Download What evolution IS and is NOT

By Massimo Pigliucci
A concept road map to understand
evolution-creation
Evolution
IS
Change in
gene frequencies
DOES NOT
REQUIRE
Intelligent
Design
IS
Descent with
modification
IS NOT
Origin
of life
IS
NOT
Origin of
the universe
1- Evolution as a change
in gene frequencies
• Theory from population genetics
• Empirical evidence from
molecular biology
• Examples: viruses, bacteria, plants,
fungi, animals (including humans)
Example: the HIV virus
• Causes a disease of the immune system
• Common among vertebrates
Two major kinds of human HIV
HIV-1 evolved from a chimp virus and attacked human populations
in the 1940s in West Africa and in the 1970s in Europe
Why is AIDS so difficult to cure?
genes
(mutations)
environment
(sexual behavior)
2 – Evolution as descent
with modification
• Studied by comparative anatomy, paleontology
• Evidence from extant
organisms’ morphology,
physiology, and
development
• Evidence from the
fossil record
Example: the evolution of whales
Mesonychids
Whales (modern
& ancient)
Artiodactyls
(hippos, pigs,
camels, sheep)
55 MYA: in the beginning
were the early Artiodactyls
• Scavengers
• Fish hunters
bears
A sleuth of intermediate forms
• 53 MYA:
Hymalaiacetus, lived in
fresh water and sea
• 50 MYA: Pakicetus, lived on
both land and water
• 45-50 MYA: Ambulocetus,
reduced limbs
sea lions
Ambulocetus
Almost like a whale
Basilosaurus & co.:
Extremely reduced limbs
by 35-40 million years ago
Modern whales and hippos
• Most common recent ancestor: 55 MYA (DNA)
• Swim before walking
• Nurse young underwater
•Testicles remain inside body
• Hairless
• No sweat
3 – Evolution is NOT a theory
of the origin of life
Evolution requires heritable
variation for selection to act
The origin of life is a problem at the interface
between physical chemistry and biology
What could solve the problem
of the origin of life?
Complexity theory and the concept
of self-organization
4 – Evolution is NOT a theory
of the origin of the universe
The universe “evolves”
only in the general
sense of change through
time.
No selection,
no mutation.
“Building blocks” of galaxies
seen from Hubble
How could then the universe
have originated?
general relativity
quantum mechanics
superstrings
Does evolution fail if it cannot
answer “origin” questions?
5 – Does an understanding of the
variety of life on earth require ID?
Logical objections:
1 - Occam’s razor and avoidance of
unnecessary hypotheses
David Hume
(1779)
2 - Hume’s dictum on extraordinary
claims and evidence
The burden of proof is on
the other side
• The story of life on earth
appears idiosyncratic,
indicating contingency
and necessity (e.g.
extinction of dinosaurs)
• Organisms are not well
designed to fit their
environment (evolution
as bricoleur: human eye)
Can you really deny the evidence?
chimpanzee
spider monkey
Homo abilis
Homo erectus
Homo sapiens
A. afarensis