IS evolution itself driving America's growing rejection of modern biology? New studies suggest this very thing.

Today's revelation that one-third of the US population rejects the idea of evolution and instead believes we were created through intelligent intervention is nothing new.

The fact that only a third of us accept that "natural processes such as natural selection" are behind our existence has had science thinking for some time.

Creationism is growing into a powerful political force. But the strength of their arguments and the forcefulness of their campaign does not entirely explain its growing success.

The debate has heated up in recent years as and a so-called "culture war" is being waged across a deepening partisan divide.

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So why does the concept of evolution cause so much upset in an era overwhelmed with science - be it in medicine, transport, communication and calculation?

"Natural selection is like quantum physics ... we might intellectually grasp it, with considerable effort, but it will never feel right to us," writes the Yale psychologist Paul Bloom.

It's about the nature of our brain. It's an amazing device at finding new and successful ways to adapting to an ever-changing world - with the minimum of effort.

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The brain has evolved, psychologists argue, to conserve its energy and speed up its processes through a series of "mental shortcuts".

This "unwillingness" to expend mental energy may be behind the difficulty of accepting complex ideas such as evolution.

Those shortcuts affecting the evolution-versus-creation debate include:

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CATEGORISATION: Our brains like neat, clearly defined categories. It helps filing things away in our memories easier. Called "essentialism", scientists feel this mental characteristic makes us want to think of different animal species as fundamentally different - instead of fundamentally similar. It makes sense: Birds have wings. Fish have fins. Accepting that they have a common ancestor appears on the surface to be counterintuitive. Understanding that similarity takes time and effort - something our brain's are not naturally inclined to do.

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CHALLENGED COMPREHENSION: The universe operates on a scale far, far vaster than the human world. Be it time. Be it space. Both are incomprehensible to most of us. And those that do need abstracts, such as mathematical equations, to give it a form of perspective.

This makes the concept of many small changes accumulating over the course of millennia push the boundaries of our comprehension. What is millennia anyway? It means little to an individual whose lifespan extends a mere 80 or so years.

It's not an intuitive concept. It doesn't fit with what we've experienced. Therefore the brain argues it isn't "common sense".

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ANTHROPOMORPHISING: This is the human tendency to give inanimate objects "minds of their own". For example; "the wind is fierce", "my computer hates me" and "it's Murphy's Law". It's a natural next step to attribute actions, activities and processes to a supernatural being or beings.

Scientists argue this trait evolved as part of our natural "fight-or-flight" stress response process. Our brains have developed to assume that objects are "alive" and therefore a threat. For example, if you discarded that scary moving shadow as being 'just a tree-branch' when it was in reality a sabre-toothed cat, you'd be dead. In such a case, the survivors would be those who "jump at shadows".

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EVERYTHING HAS MOTIVE: This mental tendency is particularly evident in children. Everything is deliberate. Everything is directed at ourselves as individuals. Everything has a purpose. In short: "Clouds are for raining on me".

Science believes this is a side-effect of our social natures. We have evolved to think about what other people are thinking in terms of objectives and motives in order to survive and advance in our social worlds. The brain just over-applies this attribute to the whole universe, including inanimate objects.

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TRIBALISM: Again, our social selves may get in the way of a challenging idea. The emotional need to belong to a group of people can easily overpower the cold, hard mental challenge of accepting an "outside" idea.

Science has long accepted that religion serves as a strong "social glue". It produces unity - an evolutionary advantage when it comes to surviving as a group. But the same trait that produces religion also produces politics, tribalism and nationalism. New ideas always find such attitudes challenging.

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But the debate isn't as simple as the above may imply.

And religion itself - while often the public face of the debate - does not appear to be totally to blame.

Today's survey also found strong differences among religious groups.

Two thirds of US white evangelical Protestants believe God created humans in their present form while 78 per cent of white "main line" Protestants believe in evolution.

Three out of four religiously unaffiliated respondents believe in evolution and just 13 per cent of them believe evolution was guided by a "supreme being".

The political divide is a little more clear-cut.

Only 43 per cent of US Republicans believe in evolution while 67 per cent of Democrats said humans have evolved over time

So blaming religion may be as lazy a mental process as the outright rejection of evolution.

Scientists argue it is just one byproduct of the basic mental traits our brain has evolved to cope with a challenging world.

Our mental programming combined with our emotional drives is what makes it so hard to accept mind-numbing concepts such as time and space.

Evolution is just the topic of the moment.

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