the belief that God had created mankind
in his own image and likeness were shed
by most Western scientists until the
middle of the 19th century they thought
all the creatures of the planet had been
conceived by a divine force that is
until Charles Darwin arrived some
researchers were already talking about
an evolution of the species but the
British naturalist was the first to
explain with evidence how evolution
might occur by natural selection
his theory radically changed biology
offering a new explanation of the origin
of human beings it also made him one of
the most influential scientists and
intellectuals in history but to get
there he had to make an extraordinary
journey before hundreds of experiments
and spend 20 years refining his ideas
[Music]
in 1831 Darwin was 22 years old and
studying at the University of Cambridge
when he was invited as a naturalist to a
great expedition he boarded the HMS
Beagle and spent almost five years
traveling several continents starting in
South America from which he brought back
dozens of life specimens illustrations
and fossils these fossils gave him one
of the first clues about evolution for
example observing the remains of a
milodon a giant animal similar to the
sloth he thought that those similarities
were probably not a coincidence there
had to be some kind of link when he
stopped at the Galapagos Islands Darwin
also observed its giant tortoises which
lived in nearby islands but showed
unique physical characteristics in each
Island in the humid areas where
vegetation was abundant the turtles had
a short neck and a dome-shaped shell
whilst in the islands with a drier
environment they had a saddle like shell
and along the neck but could he explain
that difference upon his return Darwin
spent time observing how animal breeders
and guards crossbred animals of species
to create new varieties for that
creation to be successful the artificial
selection made by man was key Darwin
realized that the natural world probably
made the same kind of selection but he
can explain how it happened until he
read the work of Thomas Robert Malthus a
British intellectual from the 18th
century in an essay on demography
Malthus said that as the population in
Europe was growing at one point it would
increase much more than the food
supplies available and that would cause
a fight for survival this idea helped
Darwin explain how evolution works in
nature there is a struggle for survival
in which the strongest individual is not
necessarily the survivor instead it's
the one which best adapts to the
environment where it lives if a living
being has any trait that helps them to
survive it will be more successful at
reproduction
those which don't adapt will die without
descendants the creatures with the most
success in reproducing past their traits
- their lineage and so on until these
variations end up becoming a new species
that's why the differences between the
Galapagos Tortoises were a product of
evolution in a drier environment those
with longer necks could reach the bushes
easily in order to get food whilst those
who lived in the humid environment could
eat grass and protect themselves from
predators
thanks to their shorter neck and the
dome-shaped shell Darwin said that all
species including humans were not
created independently but they descended
from a common ancestor from then on life
on the planet began to diversify twenty
years after his trip Darwin had written
thousands of pages but he hadn't
published any he wanted to have their
refutable evidence perhaps because he
knew that his theory was going to cause
quite a stir but everything changed when
he received a letter from Alfred Russel
Wallace an admirer and fellow naturalist
who told him that he had reached the
same conclusion evolution was produced
by natural selection
Darwin panicked facing the possibility
that Wallace could take sole credit for
the theory so the two naturalist degree
to present a joint letter explaining
their findings but a year later Darwin
published his book titled on the Origin
of Species and he became a celebrity way
beyond the scientific community his
findings shook the foundations of
Victorian Britain
like Copernicus in his time Darwin
changed the game by explaining that
diversity came from a biological process
without any interference from God Darwin
put human beings in the same
evolutionary level as all the creatures
on the planet scientific advances have
confirmed his theory and even the
Catholic Church ended up accepting
decades later that evolution is
compatible with faith and today more
than 150 years after Darwin's theory
became known we know that evolution is a
fact the planet keeps changing sometimes
dramatically and we keep changing with
it