EVOLUTIONARY TRENDS: Patterns in the History of Life
Trends: is there any order to evolution? Summary:-
Evolutionary biologists debate the existence and drivers of evolutionary
trends. The extent to which evolution is predictable or unpredictable is
uncertain. 2 lines of evidence:
1. Convergence. Convergent evolution is powerful evidence that evolution
is not random- certain things happen over and over. Non-convergence is
evidence that evolution is not purely deterministic, either.
2. Trends over time. The history of life suggests randomness, but a number
of potential patterns can be observed
• Size increase
• Complexity increase
• Behavioral complexity (intelligence)
• Diversity Increase
Is there order in the Universe?
Once this q was really easy to answer via religion. In the beginning, there was God: God
created the Night and the Day, the Heavens and the Earth. God Created Man. Existence
of the universe was by design- not just order, but intent.
Everything changes in 1859:
The publication of the Origin of Species in 1859 provided mechanisms by which one
species could transform into another.
Darwin later elaborates on these ideas in Descent of Man and propose that humans
descended from apes.
The idea of an animal ancestry for humans was difficult for some people to accept. But
Darwin’s original sin wasn’t the idea that man was an animal.
It was the idea of materialism.
It was creation without a creator- order without design
The idea that humans do not fundamentally differ from other animals is difficult for
people to accept.
Materialism is an even more subversive idea: what you see is what you get!
Materialism is the idea that the universe consists only of what we observe
There is matter, made of elemental building blocks, and energy. No spirits, no ghosts, no
eternal realms, no angels, no demons… no God
The idea dates back to the ancient Greeks, but materialistic approaches to understanding
the world take off in the Renaissance
In the 1800s, Scottish geologists start trying to explain the origins of the Earth in
materialistic terms- using processes we see acting in the world today
The landscape results from the slow rise and fall of land masses, and gradual action of
wind, water and ice over countless eons
Nobody gets upset
But Darwin reads geology books and wonders if we can explain the origin of species
according to processes we see acting all around us: variation, heredity, reproduction,
competition
From Made -> Just Happened
If so, that raises a question.
, Why did it just happen this way, and not some other way?
Is the existence of humans just a fluke: a peculiarity of an insignificant planet in an
insignificant galaxy?
Or is there some underlying order (if not intent) to the universe?
The Star Trek Hypothesis: evolution is likely to produce human-like organisms
Travelling through space in the 23rd century, the Federation encounters species that look
a lot like humans- for instance, the Vulcans.
Vulcans have upright posture, two legs, two arms with opposable thumbs, two eyes, two
nostrils, a mouth, and (pointy) ears.
But if Vulcan life evolved independently from molecules on primordial Vulcan, how likely
is it to look like us?
How likely is it that Vulcan DNA would code amino acids like ours (or that they would
even use DNA)? Have similar chemistry and physiology? Be built anything like us?
(this is partly a result of limited special effects budgets and technology of the day… but
only partly, because more recent science fiction continues to use humanoid aliens)
The Man in the High Castle: STOCHASTICITY – chance events play a huge role
In the Philip K. Dick novel, the assassination of Franklin D. Roosevelt causes the allies to
lose WW2, and America is controlled by fascists.
A minor deviation in history leads to a radically different outcome – the future is not fore
ordinated, but shaped by small chance events (real example: assassination plot by
German generals)
The Problem: is evolution random?
To understand whether evolution is random or not, we need to look for patterns- places
where evolution has tended to repeat itself, or failed to repeat itself.
1. The modern world. We can look for convergence in outcomes- places where
organisms have independently arrived at similar solutions to similar problems.
2. The fossil record. We can look at whether there are patterns in evolutionary
dynamics over time.
1. Convergence: do different animals hit on similar solutions?
E.G. Birds are a very diverse group, which makes them an interesting system for
studying evolution.
