este vacsi naklad je podla mna toto

In fact, much of the basic signalling machinery of all nervous systems might have evolved from a life-or-death adaptation that arose in the first cells on Earth, four billion years ago. Early cells probably inhabited aquatic environments, such as hot springs or brine pools, that contained a mixture of dissolved minerals including some, like calcium, that threatened life. (Important biological molecules such as DNA, RNA and ATP are known to coalesce into refractory goo when exposed to calcium – similar to the scum that forms in bathtubs.) So biologists surmise that early life must have evolved ways to keep all but the lowest levels of calcium outside its cells. This protective machinery might include proteins that pump calcium atoms out of a cell, and an alarm system that goes off when calcium levels rise. Evolution later harnessed this exquisite responsiveness to calcium to signal within and between cells – to control the beating of cilia and flagella that microbes use to move, or to control the contraction of muscle cells or trigger the electric firing of neurons in organisms such as ours. By the time nervous systems began to emerge, roughly half a billion years ago, many of the critical building blocks were already set.

povinne citanie pre vsetkych insitnych evolucnych biologov na kybci, co budu donekonecna filozofovat o tom ktora adaptacia na aky ucel sluzi