Bipedalism is one of the defining characteristics that sets us apart from other animals - but we're not as good at it as we think.
That's the finding of researchers at the University of Purdue in the United States, who studied a sample of 91 people over a period of 16 weeks.
The team of kinesiologists - experts on the mechanics of body movement - selected a group of fit and healthy undergraduate students, and asked them to record any trips, slips or falls they experienced within a 24-hour period.
In a daily email survey, the scientists asked each volunteer to record when a "foot or shin contacted the ground or other object unexpectedly," a "foot slipped while in contact with the ground," or when there was "an undesired contact of any body part (other than your feet) with the ground of lower surface."
When a student reported any incident, the researchers then followed up with a series of questions about its circumstances.
The results found that 52 percent of survey respondents fell over during the 16-week research program, with 58 percent of falls occurred while simply walking.
48 percent of the volunteers slipped, while 25 percent of the time they tripped.
In many instances ice and snow was to blame, but even when winter weather conditions were taken into account, 30 percent of respondents were found to have taken some kind of stumble or tumble.
The result? Walking is hard.
Or, as the researchers wrote in their paper published in the journal Human Movement Science:
"The fact that the majority of falls occurred while walking supports the prevailing argument that bipeds [animals with two feet] are mechanically unstable and also demonstrates that walking is a challenging task.
These results address an understudied yet important question, and highlight the mechanically unstable nature of bipedal locomotion."
The findings suggest that clumsiness and mobility problems are not the exclusive domain of the very young or the very old.
Even after millennia of standing on our own two feet, we're still learning to walk.
