○ A process of continuous change from a
lower, simpler, or worse to a higher,
more complex, or better state : growth
○ The historical development of a
biological group ( as a race or species )
○ A theory that the various types of
animals and plants have their origin in
other pre-existing types and that the
distinguishable differences are due to
modifications in successive generations
Evolution is the change in
the inherited characteristics of biological populations over
It is a processes that give rise to diversity at every level
of biological organization, including species, individual
organisms and molecules such as DNA and proteins.
Don’t you know that….
At age of 12, Darwin
confessed in a letter, that
he only washed his feet
once a month at school,
due to a lack of anything
with which to wash.
All life on Earth is descended from a last
universal ancestor that lived
approximately 3.8 billion years ago.
Repeated speciation and
the divergence of life can be inferred from
shared sets of biochemical and
morphological traits, or by shared DNA
These homologous traits and sequences
are more similar among species that
share a more recent common ancestor,
and can be used
to reconstruct evolutionary histories, using
both existing species and the fossil
Existing patterns of biodiversity have
been shaped both by speciation and
Charles Darwin was the first to
formulate a scientific argument for
the theory of evolution by means of natural
Evolution by natural selection is a process
inferred from threefacts about populations:
1) more offspring are produced than can
2) traits vary among individuals, leading
to different rates of survival and
3) trait differences are heritable.
1.1 History Of Evolutionary
Anaximander and Empedocles- they are the one
who proposed that one type of animal could
descend from an animal of another type during
the pre-Socratic Period.
Aristotle- understood all natural things, not
only living things, as being
imperfect actualizations of different fixed natural
possibilities, known as "forms", "ideas", or (in Latin
John Ray used one of the previously more
general terms for fixed natural types, "species",
to apply to animal and plant types, but he
strictly identified each type of living thing as a
species, and proposed that each species can
be defined by the features that perpetuate
themselves each generation.
The biological classification introduced
by Carolus Linnaeus in 1735 also viewed
species as fixed according to a divine plan.
In 1842 Charles Darwin penned his first sketch of
what became On the Origin of Species.
Maupertuis wrote in 1751 of natural modifications
occurring during reproduction and accumulating
over many generations to produce new species.
Lamarck- "transmutation" theory of 1809, which
viewd spontaneous generation continually
producing simple forms of life developed greater
complexity in parallel lineages with an inherent
progressive tendency, and that on a local level
these lineages adapted to the environment by
inheriting changes caused by use or disuse in
Darwin was partly influenced by An Essay
on the Principle of Population and noted
that population growth would lead to a
"struggle for existence" where favorable
variations could prevail as others perished.
Who wrote that essay?
Thomas Robert Malthus
Darwin was developing his theory of "natural
selection" from 1838 onwards until Alfred
Russel Wallace sent him a similar theory in
1858. Both men presented their separate
papers to the Linnean Society of London.
Thomas Henry Huxley applied Darwin's ideas
using paleontology and comparative
anatomy to provide strong evidence that
humans and apes shared a common ancestry.
Gregor Mendel reported that traits were
inherited in a predictable manner through the
independent assortment and segregation of
elements (later known as genes). Mendel's
laws of inheritance eventually supplanted most
of Darwin's pangenesis theory.
. Hugo de Vries connected Darwin's
pangenesis theory to Weismann's germ/soma
cell distinction and proposed that Darwin's
pangenes were concentrated in the cell
nucleus and when expressed they could move
into the cytoplasm to change the cells
De Vries developed a mutation theory
that led to a temporary rift between
those who accepted Darwinian
evolution and biometricians who allied
with de Vries.
In the 1920s and 1930s a modern
evolutionary synthesis connected
natural selection, mutation theory, and
Mendelian inheritance into a unified
theory that applied generally to any
branch of biology.
