The search for the "missing" link is called off

2 May 2012

The evolution of mankind did not begin with a bigger brain, it began with the upright gait. As curtain raiser to his lecture series "Out of Africa: Zur Globalgeschichte des Homo sapiens" ("Out of Africa: On the global history of Homo sapiens"), Professor Dr. Friedemann Schrenk, the 13th holder of the Johannes Gutenberg Endowed Professorship, takes his audience back to the roots of humanity.

Precise information on the earliest ancestors of mankind is thin on the ground. "What is actually available to us to reconstruct our own history?" asks Professor Friedemann Schrenk, only to then answer his own question: "There is not much – remains of the hardest parts, such as a few bones and a few teeth, and they don't have much to say. Unfortunately, they never come with a label stating: 'I was pre-human.'"

Nevertheless, the paleoanthropologist and 13th holder of the Johannes Gutenberg Endowed Professorship continues to strive to answer fundamental questions about the origin of the human species. In his ten-part lecture series "Out of Africa: On the Global History of Homo sapiens", he will not only be dealing with the topic himself but will also be welcoming prominent guests, including colleagues from Africa.

Traditionally, the largest auditorium of Johannes Gutenberg University Mainz (JGU) is placed at the disposal of the Endowed Professor, but even here there are frequently not enough seats. An audience of some 1,200 welcome Schrenk at his first lecture "Ursprünge – Die Suche nach dem 'missing link'' ("Origins – the search for the 'missing link'").

"There is no right or wrong"

"We are constantly on the search for a 'missing link' but, of course, once we have found it, it is no longer 'missing'. In effect, this means there is no such thing as a 'missing link'," maintains the paleoanthropologist. So he has called off the search for it; he now prefers to take his audience on a journey to search for the roots of the human race. He adds a warning, however: "There is no right or wrong in our discipline; there are only probabilities."

And what makes the matter even more difficult is the fact that a scientist's world view can determine how they interpret their sparse findings. When fragments of Homo neanderthalensis were discovered in the Neander Valley in 1857, the Germans were self-confident enough to claim that humanity had originated in Germany. "But in 1891, the cradle of humanity moved to Southeast Asia," explains Schrenk, when Eugen Dubois discovered the remains of Pithecanthropus erectus in Java. Then it came back to England: "In 1912 and 1913, certain people came to the conclusion that the cradle of humankind was in Piltdown."

A forgery that fitted the world view

To all intents and purposes, "Piltdown Man" had a large brain, strong teeth, and walked on four legs. "And this was perfectly in keeping with the contemporary world view. The trouble was that a forger had combined a skull fragment of Homo sapiens with parts of the jaw of an ape." But this forgery fitted the assumptions of the time.

When Australopithecus africanus appeared on the scientific scene in 1925, he found it hard to contend against the claims of his Piltdown competitors. "This creature walked upright but had a small skull." The fact that the upright gait came before the large brain went completely against doctrine. However, over time, this was corroborated by more and more finds – and almost all of them were made in Africa.

Schrenk looks back 13 million years into the past. Pierolapithecus catalaunicus originally lived in the tropical rain forests of Africa. He was able to stand upright on his short legs. "His fingers were straight as a poker, so he would not have been able to swing from tree limb to tree limb. Brachiation was not part of our ancestors' original skills; it is actually a late development in apes."

First steps taken in the water

The capacity to walk upright became important five to eight million years ago when there was global cooling. The African rain forest retreated and fruits were scarce, but there were now exposed areas of water on the savanna. The anthropoids that could not swim walked upright in the water to look for food there. "The water provided buoyancy that stabilized their gait." For Schrenk, this hypothesis of pre-humans wading near the shore in search of food is attractive.

"But who had the idea?" asked the paleoanthropologist. So who was it who first dared to walk on two legs? "I believe that many experimented with the upright gait." Various different forms of pre-human species evolved. "There is not a single direct line of evolution to Homo sapiens, and not even a family tree; there is an entire family bush. The last of the Homo species distinct from modern man became extinct only 12,000 years ago; this species was known as 'Flores Man'. We were never really alone in the past; it is only now that we are the only human species in the world."

Before the lecture, the President of JGU, Professor Dr. Georg Krausch, stated: "The lecture series given by our Endowed Professor is one of the highlights of academic life." Peter Radermacher, Chairman of the Friends of Mainz University, expressed similar enthusiasm: "The University's largest auditorium is full. I am glad to see a complete cross-section of society present." In 2000, the Friends created the foundation which finances the professorship with its prominent appointees.

Disagreement is desired

After about two hours, the 1,200 listeners give their verdict on the talk in the form of thunderous applause. It seems Endowed Professor Schrenk has convinced everyone – well, almost everyone. A student interrupts the ensuing discussion and shouts excitedly: "The wading ape hypothesis is not even a hypothesis; it is just a story!" Presenter Professor Dr. Andreas Cesana, Chairman of the Foundation, tries to calm him, but Schrenk is pleased by the interjection. "I've always said I wanted disagreement." And to prove it, he says to his critic: "I find that interesting; we will talk about it later."