Suffering from a bad back or painful wisdom tooth? You should blame evolution

Walking on two legs causes a host of back problems for our species

Our climb to the top of the evolutionary tree to become the planet’s most intelligent species has not come without its drawbacks.
Some of humanity’s most troublesome ailments, from back pain to our expanding waistlines, are a result of our early primate origins, say scientists.
With almost seven billion humans now on earth, our unique adaptations such as larger brains and ability to walk on two legs have clearly proved a success in the survival stakes. But these evolutionary changes are also responsible for a number of our most common ills.
Our increased brainpower has limited the amount of room left in our skull for less important body parts, such as teeth.
One often painful consequence of developing bigger brains is impacted wisdom teeth – where there is not enough room in our mouth for our final set of molars to emerge.
Princeton University anthropology professor Alan Mann said as a result ‘in many adolescent humans, the last tooth to erupt in human dental development, the third molar - the perhaps misnamed ‘wisdom tooth’ - cannot erupt normally’.
He added: ‘This condition can lead to chronic pain and to reduced reproductive fitness, but not generally death.’
Up to a quarter of the world’s population is now born without at least one wisdom tooth, which professor Mann suggesting it could well be a result of natural selection.
He said: ‘One plausible scenario might be as follows: One evening, a partner in a relationship suggests a bout of reproduction. The other partner, plagued by an impacted third molar which is painful enough to be distracting, says: 'not tonight dear, my jaw is killing me'.

The limiting of reproductive behaviour limits the number of offspring and thus, over generations, people who do not have this particular distraction, will have a slighter greater number of children.’
Evolution has also caused problems at the other end of our bodies - the foot - according to findings presented at the American Association for the Advancement of Science’s annual conference.
Researchers have found the transition from a mobile, grasping foot, such as found in other primates, to a more stable platform used for movement has come at a price.
Professor Jeremy DeSilva, from Boston University, said our evolution has left us ‘particularly susceptible to a variety of foot and ankle injuries’.
‘Many human foot problems are a result of our evolutionary history. In other words, we are not very well designed, because we were not designed,’ he said.

Tooth pain: We suffer from impacted wisdom teeth as increased brain size has left less room in the mouth

He pointed out that our modified ape feet are made up of 26 individual moving parts which ‘is essentially the biological equivalent of paper clips and duct tape’.
Using evidence from fossil records, he found ‘that we have long suffered foot problems, demonstrating that many modern foot ailments are not solely the result of our more recent, sedentary lifestyle’.
Walking on two legs is regarded as a defining characteristic that marks the difference between humans and apes. But learning to walk on our extended hind limbs has resulted in a host of back problems.
‘In turning a spine originally adapted for a quadruped into one that is perpendicular to the ground has resulted in numerous problems that are unique to our species,’ said Dr Bruce Latimer from Case Western Reserve University in Cleveland.
‘Included in such uniquely human maladies are spondylolysis, spondylolosthesis, herniated discs, spontaneously fractured vertebrae, kyphosis, and scoliosis.’
Thanks to evolution, our bigger brains needed more energy, with early humans developing foraging strategies that provided high-quality foods and required moving over larger ranges.
But with food now readily available and humans expending much less energy in their daily lives, there is increasing concerns that our diets are at odds with our lifestyles.
‘Over time, human subsistence strategies have become ever more efficient in obtaining energy with minimal time and effort,’ said Professor William Leonard from Northwestern University in Illinois.
‘Today, populations of the industrialized world live in environments characterized by low levels of energy expenditure and abundant food supplies contributing to growing rates of obesity.’
One way we can redress the balance is to take more exercise. Prof Leonard added: ‘Recent recommendations on physical activity have the potential to bring daily energy expenditure levels of industrialized societies surprisingly close to those observed among subsistence-level populations.
'These findings highlight the importance of linking physical activity and dietary recommendation in promoting nutritional health.’