Zigzagging on mount improbable?

Extinct Four-Eyed Monitor Lizard Busts Myth of a Congruent Nested Hierarchy
Günter Bechly

One of the most essential doctrines of Darwinian evolution, apart from universal common descent with modification, is the notion that complex similarities indicate homology and are ordered in a congruent nested pattern that facilitates the hierarchical classification of life. When this pattern is disrupted by incongruent evidence, such conflicting evidence is readily explained away as homoplasies with ad hoc explanations like underlying apomorphies (parallelisms), secondary reductions, evolutionary convergences, long branch attraction, and incomplete lineage sorting.

When I studied in the 1980s at the University of Tübingen, where the founder of phylogenetic systematics, Professor Willi Hennig, was teaching a first generation of cladists, we still all thought that such homoplasies are the exceptions to the rule, usually restricted to simple or poorly known characters. Since then the situation has profoundly changed. Homoplasy is now recognized as a ubiquitous phenomenon (e.g., eyes evolved 45 times independently, and bioluminiscence 27 times; hundreds of more examples can be found at Cambridge University’s “Map of Life” website).

Life’s Solution

This state of affairs compelled George McGhee, a paleobiology professor at Rutgers University, to write a book, Convergent Evolution: Limited Forms Most Beautiful (2011). He suggests that convergence is so common because viable forms are so limited. However, he fails to explain how evolution manages to find these limited solutions over and over again through a random search process. After all, selection only explains the survival of the fittest but not the arrival of the fittest.

Likewise, paleontologist Simon Conway Morris wrote two books, Life’s Solution (2003) and The Runes of Evolution (2015), in which he concluded that the incredible number of convergences came to be because evolution is not the contingent process postulated by Stephen Jay Gould (1989) in his book Wonderful Life. Gould thought that if we could somehow rewind the tape of evolution, everything would develop very differently. According to Conway Morris, the same novelties occur so often in unrelated groups that this suggests these novelties are not products of mere contingency but instead are so constrained by external factors that rewinding the tape of evolution would lead to very similar results (also see Conway Morris 2009 ).

Of course, Darwinists are not comfortable with the deeper implications of a non-contingent process of evolution (Ruse 2004, Coyne 2012, 2015), which smacks of being designed for a purpose. Apart from that, most biologists do not even read between the lines that this is basically a surrender of a fundamental paradigm of Darwinism, which claimed that similar biological novelties suggest phylogenetic relationship (common ancestry).

The problem gets worse the more we learn about the fossil record, the distribution of characters among recent organisms, and the genetic and developmental underpinnings of many characters. Some taxonomists had hoped that genomics might save biosystematics from the evil of homoplasy, since the sheer amount of data would flood the “minor” noise of homoplasies. But this turned out to be a pipe dream as the numerous conflicting molecular phylogenies easily document. Even those genetic characters that were believed to be impossible to suffer from convergence, like transposable elements, turned out to be incongruent (e.g., in the case of the gorilla, chimp, and human trichotomy), which required a whole new epicycle of ad hoc explanation in terms of incomplete lineage sorting.

The Third Eye

The third eye of vertebrates provides a perfect illustration of this point, topped by a very surprising recent discovery reviewed below. What, a third eye? I am neither talking about New Age spiritualism, nor about the cyclops of ancient Greek mythology, but about a little known light-sensing organ. 

Unpaired median dorsal eyes, along with a lateral pair of more efficient eyes, are known from crustaceans (nauplius eye), arthropods (e.g., 3 ocelli in insects), and vertebrates (third eye, pineal eye, or parietal eye on the top of the skull). The latter is always smaller than the paired lateral lens eyes, and in living species very inconspicuous. Evolutionists believe this organ to be possibly homologous to the light-sensitive spot on top of the head of lancelets, and the median eye of tunicate larvae, because phylogenetic studies suggested that tunicates are the closest relatives of vertebrates, which are sometimes supposed to have originated from a kind of neotenic tunicate larva.

All vertebrate eyes, paired lateral as well as unpaired median ones, develop from an evagination of the brain (diencephalon). The posterior part of the diencephalon (epithalamus) develops an initially single dorsal evagination (pineal complex), which then divides into two roughly bilaterally symmetric organs that rotate their location to become a caudal pineal organ (pineal gland) and a rostral parapineal organ (Kolb et al. 1998). These often retain a slight asymmetry with the pineal organ originating more right and the parapineal organ more left of the brain midline.

This corresponds with the fact that modern lampreys possess two median eyes that are either oriented on top of each other or behind each other, while some Devonian fish (e.g., arthrodira, stegoselachians, and very early lungfish) had two pineal/parietal foramina in the skull beside each other (Eakin 1973: 16-17). In modern aquatic jawed vertebrates (“fish” in everyday language), the third eye, if developed at all, is formed by the pineal organ, while the parapineal organ is more or less reduced.

In tetrapods, the caudal pineal organ is atrophied as a still photoreceptive pineal gland (epiphysis), while the rostral parapineal organ forms the third eye called the parietal eye. Among recent vertebrates the parietal eye is absent in salamanders, turtles, crocs, birds, and mammals, but very well developed in lepidosaurs (juvenile tuataras and many lizards) with a lens, cornea, and an everted retina, with the latter being more similar to that of an octopus rather than to the inverted retina of the lateral lens eyes.

In juvenile frogs and toads a similar, but less sophisticated third eye develops as a terminal vesicle of the parapineal organ.hese third eyes in vertebrates do not allow image-like vision but only differentiate light from dark. They may help in detecting shadows from predators attacking from above, as suggested by the behavior of some lizards. More importantly they are crucial for circadian and seasonal rhythms. This also happens to be the function of the pineal gland in humans, which produces the sleep hormone melatonin. Many other vertebrate species have an intracranial pineal organ as deep-brain photoreceptor. In fossil vertebrates, the possession of an extracranial third eye can be inferred from the presence of a parietal foramen between the parietal bones of the skull.

