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The Imperfection of Evolution & the Evolution of Imperfection

Some nations are populated on average by rational people.

Some nations are populated on average by morons.

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Jacques Monod1910-1976

“A curious aspect of the theory of evolution is that everybody thinks he understands it. I mean philosophers, social scientists, and so on. While in fact, very few people understand it.”

Jacques Monod (1973)

“A curious aspect of the theory of evolution is that every biologist thinks he understands it. I mean molecular biologists, physicians, geneticists, bioinformaticians, genomicists, computational biologists, biomedical engineers, and so on. While in fact, very few biologists understand it.”

Dan Graur with apologies to Jacques Monod

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Is there good design in the natural world?

The challenge for evolutionary biology is often phrased as follows: How can one explain the manner in which seemingly well designed features of an organism, where the fit of function to biological structure and organization often seems superb, are achieved without a sentient designer?

Example: The Abah river flying frog (Rhacophorus nigropalmatus), also known as Wallace's flying frog.

The argument for “intelligent design” dates back to Thomas Aquinas (13th century), who argued that organisms “act to achieve the best result.”

Since “beasts” are devoid of intelligence, an intelligent being must exist, setting the goals and providing direction to the act of achieving the best results.

The Watchmaker Metaphor

“In crossing a heath, suppose I pitched my foot against a stone, and were asked how the stone came to be there; I might possibly answer, that, for anything I knew to the contrary, it had lain there forever, nor would it perhaps be very easy to show the absurdity of this answer.”

— William Paley (1743-1805), Natural Theology (1802)

The Watchmaker Metaphor

“But suppose I had found a watch upon the ground, and it should be inquired how the watch happened to be in that place; I should hardly think of the answer I had given before, that for anything I knew, the watch might have always been there. There must have existed, at some time, and at some place or other, an artificer or artificers, who comprehended its construction, designed its use, and formed the watch for the purpose which we find it.”— William Paley (1743-1805), Natural Theology (1802)

The Watchmaker Metaphor

“Every indication of contrivance, every manifestation of design, which existed in the watch, exists in the works of nature; with the difference, on the side of nature, of being greater or more, and that in a degree which exceeds all computation.”

— William Paley (1743-1805), Natural Theology (1802)

The Watchmaker Metaphor

The existence of a watch requires us to assume the existence of a

watchmaker.

Does the existence of a shitty watch requires us to assume the existence of a shitty watchmaker?

The Slippery Slope of Intelligent Design

The Slippery Slope of Intelligent Design

Q: Is there anything that could be concluded about the Creator from the study of his Creation.

A: If one could conclude as to the nature of the Creator from a study of Creation, it would appear that God has an inordinate fondness for beetles.

J. B. S. Haldane. in “Homage to Santa Rosalia, or why are there so many kinds of animals” by G. Evelyn Hutchinson (Am. Nat. 1959).

The Slippery Slope of Intelligent Design

Organisms are shaped by EVOLUTION, i.e., by mutation, selection, random genetic drift, historical contingency, and developmental constraints.

What are the reasons behind the inability of evolutionary processes to produce good design.

• There are flaws in the process of evolution (“The Imperfection of Evolution”).

• And, there and flaws in the product of evolution (“The Evolution of Imperfection”):

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

2. The finite effective size of biological populations.3. Historical contingency & developmental

constraint

4. An evolutionary interpretation of the human genome.

Step one: Put a puppy in the oven and turn it on. Be sure to use puppy. The process does not work with old dogs.

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

Step two: Increase temperature. You will notice some behavioral responses in the puppy. These responses are evolutionarily irrelevant.

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

Step three: Further increase temperature. You will notice some physiological responses in the puppy. These responses are also evolutionarily irrelevant.

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

Step four: Further increase temperature. You will notice some biochemical response in the puppy. These response are also evolutionarily irrelevant.

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

Step five: Further increase temperature. You will notice an evolutionarily relevant response. The puppy dies, thereby removing its alleles from further evolutionary consideration.

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

Intelligent design or

Lamarckian evolution

Unintelligent design or

Darwinian evolution

As opposed to Lamarckian mechanisms, Darwinian ones lack a feedback stage from the phenotype back to the genotype .

1. The preponderance of Darwinian evolutionary mechanisms over Lamarckian ones.

Mutations are random:

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Mutations are random:

A mutation is expected to occur with the same frequency under conditions in which this mutation confers an advantage on the organism carrying it, as under conditions in which this mutation confers no advantage or is deleterious.

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“It may seem a deplorable imperfection of nature that mutation is not restricted to changes that enhance the adeptness of their carriers.”

Theodosius Dobzhansky (1970)

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The right mutation; the wrong mutant.

A mutation may occur in an individual that contributes little to the reproductive potential of a population (catholic nuns and/or motorcycle riders).

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Census population size = the total number of individuals in a population.

From an evolutionary point of view, however, the relevant size consists of only those individuals that actively participate in the reproductive process.

This part is called the effective population size and is denoted by Ne.

