Now more than a month after his dramatic surgery, Evan is aware and chattering. His father said the results are "night and day" to how his young son used to function.
"To move his legs like this and his arms, to wave them around and to speak is just remarkable," he said. "It's incredible."
While the long-term effects on Evan's development remain to be seen, for now it appears that Evan has a fresh start on life. It's possible that one day, people will never know that he and other children who undergo the operation only have half a brain.
To learn more about Evan Stauff's incredible surgery and how he's progressing, visit the family's website HERE.
ABC News' Lauren Effron contributed to this report.