Polemics

Convergence detected in the genetic structure of bats and dolphins

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Apologetics and the progress of science
Apologetics and the progress of science

We have to start this post with the definition of convergence in biology.

In evolutionary biology, convergent evolution is the process whereby organisms not closely related (not monophyletic), independently evolve similar traits as a result of having to adapt to similar environments or ecological niches.

It is the opposite of divergent evolution, where related species evolve different traits.

On a molecular level, this can happen due to random mutation unrelated to adaptive changes; see long branch attraction. In cultural evolution, convergent evolution is the development of similar cultural adaptations to similar environmental conditions by different peoples with different ancestral cultures. An example of convergent evolution is the similar nature of the flight/wings of insects, birds, pterosaurs, and bats.

All four serve the same function and are similar in structure, but each evolved independently.

Jonathan Wells explains the problem that convergence poses for naturalistic evolution:

Human designers reuse designs that work well. Life forms also reuse certain structures (the camera eye, for example, appears in humans and octopuses). How well does this evidence support Darwinian evolution? Does it support intelligent design more strongly?

Evolutionary biologists attribute similar biological structures to either common descent or convergence. Structures are said to result from convergence if they evolved independently from distinct lines of organisms. Darwinian explanations of convergence strain credulity because they must account for how trial-and-error tinkering (natural selection acting on random variations) could produce strikingly similar structures in widely different organisms and environments. It’s one thing for evolution to explain similarity by common descent—the same structure is then just carried along in different lineages. It’s another to explain it as the result of blind tinkering that happened to hit on the same structure multiple times. Design proponents attribute such similar structures to common design (just as an engineer may use the same parts in different machines). If human designers frequently reuse successful designs, the designer of nature can surely do the same.

I’m a software engineer, and we re-use components all the time for different programs that have no “common ancestor”. E.g. – I can develop my String function library and use it in my web application and my Eclipse IDE plug-in, and those two Java programs have nothing in common. So you find the same bits in two different programs because I am the developer of both programs. But the two programs don’t extend from a common program that was used for some other purpose – they have no “common ancestor” program.

Now with that in mind, take a look at this recent article from Science Daily, which Mysterious Micah sent me.

Excerpt:

The evolution of similar traits in different species, a process known as convergent evolution, is widespread not only at the physical level, but also at the genetic level, according to new research led by scientists at Queen Mary University of London and published in Nature this week.

The scientists investigated the genomic basis for echolocation, one of the most well-known examples of convergent evolution to examine the frequency of the process at a genomic level.

Echolocation is a complex physical trait that involves the production, reception and auditory processing of ultrasonic pulses for detecting unseen obstacles or tracking down prey, and has evolved separately in different groups of bats and cetaceans (including dolphins).

The scientists carried out one of the largest genome-wide surveys of its type to discover the extent to which convergent evolution of a physical feature involves the same genes.

They compared genomic sequences of 22 mammals, including the genomes of bats and dolphins, which independently evolved echolocation, and found genetic signatures consistent with convergence in nearly 200 different genomic regions concentrated in several ‘hearing genes’.

[…]Consistent with an involvement in echolocation, signs of convergence among bats and the bottlenose dolphin were seen in many genes previously implicated in hearing or deafness.

“We had expected to find identical changes in maybe a dozen or so genes but to see nearly 200 is incredible,” explains Dr Joe Parker, from Queen Mary’s School of Biological and Chemical Sciences and first author on the paper.

“We know natural selection is a potent driver of gene sequence evolution, but identifying so many examples where it produces nearly identical results in the genetic sequences of totally unrelated animals is astonishing.”

Nature is the most prestigious peer-reviewed science journal. This is solid material.

There is an earlier article from 2010 in New Scientist that talked about one of the previous genes that matched for hearing capability.

Excerpt:

Bats and dolphins trod an identical genetic path to evolve a vital component of the complex sonar systems they use to pursue and catch prey.

The finding is unusual, because although many creatures have independently evolved characteristics such as eyes, tusks or wings, they usually took diverse genetic routes to get there.

