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.
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.
Basically, there was an atheist who challenged the idea that nature is designed because there are things in nature which cause suffering, like earthquakes and volcanoes.
Now the first thing to note is that atheists commonly think that God’s job is to make humans happy. If he doesn’t make humans feel happy – regardless of their knowledge of him and relationship with him – then he is a big failure. Many atheists think that, it is one of the most common reasons why people become atheists. But of course anyone who reads the Bible and reads the story of Jesus knows that the purpose of life on God’s view is for humans to know him and to be disciples of a suffering Messiah who sacrifices himself in order to obey God the Father. So that’s the first thing to say – purpose of life not happiness, but knowledge of God and being a disciple of Jesus. This may involve all kinds of suffering, and that’s to be expected.
Second, there is a response to the problem of evil based on the necessity of natural laws. The argument goes that you can’t have genuine morality without a predictable, knowable system of natural laws.
But I want to talk about something different in this post. In the video, Dr. Rana thinks that many of the things that cause suffering in the natural world are actually necessary for life to exist at all. He provides the example of plate tectonics in his video above, and I want to take that one and add to it the example of heavy element production and the stellar lifecycle. These are both from a book called “Rare Earth”, which is written by two non-Christians – Peter Ward and Donald Brownlee, but I’ll link to web sites to make the case.
Plate tectonics.
Here’s an article from Reasons to Believe by Dr. David Rogstad, who has a PhD in physics from Caltech – the top school for experimental science. The article not only goes over the basic plate tectonics to carbonate-silicate cycle connection, but it adds a newer discovery to boot.
Excerpt:
Earthquakes are a byproduct of plate tectonics, a theory in geology developed in recent years for explaining motions near the surface of the Earth. One of the benefits from plate tectonics is that Earth maintains the right levels of carbon dioxide (CO2) in the atmosphere to compensate for the Sun’s increasing luminosity. This is accomplished by what is called the carbonate-silicate cycle. CO2 is removed from the atmosphere through weathering. The weathered products are eventually drawn into the Earth’s interior via plate tectonics. Processes inside the Earth’s interior release the CO2 back into the atmosphere via volcanoes. While all aspects of this mechanism are not yet fully understood, it has been instrumental in providing a stable environment for life on the Earth for billions of years.
New research provides yet another component that appears fine-tuned for life. In a letter in the September 27, 2007 issue of Nature together with a corresponding news release from the University of Bonn, Arno Rohrbach and his colleagues have discussed another mechanism similar to the carbonate-silicate cycle. It also depends on plate tectonics but, in this case, the mechanism controls the amount of oxygen on the surface of the Earth.
Oxygen becomes bound up in various oxides which are then drawn into the Earth’s interior, where various processes result in its being incorporated into an exotic mineral called majorite. The results reported in this letter established that majorite functions as a kind of “reservoir” for oxygen, and when the majorite ascends nearer to the surface of the Earth it breaks down and releases its oxygen. Some of this oxygen also binds with hydrogen released from the interior of the Earth to form water. The authors have referred to the whole process as an “oxygen elevator.”
They go on to say that “without the ‘oxygen elevator’ in its mantle the Earth would probably be a barren planet hostile to life. According to our findings, planets below a certain size hardly have any chance of forming a stable atmosphere with a high water content.”
This research confirms the existence of one more finely tuned mechanism that depends on plate tectonics and contributes to an environment that can support life. It also gives humans one more reason to be appreciative rather than dismayed when we experience an earthquake that breaks some precious possessions beyond repair.
Astronomer Dr. Hugh Ross who has a PhD in Astronomy from the University of Toronto and did a 5-year post-doctoral work at Caltech, adds to this with another discovery.
Excerpt:
In the December 2007 issue of Astrobiology Stanford University geophysicists Norman H. Sleep and Mark D. Zoback note that the higher tectonic activity during Earth’s early history could have played a key role in cycling critically important nutrients and energy sources for life. The production of numerous small faults in the brittle primordial crust released trapped nutrients. Such faults could also release pockets of methane gas and molecular hydrogen. The methane and hydrogen could then provide crucial energy sources for nonphotosynthetic life. Finally, the production of faults could bring water to otherwise arid habitats, such as rocks far below Earth’s surface.
