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+--- Thread: On the origin of interstellar species: How life could continue to evolve (/thread-8952.html)
On the origin of interstellar species: How life could continue to evolve - C C - Aug 16, 2020
http://nautil.us/issue/88/love--sex/how-life-could-continue-to-evolve
EXCERPTS: . . . But sexual reproduction as it exists among 99.9 percent of complex-celled life on Earth is just one way that species jazz up their genomic material. The prokaryotes —bacteria and archaea—carry out liberal amounts of horizontal gene transfer; literally the exchange of pieces of genetic code between individuals who otherwise reproduce asexually. [...] In other words, we actually live in the midst of a promiscuous free-for-all of genetic mixing and exchange taking place at multiple levels. And critically, the very persistence of these mechanisms across billions of years tells us that they are all important and, in the broader Darwinian sense, successful.
To put this another way: Regardless of the finer details of what life is built out of, we might imagine that the schemes represented by these mechanisms of genetic exchange will emerge in any persistent living system anywhere in the cosmos. That fact raises some intriguing possibilities about what we might discover beyond the bounds of Earth. All to be taken for what they are—informed but utterly speculative proposals.
[...] Scientists have debated how asteroid impacts can drive material exchange between worlds like Earth and Mars in our solar system and pass biology back and forth. There are proposals that a young Mars was actually a more likely incubator of life than a young Earth, and it only later “seeded” our world. ... If we extrapolate these ideas to more densely packed exoplanetary systems ... horizontal gene transfer could take place across many tens of millions of kilometers and between entire biospheres. ... alien biologists in these places might concern themselves with a tree of life incorporating multiple planetary incubators... it’s tempting to imagine life physically exchanging informational algorithms across an entire galaxy. Indeed, the old idea of panspermia leads to the wholesale exchange of biology between the stars. But it seems likely that living systems would need to be built differently, and perhaps operate on different timescales than on Earth, for this scenario to make sense.
[...] If we allow ourselves to imagine that life elsewhere in the cosmos has evolved toward technological manipulation of its surroundings, then it stands to reason that machine-mediated gene transfer and machine-mediated organism reproduction is happening somewhere. ... why stick to sexual reproduction involving only two gene-giving parents? We’ve recently seen a version of this in the birth of a human whose DNA was, in a limited fashion, a mix from three biological parents.
[...] a species and its biosphere might surge across the universe driven by an insatiable appetite for life-related informational algorithms (genes in essence but not necessarily in form). Exchanging and blending with anything and everything, looking for new and better pathways through the vast landscape of Darwinian selection. A 10-billion-year-old galaxy represents a fantastic repository of experiments in life. Just as with our own sexual reproduction, a mix and match of tested genes is an efficient way to explore variations that might confer increased fitness. If the aliens ever show up at Earth they won’t ask to be taken to our leader, they’ll ask for a cheek swab and a consent form... (MORE - details)