Who is Lucy?  A quick introduction

The most famous of the species Australopithecus Afarensis is known as Lucy. Her skeleton misses a face, hands and feet. More than 300 skeletal remains of her species have been found so far. These creatures are said to have lived 3.85 Million BC – 2.95 Million BC.

This species has apelike proportions of the face and braincase and strong arms with curved fingers adapted to climbing trees, but small canine teeth and a body that stood and walked upright on arched feet.

Fossil human footprints

Discovered by Mary Leakey’s team in 1978, the 23-metre-long track of footprints at an isolated site called Laetoli, Tanzania was linked to the same group of apes as Lucy. The tracks are dated at 3.6 million years old and were formed in volcanic ash that hardened over time.

(Click images to enlarge)

The two hominin trackways are said to belong to Australopithecus Afarensis and are preserved in volcanic ash. They represent at least three individuals in two parallel trackways, with one being a composite formed by at least two individuals that walked in single file.

Who left these tracks?

Mary Leakey found it intriguing that Australopithecus Afarensis had very modern human feet.  She and others said the prints were indistinguishable from those of modern humans.

How sure are we?

The prints are believed to have been made by early Australopithecus Afarensis on the grounds that its remains were found in the same sediment layer, and no other hominins are known to have existed at that time.

In the 1990’s Physical Anthropologist R. H. Tuttle of the University of Chicago said fossil bones of the known Australopithecines of 3.6 million years ago show they had feet that were distinctly apelike. Hence they were incompatible with the Laetoli prints.

Looking at the diagram above it is obvious that very few foot bones exist

Exactly how the ape-like foot developed into its modern version has remained unclear.

The fossil record is distinctly lacking in foot and hand bones, according to Matthew Bennett of Bournemouth University, UK.

“The reason is that carnivores like to eat hands and feet.  Once the flesh is gone there’s a lot of little bones that don’t get preserved, so we know very little about the evolution of hands and feet on our ancestors.”

Using technology to help solve the riddle

More recently in 2016 new 3D tests were conducted on the footprints.  There has been extensive debate as to whether the trail was made by someone with a foot that is essentially modern both in terms of anatomy and biomechanical function.  The tests found that the tracks were made by a hominin with an essentially modern biomechanical foot function.

https://www.nature.com/articles/srep21916 : Scientific Reports volume 6, Article number: 21916 (2016)

Finally some foot fossils

Dated at 3.3 million years old, the foot is from a child called Selam.  A female Australopithecus Afarensis that died before the age of four.

Below is a facial reconstruction of the baby and her foot.  Notice that the toes are missing from the fossil.  The big toe is “articulated” meaning it can walk and climb trees.

 

Is this what Australopithecus feet look like when they walk?

Little Foot is a nearly complete Australopithecus skeleton discovered in the Sterkfontein Caves in South Africa in 1994-1998.  The skeleton is an estimated 2.5 million – 3.67 million years old, dated in 2015 by means of a new radioisotopic technique.

The images are of a reconstructed foot based on the bones found and the skull.

Summary

  • Tracks in 3.6 million year old solid rock that belong to modern human feet, but was left behind by upright apes
  • Very few foot and hand bones have been recovered
  • Similar foot bones discovered in Tanzania and South Africa of the same species and timeframe are interpreted very differently when reconstructing the foot
  • Scientists are arguing amongst themselves about:
    • (a)  who left the footprints in stone
    • (b)  did the ape walk upright all the time
    • (c)  what did its feet look like
    • (c)  is this ape related to man
  • Nobody questions if the dating of the footprints is correct
  • Nobody questions whether another hominid like Homo Erectus left the tracks behind
  • Are humans much older than science cares to admit?