is important for minimizing inbreeding and loss of genetic diversity. Kessler et al. (2012) investigated vocal paternal kin recognition in the grey mouse lemur (Microcebus murinus), one of the first studies to do so. They analysed ultrasonic male courtship and alarm calls, and found that advertisement calls contain patrilineal signatures, which females use to assess relatedness of males. Alarm calls did not seem to contain these signatures. Kessler et al. (2012) conclude that paternal kin recognition is not reliant on brain size or social complexity, but could be the ancestral state from which more complex, kin-based sociality has arisen.

Summary: Foster et al. (2012)

Postmenopausal life span in humans has encouraged studies investigating the evolution prolonged post-reproductive life span in other animals. Two mechanisms are proposed: 1) increased longevity - evolutionary benefits accumulate only during the reproductive phase; 2) evolved adaptation - the post-reproductive life span increases individual "genetic" survival, resulting in increased inclusive fitness. Foster et al. (2012) used a Cox proportional hazards model (6) to study the influence of a mother killer whale’s (Orcinus orca) death on offspring survival. Neither sex disperses from the maternal group, so old mothers can maximise their inclusive fitness by increasing offspring survival and reproductive success. In addition, mothers should only help sons, as mating occurs outside the matriline. Foster et al. (2012) showed that old females assist male offspring. As reproductive success increases with male age, increased survival of sons increases the inclusive fitness of mothers. Mothers can assist with foraging or will provide support during agonistic encounters. Foster et al.'s (2012) results support the premise that a long post-reproductive life span is an evolved adaptation.