The Role of the Elderly
Origins of Us - Brains
To understand how a long childhood growing those big brains has affected our species, I've come back to Africa. I've come to meet the Hadza trice in northern Tanzania. These are modern people, but living in a similar way to our ancestors, and their lifestyle gives us an insight into how we all evolved.
I want to talk to the women about something which affects all human societies, it's a great concern to all of us, and that's childcare.
Getting enough food to feed everyone takes a long time. Looking after young children whose brains are still developing is hard work. Nibala has five children and she's got another on the way.
Nibala and children
Dr Roberts asks "Nibala, how long did you breastfeed your babies for?" Nibala replies "I breastfed my kids for 3 years then in the fourth year I weaned them."
Nibala is astounded to hear that Dr Roberts has a child that is being bottle-fed and cared for by her husband. Alien concepts that sound odd and unnatural to her.
It's normal for women here to have a baby every two to three years. Feeding the older children while breastfeeding is very difficult without help.
For Nibala, the only way she can collect enough food is with help from her mother. As in many humasn cultures, it's the grandmother's that play a vital role in caring for their grandchildren. It's thought that the need to have extra help from older women has actually affected how long we evolved to live for. Magdalena is in her seventies and helps to look after five grandchildren. And Magdalena isn't unusual. Even without modern medicine, many Hadza live well into their seventies.
Having grandmothers around like this to help look after and provide for the children is such a great advantage, and one that may have driven the evolution of our unique life histories, where women survive for decades after their reproductive years, after the menopause.
The fact that women live long past the end of their reproductive years originally baffled scientists. But it's now thought that, by living into old age and looking after their children, grandmothers could help their daughters produce lots of children in quick succession. By living longer, our species is able to breed more quickly, in far greater numbers than any other ape. And this population growth has ensured the success of our species.
Grandmothers and grandfathers would not only pass on important information to the younger generation, but by supporting their children and grandchildren, they would help the human population to expand, and eventually spread across the globe.