Early human ancestor 'Lucy' was a bad runner, and this one tendon could explain why

Live Science ^ | published December 26, 2024 | Kristina Killgrove

[BenLurkin]

The human ability to walk and run efficiently on two feet arose around 2 million years ago with our Homo erectus ancestors. But our earlier relatives, the australopithecines, were also bipedal around 4 million years ago. Given the long arms and different body proportions of species like Australopithecus afarensis, though, researchers have assumed that australopithecines were less capable of walking on two legs than modern humans.

In a study published online Dec. 18 in the journal Current Biology, a team of researchers modeled the skeletal and muscular anatomy of Lucy to determine her maximum running speed, the energetic costs associated with running, and her running endurance.

...

Australopithecines like Lucy had large upper bodies, long arms and short legs, which likely limited their running speed. But the researchers discovered that another potential reason for Lucy's slow, inefficient running may have been a differently shaped Achilles tendon and triceps surae, a group of muscles in the calf.

Modern humans have a long, spring-like Achilles tendon, the researchers noted, which connects calf and ankle muscles to the heel bone. This anatomical arrangement provides humans with the powerful and efficient ankle crucial to high running performance.

[TheBattman]

Ahhh... so sources that don’t march lockstep with your anti-biblical presupposition are automatically “not reputable”. I see -