The fact that many people's backs and feet hurt is news that's millions of years old.
It's because of the way we have evolved, uniquely from other mammals, that we also have a lot of aches and pains that our close relatives do not experience, anthropologists said last weekend at a briefing at the American Association for the Advancement of Science annual meeting.
"We've known for a long time, since Darwin's time, that humans have evolved, and that humans are not perfect, because evolution doesn't produce perfection," said Jeremy DeSilva, anthropologist at Boston University.
For instance, humans are the only mammals that can have scoliosis, a condition in which the spine has an abnormal curvature, said Bruce Latimer of Case Western Reserve University in Cleveland, Ohio.
Owners of a Homo erectus skeleton from around 1.5 million years ago and the Lucy skeleton, more than 3 million years old, both appear to have had back problems, Latimer said.
Humans evolved from an animal whose back was horizontal, parallel with the ground. But the human spine evolved to be upright, and the body needed to balance over hips and feet. That's why the spine needed curves in it, but it's still not an optimal system.
Over the course of a lifetime, with the stresses and loads of daily activities, we're apt to develop problems such as a herniated disk. Even walking, with the process of moving our arms and legs to carry an upright back, results in a constant twisting and torquing of the spine, Latimer said. No other animal has to deal with a mechanical system in this way.
Evolution is a process that tinkers with existing materials; it can't create perfection, Latimer said. "You use paper clips and duct tape to make these things work. You can't invent a brand new spine."
Humans are also the only mammals that carry things in front of them. It's recommended that you bend your knees when picking up something heavy to reduce the force on the spine, but you might find yourself in pain one day while bending over to lift a grocery bag from the trunk of your car.
"The design specs on your body are about 45 or 50 (years old)," Latimer said. "If you take care of it, your spine will get you through that. But after that, you're on your own."