Natural selection at work
Scientists have worked out many examples of natural
selection, one of the basic mechanisms of evolution.
Any coffee table book about natural history will overwhelm you with
full-page glossies depicting amazing adaptations produced by natural selection, such as the examples below.
|Orchids fool wasps into "mating" with them.
||Katydids have camouflage to look like leaves.
||Non-poisonous king snakes mimic poisonous coral snakes.
Behavior can also be shaped by natural
selection. Behaviors such as birds' mating rituals,
bees' wiggle dance, and humans' capacity to learn
language also have genetic components and are subject to
natural selection. The male blue-footed booby, shown to the right,
exaggerates his foot movements to attract a mate.
In some cases, we can directly observe natural selection.
Very convincing data show that the shape of finches' beaks
on the Galapagos Islands has tracked weather patterns: after
droughts, the finch population has
deeper, stronger beaks that let them eat tougher seeds.
In other cases, human activity has led to environmental
changes that have caused populations to evolve through natural
selection. A striking example is that of the population of
dark moths in the 19th century in England, which rose and
fell in parallel to industrial pollution. These changes can
often be observed and documented.