Among lncRNAs ("long noncoding" RNA transcripts of 200 or more nucleotides) only some are exported. The exported ones may act in regulatory roles, encode short peptides, or encode full-length "de novo" genes. Now we read about lncRNAs as transcripts for de novo genes that influence the growth of the human brain.

A research team in Beijing wanted to know what enabled those lncRNAs to be exported to the cytoplasm, because that looks like the crucial step for allowing a transcript to become translated into a protein. Comparing gene expression rates in humans, macaques and marmosets they said, We identified distinctive U1 elements and RNA splice-related sequences accounting for RNA nuclear export. They note that the sequences are selectively constrained.

They continue: It is also difficult to understand the process by which a de novo gene acquires its biological function. Under darwinian philosophy, you bet it is. But may we please deconstruct this issue? We know that the de novo gene has a function, but that it acquired it is not observed. It's a darwinian assumption that usually leads to a dead end.

The opening sentence of the research paper states Human de novo genes can originate from neutral long non-coding RNA (lncRNA) loci and are evolutionarily significant in general, yet how and why this all-or-nothing transition to functionality happens remains unclear. The word originate carries the same crippling darwinian baggage, but how the transition happens is a well-posed, timely question. The Chinese team has made good progress on that puzzle.

Unexpectedly, maternal mRNAs undergo global remodeling: after deadenylation or partial degradation into 3'-UTRs, they are re-polyadenylated to produce polyadenylated degradation intermediates, coinciding with massive incorporation of non-A residues, particularly internal long consecutive U residues, into the newly synthesized poly(A) tails. Moreover, TUT4 and TUT7 contribute to the incorporation of these U residues, BTG4-mediated deadenylation produces substrates for maternal mRNA re-polyadenylation, and TENT4A and TENT4B incorporate internal G residues. (Liu et al.)

In an introductory piece, Christopher Herd casually comments, The Ryugu samples contain thousands of different types of organic molecules, including amino acids. By modern consensus, the organics formed in the interstellar medium, before the solar system formed. These were incorporated into Ryugu's parent body, along with frozen water which later melted. Of course, there's another way to interpret that evidence, because complex organics are usually symptomatic of life, and liquid water is conducive to life.

Chandra Wickramasinghe is an astrobiologist at the University of Buckingham. Milton Wainwright is a microbiologist at the University of Sheffield. I have known both of these UK astrobiologists for decades. Now they have written a book about their shared interest in panspermia.

Wainwright also knows the history of science. Right away we read about pre-socratic Greeks who thought about "seeds" everywhere. Various theories of the origin of life are mentioned, with surprising quotes from Charles Darwin, Thomas Edison and others. French philosopher Benoit De Maillet was the first "modern" proponent of panspermia, Wainwright contends. Did Mary Shelley conceive of Frankenstein after attending a lecture about lightning and the origin of life? Informative, and intriguing.

Wickramasinghe then relates how his collaboration with Fred Hoyle grew into a life in astrobiology. I know the story, and this telling is especially compelling and concise. His spectograpic investigation of interstellar dust is more sustained and penetrating than any before it, I'm sure. Of course Chandra is frustrated that the evidence for signs of biology in the dust is often dismissed without a hearing, or is rebutted with insubstantial, implausible alternatives.

The evidence for microfossils in meteorites like ALH84001, Orgueil and Polonnaruwa gets plenty of attention, as it should. Bacteria in the high atmosphere also get scrutiny, although skeptics may argue that they're from below. To flesh out the story, some scenarios are necessarily speculative, because it's uncharted territory. Me, I'm glad to see panspermia so boldly advocated.

But this definition is incomplete. Specialists have often noticed the space-hardiness of Tardigrades. Astrobiologist Devid Tepfer has long advocated plant seeds as vectors for panspermia. Ted Steele et al. suggest cryo-preserved embryos of larger animals may survive in comets. Moreover, life in a comet may not always be dormant. A periodic pass close to a star could warm the comet enough to melt the ice and allow cells to grow.

Even far from stars, radioactive elements with long half-lives could warm a comet interior, as Hoyle and Wickramasinghe knew. Now Richard Hoover expands on that idea, suggesting that radioactivity may allow for "the transfer of intact biospheres across interstellar and possibly intergalactic distances." He's calling it "Wet Panspermia."

And Hand makes it instructive. When he sees a need, he uses helpful analogies to remind us of the relevant science. He explains how different missions and different scientists with different instruments and methods progressively enabled us to reach our current understanding of other worlds. For example, some moons have magnetic fields that are intrinsic, some that are induced, some, none at all. Each case holds important clues about the structure of that world.

Hand can also be quite imaginative about the life that might be found in those oceans. Could an underwater civilization develop metallurgy, or advanced technology? I gladly welcome such free-thinking. He also considers at length whether life elsewhere could use entirely different chemistry from ours. I think we first need to better understand life-as-we-know-it.

I'm puzzled: why doesn't panspermia get mentioned? He wonders if inhabited moons or planets might get thrown out of orbit and "transport biospheres across the galaxy" (p 134). Heck, that's panspermia at a scale seldom imagined. For finding extra-terrestrial life, he writes, "the easiest and most intuitive biosignature is perhaps the one you can judge with your own eyes: its morphology" (p 238). He must be unaware of the morphology photographed by the Opportunity rover on Mars, 27 Feb 2004. His account of the search for life by the Viking mission, 1976-1977, sticks closely to NASA's hyper-conservative party line. At least he plainly admits, "There has been only one time in the history of space exploration when looking for signs of life was the stated target of the mission [Viking]. This first time was also the last time" (p 231). If this frustrates him, he says no more about it.

Of course Hand does not stray from orthodoxy as far as I do. Still, this book moves the paradigm in the right direction. Besides, it's edifying and enjoyable. Recommended!