Evolution's top ten inventions

New Scientist lists the ten greatest evolutionary innovations in the history of life on earth. These are:

MULTICELLULARITY

Sponges are a key example of multicellular life, an innovation that transformed living things from solitary cells into fantastically complex bodies. It was such a great move, it evolved at least 16 different times. Animals, land plants, fungi and algae all joined in.

THE EYE

The invention of the eye ushered in a more brutal and competitive world. Vision made it possible for animals to become active hunters, and sparked an evolutionary arms race that transformed the planet.

THE BRAIN

Brains provided, for the first time, a way for organisms to deal with environmental change on a timescale shorter than generations.

LANGUAGE

AS FAR as humans are concerned, language has got to be the ultimate evolutionary innovation. It is central to most of what makes us special, from consciousness, empathy and mental time travel to symbolism, spirituality and morality.

PHOTOSYNTHESIS

FEW innovations have had such profound consequences for life as the ability to capture energy from sunlight. Photosynthesis has literally altered the planet's face, transforming the atmosphere and cocooning Earth in a protective shield against lethal radiation.

SEX

Important as sex is, however, biologists are still arguing over how it evolved - and why it hasn't un-evolved. That's because, on the face of it, sex looks like a losing strategy.

DEATH

Embryos as tiny as 8 to 16 cells - just 3 or 4 cell divisions after the fertilised egg - depend on cell death: block apoptosis and development goes awry. Were it not for death, we would not even be born.... Even as adults we could not live without death. Without apoptosis we would all be overrun by cancer.

PARASITISM

"They are really disgusting, but man, are they good at what they do," says Daniel Simberloff, an ecologist at the University of Tennessee and translator of the popular French text The Art of Being a Parasite. "Evolution is in large part probably driven by parasites. It is the main hypothesis for the continuation of sexual reproduction. How much more important can you get?"

SUPERORGANISMS

Take the Portuguese man-of-war. It may look like just another jellyfish blob floating on the high seas, but zoom in with a microscope and you see that what seemed like one tentacled individual is in fact a colony of single-celled organisms. These "siphanophores" have got division of labour down to a fine art. Some are specialised for locomotion, some for feeding, some for distributing nutrients.

SYMBIOSIS

Symbiosis has many definitions, but we'll take it to mean two species engaging in physically intimate, mutually beneficial dependency, almost invariably involving food. Symbiosis has triggered seismic shifts in evolution, and evolution in turn continually spawns new symbiotic relationships.