The evolution of parasitic relationships involves countless compromises and adjustments between the two partners.

Another possibility is that evolution of the system involved a horizontal gene transfer between unrelated microorganisms.

But evolution of the first Metazoan with a bilateral body plan involved much more.

The evolution of both cetaceans and birds may have involved some mechanisms in order to help increase the chance of avoiding predators.

The most optimistic view is that evolution has involved a gradual accretion of new structures, added on to primitive ones common to all mammals.

For Darwin, they pointed out, evolution involved descent and modification, not just descent.

The long-term evolution of these species has involved selection for social behaviors that make individual or group survival more likely.

Yet over the last two decades, the evolution of video games has involved a quest for the opposite.

The evolution of the horse involved a reduction in the number of toes to one, along with other changes to the ancestral equid foot.

Mimetic evolution also involved direct selection with the model acting as a "starting block" for the mimic to evolve against.