As the Bee Gees sang in their seventies hit Staying Alive, there's a lot you can tell from the way someone uses their walk. And now it seems that our ancestors may have been walking like us for at least 1.5 million years.
That's according to a study published this week in the journal Science by a team led by Matthew Bennett from Bournemouth University in the UK, who have uncovered two sets of fossilised footsteps thought to have been left behind by Homo erectus strolling through deposits of volcanic ash near Lake Turkana in northern Kenya between 1.53 and 1.51 million years ago.
Walking on two feet is a key human adaptation that first evolved around 6 millions year ago, but until now there's not been enough evidence for when the modern human gait first evolved. Apparently there aren't many feet in the fossil record, possibly because predators and scavengers like to eat them.
The oldest known footprints from the human lineage are from Australopithecus afarensis 3.7 million years ago, but those footprints from Tanzania revealed that are ancestors at that stage were waking around with a more ape-like gait, with a splayed big toe and a foot generally suited for grasping things rather than walking along the ground.
These newly discovered tracks have a shape much more similar to what you leave behind when you walk along a beach. As we walk, we first put down our heal which makes a deep impression in the sand, then we move our weight to the ball of the foot - again making a deep impression - then we propel ourselves forward on our toes, and most importantly our big toe which lies in line with our feet.
It's incredible to think that just a few individual Homo erectus left their footprints in the mud which then turned to stone to be found a million and a half years later by their descendants and used to help unpick one of the great mysteries of human evolution.