Australopithecus africanus

Discovery

Australopithecus africanus is an extinct species of early human relative that lived in South Africa a long time ago.

The first fossil of this species was found by a scientist named Raymond Dart in 1924. This was important because it showed that humans might have come from Africa, which was a new idea back then.

Physical Features

Australopithecus africanus had a small brain and teeth good for chewing tough foods. They could walk on two legs but might have also spent time in trees.

Diet

They ate many kinds of foods, such as grasses, seeds, and nuts, especially when other food was hard to find.

Relationship to Other Early Humans

Scientists are still learning how A. africanus relates to other early human relatives. Some think they might be connected to the genus Homo, which includes humans today, but others have different ideas.

Disappearance

This species lived in areas with both forests and open grasslands. Many of their fossils were found in caves. Changes in the climate and competition with other early humans may have led to their disappearance.

Research history

Discovery

In 1924, a scientist named Professor Raymond Dart found a very old skull of a young child in South Africa. This skull, called the Taung child, was special because it showed features that were a mix between apes and humans. It had a small brain but walked on two legs, which was a clue about how humans might have evolved.

Classification

When the Taung child was found, scientists did not know where to place it. It did not fit neatly into groups for either humans or apes. Over time, more fossils were discovered, and scientists began to see that this ancient creature, named Australopithecus africanus, was an important part of human history. It helped prove that humans evolved in Africa, as Charles Darwin had suggested many years earlier.

Anatomy

We know about A. africanus from four specimens. Their brains were about 420–510 cc in size. The inner ear looked more like apes, but the cochlea was like humans. A. africanus had a jaw that stuck out, a flat face, and a bony ridge above the eyes. Their teeth were large with thick coating, and their canine teeth were smaller than in apes.

A. africanus weighed about 30.7 kg and was around 124.4 cm tall. Their spine and neck bones had features from both apes and humans, meaning they could climb trees and walk upright. Their arms were longer than their legs, but not as long as in apes. Their hands had curved fingers and a precision grip that could be used for making tools. Their legs showed they walked on two legs, but with some ape-like traits. The foot looked mostly human, with a stiff middle part and an adducted big toe.

Palaeobiology

Diet

Scientists studied what A. africanus might have eaten. They found that A. africanus ate many kinds of food. This included plants from dry places, like grasses and seeds, and some insects, like locusts or termites. They may have also eaten small animals, but not many.

The teeth of A. africanus look like they could crush hard foods, such as seeds and nuts. But it seems they did not eat these very often. Sometimes, when food was hard to find, they may have used stones to crack open nuts. A. africanus did not often eat foods that cause cavities, like sugary fruits or honey. One tooth showed signs that this individual ate acidic foods, maybe citrus fruits.

Society

It is hard to know how A. africanus lived together in groups. One study of their teeth suggests that females might have moved away from where they were born, while males stayed closer to home. This is similar to how some modern humans live, where females move to new groups while males stay. The teeth of males were not very big compared to females, which might mean males did not fight much.

Pathology

Some A. africanus fossils show signs of health problems. For example, one young fossil had severe gum disease, which would have made chewing very hard. Another fossil showed signs of eating too many acidic foods, which can damage teeth. There was also a fossil that might have had a healed ankle injury, perhaps from falling from a tree, but this is not certain.

Palaeoecology

Australopithecus africanus lived in many different kinds of places. At a place called Sterkfontein, scientists found old wood from a tree that only grows in very wet forests today. This suggests that long ago, the area might have had more rain and closer forests. The animal fossils found there show a mix of open grasslands and woodlands.

Scientists think that these early humans liked cooler places and usually lived above 1,000 meters, where temperatures were comfortable during the day but cooler at night. Some scientists believe that big animals might have brought these early humans' bones into caves.