Researchers have provided new insights into the evolutionary origin of sideways walking in crabs. Their study, published today as a Reviewed Preprint in eLife, presents the largest comparative dataset on crab locomotion to help understand the origins of the animals' iconic walk, tracing it back to a common ancestor around 200 million years ago. eLife's editors say the work is valuable, with largely convincing evidence, and will be of interest to others studying animal locomotion.