But what are they? From Charles Cockell at Physics Today:
Look at the menagerie of life—for example, as depicted by Jan Brueghel the Elder in the painting to the left. The casual viewer could easily conclude that life is limitless in its scope, that its forms and shapes are constrained only by the imagination. But however trite the observation may be, life must conform to the laws of physics. Science still does not know how many possible solutions there are to building a self-replicating system within those laws, however, or to what extent physics constrains the products of the evolutionary process.
At the scale of organisms, physical laws certainly do limit the engineering solutions to life’s problems. For example, consider locomotion. In a now classic paper,3 Michael LaBarbera addressed a question that has been a favorite at biologists’ café tables since time immemorial: Why doesn’t life use wheels? People use them in a vast diversity of forms of locomotion. Why did biology reject them? Apart from the biomechanical problems of evolving rotating muscles and veins, wheels have an inherent physical problem in that they are limited in the landscapes they can navigate: They cannot overcome obstacles with a height greater than their radius unless they are lifted up.
But life does use wheels:
Whatever the physical laws are life are supposed to be, life always seems to find a way around them. Life continues to ignore what evolution experts say. The world of the extremophiles testifies to that.
Life must be fashioned by the laws of physics. Birds must conform to the principles of aerodynamics, protein folding to thermodynamics, and energy acquisition systems that use electrons to the various energy states of those subatomic particles. What is less clear is the extent to which physics narrows the range of Darwinian possibilities. The physical principles that underlie the construction of life from predominantly C-based molecules instead of Si-based ones have long been understood. More recently, however, scientists have suggested that other choices that once seemed contingent are nonrandom events based on statistical probabilities, energetic considerations, and optimal arrangements for a self-replicating, evolving system. Examples include the structure of proteins or even the 20 amino acids that life chooses from the many hundreds of possibilities to build those proteins. More.
Chances are, the explicit law of physics that life simply cannot get around will turn out to be very few. But that raises the question, why does life so obviously seek to come into existence and stay that way?
See also: Life forms found at abyssal depths
Life continues to ignore what evolution experts say
What can we hope to learn about animal minds? (which includes the strivings of life forms without brains)
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Previously believed to be only man-made, a natural example of a functioning gear mechanism has been discovered in a common insect – the plant-hopper Issus – showing that evolution developed interlocking cogs long before we did.
Interlocking cogs are wheels. And we won’t even get into the bacterial flagellumTM.