Is There Life on Mars?

Is There Life on Mars? (SA/2023)

 

 

The question of whether there is - or at some point has been - life on Mars is one that continues to excite the popular imagination, as well as arouse the professional interest of astrobiologists.

 

Indeed, the seach for microbial Martian life or, at the very least, traces of such life - so called biosignatures - is one of the main reasons NASA keep sending missions to the Red Planet.    

 

However, whilst evidence has been found that Mars could have once supported life in the past - for it wasn't always the dry and arid planet that we know today - there's nothing to indicate that life is still present now.      

 

But the thing is, I don't really understand why it matters or why anyone should care: for whilst there may or may not have been life on Mars billions of years ago, there's presently an abundant and mind-boggling variety of living organisms here on Earth - it's the freakiest show, as Bowie might say.

 

Indeed, as the above photograph illustrates, there's probably more life to be found on a single red tile of my front door step than on the entire surface of the Red Planet and surely we should cherish and preserve this life, rather than spend billions of dollars looking for alien beings.        

 

For me, a tiny baby garden snail inspires far more wonder than E.T. (Oh man, look at those molluscs go!)

They Came from Outer Space

One of the more amusing oh, if only it were true, stories doing the rounds this week concerns our old friend the octopus ... According to a group of researchers, octopuses are extraterrestrial biological entities; i.e. alien beings from another world and not just highly intelligent deep sea creatures. 

Of course, there's no actual evidence to support such a claim and it's not only been rejected by the wider scientific community, but mocked in the media: You've got to be squidding me! being a typical tabloid headline.   

Despite anticipating such a reaction, the authors of the paper published in Progress in Biophysics and Molecular Biology, boldy insist that the so-called Cambrian explosion - a sudden burst of life that occurred c. 540 million years ago - can only be explained as an event with cosmic origins.

Essentially, the idea is that alien viruses were transported to Earth by a meteor and infected the life that already existed here; in this case, a population of primitive squid-like organisms, causing them to mutate into an alien hybrid - commonly known as an octopus. Alternatively, some suggest that fertilised octopus eggs came ready frozen from out of space.

Either way, this is obviously a reimagining of the panspermia hypothesis which posits that life exists throughout the universe and was seeded on Earth via comets, asteroids, space dust, or shooting stars. It's an old idea - very old; even the ancient Greeks were speculating along these lines and the first known use of the term is found in the writings of the pre-Socratic philosopher Anaxagoras.

More recently, Fred Hoyle and Chandra Wickramasinghe have been influential proponents of the theory; indeed, the latter is one of the authors of the new paper on alien cephalopods. He and his colleagues argue that so suddenly did octopuses evolve their astonishing features (including large brains and a sophisticated nervous sytem) that it is plausible to suggest they were "borrowed from a far distant future [...] or more realistically from the cosmos at large".

Having said that, the authors concede that such an extraterrestrial explanation for the emergence of these and other unusual features does run "counter to the prevailing dominant paradigm". And, of course, there are good reasons why this is so ...

For a start, it's borderline crackpot; although they may not wear tinfoil hats, not one of the authors is a zoologist and much of the speculation rests on the claim that the genetics of the octopus is uniquely mysterious. A 2015 paper published in Nature, however, revealed that the genome of the creature in question had been fully and successfully mapped and one of the things it showed was how the octopus fits into the generally accepted theory of (terrestrial) evolution.

Thus there's simply no need to imagine an alien origin - no matter how otherworldly the octopus may be in appearance or how unnatural its abilities may seem to us.        

See: J. Steele et al, 'Cause of Cambrian Explosion - Terrestrial or Cosmic?', Progress in Biophysics and Molecular Biology, (available online 13 March, 2018): click here. 

For an earlier post in praise of the octopus that anticipates this one, click here.

Chris D. Thomas: Inheritors of the Earth - Six Key Ideas (Part 1: Sections I - III)

I. Extinction isn't the End of the World and Change is the Only Constant

Professor Chris D. Thomas is an ecologist and evolutionary biologist at the University of York who has written a book that lends scientific support to Rupert Birkin's vision in Women in Love of a far-off future in which biological diversity is even greater than it is now and unimaginable new species of life will have unfolded. Of course, Thomas doesn't share Birkin's misanthropy and long for a world free of humanity, but he does affirm that evolution never ends and that there is thus an infinite array of lovely things still to come (after - but also out of - the Anthropocene period).

