3.3 million-year-old fossil of toddler

More than 3 million years after she died, the fossil of a tiny female toddler is providing a unique look at how the children of our early human ancestors lived. She was a hominin, an early human ancestor called Australopithecus afarensis. When she died, she was almost 3 years old. Her nearly complete skeleton was discovered in the Dikika region of Ethiopia in 2002. One of the more recent elements of her skeleton to be studied is her foot. It is the most complete foot of an ancient juvenile ever discovered.

Australopithecus afarensis

The anatomy of her foot was incredibly well-preserved, allowing researchers to study how a toddler hominin would have walked. At 2½ years old, she would've been walking on two legs. But when researchers analyzed the skeletal structure of her foot, they noticed that the base of the big toe would have allowed her to be a great climber. So although the afarensis toddlers could walk, they probably spent more time in trees than on foot, unlike adults. A 2017 study of her nearly intact spinal column, vertebral bones, neck and rib cage also revealed that part of human skeletal structure was established millions of years before expected. Like modern humans, she had 12 thoracic vertebrae and 12 pair of ribs -- fewer than most apes. Evidence combined shows what a critical, pivotal species afarensis was for human evolution.