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The humans we are today are drastically different from our centenarian ancestors and even more so from our relatives born before that. We have gotten physically taller, intellectually more advanced and have developed an advanced immune system capable of battling more diseases than ever.

A human infant's brain is the largest among all primates; however they also maintain the highest proportion of body fat. The supply of nutrients from mother to unborn child is limited and unbalanced due to the infant's body and brain battling against one another for resources.

Scientists at the University of Southampton have shown that this decision could have an effect on how fat we are as children. They measured the blood flow from the placenta to the unborn baby of 381 pregnant women and the distribution of this blood to either the liver of the baby or bypassing the liver to supply the brain and heart. This was then compared with the infant's body fatness at birth and at four years old.

According to the University of South Hampton, The findings suggest that greater blood flow to the baby's liver in late pregnancy was associated with greater body fatness in the infant at birth and at age four. In contrast, lower liver blood flow and a "brain-sparing" blood flow pattern (when the blood bypasses the liver and goes to the brain) occurred when the placenta was smaller and less able to meet the baby's demand for essential nutrients in the womb.

 "In our evolutionary past, the demands of a big brain have led the unborn baby to develop blood flow responses," explains Keith Godfrey, Professor of Epidemiology and Human Development, at the University who led the study, "which preserve nutrient delivery to the brain when the supply of essential nutrients from the mother cannot meet the baby's requirements."

"Our data suggests that to adjust blood flow through the baby's liver enables the liver to produce more fat -- this acts as an energy reserve, protecting brain development during periods of illness or under-nutrition in early infancy. This strategy has brought with it a predisposition to obesity and later diabetes in contemporary societies with abundant nutrition in later postnatal life."

Professors Guttorm Haugen from the University of Oslo and Torvid Kiserud from the University of Bergen were part of the research team. They add, "Although further studies are needed, our findings add weight to current concerns that the current epidemic of childhood obesity and associated disorders may partly have its origins through adaptations made by the developing baby during pregnancy."

Although the findings were independent of an association between the mother's body fatness and the body fatness of her infant, a mother's nutritional and lifestyle decisions can affect the nutrients allocated to the child, thereby reducing the risk of obesity in their children and improving the health of the next generation.