The Tree of Life

A little History of Evolution

Imagine that this tree trunk with its annual rings, which was fossilized millions of years ago, stands for the age of the living beings on earth. Each ring bridges millions of years, ten rings stand approximately for a time epoch. And only at the very edge, almost at the fossilized bark, humans emerge - Homo Sapiens.

Pretty much in the middle of the tree trunk, about 3.5 billion years ago sits the ancestor of all life forms - Luca (Last Universal Common Ancestor), a grain of life consisting of a series of four bases. These four bases are crucial when it comes to cell reproduction. Luca has a basic structure of a cell (cytoplasm) and a thin cell membrane. From this primitive form of life, the three major types of evolutionary history developed: all multicellular organisms (eukaryotes), unicellular bacteria and even simpler forms of life, without a complex nucleus, but with a self-contained DNA. These are found in almost all areas of the world, both in volcanoes and deep-sea trenches: Archaea.

Scientists discovered a sort of granule in archaea, which was previously thought to exist only in bacteria and eukaryotes. These granules, with the complicated name acidocalcisomes, are internal cellular stores of phosphorus, which is responsible for energy supply, and metal ions, or salts.

They are found in almost all larger groups of living organisms, in bacteria, slime moulds, amoebae, algae and also in human blood platelets. So, they already existed in two out of three domains. Now they have been found in archaea.

Since all three groups have this granule in common, we can assume that this very part was the beginning of life so many billions of years ago. This grain was probably one of the first building blocks for Luca and consequently one of the first building blocks for life itself. A grain full of potential, a grain full of life.

One of the first complex creatures, found on our tree trunk, halfway between the core and the edge, was Haikouichthys, a very primitive fish, but also one of our oldest ancestors.