Читать книгу Astrobiology - Charles S. Cockell - Страница 55

Some people say that astrobiologists are narrow-minded and that alien life forms, if they exist, will be constructed in ways unimaginable to us and possibly very differently from life on Earth. Do you agree with this? As you progress through this and later chapters, you might like to consider at what level of hierarchy this statement may or may not be true. Hydrogen bonding, for example, would be expected to be the same anywhere in the Universe, as it is determined by the interactions between atoms in the universal Periodic Table. So too with all the forms of bonding explored in this chapter. Surely, therefore, are we are on safe ground to say that if life exists elsewhere it would use the same types of bonding to hold its atoms, ions, and molecules together? In Chapter 4, we look at how molecules in terrestrial life are put together. Are these molecules universal structures? Would we expect cells to be put together using the same basic molecules? We then progress in Chapter 8 to look at the evolutionary relationships between whole organisms. Are these universal? Consider at what scale in the structure of life from atoms to communities of organisms you would be confident to say that all life in the Universe would share identical characteristics. In other words, at what level of the hierarchy of life's structure is biology deterministic and where can contingency, or chance, play a role? If you could run evolution again, what structures of life could you confidently predict would reappear?