  Therefore, we have a pretty good knowledge about the distribution of third eyes in fossil and modern vertebrates. Here is a list of the haves and have nots:

lampreys, but not the blind hagfish

Paleozoic agnathan fish like ostracoderms and placoderms

pelagic sharks

some ray-finned fish (e.g., Paleozoic stem actinopterygians, paddlefish, catfish, tuna, and even the blind cave fish Astyanax mexicanus)

fossil “crossopterygians,” but not the modern coelacanth

early fossil lungfish, but not all modern ones

lobe-finned and “stegocephalian” stem tetrapods (e.g., Eusthenopteron, Elpistostege, Panderichthys, Tiktaalik, Acanthostega, Seymouria)

stem amphibians (Temnospondyli) and modern juvenile frogs and toads (Anura), but not salamanders (Urodela) and caecilians (Gymnophiona)

stem reptiles (e.g., Paleothyris)

Parareptilia (Anapsida like Captorhinus)

Lepidosauria (well visible in tuatara juveniles, mosasaurs, monitor lizards, iguanas, true lizards), but not snakes, geckos, and chameleons

Ichthyopterygia (ichthyosaurs)

Sauropterygia (placodontians, nothosaurs, plesiosaurs)

the oldest and most primitive stem turtle, Eunotosaurus, but not any later turtles (including Pappochelys)

early archosauromorphs like Prolacerta, proterosuchids, and arguably Triopticus primus, but not any more advanced archosauriforms (incl. Euparkeria, Phytosauria, crocodiles, pterosaurs, dinosaurs, and birds)

Permian mammal-like reptiles (“pelycosaurs,” “therapsids,” Cynognathia), but not any mammals (including Triassic primitive mammaliaforms like Morganucodon)

Guess what evolutionists must assume? Based on the just mentioned distribution of pineal and parapineal eyes and the parietal foramen: primitive agnathan vertebrates had two median eyes formed by the pineal and parapineal organ. These were retained at least up to the early ancestors of lungfish (documented by their paired parietal foramen), but the parapineal eye was independently reduced in Chondrichthyes (sharks and rays), ray-finned fish, coelacanths, and modern lungfish. In most modern bony fish (including ray-finned fish, coelacanths, and some modern lungfish) the pineal eye was reduced multiple times independently. In the tetrapod lineage the pineal eye was reduced as well, and only the parapineal eye retained as the parietal eye. This parietal eye was then reduced independently in non-anuran amphibians, some lizards, snakes, turtles, archosaurs (crocodiles, pterosaurs, dinosaurs, birds), and in mammals.

Consequently, only juvenile frogs and toads and well as juvenile tuataras and many lizards retained a parapineal parietal eye among living land vertebrates. What a wild ride. And all along the way, the magic wand of natural selection allegedly explains why the same organ appears and disappears and reappears, because it gains adaptive value and loses it, and gains it again. Not convinced? Neither am I. But the biggest surprise is yet to come.

Fasten Your Seatbelts, Please

Clearly, the presence or absence of a third eye in vertebrates shows an extremely incongruent pattern. Evolutionists need to explain away this incongruence. Since most groups of Paleozoic vertebrates had a third parietal eye, evolutionists have to assume that many different groups of vertebrates independently “decided” after the Permo-Triassic mass extinction that they could simply dispense with this previously so useful and adaptive innovation. Therefore, evolutionists need not only the ad hoc assumption of multiple independent secondary reductions, but also a causal explanation for this strange phenomenon.

Suggested explanations include reduced color vision correlated with freshwater habitat, or nocturnal lifestyle, or a transition to endothermia (Gerkema et al. 2013, Benoit et al. 2016, Emerling 2017a)

. Nocturnality as an explanation would indeed agree with the fact that the third eye is absent in the nocturnal geckos and in snakes, which are believed to have originated from a nocturnal burrowing ancestor, and that it is only prominent in juvenile tuataras, which have a diurnal lifestyle, while it is obliterated in adults, which have a nocturnal lifestyle. However, that two different causal explanations (nocturnal bottleneck versus transition to endothermia) have been suggested for the reduction of the parietal eyes in mammals shows that we are actually dealing with contrived ad hoc explanations. Whatever the data might be, a fancy narrative could easily be forged to explain this evidence.

Emerling (2017a) demonstrated that the photosensitive opsin proteins parietopsin and parapinopsin, found in the third eye of lampreys and lizards, are only present as nonfunctional pseudogenes in turtles, crocodiles, and birds, which all lack a third eye (Caspermeyer 2017).

 To be fair, remnants of broken genes (pseudogenes), if they should truly be devoid of function (many ID proponents would predict this to be false), may indeed lend some support to the notion of common ancestry and a secondary reduction of the third eye in these groups. This was readily emphasized by Emerling (2017b), who clearly seems to have an evolutionary axe to grind, at his personal blog Evolution for Skeptics.

However, he admitted in his technical paper that these pseudogenes in turtles, crocodiles, and birds actually do not share inactivating mutations, so that the inactivation cannot be easily attributed to a common archelosaurian ancestor. This is at least strange for crocs and birds, because even their assumed archosauriform ancestors already shared the absence of a parietal eye, so that the inactivation should be expected to be homologous. Apart for this issue, merely appealing to common ancestry and multiple secondary reduction of course does nothing to explain what really is going on.

Emerling is aware of this and therefore suggested a nocturnal bottleneck in crocodylians as a causal explanation for their loss of the parietal eye. However, there is no evidence at all for such a bottleneck in the archosaur stem line, and this is fatal for his argument because it is not just crocodylians but all archosaurs that lack a parietal eye and its opsins, so that a nocturnal bottleneck in crocs would be totally irrelevant and much too late to explain anything. This also shows that the shared endothermia of birds and mammals is no good explanation for their shared lack of the parietal eye and its opsins either, because birds are believed to have ultimately originated from archosaurs that already lacked a parietal eye but were not endothermic at all. Most of the ad hoc explanations that may seem plausible at first sight thus become rather dubious at closer examination.

A Much Bigger Problem

Anyway, a much bigger problem for Darwinism arises from independent (homoplastic) gains of complex characters, rather than independent losses, especially when highly implausible evolutionary scenarios are implied. Here is a recent example for this that also involves the median eyes of vertebrates.

Based on two fragmentary fossils, Smith et al. (2018)

 just described the new monitor lizard Saniwa ensidens from the 49 million year old Bridger Formation in Wyoming. Both known specimens surprisingly had four eyes! Additional to the normal pair of lateral lens eyes, and the usual parietal third eye of lizards, this new species actually had a forth pineal eye like a lamprey. Not a single other jawed vertebrate has something remotely like this, even though this fossil lizard is the closest relative of the modern monitor lizard genus Varanus and thus deeply nested within modern land vertebrates.

What? This sounds almost too weird to be true. Yet since the article was published on April 2, 2018, in the prestigious journal Current Biology it is definitely not an April Fools’ prank. The authors bite the bullet and boldly propose that the extinct monitor lizard re-evolved a fourth eye from the pineal organ, similar to the assumed ancestral state in lampreys. This means that even though a pineal eye was at least lost since the origin of tetrapods about 390 million years ago, 340 million years later just another ordinary species of monitor lizards came along and said, “Hey, what about having four eyes again?” It then re-evolved this organ that was obviously not of any sufficient adaptive value to any other tetrapod in the history of life to let evolution’s unlimited creative power do its magic. Nevertheless, this remarkable effort did not save this species from extinction without any surviving descendants, while numerous monitor lizards without fouth eye were more lucky.