Faulting, generated by active and widespread tectonics, allowed a youthful Earth to support diverse and abundant life. This enhanced diversity and abundance of life quickly transformed Earth’s surface into an environment safe for advanced life. Also, the buildup of biodeposits for the support of human civilization occurred more rapidly due to active tectonics.
The more rapid preparation of Earth for humanity is critical. Without such rapid preparation, humans could not come upon the terrestrial scene before the Sun’s increasing luminosity would make their presence impossible (due to excessive heat).
So that’s the science behind earthquakes. So that’s a brief look at why we need plate tectonics for life, and we just have to buck up and take the earthquakes with it. It’s not God’s job to give us happiness and health. That’s not his plan. People who complain about earthquakes have to show how God could get the life-permitting effects of earthquakes without wrecking his ability to succeed in his plan to make people know him and follow him. But how can an atheist do that? They can’t. I think that people just need to realize that humans are not in charge here and we have to live with that. We have to accept that we didn’t make the universe, and we don’t get to decide what purpose it has. God decides.
On to star formation.
Star formation
Atheists often complain that the universe is too big or too old (which is actually the same thing, since the more time passes, the more it expands). The fact of the matter is that life appeared the earliest it could appear – we needed the universe to be a certain age before it could support life.
The second parameter of the universe to be measured was its age. For many decades astronomers and others have wondered why, given God exists, He would wait so many billions of years to make life. Why did He not do it right away? The answer is that, given the laws and constants of physics God chose to create, it takes about ten to twelve billion years just to fuse enough heavy elements in the nuclear furnaces of several generations of giant stars to make life chemistry possible.
Life could not happen any earlier in the universe than it did on Earth. Nor could it happen much later. As the universe ages, stars like the sun located in the right part of the galaxy for life (see chapter 15) and in a stable nuclear burning phase become increasingly rare. If the universe were just a few billion years older, such stars would no longer exist.
The trick for getting from helium to the generation of planets, and ultimately to life, was the formation of carbon, the key element for the success of life and for the production of heavy elements in stars. Carbon could not form in the early moments following the Big Bang, because the density of the expanding mass was too low for the necessary collisions to occur. Carbon formation had to await the creation of giant red stars, whose dense interiors are massive enough to allow such collisions. Because stars become red giants only in the last 10% of their lifetimes (when they have used up much of the hydrogen in their cores), there was no carbon in the Universe for hundreds of millions to several billion years after the Big Bang—and hence no life as we know it for that interval of time.
[…]The sequence of element production in the Big Bang and in stars provided not only the elements necessary for the formation of Earth and the other terrestrial planets but also all of the elements critical for life—those actually needed to form living organisms and their habitats.
[…]The processes that occurred during the billions of years of Earth’s “prehistory” when its elements were produced are generally well understood. Elements are produced within stars; some are released back into space and are recycled into and out of generations of new stars. When the sun and its planets formed, they were just a random sampling of this generated and reprocessed material. Nevertheless, it is believed that the “cosmic abundance” mix of the chemical elements—the elemental composition of the sun—is representative of the building material of most stars and planets, with the major variation being the ratio of hydrogen to heavy elements.
[…]Many stars are similar in composition, but there is variation, mainly in the abundance of the heavier Earth-forming elements relative to hydrogen and helium. The sun is in fact somewhat peculiar in that it contains about 25% more heavy elements than typical nearby stars of similar mass. In extremely old stars, the abundance of heavy elements, may be as low as a thousandth of that in the sun. Abundance of heavy elements is roughly correlated with age. As time passed, the heavy-element content of the Universe as a whole increased, so newly formed stars are on the average more “enriched” in heavy elements than older ones.
[…]The matter produced in the Big Bang was enriched in heavier elements by cycling in and out of stars. Like biological entities, stars form, evolve, and die. In the process of their death, stars ultimately become compact objects such as white dwarfs, neutron stars, or even black holes. On their evolutionary paths to these ends, they eject matter back into space, where it is recycled and further enriched in heavy elements. New stars rise from the ashes of the old. This is why we say that each of the individual atoms in Earth and in all of its creatures—including us—has occupied the interior of at least a few different stars.
