Grandmas are the foundation of family life, community, and work. Researchers now believe that they might also be a key component in the lives of giraffes.
According to experts, female giraffes can live up to eight years after the time they stop reproducing.
According to Dr Zoe Muller (a University of Bristol giraffe expert and co-author of this research, female adults live longer lives than their child-bearing years.
This trait was once considered an anomaly in nature. It is only humans and killer whales that are known to experience the menopause. The latter spends about 35% of their lives in a post-reproductive condition. Other animals, such as elephants, can also live many years after losing their fertility or ending it.
Muller observed that the phenomenon of long post-reproductive lives has led to the grandmother hypothesis, a theory that may not be without controversy. It suggests that post-reproductive women help with the survival and rearing the offspring of their relatives.
Muller stated that elephants have a reputation for having older matriarchs and post-reproductive women are considered to be knowledge repositories. Research has shown that in times of drought and famine, the survival rate of a group with older females is higher when they have grandmothers.
Similar benefits were seen in killer whales orcas when grandmothers were present.
Muller stated that this would indicate that the older females help the group to find resources during difficult times. Complex social animals can benefit greatly from older females staying around after having children.
Muller and Prof Stephen Harris, her co-author, wrote in the journal Mammal Reviews. They analyzed the evidence to suggest that post-reproductive females (or grandmothers) may play a similar role within the social systems for giraffes.
Muller stated that giraffes have traditionally been seen as very unsocialized, one-dimensional animals. They don't have any social systems and are just kinda aloof and move about randomly.
She said that her research and the findings of the new review of evidence suggest otherwise. Evidence of giraffes and elephants having complex social systems and living in matriarchies suggests that they may have an intricate social system.
Although it hasn't been proved, it is most likely because in complex societies, where grandmothers are still around, they often transfer survival benefits along matrilineal lines to related animals so that they can look after their children and their sisters, Muller said.
This does not necessarily mean that males are submissive. However, it does indicate that the social system's core units are made up of females just like humans. Our hunter-gather societies had groups that were made up of women.