Despite widely published reports that 'Angelina Jolie' was originally cast as the lead, but dropped out, Besson has since denied them and admitted that he only met with a couple of actresses to discuss playing the lead role. He says when he saw how strongly Johansson reacted to the story, she immediately landed the part.
In an interview on 08/03/2014 (evening news on France 2), Luc Besson said that this project took 10 years to become a reality. Also, he admitted that he knew that some scientific assumptions were erroneous, e.g. that humans use only 10% of their brain. Nonetheless, he said that "[such assumption] would be a great start for a sci-fi movie".
Lucy meets a human-looking ape while travelling through time, who represents the 'missing link' between apes and humans, also known as 'Lucy'. She lived 3.2million years ago and was the first ape to walk upright like humans.