  In his review of the surprising discovery Witmer (2018) notes:

How could a pineal eye simply re-evolve? … But why Saniwa? What’s special about this lizard? Nothing is special, as far as we can tell. Smith and colleagues offer some suggestions, but it’s fair to say that the functional benefit of having both parapineal and pineal eyes remains obscure. This finding also means that all of a sudden we’re no longer sure which organ — pineal or parapineal eye — was peeking through the parietal foramen of a host of extinct ancient tetrapods.

Finally, there is a last punchline mentioned by  Witmer (2018):

In 1893, Belgian paleontologist Louis Dollo formulated the Law of the Irreversibility of Evolution, which simply states: that which is lost shall not be regained. Some laws are meant to be broken, and the re-evolution of a pineal eye in Saniwa is not the first atavism to be reported. Still, it’s not a common occurrence, and it’s so rare in this case that it raises new questions.

Obviously, evolutionary “laws” are quite malleable and have to give way when they become too cumbersome. Conflicting evidence does not matter, broken laws do not matter. What really matters is preserving the great narrative of pond scum to us.

We can safely conclude: it is an epic myth, willingly perpetuated by evolutionary biologists, that the similarities between organisms mostly fall in a hierarchic pattern of nested groups and thus suggest common ancestry and indicate phylogenetic relationship. In reality this claim is contradicted by a flood of incongruences and reticulate patterns that shed doubt on fundamental paradigms of evolutionary biology like the notions of homology and common descent. This inconvenient conflicting evidence is explained away with a pile of ad hoc hypotheses, correlated with more and more contrived and implausible evolutionary scenarios.

Literature:

• Benoit J, Abdala F, Manger PR, Rubidge BS 2016. The sixth sense in mammalian forerunners: Variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids. Acta Palaeontologica Polonica 61 (4): 777–789.
• Caspermeyer J 2017. How Turtles and Crocodiles Lost the Parietal “Third” Eye and Their Differing Color Vision Adaptations. Molecular Biology and Evolution 34(3), 776–777.
• Conway Morris S 2003. Life’s Solution: Inevitable Humans in a Lonely Universe. Cambridge Univ. Press, 464 pp.
• Conway Morris S 2009. Evolution: like any other science it is predictable. Philosophical Transactions of the Royal Society B 365, 133–145.
• Conway Morris S 2015. The Runes of Evolution. Templeton Press, 528 pp.
• Coyne J 2012. Paleobiologist Simon Conway Morris gives evidence for God from evolution. Why Evolution is True September 10, 2012.
• Coyne J 2015. Simon Conway Morris’s new book once again claims that the evolution of human-like creatures was inevitable. He’s wrong. Why Evolution is True May 3, 2015.
• Eakin RM 1973. The Third Eye. University of California Press, 157 pp.
• Emerling CA 2017a. Archelosaurian color vision, parietal eye loss, and the crocodylian nocturnal bottleneck. Molecular Biology and Evolution 34(3), 666–676.
• Emerling CA 2017b. Turtles, birds and crocodylians have genetic remnants of a ‘third eye’. Evolution for Skeptics June 16, 2017.
• Gerkema MP, Davies WIL, Foster RH, Menaker M, Hut RA 2013. The nocturnal bottleneck and the evolution of activity patterns in mammals. Proceedings of the Royal Society B 280: 20130508.
• Gould SJ 1989. Wonderful Life. The Burgess Shale and the Nature of History. W.W. Norton Co.
• Kolb H, Fernandez E, Nelson R (eds) 1995. Webvision – The Organization of the Retina and Visual System. University of Utah Health Sciences Center, Internet book.
• McGhee GR 2011. Convergent Evolution: Limited Forms Most Beautiful. MIT Press, 336 pp.
• Ruse M 2004. Book Review 2: Life’s Solution: Inevitable Humans in a Lonely Universe. Palaeontologia Electronica 2:3.
• Smith KT, Bhullar BAS, Köhler G, Habersetzer J 2018. The Only Known Jawed Vertebrate with Four Eyes and the Bauplan of the Pineal Complex. Current Biology 28, 1101–1107.
• University of Cambridge. Map of Life — Convergent Evolution Online.
• Witmer LM 2018. Paleoneurology: A Sight for Four Eyes. Current Biology 28: R311-R313.

Faith,the superlative of knowledge not its antithesis.

“Faith” and the Multiverse: A Response
Paul Nelson

Regarding “Multiple Problems with the Multiverse,” I grasp the argument Professor Brian Keating is making in his PragerU video — namely, that current cosmologists who invoke a multiverse do so on the slenderest (or no) evidence. However, his use of the word “faith” in this context is really pernicious.

“Faith,” in the Biblical sense, is never the antonym of “knowledge.” A much better use of “faith” would mean “trust on the basis of evidence already provided,” which (to my understanding) fits well with every Biblical episode where faith is mentioned or commended.

Furthermore, faith is held up consistently throughout the Bible as most praiseworthy, and indeed, the gift of God (Ephesians 2:8). Rather a sharp reversal in reference, therefore, when the same noun is used to denote groundless credulity.

Which, really, is what Professor Keating means: “I don’t have enough credulity to posit a multiverse.” Even that word choice, however, fails, because it entails that theists are also credulous, only to a lesser degree.

What is being lost in this rhetoric? Truth and falsehood. Not degrees of greater or lesser credulity. Why not say, “While attractive for many philosophical reasons, the multiverse is a false hypothesis”?

I fear that when we hold our own positions, not because we know (or even believe) they are actually true, but for other reasons, we cannot say that an opposing position is false: we can’t know that to be the case. So then the discussion becomes who has the bigger or smaller credulity heap, on which they are standing.

Please — let’s break this noxious intellectual habit of using “faith” as the antonym of “knowledge.”

In the lion's den?

Online Seminar: Paul Nelson Will Discuss Ontogenetic Depth — in Depth! 
Evolution News | @DiscoveryCSC

This Saturday, April 21, Discovery Institute Senior Fellow Paul Nelson will give an online seminar about the controversial and widely-thought-to-be-debunked concept of “ontogenetic depth” (OD). Join us at 4 PM Eastern, which is 3 PM Central or 1 PM Pacific.  At the ordained hour, just go here.

OD has been proclaimed a “pseudoscientific idea” by no less an authority than Wikipedia, and Paul himself readily acknowledges OD is currently impossible to measure — so why on earth would he bother talking about OD live, while fielding questions?

Possible answers:

Paul is obviously crazy and has been for a long time.

Paul doesn’t know when to stop digging.

Never was there a more fitting acronym for a scientific idea than “OD.”

Paul has grown fond of “Paul Nelson Day” and doesn’t want our critics to forget it again next year (see Stockholm Syndrome).

OR, counter-intuitively — perhaps there is much more to OD than seems apparent.

We’ll go with the last and counter-intuitive answer, so tune in. Background reading on OD is here and here (2011 series) and here, here, and here (2015 series).

On one of natural history's other 'explosions'.

