What is Evolution??

What is Evolution??
Evolution is a theory based on substantial
Def: All the changes that have formed life
on earth from its earliest beginnings to the
diversity that characterizes it today.
Pioneers of evolution include:
Darwin, Malthus, Lamarck, Lyell, Wallace
 Malthus (1766- 1834): Population growth
 Lamarck (1744 – 1829): Lamarck developed
two laws to explain evolution: the law of use
and disuse, and the law of inheritance of
acquired characteristics.
 Lyell (1797 – 1875): Wrote Principles of
Geology- said “The present is the key to the
 Wallace (1823 – 1923): Biogeography; first to
form theory of natural selection
Lamarck Law 1:
 (Use and disuse) In every animal which has
not passed the limit of its development, a more
frequent and continuous use of any organ
gradually strengthens, develops and enlarges
that organ, and gives it a power proportional to
the length of time it has been so used; while
the permanent disuse of any organ
imperceptibly weakens and deteriorates it, and
progressively diminishes its functional capacity,
until it finally disappears.
Lamarck Law 2:
 (Inheritance of acquired characteristics) All the
acquisitions or losses wrought by nature on
individuals, through the influence of the
environment in which their race has long been
placed, and hence through the influence of the
predominant use or permanent disuse of any
organ; all these are preserved by reproduction
to the new individuals which arise, provided
that the acquired modifications are common to
both sexes, or at least to the individuals which
produce the young.
So who was Darwin, anyway,
and why do we care?
 Darwin relied on years of close observations
and data to develop his theories on evolution.
 Most well known for descriptions of Galapagos
 He concluded that birds were adapting to their
environment by having different beak sizes for
their available food source.
 Revolutionized the theory of evolution at a very
controversial time in history.
 Darwin proposed that species were evolving by
process of natural selection – a process by
which organisms best suited to their
environment reproduce more successfully than
other organisms.
 For natural selection to occur, has to be some
certainties about the population:
- Organisms have to reproduce
- Has to be variation within the population
- Traits have to have a genetic basis
- Trait provides advantage to organism
Some Vocab. To Know…
 Adaptation: an inherited trait that
increases an organism’s chance of
survival in a particular environment.
 Fitness: the ability of individuals to
survive to pass on their genes.
 Population: interbreeding single-species
 Species: a group of organisms of a single
type that are capable of producing fertile
Which moth
started to
appear after
the industrial
Other evidence…
For Homework…
Answer the following questions. Be ready to
discuss your answers the beginning of
1. Why is there variation among all living
organisms? Provide two concrete
examples as to how this helps species
2. Name one important person besides
Darwin who helped influence the theory of
evolution. What were some of their
contributions and during what time period
did they occur?