Category Archives: Polemics

Polemics

The connection between our moon, plate tectonics and habitability

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

I found an interview with Peter Ward (atheist) and Donald Brownlee (agnostic) discussing astrobiology in Forbes magazine. They were asked about how important plate tectonics are for a planet to be able to support complex life.

Excerpt:

Astrobiologists often cite the sheer numbers of stars and galaxies as evidence that complex life elsewhere must surely have evolved somewhere. But is probability enough?

Without a moon, we don’t have any idea of how commonly a planet could have the long-term stability needed for complex life. Until we “get” that, going to the sheer numbers argument is useless. Without that moon-forming collision, we wouldn’t have plate tectonics. Without plate tectonics, we might have microbes but we’d never get to animals.

What about the rarity of earth’s crustal dichotomy of oceans and continents?

If you can’t make granite, you’re not going to have continents. But granite formation is a consequence of our moon-forming collision. That scrambled the entire density of our crust. Mars doesn’t have granite; all it’s got is this volcanic basalt. To build granite you need a planetary subduction [or plate tectonic] process.

In triggering complex life, how important were plate tectonics’ role in the continual recycling of earth’s atmosphere?

It’s this recycling that allows for a very rich planetary atmosphere with an extended life. Photosynthesis gets you oxygen, but how do you get enough photosynthesis to get oxygen at 10 to 20 percent? You’ve got to have a shoreline next to a rich sea with rocks eroding into it in order to provide the nitrogen and phosphates for [plant] photosynthesis.

This article from Astrobiology explains more about the importance of plate tectonics.

Excerpt:

Plate tectonics is the process of continents on the Earth drifting and colliding, rock grinding and scraping, mountain ranges being formed, and earthquakes tearing land apart. It makes our world dynamic and ever-changing. But should it factor into our search for life elsewhere in the universe?

Tilman Spohn believes so. As director of the German Space Research Centre Institute of Planetary Research, and chairman of ESA’s scientific advisory committee, he studies worlds beyond our Earth. When looking into the relationship between habitability and plate tectonics, some fascinating possibilities emerged.

It is thought that the best places to search for life in the Universe are on planets situated in “habitable zones” around other stars. These are orbital paths where the temperature is suitable for liquid water; not so close to the star that it boils away, and not so far that it freezes. Spohn believes that this view may be outdated. He elaborates, “you could have habitats outside those, for instance in the oceans beneath ice covers on the Galilean satellites, like Europa. But not every icy satellite would be habitable. Take Ganymede, where the ocean is trapped between two layers of ice. You are missing a fresh supply of nutrition and energy.”

So planets and moons that lie beyond habitable zones could host life, so long as the habitat, such as an ocean, is not isolated. It needs access to the key ingredients of life, including hydrogen, oxygen, nitrogen, phosphorous and sulphur. These elements support the basic chemistry of life as we know it, and the material, Spohn argues, must be regularly replenished. Nature’s method of achieving this on the Earth appears to be plate tectonics.

Spohn found that the further he delved into the issue, the more important plate tectonics seemed to be for life. For example, it is believed that life developed by moving from the ocean to the kind of strong and stable rock formations that are the result of tectonic action. Plate tectonics is also involved in the generation of a magnetic field by convection of Earth’s partially molten core. This magnetic field protects life on Earth by deflecting the solar wind. Not only would an unimpeded solar wind erode our planet’s atmosphere, but it also carries highly energetic particles that could damage DNA.

Another factor is the recycling of carbon, which is needed to stabilize the temperature here on Earth. Spohn explains, “plate tectonics is known to recycle carbon that is washed out of the atmosphere and digested by bacteria in the soil into the interior of the planet from where it can be outcast through volcanic activity. Now, if you have a planet without plate tectonics, you may have parts of this cycle, but it is broken because you do not have the recycling link.”

It has also been speculated that the lack of tectonic action on Venus contributed to its runaway greenhouse effect, which resulted in the immense temperatures it has today.

Most planets don’t have a moon as massive as ours is, and the collision that formed the moon is very fine-tuned for life. This is just one of the many factors that needs to be present in order to have a planet that supports complex, carbon-based life.

If you want to learn more about this data, I recommend watching “The Privileged Planet” DVD, and someone posted it on YouTube:

If you haven’t seen it, and have 90 minutes, this is time well-spent.

Polemics

New software calculates the probability of generating functional proteins by chance

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

Here’s an article sent to me by JoeCoder about a new computer program written by Kirk Durston.

About Kirk:

Kirk Durston is a scientist, a philosopher, and a clergyman with a Ph.D. in Biophysics, an M.A. in Philosophy, a B.Sc. in Mechanical Engineering, and a B.Sc. in Physics. His work involves a significant amount of time thinking, writing and speaking about the interaction of science, theology and philosophy within the context of authentic Christianity. He has been married for 34 years to Patti and they have six children and three grandchildren. He enjoys landscape photography, antiques of various types, wilderness canoeing and camping, fly fishing, amateur astronomy, reading, music, playing the saxophone (alto), and enjoying family and friends.

Kirk grew up on a cattle and grain farm in central Manitoba, Canada, where he spent countless hours wandering around on his own in the forest as a young boy, fascinated with the plants and animals that are native to that region of the province. Throughout his teen years he spent six days a week in the summer working as a farm hand with cattle and grain. He left his father’s farm at the age of 19 to go to university.

