Researchers at the University of Zurich have released a study that shows the extent to which paternal assistance while bringing up baby mammals increases brain sizes, and thus intelligence.
The bigger the brain, the smarter the mammal. This statement has been proven, yet what was left to speculation was exactly how did the brain become bigger in the first place.
Another known fact is that in order for females to raise their young properly they are dependent on assistance from those around her.
Big brains come at a price. The bigger the brain, the more energy the mammal requires to fuel it adequately, so an infant consumes two-thirds of its energy purely on caring for its brain. This energy comes from milk and subsequently food. A mother alone cannot easily provide enough for her young, especially when it is a bigger litter.
She thus depends on the assistance of those in her pack, or those around her.
Fathers are the most reliable
Up until now there was no differentiation as to the importance of a father or other group members in helping a mother rear her young. This is precisely what evolutionary biologist Sandra Heldstab and her colleagues from the Anthropological Institute of the University of Zurich are showing for the first time: that it definitely plays a role.
In their study, researchers sampled around 480 mammal species and compared brain sizes and the extent and frequency of fatherly care and those of other group members.
Heldstab says, "Fathers help the boys rearing consistently and reliably, while the support of other group members such as older siblings is much less reliable."
For example, once siblings become sexually mature they typically leave the group and join another, whereas fathers remain behind. Furthermore, paternal assistance is usually more experienced compared with younger, less mature members of the group or pack.
Evolution kicks in
Evolution will take an alternative path if the support for the female in raising her young is unstable. For instance, the mother will start producing larger litters, with smaller-brained offspring. If she receives enough help, they all survive. If she doesn't, the opposite happens.
So in terms of evolution, it ensures that even with little help, some of the little ones survive even if the mother does not necessarily put in much energy into assisting only one big-brained mammal to survive due to unreliable assistance.
Thus, the research demonstrates that only a stable and reliable energy supply - for example through paternal help - enables a big brain in the course of evolution.
Humans as the exception
People, however, operate differently. Due to circumstance, for example, the help of other relatives or non-relatives such as child care, are readily available to most humans. In turn, this allows humans to develop larger brains, the largest in the entire animal kingdom in relation to body size.
"Mammals can only rely on the help of their fathers. Fortunately, we humans can rely on the help of others,"says Sandra Heldstab.