Early human ancestors used their hands to both climb trees and make tools, new study shows

By: Christina Larson, The Associated Press Posted: 2:09 PM CDT Wednesday, May. 14, 2025

WASHINGTON (AP) — Our hands can reveal a lot about how a person has lived – and that’s true for early human ancestors, too.

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WASHINGTON (AP) — Our hands can reveal a lot about how a person has lived – and that’s true for early human ancestors, too.

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This article was published 14/05/2025 (465 days ago), so information in it may no longer be current.

WASHINGTON (AP) — Our hands can reveal a lot about how a person has lived – and that’s true for early human ancestors, too.

Different activities such as climbing, grasping or hammering place stress on different parts of our fingers. In response to repeated stress, our bones tend to thicken in those areas.

To study how ancient humans used their hands, scientists used 3D scanning to measure and analyze the bone thickness of fingers.

This artist rendering shows hands of early human ancestors, called Australopithecus sediba and Homo naledi, found in South Africa. The left images show photos of the bones, and the right images show how the fingers absorbed stress during daily activities. Red areas absorbed more stress than blue ones, which scientists can tell based on bone thickness. (Tracy Kivell via AP)

They focused on the fossil hands of two early human ancestor species recovered from excavations in southern Africa, called Australopithecus sediba and Homo naledi. The individuals lived around 2 million years ago and around 300,000 years ago, respectively.

Both ancient human species showed signs of simultaneously using their hands to move around – such as by climbing trees – as well as to grasp and manipulate objects, a requirement to being able to make tools.

“They were likely walking on two feet and using their hands to manipulate objects or tools, but also spent time climbing and hanging,” perhaps on trees or cliffs, said study co-author and paleoanthropologist Samar Syeda of the American Museum of Natural History.

The research was published Wednesday in Science Advances.

The findings show there wasn’t a simple “evolution in hand function where you start off with more ‘ape-like’ and end up more ‘human-like,’” said Smithsonian paleoanthropologist Rick Potts, who was not involved in the study.

Complete fossil hands are relatively rare, but the specimens used in the study gave an opportunity to understand the relative forces on each finger, said Chatham University paleontologist Erin Marie Williams-Hatala, who was not involved in the study.

“Hands are one of the primary ways we engage with world around us,” she said.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.