New Model of Chirality Untestable
It’s one of the biggest mysteries for evolutionary biologists: the origin
of handedness in biomolecules. A new solution is all hat and no cattle.
No materialist origin-of-life theorist has ever solved this problem: why are all the amino acids in proteins left-handed, and the sugars in nucleic acids right-handed? Biochemists know that molecules made up of mixed hands don’t work. They are destroyed by living cells, and if they get in, they can cause serious diseases. But there’s nothing physically different between left- and right-handed or “chiral” molecules except their geometry; they have the same physical properties. Like our hands, they are mirror images of each other; the same except impossible to superimpose.
How could chance come up with 100% one-handed (homochiral) molecules? This problem was explained in detail by Dr James F Coppedge in his book, Evolution: Possible or Impossible? in chapter 3. Then he calculated the probability of chance achieving homochirality for a protein in chapter 4. The results were dismal for evolution, even when granted very generous concessions for a certain amount of preference for one hand in a growing chain. No physical mechanism for that preference was known at that time or since.
Now, researchers at Ohio State have proposed a mechanism by appealing to the weak nuclear force. But does it work?
How Earth’s molecules got their “handedness” (Ohio State University, 20 Feb 2023). Dr. James Cowan enters the ring.
“The reason why many of the key molecules of life only have one preferred handedness is a bit of a mystery,” said Cowan. “As to how it came about, the process must reflect something very special about how early chemistry developed a preferred form of nucleic acids and proteins.”
Cowan seems to be personifying chemistry. How could blind chemistry under mindless laws develop a preference?
Cowan and co-author R.J Furnstahl, a professor of physics at Ohio State, describe a model where the development of preferred chiral molecules evolves through a fundamental interaction called the weak nuclear force. The second weakest interaction after gravity, it’s a phenomenon which causes protons to decay into neutrons and vice versa. This challenges previous thoughts on the origin of Earth’s chirality, which suggested it came about following meteorite impacts on the planet during its early formation. Instead, their work is consistent with the RNA-based chemistry in the “RNA World model,” in which the formation of ribonucleic acids was a key step in how all the other molecules of life might have been made.
That’s a poor start, because the RNA World model is riddled with problems, as shown in a “Long Story Short” video and another “Long Story Short” episode about chirality. See also criticisms of the RNA World from 13 Mar 2019, 20 Mar 2018 and 16 Aug 2016.
Wouldn’t it be nice if natural laws forced a preference? Cowan begins with his model appealing to natural law, but quickly leaps into speculation with calls for imagination.
By combining elements of biology, nuclear physics and chemistry, Cowan and Furnstahl provide an explanation for how a preferred handedness in the building blocks of life evolved not from extraterrestrial molecules, or by random chance, but through a fundamental force of nature that laid the molecular foundation that would eventually come to support and influence life on Earth.
“Imagine a universe where there was a right glove, but no left glove,” said Cowan. “Over the course of a few million years, this preference for a particular hand becomes apparent, and is then repeated and amplified, and eventually allowed to dominate.”
Does such a universe exist outside of his imagination?
The study concludes that the weak nuclear force, in tandem with Earth-abundant metals like calcium, which amplifies the effect, could have acted like a seed, influencing prebiotic chemistry in a way that prompted preferred chirality to emerge symbiotically with the rest of nature’s early building blocks.
He thinks this is a “very satisfying” approach, but we care about the science, not the seance. We don’t pay attention to emotion or tricks. Can Cowan demonstrate this in the lab? If natural forces can do this, show us.
Though their research is purely theoretical at the moment, the study notes that with the right technology, there are a few ways their mechanism could be proven. Unfortunately for researchers, it’s way too tedious a process to recreate primordial timescales in the lab.
“In terms of making the molecules that living organisms are based on, those reactions are occurring on the timeframes of hundreds of thousands of years,” said Cowan. “Of course, we don’t have that long to wait around to test the hypothesis in the lab.”
Gong. Next act. ‘But wait!’ Cowan insists. ‘Can I get one more idea into the record?’
While extensive chemistry experiments could potentially be done with the help of heavy elements like uranium, which could help yield a result in only a few years, another more practical way to test the hypothesis behind their research might be to use spectroscopy – splitting light into different wavelengths to study its properties – to look at nearby exoplanets to try and determine if the molecules there exhibit a preferred “handedness” as well.
“If there was a preferred handedness, and it was the same type that we would observe on Earth, then that would be very, very strong evidence that nature actually directs the evolution of biological chemistry,” said Cowan.
The judges confer and realize that this test begs the question of materialism. It assumes that similarities prove the natural-law hypothesis, when they could as well be explained by design. They hit the gong again.
Cowan at least gets his paper into the record:
> Cowan and Furnstahl, Origin of Chirality in the Molecules of Life. American Chemical Society, Earth and Space Chemistry, dated 22 Octg 2022.
The value of Cowan’s attempt is that it shows that this fundamental problem is no closer to a solution than before. Cowan would not have gone to such leaps of speculation if it were easy to show that unguided natural forces could produce homochirality. We’re going on 50 years since Dr James Coppedge wrote about this, and 150 years since Louis Pasteur first observed chirality and determined that chirality was a defining characteristic of life. Cowan scores points for facing this problem, but gets the gong for dishing out vaporware and futureware, leaving the judges with a completely untestable (and therefore unscientific) hypothesis.
Other problems with his proposal come to mind. For one, it is not enough to get an excess of one hand over the other (called an “enantiomeric excess”) in a primordial soup. The mix has to be 100% homochiral. One wrong-handed building block spoils the molecule. For another, this theory is testable and has been tested: it fails. Whenever chiral molecules are found in unguided solutions, they revert to both-handed or “racemic” mixtures. If Cowan’s force was strong, we would see it in the lab. We do not. Since he cannot propose a way to show it working, we can dismiss his idea as a just-so story.
One can gauge the success of a theory on its progress over time. Secular origin-of-life theories are still at square one after a century of trying and millions of dollars spent. It’s past time for them to give in and recognize that intelligence is the best way to explain chirality in life. The first reason is that a mind can easily select same handedness quickly, where chance and natural law cannot in multiple billions of years. A second reason is that chirality is functionally important. Mixed-hand biomolecules would not work. There is a functional specification in having biomolecules in one form.
The fit of biomolecules to function in a way that defies nature is powerful evidence of intelligent design.