News Humans Deep African roots for toolmaking method Stone-trimming technique originated earlier than thought, archaeologists contend Share this:FacebookTwitterPocketRedditPrint By Bruce Bower October 28, 2010 at 2:02 pm This article is only available to Science News subscribers. Subscribers, enter your e-mail address to access our archives. Client key* E-mail* Log in Not a subscriber? Science News is a nonprofit. Support us by subscribing now. Subscribe