Canada? Can anything good come out of Canada? Oh well, at least he’s not from Scotland. Anyway, on to the research, that’s what we care about. Code!

Summary of the article:

  • Biological life requires proteins
  • Proteins are sequences of amino acids, chained together
  • the order of amino acids determines whether the sequence has biological function
  • sequences that have biological function are rare, compared to the total number of possible sequences
  • Durston wrote a program to calculate the number of the probability of getting a functional sequence by random chance
  • The probability for getting a functional protein by chance is incredibly low

With that said, we can understand what he wrote:

This program can compute an upper limit for the probability of obtaining a protein family from a wealth of actual data contained in the Pfam database. The first step computes the lower limit for the functional complexity or functional information required to code for a particular protein family, using a method published by Durston et al. This value for I(Ex) can then be plugged into an equation published by Hazen et al. in order to solve the probability M(Ex)/N of ‘finding’ a functional sequence in a single trial.

I downloaded 3,751 aligned sequences for the Ribosomal S7 domain, part of a universal protein essential for all life. When the data was run through the program, it revealed that the lower limit for the amount of functional information required to code for this domain is 332 Fits (Functional Bits). The extreme upper limit for the number of sequences that might be functional for this domain is around 10^92. In a single trial, the probability of obtaining a sequence that would be functional for the Ribosomal S7 domain is 1 chance in 10^100 … and this is only for a 148 amino acid structural domain, much smaller than an average protein.

For another example, I downloaded 4,986 aligned sequences for the ABC-3 family of proteins and ran it through the program. The results indicate that the probability of obtaining, in a single trial, a functional ABC-3 sequence is around 1 chance in 10^128. This method ignores pairwise and higher order relationships within the sequence that would vastly limit the number of functional sequences by many orders of magnitude, reducing the probability even further by many orders of magnitude – so this gives us a best-case estimate.

There are only about 10^80 particles in the entire physical universe – 10^85 at the most. These are long odds. But maybe if we expand the probabilistic resources by buying more slot machines, and we pull the slot machine lever at much faster rate… can we win the jackpot then?

Nope:

What are the implications of these results, obtained from actual data, for the fundamental prediction of neo-Darwinian theory mentioned above? If we assume 10^30 life forms with a fast replication rate of 30 minutes and a huge genome with a very high mutation rate over a period of 10 billion years, an extreme upper limit for the total number of mutations for all of life’s history would be around 10^43. Unfortunately, a protein domain such as Ribosomal S7 would require a minimum average of 10^100 trials, about 10^57 trials more than the entire theoretical history of life could provide – and this is only for one domain. Forget about ‘finding’ an average sized protein, not to mention thousands.

So even if you have lots of probabilistic resources, and lots of time, you’re still not going to get your protein.

Compare these numbers with the 1 in 10^77 number that I posted about yesterday from Doug Axe. There is just no way to account for proteins if there is no intelligent agent to place the amino acids in sequence. When it comes to writing code, writing blog posts, writing music, or placing Scrabble letters, you need an intelligence. Sequencing amino acids into proteins? You need an intelligence.

Polemics

How likely is it for blind forces to sequence a functional protein by chance?

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

How likely is it that you could swish together amino acids randomly and come up with a sequence that would fold up into a functional protein?

Evolution News reports on research performed by Doug Axe at Cambridge University, and published in the peer-reviewed Journal of Molecular Biology.

Excerpt:

Doug Axe’s research likewise studies genes that it turns out show great evidence of design. Axe studied the sensitivities of protein function to mutations. In these “mutational sensitivity” tests, Dr. Axe mutated certain amino acids in various proteins, or studied the differences between similar proteins, to see how mutations or changes affected their ability to function properly.10 He found that protein function was highly sensitive to mutation, and that proteins are not very tolerant to changes in their amino acid sequences. In other words, when you mutate, tweak, or change these proteins slightly, they stopped working. In one of his papers, he thus concludes that “functional folds require highly extraordinary sequences,” and that functional protein folds “may be as low as 1 in 10^77.”11 The extreme unlikelihood of finding functional proteins has important implications for intelligent design.

Just so you know, those footnotes say this:

[10.] Douglas D. Axe, “Estimating the Prevalence of Protein Sequences Adopting Functional Enzyme Folds,” Journal of Molecular Biology, 1-21 (2004); Douglas D. Axe, “Extreme Functional Sensitivity to Conservative Amino Acid Changes on Enzyme Exteriors,” Journal of Molecular Biology, Vol. 301:585-595 (2000).

[11.] Douglas D. Axe, “Estimating the Prevalence of Protein Sequences Adopting Functional Enzyme Folds,” Journal of Molecular Biology, 1-21 (2004).

And remember, you need a lot more than just 1 protein in order to create even the simplest living system. Can you generate that many proteins in the short time between when the Earth cools and the first living cells appear? Even if we spot the naturalist a prebiotic soup as big as the universe, and try to make sequences as fast as possible, it’s unlikely to generate even one protein in the time before first life appears.

Here’s Doug Axe to explain his research:

If you are building a protein for the FIRST TIME, you have to get it right all at once – not by building up to it gradually using supposed Darwinian mechanisms. That’s because there is no replication before you have the first replicator. The first replicator cannot rely on explanations that require replication to already be in place.