In a suspension of disbelief, the countless readers who have picked up J.R.R. Tolkien’s Lord of the Rings books have readily accepted that Ents, the ancient treelike creatures of the fictional Fangorn forest, walk, talk and even dispense wisdom for hobbits lost in the woodland they shepherd. But while our imaginations can readily accept that tree people walk around Middle Earth, it can be harder to fathom how the first creatures that lived on our own planet came into being and started moving around.