evidence: Scientists have long pointed to changes in climate, such as the onset of wet or dry periods, as the key driving force behind the adaptation of our early ancestors. The new study puts this idea to the test by examining a detailed record of environmental changes over almost a million years, etched into a 456-foot-long core of sediment layers extracted from an ancient lake. [...] Windows into our ancient ancestors’ lives at this time reveal they were surprisingly advanced for such an early date. Their tools were diverse and much more compact, including small triangular stone points that could have been used as projectiles. "Things start out big and clunky and they become small and portable," Potts says of the shift. "It’s like the history of technology ever since." [...] With resources scarce or in flux, ancient humans were likely forced to travel farther away from familiar lands, she notes. "Did that lead to them discovering different types of resources? Did that lead to increased cooperation with other groups to survive? Did it lead to advances in technology to help them eke out a living?" Krueger wonders. "These are the questions this study is exploring."