Ardipithecus kadabba

Ardipithecus kadabba (abbreviated Ar. kadabba) is a species of very early hominid. It is now extinct. It lived from around 5.8 million to 5.2 million years ago.^[1]

Drawing of an Ardipithecus using a stone to break nuts, like chimpanzees do

It is one of two species in the genus Ardipithecus. The other is Ardipithecus ramidus.

The name "kadabba" refers to the word for "oldest ancestor" in the Afar language of Ethiopia.^[2]

Discoveries

The first Ar. kadabba fossil was found in 1997 by paleoanthropologist Yohannes Haile-Selassie. At first, he thought the fossil came from a subspecies of Ar. ramidus. Then he found another 11 specimens from at least 5 individuals.^[3]

These specimens included hand and foot bones, partial arm bones, and a collarbone.^[2] They were later dated to be 5.6 million to 5.8 million years old.^[2]

In 2002, scientists found six Ar. kadabba teeth at the Asa Koma archaeological site in the Afar Depression.^[2] These confirmed that Ar. kadabba was its own unique species, not a subspecies of A. ramidus.^[4] Scientists later learned that Ar. kadabba came before Ar. ramidus and was probably its ancestor.^[5]

In total, scientists have found 19 Ar. kadabba specimens that include parts of the teeth, jaw, feet, and hands and arms.^[2]

Description

A 5.2-million-year-old toe bone found by Haile-Selassie shows an adaptation for walking upright. This suggests that Ar. kadabba may have been bipedal.^[6]

Their bodies and brains were probably a similar size to modern chimpanzees'.^[2] Their diet probably included a lot of tough, fibrous foods, like hard nuts.^[2]

Based on fossil animal evidence found near Ar. kadabba remains, the species lived in a wooded area with access to permanent fresh water sources (like lakes and springs). The area included swamps and grasslands.^[6]