Researchers leading a study into fossilized human remains in Kenya claim to have found that there were at least three distinct species of humans living in Africa two million years ago, providing a twist to the theory of evolution.

The findings were published in the journal Nature and detail the exact measurements of the face, jawbones and teeth of the human species that researchers say roamed Africa around 1.78 to 1.95 million years ago.

"Our past was a diverse past," said Dr. Meave Leakey of the Turkana Basin Institute in Nairobi, who led the research, "our species was evolving in the same way that other species of animals evolved. There was nothing unique about us until we began to make sophisticated stone tools."

Previously held theories of evolution suggested that humans evolved directly from a common primate ancestor, which stands in opposition to traditional Christian beliefs that the Earth is only a few thousand years old and that the biblical account of God creating the world, mankind and all animals in Genesis is to be taken literally.

The recent scientific discoveries in Kenya, however, pull the debate in another direction by suggesting that there were a host of different species and subspecies of humans that did not survive, rather than one linear form of evolution that all humans followed.

"Humans seem to have been evolving in different ways in different regions. It was almost as if nature was developing different human prototypes with different attributes, only one of which, an ancestor of our species, was ultimately successful in evolutionary terms," suggested Professor Chris Stringer of the Natural History Museum in London.

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The discovery also adds weight to a number of other cases where scientists have been debating whether ancient human remains belonged to a separate species or if they were just another step in the evolutionary process, the BBC reported.

"For a long time the oldest known human ancestor was thought to be a primitive species, dating back to 1.8 million years ago, called Homo erectus. They had small heads, prominent brows and stood upright," according to the BBC.

"But 50 years ago, researchers discovered an even older and more primitive species of human called Homo habilis that may have coexisted with H. erectus. Now it seems H. rudolfensis was around too and raises the distinct possibility that many other species of humans also existed at the time," the report adds.

Photographs of the Kenya remains were also made available on the Nature journal's website.