In the last 10,000 years, humans have got smaller and our brains have shrunk
I suppose I should say a few words about the story below. The facts as given are sound but they omit to mention that the decrease in brain size in late prehistoric times was linked to known brain mutations (genes MCPH1 and ASPM) taking place at that time which seem to have led to an increase in IQ -- as indicated by the sudden arrival of early civilization in the Middle East. What presumably happened was an increase in the degree of folding in the brain, thus giving a bigger surface area even while overall size decreased. In short, human brains with the mutation became more efficient at that time.
And once civilization had arrived, selection for hunter characteristics (height, muscle etc.) diminished greatly, leading to a shrinking in those attributes. Social characteristics (e.g. verbal ability) were selected for instead
Having conquered Everest and landed on the Moon, it is tempting to think we are bigger and better than our ancestors. But on a purely physical basis, it seems, we just don’t measure up. Mankind is actually shrinking.
Cambridge University experts say humans are past their peak and that modern-day people are 10 per cent smaller and shorter than their hunter-gatherer ancestors.
And if that’s not depressing enough, our brains are also smaller.
The findings reverse perceived wisdom that humans have grown taller and larger, a belief which has grown from data on more recent physical development.
The decline, say scientists, has happened over the past 10,000 years. They blame agriculture, with restricted diets and urbanisation compromising health and leading to the spread of disease.
The theory has emerged from studies of fossilised human remains found in Africa, Europe and Asia. The earliest, from Ethiopia, date back 200,000 years, and were larger and ‘more robust’ than their modern-day counterparts, said Dr Marta Lahr, an expert in human evolution.
Fossils found in Israeli caves and dating from 120,000 to 100,000 years ago, reveal a people who were tall and muscular, a pattern that continued uninterrupted until relatively recent times. An average person 10,000 years ago weighed between 12st 8lb and 13st 6lb. Today, the average is between 11st and 12st 8lb.
Dr Lahr, who last week presented her findings to the Royal Society, Britain’s most prestigious scientific body, described the changes as ‘striking’. ‘We can see that humans have continually evolved but in body size it is not until the last 10,000 years that they have changed substantially, so the question is why this should have happened.’
The male brain of 20,000 years ago measured 1,500 cubic centimetres. Modern man’s brain averages just 1,350 cubic cm – a decrease equivalent to the size of a tennis ball. The female brain has shrunk by about the same proportion. It doesn’t mean we are less intelligent – rather we have learnt to make the best use of our resources.
Dr Lahr said: ‘Over evolutionary time there would have been huge energy savings in making the brain smaller but more efficient – as we see today with computer processors.’
Robert Foley, a Cambridge University professor of human evolution, said: ‘Becoming human, in an evolutionary sense, is a continuous and gradual process. Our species, rather than being a fixed entity, is more like a piece of putty, changing shape and dimensions all the time.’