Our Pre-Human Ancestors

Proconsul was about the size of a 1 yr. old child

Our oldest known ancestor

25 million years ago, there was a small primate known as Proconsul. There is wide, but far from unanimous, agreement that Proconsul may be our oldest yet known ancestor. Proconsul was very apelike and it was also very small - about 10 kg. or 22 lbs.

Branching off of the apes.
Proconsul survived and evolved slowly* into larger primates. Now and then a group would branch off and go on a separate evolutionary path of their own. Monkeys branched off about 40 million years ago, long before Proconsul existed. We did not descend from monkeys.
We all descended from Proconsul or from another creature very much like him.
• 16 million years ago - The first to go (and survive) were the Hylobates that have evolved into modern gibbons.
• 14 million years ago - The Pongo group left, evolving into modern orangutans.
• 12 million years ago - The gorillas separated.
•   7 million years ago - The Pan group - evolving into chimpanzees and bonobos - separated.

* The speed of evolution

Lucy was about 1,300 mm tall or roughly four feet. Evolution has very, very slowly increased the height of these creatures by about 1,000 mm over a span of 20,000,000 years. That is about one millimeter every twenty thousand years.
5.5 million years ago - Founding of Ardipithecus ramidus
Ardipithecus was the first bipedal hominin and the first to begin to develop language abilities.

5 million years ago - Founding of the Australopithecenes

Australopithecus generated several dead-end branches, but Australopithecus anamenis seems to have evolved into the A. afarensis that left us the famous fossil "Lucy".

3.2 million years ago: "Lucy", the famous Australopithecus afarensis

It is thought the A. afarensis lived over a wide area in East Africa. Fossils and footprints have been found many places, but the best fossils were found in the Afar Region of Ethiopia. Some of them may have used the Lomekwi culture of stone tools found near Lake Turkana, Kenya. There is debate as to whether A. afarensis is actually a different species from the preceeding A. anamensis. If they are the same, then the date is pushed back to about 5 million years.

2.5 million years ago: Australopithecus africanus lived in southern Africa.

Until recently, there has been no consensus that A. africanus is a human ancestor except for the convenient time located about halfway between A. afarensis and Homo habilis, but a very recent discovery of A. africanus fossils seems to support that placement.

2.5 million years ago: Australopithecus garhi lived in Afar, Ethiopia.

A. garhi fits neatly into a time slot located about halfway between A. afarensis and Homo habilis and is from the same area.
Family Tree

Variations on Proconsul's family tree: ---➤
These differ mostly as to whether Ergaster and Erectus are the same and which came first.