The processes of evolution and extinction are constantly
happening, changing the diversity of life on Earth. What we do to
the world around us affects these processes dramatically and
threatens the survival of life as we know it.
Above: The dodo, an icon of
extinction.
Click on any of the images below to see a larger version of the
object and find out more about it.
Life evolves
Life on Earth has changed dramatically over millions of years.
The process through which living things change their appearance and
behaviour over successive generations is called evolution.
Evolution takes place mostly by natural selection. Some living
things are better suited to a particular environment and produce
more surviving offspring. As environments change, only the best
adapted individuals survive and over time, populations and species
change. How do we know this? Today’s living things and fossils from
the distant past provide evidence for evolution.
Producing new species
Over time individual animals in a population may change in
appearance through natural selection. But how do new species arise?
Or even whole groups, such as vertebrates or birds?
Natural selection and chance events can lead to changes in the
appearance and genetics of individual animals. Eventually they may
become so different from their ancestors that they are recognised
as a new species. This is called speciation and it can happen
rapidly or over many generations.
Human impact
People have always had an impact on other species and natural
environments. The Survival gallery also examines the
ever-increasing impact of today’s huge and expanding human
population.
Burning oil, gas and coal for energy is affecting climate and
environments globally. Forests and other habitats are being
destroyed for their natural resources. Fish and other marine life
are scoured from the oceans for food and fertiliser. Trade and
industry are polluting water, land and air. Countless thousands of
species are in danger. Are we on the brink of the next mass
extinction?