The Dinosaur “Explosion”
Cornelius Hunter

In the famed Cambrian explosion most of today’s animal phyla appeared abruptly in the geological strata. How could a process driven by blind, random mutations produce such a plethora of new species? Evolutionist Steve Jones, in his book Darwin’s Ghost (2000), has speculated that the Cambrian explosion was caused by some crucial change in DNA. “Might a great burst of genetic creativity have driven a Cambrian Genesis and given birth to the modern world?” (p. 206)

What explanations such as this do not address is the problem of how evolution overcame such astronomical entropic barriers. Rolling a dice, no matter how creatively, is not going to design a spaceship.

The Cambrian explosion is not the only example of the abrupt appearance of new forms in the fossil record, and the other examples are no less easy for evolution to explain. Nor has the old saw, that it’s the fossil record’s fault, fared well. There was once a time when evolutionists could appeal to gaps in the fossil record to explain why the species appear to arise abruptly, but no more. There has just been too much paleontology work, such as a new international study on dinosaurs published this week, confirming exactly what the strata have been showing all along: new forms really did arise abruptly.

The new study narrows the dating of the rise of dinosaurs in the fossil record. It confirms that many dinosaur species appeared in an “explosion” or what “we term the ‘dinosaur diversification event (DDE)’.” It was an “explosive increase in dinosaurian abundance in terrestrial ecosystems” (emphasis added). As the  press release explains:

First there were no dinosaur tracks, and then there were many. This marks the moment of their explosion, and the rock successions in the Dolomites are well dated. Comparison with rock successions in Argentina and Brazil, here the first extensive skeletons of dinosaurs occur, show the explosion happened at the same time there as well.

As lead author Dr. Massimo Bernardi at the University of Bristol explains, “it’s amazing how clear cut the change from ‘no dinosaurs’ to ‘all dinosaurs’ was.”

There just isn’t enough time, and it is another example of a failed prediction of the theory of evolution.

Geologists' rewrites make a mess of Darwinian storytelling re:the cambrian explosion.

Geologists Kick Out Props for Evolutionary Theories of the Cambrian Explosion

Evolution News & Views 

Reading the Darwinist explanations for the Cambrian explosion is like watching a game of "Who's Got the Button?" The biologists are sure the paleontologists have the reasons for this unprecedented appearance of animals in the fossil record. The paleontologists, in turn, point to the geologists for it. And the geologists rely on the opinion that the biologists have handfuls of explanatory buttons. When you inspect each one's hands, though, they come up empty.

It was the geologists' turn to show their empty hands. In the Geological Society of America Bulletin, two papers undermine popular assumptions used by the biologists and paleontologists to account for the explosion. Ask yourself if their work sounds like "settled science."

No Oxygen Rise Here, Mate

In the first paper by Sperling et al., geologists from Harvard and Queens College undermine the notion (commonly asserted by the biologists) that it was a rise in oxygen levels that triggered the explosion. Not that we ever found that explanation credible (#1, #2, #3, #4), but at least it gave the biologists a story with which to entertain the uninformed. No longer; these geologists found no evidence to support a global oxygen rise in the Ediacaran period that preceded the Cambrian.

The causes behind the appearance of abundant macroscopic body and trace fossils at the end of the Neoproterozoic Era remain debated. Iron geochemical data from fossiliferous Ediacaran successions in Newfoundland suggested that the first appearances correlated with an oxygenation event. A similar relationship was claimed to exist in the Mackenzie Mountains, Canada, although later stratigraphic studies indicated that the sections analyzed for geochemistry were incorrectly correlated with those hosting the fossils. To directly connect fossil occurrences with geochemistry in the Mackenzie Mountains, we conducted a multiproxy iron, carbon, sulfur, and trace-element geochemical analysis of stratigraphic sections hosting both the Cryogenian "Twitya discs" at Bluefish Creek as well as Ediacaran fossils and simple bilaterian traces at Sekwi Brook. There is no clear oxygenation event correlated with the appearance of macroscopic body fossils or simple bilaterian burrows; however, some change in environment -- a potential partial oxygenation -- is correlated with increasing burrow width higher in the Blueflower Formation. Data from Sekwi Brook suggest that these organisms were periodically colonizing apredominantly anoxic and ferruginous basin. This seemingly incongruent observation is accommodated through accounting for differing time scales between the characteristic response time of sedimentary redox proxies versus that for ecological change. Thus, hypotheses directly connecting ocean oxygenation with the appearance of macrofossils need not apply to all areas of a heterogeneous Ediacaran ocean, and stably oxygenated conditions on geological time scales were not required for the appearanceof these Avalon-assemblage Ediacaran organisms. At least in the Mackenzie Mountains, the appropriate facies for fossil preservation appears to be the strongest control on the stratigraphic distribution of macrofossils. [Emphasis added.]

For non-specialists, this basically means that the evidence connecting oxygenation (a geochemical condition) with Ediacaran and Cambrian fossils is equivocal at best. The geologists appear to be trying hard not to rule it out ("a potential partial oxygenation"), but throughout the paper, they reveal contradictions with the oxygen hypothesis. Some of the best fossils appear in non-oxygenated rocks, and other well-oxygenated rocks have no fossils. Moreover, earlier studies that seemed to find a correlation were flawed.

The first step in distinguishing coincidence from correlationis determining whether temporal linkages represent a global pattern, regional events, or simply the unrelated appearanceof organisms during a time interval characterized by broadly increasing oxygen levels. Neoproterozoic oxygenation, if present, is increasingly being recognized as regionally heterogeneous (Kah and Bartley, 2011). This is reflected in iron speciation data from the southern Canadian Cordillera showing an increased prevalence of anoxic conditions during the mid- Ediacaran (Canfield et al., 2008), in contrast to the Newfoundland data, and data from the Wernecke Mountains of northwestern Canada which show no change at all(Johnston et al., 2013). Other regions such as Namibia also show heterogeneous but generally anoxic and ferruginous conditions through the late Ediacaran (Wood et al., 2015).Analyzed collectively and statistically, a global database of Proterozoic and Paleozoic iron speciation data shows no overall change to the oxygenation state of marine environments between the Ediacaran and Cambrian (Sperling et al., 2015). These database analyses do not rule out an increase in oxygen through this time period, but they do limit the magnitude of such a change to much less than is normally depicted (e.g., Holland, 2006).

Their research in Canada also finds interesting geological evidence that contradicts the picture of slow, gradual deposition. For instance, some of the fossils are found in turbidites, which represent underwater landslides. Other fossils appear encased in strata that appear to have been formed in offshore storm surges. There are unconformities, slumps, and gaps.

