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# When Did Human Ancestors Stop Regularly Moving Through the Trees?
- URL: https://theparnassian.com/en/issledovateli-sravnili-prochnost-kostei-ruk-i-nog-u-dvukh-iskopaemykh-predkov-cheloveka-i-predpolozhili-chto-mozhno-opredelit-kogda-predki-cheloveka-perestali-reguliarno-peredvigatsia-p/
- Published: 2026-09-22T17:46:17.000Z
- Updated: 2026-10-01T05:25:07.000Z
- Author: Alexandr Radayev
- Tags: Archaeology, Science, Nature

Researchers have compared the strength of the arm and leg bones in two fossil human ancestors and suggest that it is possible to determine when our ancestors ceased to travel regularly through the trees.  
  
The first skeleton belongs to an individual australopithecine known as Little Foot. Australopithecines are a genus of fossil primates that lived in Africa and already walked on two legs, yet retained many features of an arboreal way of life. The skeleton was found in the Sterkfontein cave in South Africa and is 3.67 million years old. The second skeleton belongs to a representative of the early genus Homo; it was discovered at Dmanisi in Georgia and is 1.8 million years old.

The researchers measured the relative strength of the limb bones. This indicator reflects the loads the bones bore during life: in species that climb a great deal, the arm bones are stronger relative to the leg bones. The ratios obtained were compared with those of modern humans, chimpanzees, gorillas and orangutans.

It emerged that the limb proportions of Little Foot are close to those of the African great apes. This means that the australopithecine could move through the trees, despite its large body size and shin bones that resemble human ones. In the Homo individual from Dmanisi, the ratio of limb strength falls within the range observed in modern humans.

From this the authors conclude that the transition to life on the ground, and to reliance on the lower limbs alone, took place about 1.8 million years ago, that is, at the same time as the enlargement of the brain. The reasons for the transition remain unclear; they may be connected with a change in the distances travelled, with methods of obtaining food, and with other circumstances that demanded stronger legs and greater dependence on a terrestrial way of life.

![](https://theparnassian.com/content/images/2026/09/file_16.jpg)