Mangabeys close up (IMAGE) Dartmouth College Caption Dartmouth researchers report that apes and early humans evolved more flexible shoulders and elbows than monkeys (above) to safely get out of trees. For early humans, these versatile appendages would have been essential for gathering food and deploying tools for hunting and defense. Credit Luke Fannin, Dartmouth Usage Restrictions N/A License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.