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]

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]

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]

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]