In sum, the idea that biologists and paleontologists can expect to find a gradual increase in oxygen below the Cambrian boundary is mistaken. Figure 7 of the paper correlates outcrops from China, Africa, the U.S., and Canada. There's no pattern. "Redox change [i.e., change in reducing vs oxidizing conditions] may correspond to the appearance of megascopic fossils in some sections, but stable oxygenation on geologic time scales is not required." So if it's not oxygen, what is it? "The most obvious explanation is simply the distribution of beds capable of preserving fossils." Some places were suitable for preserving fossils, and some weren't. That's all.

Importantly, these data suggest that oxygenation of a basin is not required for the appearance of many Ediacaran taxa. To a first-order approximation, more so than oxygenation, the appearance of fossils of large eukaryotes throughout the entire Cryogenian and Ediacaran succession in NW Canada isdictated almost entirely by the appearance of event beds suitable for their preservation and presentation.

More on the second paper tomorrow.

More on why the search for a purely chemical cause for abiogenesis is a fool's errand

The American Chemical Society recently dedicated a whole issue of Accounts of Chemical Research to the puzzle of life's chemical origins. The issue does a thorough job of bringing together some of the latest theories and research in the field, and several of the articles address fundamental problems in certain models of origin-of-life research. For example, a paper by Benner et al. points out that the RNA-world model is unattractive because the chemical bonds involved are unstable and the reaction requirements are too specific and unlikely for an early Earth environment.

Another article addresses a possible solution to nature's preference for left-handed amino acids and right-handed sugars (also known as homochirality).

A couple of papers try to explain why DNA is composed of the particular bases A, T, C, and G. Several others discuss self-replicating systems. Another paper discusses how proto-cells may have been formed from lipid micelles. And still others assume an "RNA-first" world, while a few prefer a "metabolism-first" world.

Indeed, this collection offers some of the latest research in the field. We will address a sampling of the research papers. If you want some background on origin-of-life research, see Casey Luskin's recent article "Top Five Problems with Current Origin-of-Life Theories."

Let's first address the editors' introduction, which makes use of some remarkably convoluted rhetoric.

The editors define chemical evolution as including "the capture, mutation, and propagation of molecular information and can be manifested as coordinated chemical networks that adapt to environmental change." In this type of system, one in which information-carrying molecules must be made and propagated, the editors concede that building life from the bottom up requires some aspect of molecular intelligence:

These diverse approaches to deconvolution and reintegration of the origins of the cell, projected in collaboration through the lens of chemical evolution, suggest a remarkable degree of intrinsic molecular intelligence that guide the bottom-up emergence of living matter.
The term "molecular intelligence" is not typically used in origin-of-life research, despite the authors' statement that it is not a new concept: in their view, Darwin's own theory of life beginning in a chemically rich "warm pond" is an example of molecular intelligence. While there are several ways to describe molecular behavior, from statistical mechanics to Brownian motion to self-assembly, making molecules the intelligent actor in the origin of life ascribes a property to molecules that we have yet to prove. They are information-carrying. They are self-replicating. But to say they have intelligence implies that molecules are capable assembling themselves into meaningful structures, something that usually requires knowledge of the end product. This is akin to saying a Lego model of the Millennium Falcon was built by the Legos themselves which (who?) are endowed with an intrinsic "construction intelligence." (Actually, this analogy would be more accurate if the Legos built a working model of the Millennium Falcon that can conduct self-repairs and can self-replicate.)
Let's try to unpack the final paragraph of the editors' introduction:

While our objective is to decipher the evolutionary rules that directed the transition from inanimate matter to life, we recognize that the march of molecular history likely had many pathways.
One of the fundamental research problems in chemical evolution is the transition from non-life to life. This requires more than having the component parts present. In order for this bottom-up, parts-to-whole approach to work, there is some threshold that must be crossed that sets in motion the operations of a cell (or a proto-cell) such that it has the characteristics of a self-sustaining, living organism. That threshold remains a mystery in chemical evolution research.
Accordingly, this issue circumscribes the functional concepts, leveraging Nature's platforms for molecular information, using its existing chemical inventory or libraries, and, with selective and judicious tinkering along the way, elaborates the basic rules of bottom-up self-assembly guided by both digital and analog molecular recognition systems.
This appears to mean that rather than re-inventing the wheel, so to speak, this issue of the journal will focus on deducing the rules for constructing an organism from the bottom-up. The authors will do this by using what we already know about DNA and RNA to construct system using known chemicals and enlisting the help of chemists to guide the reactions where they see fit to do so. But this calls into question just what is meant by "self"-assembly. In materials science, self-assembly is usually regarded as repeated, ordered patterns of specific molecules under the right environmental conditions. The setup for making even a simple self-assembled system (e.g. a self-assembled monolayer) requires quite a bit of forethought and planning on the part of the chemist.
In addition, the diversity in approaches to understanding and employing chemical evolution is as important as the diversity in chemical composition required to promulgate evolution itself and suggests that collaboration among these diverse approaches to gaining insights into chemical evolution and working toward the interfaces among them will be extraordinarily rich with opportunities.
In origin-of-life research, there are, broadly speaking, two camps: The RNA-first world, and the metabolism-first world. There are several nuances to each position, but for brevity's sake, we can think of the RNA-first camp as those who believe the first biomolecules were nucleotides (adenine, uracil, cytosine, and guanine), while the metabolism-first camp believes the first biomolecules were amino acids (e.g., glycine, alanine, thiamine). The RNA-first camp assumes that ribozymes were key players in the formation of the first genetic code. The metabolism-first camp relies on the self-assembly of biomolecules to form the first protein or the first metabolic pathway. (See here for more information on the RNA-world hypothesis.)
These are two fundamentally different approaches to the origin of life. Both have strengths and both have problems. The editors say that there were "multiple pathways" to the origin of life and so perhaps both are right. They assume that collaboration between the camps will lead to greater understanding, but this seems unjustifiably optimistic.

Proposing compromise may seem like a commendable thing -- it's generally a safe way of making yourself appear to be taking the moral high ground. But in this case, the respective approaches have completely different starting assumptions. Each begins with a different set of building blocks, not to mention a different synthetic process. It is also strange to assume that there were many paths to the origin of life yet that somehow these disparate paths came together to form early organisms. How, exactly? More on this later.

On the problem with the extrapolation to macroevolution

Suggested Readings on the Problem of Animal Macroevolution
Evolution News & Views February 25, 2016 3:47 AM

An email correspondent asks:

Given the saltations seen in the fossil record (as well as molecular data), it seems that the gradual ratcheting of "point mutation by point mutation" evolution has little efficacy in explaining the diversity of life. Doug Axe has done work on this. Are there other clear demonstrations of the improbability of getting from one adaptive peak to another via this model?

Yes, an enormous literature exists within evolutionary biology about the implausibility of point-mutation-by-point-mutation transitions between adaptive peaks. The following list, which focuses only on animal macroevolution, runs only to 2011. Many more recent papers have been published.