Thomas begins by setting out a familiar tale of woe concerning the negative effect that mankind is said to have had on the Earth. Whilst conceding the importance of recognising ways in which human activity threatens the existence of life, he quickly counters this doom-laden narrative of eco-apocalypse and suggests we take a broader view, considering all the evidence and not just those facts that reinforce the moral and political concerns of those who subscribe to a green philosophy based on a desire to save the planet.     

Essentially, Thomas is arguing that short-term ecological upheaval and species extinction pales into insignificance when seen from the perspective of evolution. Ultimately, no matter how great the losses, there will be winners; that is to say, species that will not only survive, but thrive; not only thrive, but diversify into an unimaginable variety of new species. Periods when the levels of extinction are high - as they are presently - obviously present setbacks; "but in the end they have provided new opportunities for enterprising creatures that have been able to exploit the new conditions" [7]. Come back in a million years, says Thomas, and you're likely to be astonished at what you'll find.  

We might not like it, but never-ending change is the only constant; the world is in a state of permanent flux. Futile attempts to conserve the world as it is - or, even more vainly, to restore it to some earlier, more pristine, more natural state - are not only untenable, but "implicitly dismiss as undesirable the continuing biological gains of the human epoch" [8]. Further, the logic of such a way of thinking can have ugly consequences, such as the call to eradicate alien arrivals and exterminate impure hybrids. Rather than "swim against the tide of ecological and evolutionary change" [9], writes Thomas, we should go with the flow and joyfully facilitate and accelerate biological processes.


II. The Future Walks Among Us

Just to be clear: Thomas isn't arguing that we shouldn't, for example, try to prevent unsustainable fishing and the dumping of plastic into the oceans. But, we need to open our eyes to the evolutionary reality of the world and acknowledge biological gains made. It can also be strangely comforting to realise that we can glimpse the future within the present; that the "inheritors of the future Earth are already among us today" [43], just as birds and mammals were coexistent with the dinosaurs for millions of years and did not "suddenly appear after the asteroid hit" [41] (an idea that greater knowledge of the fossil record plus revolutionary advances in molecular biology has shown to be false).

These inheritors, as Thomas calls them, might not be the wild and charismatic megafauna that most people worry about (tigers, gorillas, pandas, polar bears, etc.), but we should probably get over our sentimental privileging of such beasts and recognise that domestic animals and household pets - as well as cereal crops - have all been incredibly successful by taking advantage of "a gullible primate" [45] in order to ensure their survival and global proliferation.

It's a Lawrentian nightmare, but there are now about 1.5 billion cattle, 1.2 billion sheep, 1 billion pigs and an astonishing 22 billion chickens in the world, all being fed and cared for in addition to the 1 billion cats and dogs, by 7 billion human beings. In other words, "the present is not a dip in the total numbers or combined weight [biomass] of large animals ... it is a substantial increase" [47] and the Anthropocene remains "just as much an age of mammals and birds as it ever was" [47].

Thomas concludes that "it's time to stop yearning for a pristine, wild world ... [as] there is no longer any such thing as human-free nature" [53] and we cannot reverse time. Besides, many species of large non-domestic animal are recovering in number and returning to their former lands; bears, bison, wolves, deer, boar, etc. Such recoveries seem likely to become more widespread (albeit within human-managed spaces) and the chances are "there will be considerably more large wild mammals in existence one hundred years from now than there are today" [51].


III. On Accelerated Evolution

Ecological transformation is one thing; evolutionary change is something else - something, in the long run, far more fundamental. Evolution, as Thomas says, is how life on Earth responds to and recovers from natural disasters, including periods of mass extinction.

People often parrot the phrase sixth extinction and like to blame humanity for it. But perhaps we should also consider whether this will in turn trigger a new flourishing of life. Thomas certainly seems to think so. Further, he argues that new species are already "coming into existence with immodest haste, adapting to new conditions" [118] - such as the Italian sparrow.