Analysis of a specific gene has now demonstrated that although bats live in air and dolphins in water, where sound travels five times faster, they independently evolved a near-identical gene that allows them to accept high-frequency sound in the ear – vital for sonar.

The gene makes prestin, a protein in hair cells of the cochlea, which is the organ in the inner ear where sonar signals are accepted and amplified. Prestin changes shape when exposed to high-frequency sound, and this in turn deforms the fine hair cells, setting off an electrical impulse to the brain. So the protein has the important jobs of detecting and selecting high-frequency sounds for amplification.

When researchers examined the molecular structure of the prestin gene from a range of animals, they found that the variants in echolocating bats and dolphins were virtually indistinguishable.

Indistinguishable genes in animals that don’t share a common ancestor? Maybe a better explanation for the evidence we have is – common designer.

Commentary

Five things to learn from “The Hobbit”

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Gabriel Belmont looks up at his destination: Dracula's castle
Gabriel Belmont looks up at his destination: Dracula’s castle (from Castlevania)

Since I mentioned “The Hobbit” in my biographical page at the top of the blog, I thought it might be worth linking to something about it.

This is from the Art of Manliness blog.

The 5 things:

  1. You can aspire to and achieve greatness no matter who you are and no matter your stage in life
  2. A great leader knows when it’s time to step back and let go
  3. There are some things in life we just have to accomplish on our own
  4. To simply continue on is one of the bravest things that can be done
  5. A great story always has conflict or hardship

And my favorite of the five – the one that had meaning for me – is #5:

5. A great story always has conflict or hardship. Imagine your life as a story. Not too long ago, we even had a guest post about this — our life is a journey, and a heroic one at that. Imagine yourself sitting down with your grandkids and telling them the story of you. “Well, I made some money, bought a few cars, sat around and watched TV for a few hours every night, and that’s about it.” Pretty boring, isn’t it? Now imagine that you can start hours worth of stories with, “I explored…I traveled…I fell in love…I fought and won…I overcame…I sweated…” Not only would the story be better, but you likely would be far more satisfied with the course of your life.

J.R.R. Tolkien agrees. “Now it is a strange thing, but things that are good to have and days that are good to spend are soon told about, and not much to listen to; palpitating, and even gruesome, may make a good tale, and take a deal of telling anyways.” He is saying that a life of good ease is a boring one. It’s often what the American dream aspires to, but the reality is that personal growth, and even enjoyment, are things that come out of some kind of challenge. Whether it’s huffing and puffing and groaning your way up a mountain for the view at the top, or getting laid off and finally realizing you don’t want to be in a cubicle anymore, joy is often found after a bit of trudging. Don’t shy away from challenge. Embrace it, and know that someday it’ll make for a great story.

The Hobbit was the first big book that I ever read as a child, and I think that it inspired me to move far away from home as soon as I completed graduate school, so I could make my fortune. An adventurous spirit isn’t free – it has to be put into a boy by what he reads. When I was young, I read “The Hobbit”. You should make your children read “The Hobbit”. Put into their minds at a young age the idea that life is an adventure, that dangers and hardships are normal, and that character counts. Put into their minds that all goodness requires sacrifice. I think that things are going to get harder for Christians going forward so it’s better that they be ready for it.

Polemics

Why is the universe so big, and why is so much of it hostile to life?

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Chris Kyle, Navy SEAL
Chris Kyle, Navy SEAL, can hit a very small target from a mile away – very improbable

Review: In case you need a refresher on the cosmological and fine-tuning arguments, as presented by a professor of particle physics at Stanford University, then click this link and watch the lecture.

If you already know about the standard arguments for theism from cosmology, then take a look at this post on Uncommon Descent.

Summary:

In my previous post, I highlighted three common atheistic objections to to the cosmological fine-tuning argument. In that post, I made no attempt to answer these objections. My aim was simply to show that the objections were weak and inconclusive.

