How did life begin on the early Earth? We know that life today is driven by the universal laws of chemistry and physics. By applying these laws over the past ?fty years, en- mous progress has been made in understanding the molecular mechanisms that are the foundations of the living state. For instance, just a decade ago, the ?rst human genome was published, all three billion base pairs. Using X-ray diffraction data from crystals, we can see how an enzyme molecule or a photosynthetic reaction center steps through its catalytic function. We can even visualize a ribosome, central to all life, translate - netic information into a protein. And we are just beginning to understand how molecular interactions regulate thousands of simultaneous reactions that continuously occur even in the simplest forms of life. New words have appeared that give a sense of this wealth of knowledge: The genome, the proteome, the metabolome, the interactome. But we can't be too smug. We must avoid the mistake of the physicist who, as the twentieth century began, stated con?dently that we knew all there was to know about physics, that science just needed to clean up a few dusty corners. Then came relativity, quantum theory, the Big Bang, and now dark matter, dark energy and string theory. Similarly in the life sciences, the more we learn, the better we understand how little we really know. There remains a vast landscape to explore, with great questions remaining.

How did life begin on the early Earth? We know that life today is driven by the universal laws of chemistry and physics. By applying these laws over the past ?fty years, en- mous progress has been made in understanding the molecular mechanisms that are the foundations of the living state. For instance, just a decade ago, the ?rst human genome was published, all three billion base pairs. Using X-ray diffraction data from crystals, we can see how an enzyme molecule or a photosynthetic reaction center steps through its catalytic function. We can even visualize a ribosome, central to all life, translate - netic information into a protein. And we are just beginning to understand how molecular interactions regulate thousands of simultaneous reactions that continuously occur even in the simplest forms of life. New words have appeared that give a sense of this wealth of knowledge: The genome, the proteome, the metabolome, the interactome. But we can't be too smug. We must avoid the mistake of the physicist who, as the twentieth century began, stated con?dently that we knew all there was to know about physics, that science just needed to clean up a few dusty corners. Then came relativity, quantum theory, the Big Bang, and now dark matter, dark energy and string theory. Similarly in the life sciences, the more we learn, the better we understand how little we really know. There remains a vast landscape to explore, with great questions remaining.

Der Entschluss, ein Buch uber den Ursprung (bzw. die Ursprunge) des - bens zu verfassen, setzt voraus, dass man von diesem wissenschaftlichen "grossen Problem" noch immer fasziniert ist, wenn auch die erste intensive Beschaftigung mit dieser Thematik mehr als drei Jahrzehnte zuruckliegt. Experimentelle Arbeiten uber Protein-Modellsubstanzen unter den si- lierten Bedingungen der Urerde fuhrten zur Entstehung eines der ersten deutschsprachigen Bucher uber "Chemische und Molekulare Evolution", das ich mit Klaus Dose (Mainz), von dem auch die Initiative ausging, v- fasste. Die enorme Erweiterung und Differenzierung dieses Forschungsgebietes fuhrte in den letzten Jahren zur Grundung eines neuen, interdisziplinaren Wissenschaftszweiges, der "Exo-/Astrobiologie". Sie verfolgt das we- gespannte, ehrgeizige Ziel, das Phanomen "Leben" im gesamten Kosmos zu erforschen. In den folgenden Kapiteln wird ein UEberblick uber die vielfaltigen - muhungen von Wissenschaftlern gegeben, Antworten auf die Frage nach dem "Woher" des Lebens zu finden. Dabei ist uber Erfolge, aber auch Misserfolge sowie uber Diskussionen und gelegentlich harte Kontroversen zu berichten. Es soll aber auch deutlich dargestellt werden, wie viele of- ne Fragen und ungeklarte Ratsel noch auf eine Antwort warten. Es sind - ren mehr, als gern eingestanden wird! - Die Fulle an wissenschaftlichen Publikationen macht es leider unmoeglich, uber alle Bereiche dieses int- disziplinar ausgerichteten Teilgebietes der Naturwissenschaften mit gl- cher Ausfuhrlichkeit zu berichten.