These papers represent a sample of biological thinking about the problem of animal macroevolution, or macroevolution generally, over the past three decades. The authors agree that some amendment, perhaps radical, is needed to fix "textbook" (standard) neo-Darwinian theory, in order to solve the open question of how animal form and complexity arose via an undirected evolutionary process.

They do not, however, agree on the solution, and may disagree strongly among themselves, for instance, on the question of whether animal embryos will tolerate deep changes to their essential developmental control networks. The authors come from a range of disciplinary backgrounds, such as genetics, developmental biology, paleontology, and comparative anatomy. None is an advocate of intelligent design, and none would see his ideas as supporting intelligent design.

A recommendation: While all the articles are thoughtful, if the reader is pressed for time, Thomson's 1992 article is the shortest and most accessible, while Miklos's 1993 article, although the longest, is the most wide-reaching and vigorously argued.

1. John F. McDonald, "The Molecular Basis of Adaptation: A Critical Review of Relevant Ideas and Observations," Annual Review of Ecology and Systematics 14 (1983):77-102.

In 1983, geneticist John McDonald (at the time, at the University of Georgia) surveyed the evidence bearing on the role of genetic variation in macroevolutionary change. He argued that "naturally segregating" variation -- that is, of the character or magnitude normally seen in animal populations -- appeared to play a limited role, if any, in "macroevolutionary events" (p. 92). So striking was this pattern that McDonald dubbed it "a great Darwinian paradox" (p. 93), placing the following points in italics for emphasis:

Those loci that are obviously variable within natural populations do not seem to lie at the basis of many major adaptive changes, while those loci that seemingly do constitute the foundation of many, if not most, major adaptive changes apparently are not variable within natural populations. [p. 93]

2. Keith Stewart Thomson, "Macroevolution: The Morphological Problem," American Zoologist 32 (1992):106-112.

Keith Thomson is a vertebrate paleontologist and anatomist who taught at Yale and Oxford; at the time this paper was published, he was president of the Academy of Natural Sciences in Philadelphia. Throughout his career, Thomson has been concerned with the explanatory adequacy of neo-Darwinism. "The basic article of faith of a gradualist [neo-Darwinian] approach," he writes in this paper,

is that major morphological innovations can be produced without some sort of saltation. But the dilemma of the New Synthesis [textbook theory] is that no one has satisfactorily demonstrated a mechanism at the population genetic level by which innumerable very small phenotypic changes could accumulate rapidly to produce large changes: a process for the origin of the magnificently improbable from the ineffably trivial.

3. George L.G. Miklos, "Emergence of organizational complexities during metazoan evolution: perspectives from molecular biology, palaeontology, and neo-Darwinism." Memoirs of the Association of Australasian Palaeontologists 15 (1993):7-41.

George Miklos is an Australian geneticist (who, when this paper was published, worked at the Australian National University in Canberra). His 1993 paper, the longest in this collection of articles, is an often vehement manifesto attacking the explanatory claims of neo-Darwinian theory, largely on the grounds that textbook theory completely ignores the relevant level of mechanistic detail where macroevolutionary change is concerned. From the Abstract:

The popular theory of evolution is the modern synthesis (neo-Darwinism) based on changes in populations underpinned by the mathematics of allelic variation and driven by natural selection. It accounts more for adaptive changes in the colouration of moths, than in explaining why there are moths at all. This theory does not predict why there were only 50 or so modal body plans, nor does provide a basis for rapid, large-scale innovations. It lacks significant connection with embryogenesis and hence there is no nexus to the evolution of form. It fails to address the question of why the anatomical gaps between phyla are no wider today than they were at their Cambrian appearance....I believe that the search for the Holy Grail (evolution of complex morphologies and nervous systems) has been conducted in the wrong place and at the wrong levels by evolutionary biologists. [p. 7]

4. Robert L. Carroll, "Toward a new evolutionary synthesis," Trends in Ecology and Evolution 15 (2000):27-32.

Robert Carroll is a vertebrate paleontologist and professor emeritus at McGill University in Montreal. In this article, he argues:

Research in many disciplines over the past 40 years has demonstrated that the patterns, processes and forces of evolution are far more diverse than hypothesized by Darwin and the framers of the evolutionary synthesis...Increasing knowledge of the fossil record and the capacity for accurate geological dating demonstrate that large-scale patterns and rates of evolution are not comparable with those hypothesized by Darwin on the basis of extrapolation from modern populations and species. [p. 27]

5. Scott F. Gilbert, John M. Opitz, and Rudolf A. Raff, "Resynthizing Evolutionary and Developmental Biology," Developmental Biology 173 (1996):357-72.

The authors are developmental biologists (Gilbert at Swarthmore College and Raff at Indiana University) and a medical geneticist specializing in developmental anomalies (Opitz at the University of Utah). In this paper, published during a period of rapid growth for the young field of "evo-devo" (evolutionary developmental biology), the authors argue that, despite its merits with smaller-scale phenomena, "the Modern Synthesis" (textbook neo-Darwinism) fails to explain macroevolution. They write:

Starting in the 1970s, many biologists began questioning its adequacy in explaining evolution. Genetics might be adequate for explaining microevolution, but microevolutionary changes in gene frequency were not seen as able to turn a reptile into a mammal or to convert a fish into an amphibian. Microevolution looks at adaptations that concern only the survival of the fittest, not the arrival of the fittest. As Goodwin (1995) points out, "the origin of species -- Darwin's problem -- remains unsolved."

6. Douglas Erwin, "Evolutionary uniformitarianism," Developmental Biology 357 (2011):27-34.

Douglas Erwin is an invertebrate paleontologist at the Smithsonian's National Museum of Natural History and a leading expert on the origin of animal body plans. He collaborates frequently with developmental biologist Eric Davidson (see reading 7, below) on macroevolutionary questions. In this paper, Erwin argues that the manifold discontinuities among the animal groups -- what he calls "the clumpy distribution of morphologies" (p. 27) -- is not an artifact of sampling, but the real signal of history. Neo-Darwinism, he continues, "attempted to rescue [its] uniformitarian explanations by 'explaining away' this empirical pattern as a result of various biases" (p. 33). In Erwin's view, however, the processes of evolution have changed fundamentally over time, and evolutionary events possible in the Cambrian, such as the origin of the animal phyla, were unique occurrences.

