A potential third European ancient ancestor of man has been proposed by researchers from Spain and the Netherlands in the Feb. 20, 2014, edition of the journal Public Library of Science based on the recent discovery of a new skull in the Dmanisi site in the Republic of Georgia.
The skull designated D4500 has a unique jaw structure that has not been seen before in early human ancestors in Europe or Africa. The mandible differs in size and shape from all the other mandibles found at the same site.
The researchers made a scrupulous comparison of anatomy and physiology between the D4500 jaw and existing species of humans and human ancestors from Africa and Europe. Denisovans and Neanderthals were included in the examination.
The researchers eliminated any disease as being the cause of the large size of the jaw. Differences in size due to sex were also negated. Differences in diet and tooth wear due to diet were eliminated as a cause of the large size of the jaw in D4500.
The skull dates to between 1.77 million years ago and 1.81 million years ago. The time frame predates any known entry of Africans into Europe and predates any known existence of Neanderthals.
The researchers propose that this skull represents a new early human ancestor called Homo erectus ergaster georgicus. This is a new species of early human ancestor.