What he’s saying is that heavy elements are created gradually because of the star formation lifecycle. The first generation of stars are metal-poor. The next generation of stars is better. And so on until we get to stars that can support life by providing a steady, stable amount of energy – as well as other benefits like planets with an atmosphere. Our planet is 4.5 billion years old, and the universe is about 14 billion years old. Simple life appears about 4 billion years ago on Earth. That means we got life practically immediately, given that we had to develop the heavy elements needed to make a life-supporting star, a life-supporting planet and us.
UPDATE: Sean from ReligioPolitical Talk pointed out this related post out to me:
Another examples is that hurricanes help to regulate the earths temperature, and cause “sea deserts” to bloom… assisting in many ways earth’s climate:
“Some parts of the ocean are like deserts, because there isn’t enough food for many plants to grow. A hurricane’s high winds stir up the ocean waters and help bring nutrients and phytoplankton to the surface, where they get more sunlight, allowing the plants to bloom,” Babin said. (NASA)
….”Most certainly,” says Steve DiMarco, a Texas A&M University oceanography professor who for 16 years has studied the Gulf of Mexico, which has a “dead zone” where oxygen-depleted water can kill marine life.
In early July, most of the Texas-Louisiana shelf from Freeport, Texas, to the Mississippi River Delta was hypoxic – meaning the salt water has lost large amounts of oxygen. Later in July, Hurricane Dolly disrupted the dead zone and re-oxygenated the shallow waters south of Louisiana and the entire shelf off Texas. Oxygen levels started to drop again within days after the storm.
In early August, Hurricane Eduard re-oxygenated the Louisiana shelf, but by mid-August oxygen concentrations dropped to hypoxic levels.
And guess what?
Hurricane Ike re-oxygenated the shelf when it made landfall Sept. 12 in Texas. The latest data collected in October showed oxygen concentrations nearly all at normal levels, DiMarco said….
About one third of Americans believe in intelligent design, according to a recent Gallup poll. That’s the idea that humans evolved over time from lesser life forms – with the process guided by God. It’s added a new dimension to the old debate over where humans come from and raised serious concern in the scientific world about mixing faith with science.
Stephen C. Meyer, author of Darwin’s Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design
Michael Ruse, Director of the History and Philosophy of Science Program at Florida State University
Meyer: the Dover people made a mistake by trying to go to the courts to get things into the schools
Meyer: intelligent design is about research, writing books and papers based on what we learn from science
Moderator: (to Ruse) is intelligent design dangerous?
Ruse: yes, intelligent design is not about cosmic fine-tuning, origin of life, molecular machines or Cambrian explosion
Ruse: intelligent design is about abstinence, prayer in schools, pro-life and man-woman marriage
Ruse: my reason for opposing ID is the socially conservate agenda which emerges from protein folding calculations
Ruse: I don’t want to be drafted to fight in Vietnam, I don’t want them to take away my drugs, etc. so that’s why I believe Darwinism
Moderator: (to Meyer) why do you want to take abortion away, you meany?
Meyer: actually, intelligent design is about science, and in any case National Review gave my book a bad review
Moderator: (to Ruse) are science and religion in conflict?
Ruse: well religion can just abstain from making any claims about the physical world, and just stick to subjective nonsense – that’s fair
Moderator: (to Meyer) isn’t all opposition to evolution rooted in fundamentalist religion?
Meyer: you can believe in Darwinism and be a theist, but the real reason for doubting Darwinism is scientific evidence, not religion
Tell me how you think Dr. Meyer did in the comments. I think that Ruse is a bloviating boffin – a buffoon who blows smoke and has no idea what the science shows. He admits his motivations are political in the debate. And that’s as far as it goes. Evolution, because I don’t like that my girlfriend is making me wait for sex until we’re married. That’s the whole breadth of his opposition to the science. All the science was cited by Meyer, and Ruse had nothing to say in response. No evidence, certainly. But he’s a nice guy, and I appreciate him debating the issue. Things are tough right now for his side.