The branch of Biology
that studies genes and
Evolution in organisms occurs through changes in
heritable traits – particular characteristics of an
organism. In humans, for example, eye colour is
an inherited characteristic and an individual might
inherit the "brown-eye trait" from one of their
Genotype- traits are controlled by genes and the
complete set of genes within an
Phenotype- the complete set of observable traits
that make up the structure and behaviour of an
Heritable traits are passed from one generation to
the next via DNA, a molecule that encodes genetic
information. DNA is a long polymer composed of
four types of bases
Portion/s of a DNA
molecule that specify a
single functional unit.
White peppered moth
Black morph in peppered moth evolution
Divergence in the
structural or functional
characteristics of an
organism from the
species or population
norm or average.
organism's phenotype results from
both its genotype and the influence
from the environment it has lived in.
A substantial part of the variation in
phenotypes in a population is
caused by the differences between
their genotypes. The modern
evolutionary synthesis defines
evolution as the change over time in
this genetic variation.
Variation disappears when a new
allele reaches the point of _____ —
when it either disappears from the
population or replaces the ancestral
A relatively permanent change in
hereditary material involving either
a physical change in chromosomes
relations or a biochemical change
in the codons that make up genes
Mutations are changes in the
DNA sequence of a cell's
Mutations can involve large sections of a
chromosome becoming duplicated (usually
by genetic recombination), which can introduce
extra copies of a gene into a genome. Extra
copies of genes are a major source of the raw
material needed for new genes to evolve. This
is important because most new genes evolve
within gene families from pre-existing genes that
share common ancestors. For example, the
human eye uses four genes to make structures
that sense light: three for colour vision and one
for night vision; all four are descended from a
single ancestral gene.
______ are large enzymes that produces
antibiotics; they contain up to one hundred
independent domains that each domains
catalyzed one step in the overall process, like
a step in an assembly line.
a. Polytetide Synthase
c. Poliketide Synthase
d. Polimetide Synthase
Is the exchange of genes between populations
and between species. It can therefore be a
source of variation that is new to a population or
to a species. Gene flow can be caused by the
movement of individuals between separate
populations of organisms, as might be caused
by the movement of mice between inland and
coastal populations, or the movement
of pollen between heavy metal tolerant and
heavy metal sensitive populations of grasses.
Evolution by means
of natural selection is the
process by which genetic
mutations that enhance
reproduction become and
remain more common in
successive generations of
It has often been called a "self-
evident" mechanism because it
necessarily follows from three
1. Heritable variation exists within
populations of organisms.
2. Organisms produce more progeny
than can survive.
3. These offspring vary in their ability
to survive and reproduce.
The central concept of natural
selection is the evolutionary fitness of
an organism. Fitness is measured by
an organism's ability to survive and
reproduce, which determines the size
of its genetic contribution to the next
generation. However, fitness is not the
same as the total number of offspring:
instead fitness is indicated by the
proportion of subsequent generations
that carry an organism's genes.
An aspect of the developmental
pattern of the organism which
enables or enhances the probability
of that organism to survive and
b. Adaptive traits
Adaptation is the process that
makes organisms better suited
to their habitat. Also, the term
adaptation may refer to
a trait that is important for an
The following definitions are due to Theodosius
1. Adaptation is the evolutionary process whereby
an organism becomes better able to live in
its habitat or habitats.
2. Adaptedness is the state of being adapted: the
degree to which an organism is able to live and
reproduce in a given set of habitats.
3. An adaptive trait is an aspect of the
developmental pattern of the organism which
enables or enhances the probability of that
organism surviving and reproducing.
Tyrannosaurus rex. Non-avian dinosaurs died
out in the Cretaceous–Paleogene extinction
event at the end of the Cretaceous period.
Extinction is the disappearance of an entire
species. Extinction is not an unusual event,
as species regularly appear through
speciation and disappear through
extinction. Nearly all animal and plant
species that have lived on Earth are now
extinct, and extinction appears to be the
ultimate fate of all species.These
extinctions have happened continuously
throughout the history of life, although the
rate of extinction spikes in occasional
mass extinction events.
Human activities are now the
primary cause of the ongoing
extinction event; what event or
phenomenon may further
accelerate extinction in the future?