7. Eric Davidson, "Evolutionary biology as regulatory systems biology," Developmental Biology 357 (2011):35-40.

Eric Davidson was a developmental biologist at Caltech who pioneered the study of the purple sea urchin (Strongylocentrotus purpuratus) as a model system. In his books and articles, he strongly attacked the explanatory shortcomings of neo-Darwinism, arguing that the theory focuses attention at the wrong level (small-scale variation), neglecting the genuine mechanisms of body plan construction. This paper gives a good overview of Davidson's recent thinking, starting with his critique of neo-Darwinian theory:

Of [neo-Darwinism], I shall have nothing to say, as mechanistic developmental biology has shown that its fundamental concepts are largely irrelevant to the process by which the body plan is formed in ontogeny. In addition it gives rise to lethal errors in respect to evolutionary process. Neo-Darwinian evolution is uniformitarian in that it assumes that all process works the same way, so that evolution of enzymes or flower colors can be used as current proxies for study of evolution of the body plan. It erroneously assumes that change in protein coding sequence is the basic cause of change in developmental program; and it erroneously assumes that evolutionary change in body plan morphology occurs by a continuous process. All of these assumptions are basically counterfactual. This cannot be surprising, since the neo-Darwinian synthesis from which these ideas stem was a pre-molecular biology concoction focused on population genetics and adaptation natural history, neither of which have any direct mechanistic import for the genomic regulatory systems that drive embryonic development of the body plan. [pp. 35-36]

8. Andreas Wagner, "The molecular origins of evolutionary innovations," Trends in Genetics 27 (2011):397-410.

Andreas Wagner is a theoretical biologist at the Institute of Evolutionary Biology, University of Zurich. His research focuses on how complex systems function, respond to perturbation, and are modified by evolutionary processes. Recently, he has been addressing the problem of innovation, or the origin of complex novelties in organisms, the sine qua non of any evolutionary theory: How did new structures -- body plans, organ systems, etc. -- come to be, where they did not exist before? In this paper, Wagner begins by expressing his dissatisfaction with standard (neo-Darwinian) theory:

We know many examples of innovations, each a fascinating piece of natural history. However, we know few of the principles that explain the ability of living things to innovate through a combination of natural selection and random genetic change. Random change by itself is not sufficient, because it does not necessarily bring forth beneficial phenotypes. For example, random change might not be suitable to improve most man-made, technological systems. Similarly, natural selection alone is not sufficient: As the geneticist Hugo de Vries already noted in 1905, "natural selection may explain the survival of the fittest, but it cannot explain the arrival of the fittest." Any principle of innovation needs to explain how novel, beneficial phenotypes can originate. [p. 397]


These brief summaries are intended to orient the reader who may be unfamiliar with the authors or the disputes, but cannot substitute for a careful reading of the papers themselves. These papers are only a tiny sample, of course, of a very much larger scientific literature addressing the problem of macroevolution.

What's this,the human brain is extremely sophisticated?(Who knew?)

Brain connections “more sophisticated than thought” (straight face here)

Hello, base, do we have a connection? The human brain is said by many to be the most sophisticated known item in the universe.

Never mind, from ScienceDaily::


Inhibitory connections between neurons act as the brain’s brakes, preventing it from becoming overexcited. Researchers thought inhibitory connections were less sophisticated than their excitatory counterparts because relatively few proteins were known to exist at these structures. But a new study overturns that assumption, uncovering 140 proteins that have never been mapped to inhibitory synapses. Some of the proteins have already been implicated in autism, intellectual disability and epilepsy, suggesting new treatment avenues. – Akiyoshi Uezu, Daniel J. Kanak, Tyler W.A. Bradshaw, Erik J. Soderblom, Christina M. Catavero, Alain C. Burette, Richard J. Weinberg, and Scott H. Soderling. Identification of an Elaborate Complex Mediating Postsynaptic Inhibition. Science, September 2016 DOI: 10.1126/science.aag0821 Paper. (paywall) More.

Memo to the new atheists from one of their own:don't open the champagne just yet.

Atheism is doomed: the contraceptive Pill is secularism's cyanide tablet

 
 
 The 1960s counterculture slogan “make love, not war” could have been invented for the Hutterites, a conservative, pacifist Anabaptist community in the US and Canada. Numbering 400 at the end of the 19th century, when they moved to Dakota on the point of extinction, there are almost 50,000 Hutterites today, despite conversion being extremely rare (they speak an archaic form of High German and live in the middle of nowhere, which makes it unlikely they’ll turn up at your doorstep with a funny grin).

They are not alone. The Mormons continue to grow by 40 per cent every decade, largely thanks to a high birth rate, so much so that by 2080 there will be anywhere between 63 and 267 million Mormons, depending on whether that figure falls to 30 per cent or 50 per cent.

And Evangelical Christians now account for two thirds of white American Protestants, while the ultra-Orthodox account for 17 per cent of British Jewry, but 75 per cent of children.

Across the western world the fertility rate of religious conservatives far outstrips that of non-believers, so much so that modern liberal secularism is endangered. That, anyway, is the thesis of Shall the Religious Inherit the Earth?, a fascinating new book by Eric Kaufmann of Birkbeck University, which is published later this month. It may well be one of the most significant books of our era.

It used to be taken for granted that, just as liberal democracy meant the end of history, so it also meant the end of religion. Once people became rich, educated and sexually liberated, they left irrational beliefs and other such nonsense behind.

Christianity declined steadily from the mid-19th century but it wasn’t until the 1960s that European societies were able to fully abandon the emotional baggage of their civilisation’s infancy, and especially its repressive attitude to sex.

But if what Kaufmann is saying is true – and the demographic data suggests it is – then the contraceptive Pill was not so much secular Europe’s liberation as its cyanide tablet.

The good news is that Europe will not become Islamicised (although Kaufmann’s estimate of 20 or 25 per cent is Islamic enough). The bad news (for some) is that it will become Evangelical Protestant instead. This will at least be encouraging for Israel, although whether it will be the same progressive, secular Israel where gays can serve in the military is another matter, as by the second half of the century the ultra-Orthodox will be the majority.

New Atheists comfort themselves with the idea that religious people will continue to drift their way, like rustics to the city, but the figures do not bear this out. It is true that liberal religious people continue to embrace atheism at a rate that alarms the Roman Catholic, Anglican and Methodist Churches, and Reform synagogues. Once religions start to accept secularism and rationality, their young people usually reach the logical conclusion of doubt – unbelief.

More conservative religions do not have that problem. Only 5 per cent of the more traditional Amish leave the faith, and when a community’s birth rate outstrips the national average by 200 or 300 per cent they can easily afford to lose one in 20 of the flock.

While the likes of Richard Dawkins aim their bile at traditional Christianity, fundamentalists are largely immune to their attacks, and become only stronger as the more committed members of the established churches head their way. Those religions that survive will become more conservative.

God alone knows what will happen to the Church of England this century, but we can safely say that the Catholic Church will become smaller but more committed. It will continue to exist at the margins of an atheist-dominated Europe ruled by an increasingly intolerant secular Left.

Widespread anti-religious feeling will only get more intense as the coming demographic changes outlined by Kaufmann appear to ring true, and as Evangelical Christians start to become more significant in, for example, the British Conservative Party.