Let’s go back to the original three objections:

1. If the universe was designed to support life, then why does it have to be so BIG, and why is it nearly everywhere hostile to life? Why are there so many stars, and why are so few orbited by life-bearing planets? (Let’s call this the size problem.)

2. If the universe was designed to support life, then why does it have to be so OLD, and why was it devoid of life throughout most of its history? For instance, why did life on Earth only appear after 70% of the cosmos’s 13.7-billion-year history had already elapsed? And Why did human beings (genus Homo) only appear after 99.98% of the cosmos’s 13.7-billion-year history had already elapsed? (Let’s call this the age problem.)

3. If the universe was designed to support life, then why does Nature have to be so CRUEL? Why did so many animals have to die – and why did so many species of animals have to go extinct (99% is the commonly quoted figure), in order to generate the world as we see it today? What a waste! And what about predation, parasitism, and animals that engage in practices such as serial murder and infant cannibalism? (Let’s call this the death and suffering problem.)

In today’s post, I’m going to try to provide some positive answers to the first two questions: the size problem and the age problem.

Here’s an excerpt for the size argument:

(a) The main reason why the universe is as big as it currently is that in the first place, the universe had to contain sufficient matter to form galaxies and stars, without which life would not have appeared; and in the second place, the density of matter in the cosmos is incredibly fine-tuned, due to the fine-tuning of gravity. To appreciate this point, let’s go back to the earliest time in the history of the cosmos that we can meaningfully talk about: the Planck time, when the universe was 10^-43 seconds old. If the density of matter at the Planck time had differed from the critical density by as little as one part in 10^60, the universe would have either exploded so rapidly that galaxies wouldn’t have formed, or collapsed so quickly that life would never have appeared. In practical terms: if our universe, which contains 10^80 protons and neutrons, had even one more grain of sand in it – or one grain less – we wouldn’t be here.

If you mess with the size of the universe, you screw up the mass density fine-tuning. We need that to have a universe that expands at the right speed in order to form galaxies, stars and planets. You need planets to have a place to form life – a place with liquid water at the surface.

And an excerpt for the age argument:

(a) One reason why we need an old universe is that billions of years were required for Population I stars (such as our sun) to evolve. These stars are more likely to harbor planets such as our Earth, because they contain lots of “metals” (astronomer-speak for elements heavier than helium), produced by the supernovae of the previous generation of Population II stars. According to currently accepted models of Big Bang nucleosynthesis, this whole process was absolutely vital, because the Big Bang doesn’t make enough “metals”, including those necessary for life: carbon, nitrogen, oxygen, phosphorus and so on.

Basically, you need heavy elements to make stars that burn slow and steady, as well as to make PEOPLE! And heavy elements have to be built up slowly through several iterations of the stellar lifecycle, including the right kinds of stellar death: supernovae.

Read the rest! These arguments come up all the time in debates with village atheists like Christopher Hitchens and Richard Dawkins. It’s a smokescreen they put up, but you’ve got to be able to answer it using the scientific evidence we have today. They always want to dismiss God with their personal preferences about what God should or should not do. But the real issue is the design of the cosmological constants that allow life to anywhere. That’s the part that’s designed. And that’s not a matter of personal preference, it’s a matter of mathematics and experimental science.

One last parting shot. If God made the universe have life everywhere, the first thing atheists would say is “See? Life evolves fine by itself without any God!” The only way to recognize a marksman is when he hits a narrow target (not hostile to life) from a wide range of possibilities that have no value (hostile to life). We don’t credit Chris Kyle for hitting the wall above an Islamic terrorist from a mile away, we credit Chris Kyle for hitting an Islamic terrorist a mile away. The design is not how much of the universe is hospitable to life versus how much is hostile to life. The design is in the cosmological constants – where we are in the narrow band that is hospitable to life and not in the huge regions that are hostile to life.

You can read the best explanation of the design argument in this lecture featuring Robin Collins. That link goes to my post which has a summary of the lecture. He has a new lecture that I also blogged about where he extends the fine-tuning argument down to the level of particle physics. I have a summary of that one as well.