2. The finite effective size of biological populations.

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Ne (effective population size) is usually much smaller than N (census population size)

2. The finite effective size of biological populations.

Historical humancensus populationsizes

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Ne (effective population size) is usually much smaller than N (census population size)

2. The finite effective size of biological populations.

Current human census population size = >7,000,000,000Long-term effective population size = ~10,000

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Ne (effective population size) is usually much smaller than N (census population size)

Various factors contribute to this difference: • overlapping generations.• variation in the number of offspring

among individuals.• number of males involved in

reproduction is different from the number of females.

• long-term variations in population size. • bottlenecks

2. The finite effective size of biological populations.

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2. The finite effective size of biological populations.

The effective population size affects all three parameters of the evolutionary process.

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The fate of an allele is determined largely by chance (random genetic drift) if the selection coefficient is small, or if the effective population size is small.

s< 1/(2Ne)

In organisms with LARGE effective population sizes, the strength of natural selection is relatively strong.

In organisms with SMALL effective population sizes, the strength of natural selection is relatively weak.

2. The finite effective size of biological populations.

In organisms with LARGE effective population sizes, the strength of natural selection is relatively strong.

In organisms with SMALL effective population sizes, the strength of natural selection is relatively weak.

2. The finite effective size of biological populations.

The majority of new mutations are mildly deleterious. In humans and elephants, selection is not sufficiently strong to eliminate many such deleterious mutations.

In organisms with LARGE effective population sizes, the strength of natural selection is relatively strong.

In organisms with SMALL effective population sizes, the strength of natural selection is relatively weak.

2. The finite effective size of biological populations.

Humans and elephants are expected to accumulate numerous deleterious mutations in their genome.

The theory according to which evolution is constrained by historical precedent (developmental constraint). Evolution can only elaborate on what already exists.

Stephen Jay Gould: “If we rewind the tape of evolution backwards and replay it, would life evolve in the same way or in some very different manner?”

3. Historical contingency and developmental constraint

“The evolution of a phenotype is contingent on the particular history of a population. Historical contingency is especially important when it facilitates the evolution of key innovations that are not easily evolved by gradual, cumulative selection.”

3. Historical contingency and developmental constraint

3. Historical contingency and developmental constraint

Different characters are constrained developmentally. No matter how long the mammalian neck is, there can only be 7 cervical vertebrae.

3. Historical contingency and developmental constraint result in the existence of “unitelligent designs”

• trade offs, i.e., the inability to optimize traits simultaneously.

• suboptimal constructs, defying the notion of good design.

• useless vestigial traits.

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Penguin knees are entirely within the body of the bird and cannot pivot.

Examples of Unintelligent Design

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Examples of Unintelligent Design

Ectopic pregnancy = The cavity between the ovary and the fallopian tube may result in the implantation of a fertilized egg into the fallopian tube, cervix or ovary rather than the uterus. In nature, ectopic pregnancy invariably leads to the the deaths of both mother and baby.

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Examples of Unintelligent Design

Can you design a more stupid and more comical route for the vas deferens? The designer of the route from the testis to the penis could have used a good GPS.

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Examples of Unintelligent Design

The route of the recurrent laryngeal nerve travels from the brain to the larynx by looping around the aortic arch. This results in a waste of nerve length and a loss of signal. 5-6 meters in giraffes.

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Examples of Unintelligent Design

The birth canal passes through a narrow pelvis requiring the skull of the baby to deform at birth. If the baby’s head is significantly larger than the pelvic opening, the baby cannot be born naturally. Prior to modern surgery, such a complication invariably lead to the death of the mother, the baby, or both.

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Unitary pseudogenes

Examples of Unintelligent Design

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Humans cannot synthesize vitamin C. Lack of vitamin C results in scurvy and eventually death.

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Unitary pseudogenes

Examples of Unintelligent Design

Humans cannot synthesize vitamin C. Lack of vitamin C results in scurvy and eventually death.

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Examples of Unintelligent Design

Because human faces are significantly flatter than those of other primates while retaining the same tooth set as in primates, humans have crowded teeth and poor sinus drainage. This arrangement results in a number of problems, most notably sinusitis and wisdom tooth impaction.

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Examples of Unintelligent Design

The pharynx is used for both ingestion and respiration, with the consequent drastic increase in the risk of choking.

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Examples of Unintelligent Design

The retina is “inside out.” The nerves and blood vessels lie on the surface of the retina instead of behind it, as is the case in many invertebrate species. This arrangement forces a number of complex adaptations and gives mammals a blind spot. Humans need six muscles to move the eye, when three would have sufficed with more intelligent design.

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Examples of Unintelligent Design

The breathing reflex is stimulated not directly by the absence of oxygen but rather indirectly by the presence of carbon dioxide. As a result, at high altitudes, oxygen deprivation can occur if individuals who do not consciously increase their breathing rate.

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Sometimes unintelligent design can be beautiful. An example of a “tradeoff” between pleasing complexity and time to completion.

Construction started 1882 Anticipated completion 2026 (?)

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Evolution is an imperfect mechanism through which imperfect structures are produced.

Pleuronectes platessa(European plaice)

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Examples of Intelligent Design (reluctantly including the Mojito shoe)

Robotic fire extinguisher

iPadSegway

Rubik’s cube

Ergonomic violin

The Mojito flip-flop shoe designed by London architect Julian Hakes is made of carbon fiber—to give it strength and spring—and laminated with rubber on the bottom.

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Coffee tables made using evolutionary processes

Intelligently designed coffee table