Penguinus: The Great Auk
Auks are diving birds
that use their wings
to propel themselves
underwater
Largest species-
Penguinnis impennis-
took this to such an
extreme that it lost
the ability to fly-
formerly inhabited
islands in the North
Atlantic
The name is thought
to derive from the
Welsh ‘pen gwyn’ –
“white head”
Spheniscidae:
Penguins
Trends: is there any order to evolution? Summary:-
Evolutionary biologists debate the existence and drivers of evolutionary
trends. The extent to which evolution is predictable or unpredictable is
uncertain. 2 lines of evidence:
1. Convergence. Convergent evolution is powerful evidence that evolution
is not random- certain things happen over and over. Non-convergence is
evidence that evolution is not purely deterministic, either.
2. Trends over time. The history of life suggests randomness, but a number
of potential patterns can be observed
• Size increase
• Complexity increase
• Behavioral complexity (intelligence)
• Diversity Increase
Is there order in the Universe?
Once this q was really easy to answer via religion. In the beginning, there was God: God
created the Night and the Day, the Heavens and the Earth. God Created Man. Existence
of the universe was by design- not just order, but intent.
Everything changes in 1859:
The publication of the Origin of Species in 1859 provided mechanisms by which one
species could transform into another.
Darwin later elaborates on these ideas in Descent of Man and propose that humans
descended from apes.
The idea of an animal ancestry for humans was difficult for some people to accept. But
Darwin’s original sin wasn’t the idea that man was an animal.
It was the idea of materialism.
It was creation without a creator- order without design
The idea that humans do not fundamentally differ from other animals is difficult for
people to accept.
Materialism is an even more subversive idea: what you see is what you get!
Materialism is the idea that the universe consists only of what we observe
There is matter, made of elemental building blocks, and energy. No spirits, no ghosts, no
eternal realms, no angels, no demons… no God
The idea dates back to the ancient Greeks, but materialistic approaches to understanding
the world take off in the Renaissance
In the 1800s, Scottish geologists start trying to explain the origins of the Earth in
materialistic terms- using processes we see acting in the world today
The landscape results from the slow rise and fall of land masses, and gradual action of
wind, water and ice over countless eons
Nobody gets upset
But Darwin reads geology books and wonders if we can explain the origin of species
according to processes we see acting all around us: variation, heredity, reproduction,
competition
From Made -> Just Happened
If so, that raises a question.
, Why did it just happen this way, and not some other way?
Is the existence of humans just a fluke: a peculiarity of an insignificant planet in an
insignificant galaxy?
Or is there some underlying order (if not intent) to the universe?
The Star Trek Hypothesis: evolution is likely to produce human-like organisms
Travelling through space in the 23rd century, the Federation encounters species that look
a lot like humans- for instance, the Vulcans.
Vulcans have upright posture, two legs, two arms with opposable thumbs, two eyes, two
nostrils, a mouth, and (pointy) ears.
But if Vulcan life evolved independently from molecules on primordial Vulcan, how likely
is it to look like us?
How likely is it that Vulcan DNA would code amino acids like ours (or that they would
even use DNA)? Have similar chemistry and physiology? Be built anything like us?
(this is partly a result of limited special effects budgets and technology of the day… but
only partly, because more recent science fiction continues to use humanoid aliens)
The Man in the High Castle: STOCHASTICITY – chance events play a huge role
In the Philip K. Dick novel, the assassination of Franklin D. Roosevelt causes the allies to
lose WW2, and America is controlled by fascists.
A minor deviation in history leads to a radically different outcome – the future is not fore
ordinated, but shaped by small chance events (real example: assassination plot by
German generals)
The Problem: is evolution random?
To understand whether evolution is random or not, we need to look for patterns- places
where evolution has tended to repeat itself, or failed to repeat itself.
1. The modern world. We can look for convergence in outcomes- places where
organisms have independently arrived at similar solutions to similar problems.
2. The fossil record. We can look at whether there are patterns in evolutionary
dynamics over time.
1. Convergence: do different animals hit on similar solutions?
E.G. Birds are a very diverse group, which makes them an interesting system for
studying evolution.
Penguinus: The Great Auk
Auks are diving birds
that use their wings
to propel themselves
underwater
Largest species-
Penguinnis impennis-
took this to such an
extreme that it lost
the ability to fly-
formerly inhabited
islands in the North
Atlantic
The name is thought
to derive from the
Welsh ‘pen gwyn’ –
“white head”
Spheniscidae:
Penguins