Do you believe that WE humans
really descended from APES??
Since scientists developed the
ability to decode the genome
and compare the genetic
makeup of species, some
people have been stunned to
learn that about 98.5% of the
genes in people and
chimpanzees are identical.
Humans share a common ancestor
with modern African apes (i.e.,
gorillas and chimpanzees), making
us very, very distant cousins. We are
therefore related to these other living
primates, but WE DID NOT
DESCEND FROM THEM.
from apes in
2. Humans have elaborate
forms of communication and
3. Humans habitually
walk upright, can
small objects, and
1.1 Human Ancestor
Most scientists believe our common ancestor
existed 5 to 8 million years ago. Then two
species broke off into separate lineages, one
ultimately evolving into gorillas and chimps,
the other evolving into early humans called
hominids. In the millions of years that
followed, at least a dozen different species of
humanlike creatures have existed, reflected
in the fossil discoveries of
paleoanthropologists, although many of
these species are close relatives but not
actual ancestors of modern humans.
______ are the remains or
impressions of living things
hardened in rock.
The earliest humans were found in Africa,
which is where much of human evolution
occurred. The fossils of these EARLY
HOMINIDS, which lived 2 to 6 million
years ago, all come from that continent.
Most scientists believe early humans
migrated out of Africa into Asia between 2
million and 1.7 million years ago, entering
Europe some time within the past 1
million years. What follows are some
highlights of the early human species that
have been identified by scientists to date.
The name australopithecine means
“southern ape,” in reference to South
Africa where the first known fossils
were found. Many more australopith
fossils have been found in the Great
Rift Valley in eastern Africa, in
countries including Ethiopia,
Tanzania, Kenya, and Chad.
The best-known australopith specimen is
“Lucy,” the partial skeleton of a female
discovered in 1974 in Hadar, Ethiopia.
Lucy belongs to a species,
Australopithicus afarensis, which thrived
in eastern Africa between 3.9 million and
3 million years ago. Scientists have found
several hundred A. afarensis fossils in
Hadar. Lucy lived 3.2 million years ago.
By about 2.7 million years ago, so-
called robust australopiths (in
contrast to the earlier, gracile forms)
had evolved, with wide molars and
premolars and a facial structure that
indicate that these robust
australopiths chewed their food,
primarily tough, fibrous plants,
powerfully and for long periods.
The Genus Homo
The genus Homo first evolved at least 2.3
million to 2.5 million years ago. The most
significant difference between members
of this genus and australopiths, with
which they overlapped, was their
significantly larger brains (about 30
percent larger, though still small
compared to modern humans).
3 periods of Homo Evolution
1. Early Period
Species of early Homo, among them
Homo habilis, resembled australopiths in
many distinct ways, but they had smaller
teeth and jaws, more modern-looking
feet, and hands capable of making tools.
They probably lived from between 2.5 or
2.3 million and 1.6 million years ago.
2. Middle Period
The middle Homo species, including
Homo erectus, evolved anatomically to
be more similar to modern humans but
their brains were relatively small (though
bigger than australopiths). They
probably overlapped with earlier Homo
species, as they developed perhaps
between 2 million and 1.8 million years
3. Late Period
The final transition, from the middle
to late periods, happened about
200,000 years ago. Late Homo
species, including Neanderthals and
Homo sapiens, evolved large and
complex brains, leading eventually
to language, and developed culture
as an increasingly important aspect
of human life.
Scientists have dated the oldest known fossils with
skeletal features typical of modern humans from
195,000 years ago. Early anatomically modern
Homo sapiens fossils have come from sites in
Sudan, Ethiopia, South Africa, and Israel. Many
scientists have therefore concluded that modern
Homo sapiens evolved in Africa and began
spreading to other parts of the world 90,000 years
ago or a little earlier, although whether, how, why,
and when this happened is still in dispute. And it
was not until about 40,000 years ago that
anatomically modern humans, HOMO SAPIENS