We getting shorter and our brains are shrinking

People have got shorter and our brains have shrunk - and scientists believe farming could be to blame. Modern humans are about 10 percent smaller and shorter than our hunter-gatherer ancestors, scientists have found, and our brains have fallen in size by the same proportion. Most of that decline in physical size has occurred since the advent of farming about 10,000 years ago. The findings run contrary to the popular notion that humans are growing progressively larger and taller. Research shows that declines in height occurred in 19 of 21 societies that switched from hunter-gathering to farming - perhaps the greatest change in lifestyle in human history. The findings pose a puzzle since societies that switch to farming usually experience a population boom as food becomes more plentiful. Decline in stature is a phenomenon more commonly linked to food shortages and malnutrition. Amanda Mummert, an anthropologist at Emory University in Atlanta, Georgia, suggests the drop in heights could be linked to a shortage of micro-nutrients as human diets took in less variety. Although calories were abundant, the vitamins and minerals essential to growth - and which are only gained through a varied diet - may have become less common in people's diets. One example of such a change was in China, where early farmers relied on cereals like buckwheat, maize and rice - all of which lack niacin, a vital nutrient for growth. 'This counter-intuitive increase in nutritional diseases resulted from seasonal hunger, reliance on single crops deficient in essential nutrients, crop blights, social inequalities and trade,' she told the Sunday Times. Systematic studies of fossilised human remains found across Africa, Europe and Asia seem to back up Miss Mummert's findings. According to Dr Marta Lahr, co-director of Cambridge University's Leverhulme Centre for Human Evolutionary Studies, when human beings first emerged, around 200,000 years ago, they were tall and muscular. The earliest human remains yet discovered date back to this time, and were found in Ethiopia. According to Dr Lahr, these people had cranial features similar to modern humans, but were significantly larger and more robust. Human fossil evidence over the next 190,000 years is patchy and incomplete, but it shows that humans remained tall and robust even as human culture began to emerge, as shown by the appearance of tools, weapons, needles and even musical instruments. This size was maintained until about 10,000 years ago - the time of the advent of farming - when many populations began to show reductions in stature - and brain size. But other researchers are less certain about the role agriculture has played in shrinking human proportions. Chris Stringer, professor of human origins at the Natural History Museum in London, concedes that early humans were had bigger bodies and brains than modern people. 'Some of this must be down to the demands of a Palaeolithic lifestyle in terms of a strong-muscled skeleton on the one hand, and the shielding effect of cultural innovations and a more sedentary lifestyle on the other, but it is unclear whether that is the whole story,' he told the Times. The height difference between early and modern humans may even out, as improved nutrition in recent decades seems to be leading to a sharp increase in people's weight and height. But even if agriculture were the reason why modern humans are smaller than our forebears, it would not solve the puzzle of why brains have also shrunk. The Homo sapiens with the biggest brains lived 20,000 to 30,000 years ago in Europe. Known as Cro-Magnons, they were tall with barrel chests and large jaws. Their brains had an average volume of 1,500cc. These days, the male human brain averages 1,350cc, a decrease equivalent in volume to a tennis ball. Female brains have shrunk by about the same proportion. Dr Lahr thinks that part of the answer may lie in improving efficiency - brain function commands about a quarter of all the energy used by the body. Like advances in silicon chip technology, huge energy savings can be made by getting the same work out of less equipment. 'We may have smaller brains than early humans but it doesn't mean we are less intelligent,' she said.