In a crucial passage, he continues:

"Remarkable as it might seem, new plant species may be coming into existence faster today than at any time in the history of our planet. A new era has arrived in which we see an acceleration of evolutionary change and the genesis of new life-forms. Given that many of them would not exist but for humans, they challenge us to contemplate the relationship between humanity and nature." [118]

We should abandon our human (all too human) guilt about our place in the world and our influence upon it. We should abandon also our privileging of old species over new and the mad desire to save everything. Life doesn't need saving, it needs accelerating and diversifying and the rapid evolution taking place not just in plants, but in animals, fungi and microbes, is something to marvel at.

"Great replacements have frequently been at the heart of large-scale and long-term evolutionary change ..." [140] and rather than always try to conserve things and weeping over the creatures that disappear into the void, we might seek to "build new biological communities composed of compatible species so that future ecosystems are more robust than those that currently exist" [126].


See: Chris D. Thomas, Inheritors of the Earth: How Nature is Thriving in an Age of Extinction (Allen Lane, 2017). 

To read Part 2 of this post (Sections IV-VI) click here. 

Two Inconvenient Truths

Poster by Stanislav Petrov 

deviantart.com 

I: Habitat Heterogeneity Leads to Greater Biodiversity 

According to the ecologist and evolutionary biologist Chris D. Thomas, paradise hasn't been lost because we never had it to begin with: "The harmonious coexistence of humans and the rest of nature in the distant past is a romanticized and largely fictional notion" [59].

Thus it is that the relationship between man and nature remains an often violent one, involving environmental destruction and species extinction. Having said that, human beings have also (inadvertently perhaps) created a "world of new opportunities for those animals and plants capable of seizing them" [59].

Already I can hear the obvious objection from the green lobby: There were once huge areas of land covered by dense forest. Animals and plants wouldn't need new opportunities if only we conserved what remained of these primordial environments.

And, yes, it's true, ancient woodland does contain a great number of trees and many rare species.

However, it's only by converting it into a mixed landscape consisting of a patchwork of forest and various human-created habitats, that the number of species significantly increases: "This is because new species move into human-created habitats faster than the previous residents of the region die out." [67]

This, obviously, is an inconvenient truth for those who oppose all deforestation, for example, and dream of protecting pristine nature as they imagine it. But it's a truth, nevertheless, that if you want to maximise the number of animals and plants, then accelerating habitat heterogeneity is the way to go.


II: Life Prefers Warm and Wet

To say that the world's climate is getting hotter is to state a scientific fact. But to claim that global warming will prove catastrophic for life on Earth is a moral and ideological interpretation of that fact - and a misinterpretation too. For most animals and plants like it warm and wet and will exhibit enhanced physiological performance if the global thermostat is nudged up a degree or two.

Of course, there will be climate change casualties; "at least 10 per cent of all species that live on the land are expected to perish, and possibly double this number" [78]. But the rest - being naturally more dynamic and adaptable - are likely to survive and prosper by migrating, if necessary, to where the conditions best suit them.

Conservationists may not like it, but life is chaotic and in a state of constant flux. Nothing has ever stayed the same and as soon as you begin to think on grand timescales you realise that species are essentially nomadic: "Biological communities are transient. ... That is how species survive climate change. They move around. ... Any attempt by humans to keep things just as they are is utterly pointless." [84]

Thanks to human activity, it's going to get warmer. And wetter. Warmer and wetter than it has been for three million years. But, amazingly, around two-thirds of the species that researchers have studied in recent decades have already wised up to the fact and "shifted their distributions in response" [91].

At the present rate of movement, within just a few centuries we will have a "new biological world order" [92] as subtropical species, for example, move into the temperate zones and former inhabitants of the temperate region "try their luck in the polar world" [92-3]. And this will very likely increase biodiversity, even if the total number of species on Earth is likely to be lower.

I'm not trying to pick a fight with Al Gore or cause Vivienne Westwood to get her knickers in a twist by pointing out this inconvenient truth concerning global warming; I'm not even advocating that we should stop thinking seriously about climate change and its likely consequences.

I'm simply saying - in agreement with Chris Thomas - that we need to accept the reality of the world we live in and encourage the movement of so-called invasive species "because botanical and zoological world travellers will form the basis of the world's new ecosystems, just as they have when the climate has changed in the past" [94].

See: Chris D. Thomas, Inheritors of the Earth: How Nature is Thriving in an Age of Extinction (Allen Lane, 2017). All page numbers given in the text refer to this work. 

To read a related post to this one - on biodiversity in the Anthropocene - click here.