When that historic discovery was made in 1856, three years before Charles Darwin published his theory of evolution; it began a debate about the origins of mankind, which still continues today.

This year marks the 150th anniversary of the discovery of the "Neanderthal Man." An international exhibition and congress in July in Bonn brought together 220 scientists from 20 countries, to discuss topics ranging from the origin of Neanderthal man, to the species' relationship to modern humans.

Wighart von Königswald, Chair of Paleontology at the University of Bonn, and co-organizer of the symposium, said the importance of the discovery of Neanderthal man cannot be underestimated.

Another type of man

"It was the first fossil man and the first clear evidence that there is some other one like modern man," said von Königswald. "It was a time when one discovered that all aborigines of the various continents in those days were absolutely human beings and they did interbreed with Europeans. With Neanderthal man, it became clear that there were other types of man in the past."

Initially, however, this theory was unpopular. Von Königswald said amateur naturalist Johann Carl Fuhlrott, who was the first to pronounce the Neanderthal's bones as human, was disbelieved by many, as this notion contradicted literal interpretations of the Bible.

"It took quite some time until this was accepted, and even in the publication of 1859 when Fuhlrott described this material, the editor of the journal said, 'It's a nice discovery, but we do not agree at all with this interpretation.' The author was right, not the editor," von Königswald said.

Nowadays, Fuhlrott is regarded as one of the founders of paleoanthropology. In the 150 years since his discovery, scientific advances have helped to uncover many facts about Neanderthals.

For example, according to Ralf Schmitz, an archaeologist and co-organizer of the "Roots" exhibition at the Rheinisches Landesmuseum in Bonn, scientists now know what the Neanderthal man discovered in Germany was like, and how he would have lived.

Getting to know the relatives

"We know his age -- he died at the age of 42. His geo-chronological age is 42,000 years, his food was mostly meat, and in the rediscovery campaign of the Neanderthal type locality, we found stone implements and animal bones," Schmitz said. "For the first time, we have an idea of the culture of that special type specimen."

It is now accepted that Neanderthals inhabited Europe and parts of western Asia and scientists now know part of Neanderthal man's DNA code, which Schmitz helped to crack in 1997, with fellow archaeologist Jürgen Thissen.

But, Schmitz is quick to add, there's still a lot scientists don't know. For example, why the species became extinct.

Extinction questions still relevant

"Perhaps they have had fewer children than the anatomically modern humans, perhaps the modern humans brought diseases, or perhaps they pressured them into bad grounds for hunting," Schmitz said.

Schmitz added that the question of why Neanderthals became extinct is an important one.

"Neanderthals are very fascinating people, because they disappeared only 30,000 years ago," he said. "It was the last archaic type of man who lived on earth parallel to us for a long time, and the question is when Neanderthals could go extinct, could we also go extinct? That's a very important question."

The conference in Bonn couldn't answer this specific question, but was organized to help find the answers to questions such as these and provide a forum for scientists to discuss Neanderthal technology, anatomy and environment.

Similarities between modern and Neanderthal man

Erik Trinkaus, professor of anthropology at Washington University in the United States, has worked on two of the fossils displayed in the "Roots" exhibition, and said he believes although Neanderthals are not our direct ancestors, the two species have many similarities.

"We used to think that there was a major behavioral shift, improvement in overall efficiency of and social organization between the two groups, but the more we look at them, the more we find that in many ways, Neanderthals and early modern humans are very similar to each other behaviorally, functionally," he said.

"They're not biologically identical, they look different and we can tell them apart easily, but when you look at them in terms of their behavioral patterns, the changes are fairly subtle," Trinkaus added.