But that smaller, more orthodox Catholic Church will have a huge inbuilt advantage – what French Canadian Catholics used to call “revenge of the cradle”. Many orthodox Catholics I know have 3 or 4 children – that’s not a recklessly high number, but in a society where the atheist fertility rate is around 1 child per woman, that advantage will show over a few decades, especially since orthodox Catholics have a far smaller drop-off rate than their liberal brethren.

Much as this will anger the New Atheists, which is a plus, Kaufmann’s thesis is disturbing. Personally I prefer Tel Aviv to Jerusalem, and Anglican civilisation to some of the wackier strains of Evangelical Christianity. As for fundamentalist Islam…

It’s happened before: Kaufmann believes that Christianity’s rise from 40 followers to 6 million within three centuries had less to do with conversions that with higher birth rates, since the Christians rejected such pagan practises as polygamy and infanticide.

Today we view the ancient world’s attitude to infanticide as barbaric and incomprehensible, but perhaps future generations will look at our attitudes to abortion in the same way – that's not because pro-lifers would have won the argument, simply that (in addition to the effect of the Pill) abortion is killing the atheists of tomorrow.

Why chirality remains a problem for origin of life science.

Tagish Lake Meteorite Does Not Solve the Homochirality Problem
Evolution News & Views


Amino acids, the building blocks of proteins, share a puzzling feature. All amino acids used in making proteins are "left-handed" amino acids.

In chemistry, we call molecules "left-handed" or "right-handed" based on how things attach to a carbon atom. Imagine the palm of your hand is a carbon atom, and your fingers are different molecules attached to the carbon (e.g., a hydrogen, an amine, a carboxylic acid). Notice that both of your hands have the same "things" attached to it, but in a different order such that your hands are mirror images of each other. My right and left hands both have a pinky finger, a thumb, and an index finger, but the arrangement is different. The same thing happens to carbon atoms that have different things attached to it; you can get molecules that are mirror images of each other. These mirror images are mostly chemically equivalent. (See here and here for more on homochirality.)

The interesting part of this is, when we try to make amino acids in the lab, we always end up with a 50/50 mixture of right- and left-handed amino acids. But when scientists try to construct proteins from this 50/50 mixture, the proteins do not function properly. Right-handed amino acids do not work. So the big question is: How did nature make only left-handed amino acids? Or was there a 50/50 mixture and nature somehow isolated only the left-handed ones to make proteins?

Scientists from the Goddard Astrobiology Analytical Laboratory believe their recent studies on a Tagish Lake (British Columbia) meteorite sample may provide an answer to this question. (See here for the press release. The research paper is still in press). They found that the Tagish Lake sample has an excess of left-handed aspartic acid, one of the 20 amino acids used in protein construction. They also noted, however, that the sample contains only a slight left-handed excess (8% greater) of alanine, another one of those 20 amino acids. They, therefore, conclude that the amino acids on the meteorite sample are not from biological contamination from Earth, but were formed in space. Furthermore, the excess left-handed aspartic acid must have formed and been isolated somehow inside the meteorite, as opposed to being exposed to certain types of radiation that may cause a slight excess of one hand of amino acids over another.

The Tagish Lake meteorite has many unique properties that have made its classification difficult. It has been a subject of interest since January 2000 when it landed. For a look at some of the unique features of the Tagish Lake meteorite, see here. Importantly, the meteorite contained many more organic compounds than just amino acids.

The Goddard Astrobiology Analytical Laboratory researchers conclude that the amino acids must have formed within the meteorite, and the left-handed excess of aspartic acid is likely due to crystallization that occurs in the presence of water. Alanine, on the other hand, does not crystallize in the same way. This is why there was only a left-handed excess of aspartic acid but a minimal excess of alanine. They speculate that perhaps the early Earth formed left-handed amino acids in a similar way -- by forming crystals in the presence of water.

The fact that a particular handedness can be isolated through crystallization is not news. Chemists do this in the lab when they want to isolate a left- or right-handed molecule. This only works if the molecule can form crystals that only contain one hand. Not all molecules form crystals and not all molecules form crystals that are purely left- or purely right-handed. Alanine is not a good candidate for isolating one form using crystallization because alanine crystals form from combinations of left- and right-handed molecules, giving the chemist crystals that are 50/50 left- and right-handed.

So what makes this finding so interesting? The researchers reason that because they have found a left-handed excess of aspartic acid that formed naturally, they speculate that nature could do this on Earth or perhaps the early Earth was seeded from amino acids that traveled on a meteorite similar to this one.

Unfortunately, this does not quite solve the left-handed (or "homochirality") problem. You see, in order to form left-handed crystals of aspartic acid, there needs to be a slight abundance of left-handed molecules in the first place. In other words, crystals do not form from a true 50/50 mixture. There must be a slight excess of left-handed molecules to form pure left-handed crystals. Given the alanine observation (an 8% excess of left-handed molecules), we might conclude that something caused a slight excess, such as polarized light interacting with the amino acids. This is a possibility, but of the amino acids found on the meteorite, only aspartic acid and alanine are mentioned, meaning that whatever caused the slight excess did not affect all of the amino acids.

Another glaring problem is, while crystallization may be an explanation for how some left-handed amino acids were isolated in nature, it does not explain all of the amino acids. Not all of the amino acids form homochiral crystals. So were there two different mechanisms that happened to isolate only left-handed versions of all 20 of the predominant amino acids? This seems to be a bit of a stretch, and does not solve the mystery of why nature prefers left-handed amino acids.

The NASA report ends, as much origin-of-life research ends, with more speculation and storytelling than actual findings or viable conclusions:

This process only amplifies a small excess that already exists. Perhaps a tiny initial left-hand excess was created by conditions in the solar nebula. For example, polarized ultraviolet light or other types of radiation from nearby stars might favor the creation of left-handed amino acids or the destruction of right-handed ones, according to the team. This initial left-hand excess could then get amplified in asteroids by processes like crystallization. Impacts from asteroids and meteorites could deliver this material to Earth, and left-handed amino acids might have been incorporated into emerging life due to their greater abundance, according to the team. Also, similar enrichments of left-handed amino acids by crystallization could have occurred on Earth in ancient sediments that had water flowing through them, such as the bottoms of rivers, lakes, or seas, according to the team." [emphasis added]
All of these statements are speculative and do not necessarily follow from the actual findings in the meteorite. The meteorite shows that aspartic acid, which we already know forms homochiral crystals, formed homochiral crystals while alanine, which we know forms crystals with a 50/50 composition, had a slight left-handed excess. This says nothing about how these amino acids could have formed on the early Earth.

Furthermore, the Tagish Lake sample contained multiple organic compounds, not just amino acids, so if these meteorites provide a naturalistic example of possible origin-of-life mechanisms, we need to consider the presence of other compounds that nature apparently did not "choose" to employ. These findings, therefore, do not help us understand why nature builds proteins from 20 particular organic compounds that are specifically left-handed or where those 20 amino acids came from.