© J. DeSilva and Cody PrangTINY WALKER - A fossil of an ancient hominid child’s foot (shown here from different angles) suggests that members of Lucy’s species, Australopithecus afarensis, walked upright early in life.
Walking was afoot long ago among toddler-aged members of a hominid species best known for Lucy's partial skeleton.
A largely complete, 3.3-million-year-old child's foot from
Australopithecus afarensis shows that the appendage
would have aligned the ankle and knee under the body's center of mass,
a crucial design feature for upright walking, scientists report July 4 in
Science Advances.
"The overall anatomy of this child's foot is strikingly humanlike," says study director Jeremy DeSilva, a paleoanthropologist at Dartmouth College in Hanover.
But the foot retains some hints of apelike traits. Compared with children today, for example, the
A. afarensis child - only about 3 years old at the time of death - had toes more capable of holding onto objects or anyone who was carrying her, the team found. Those toes included a somewhat apelike, grasping big toe. "Young children having some ability to grasp mom could have made a big energetic difference for
Australopithecus afarensis adults as they traveled," DeSilva says.
Scientific debate about whether
A. afarensis, which may have been ancestral to humans, primarily walked upright or hung out in trees has raged for nearly 40 years. Accumulating lower-body fossils, including
foot bones (
SN: 3/12/11, p. 8), as well as
ancient footprints (
SN: 1/21/17, p. 8), point to an adept two-legged stride among
A. afarensis adults. But little was known about whether
A. afarensis tykes walked early in life or slowly developed a stride-worthy stance.
Comment: Further reading: