It helped us reach our “prime.” The Progression of Man apparently wasn’t as gradual as once thought. UK researchers found that our ancestors experienced a rapid growth spurt between 2 and 2.5 million years ago, potentially due to increased meat consumption and walking upright, per a beefy study published in the Proceedings Of The National Academy of Sciences. The authors set out to shed light on the size discrepancy between modern humans, whose average weight clocks in at 137 pounds globally ,