Human Extraterrestrials

Introduction

Even though science fiction is often focused on the future, its assumptions are tied to the present.

Aldrin descends from Apollo 11In some respects this is obvious.  A story about the near future can become dated by history itself.  Every SF story prior to 1969 that describes the first moon landing in detail (happy 51st anniversary, last week!) is obsolete.  And every story that predicted a smooth reach out into colonizing the solar system directly after that first landing, unfortunately, is also defunct.  Stories can also be rendered unbelievable by scientific advance:  all the delightful tales based on a habitable Venus or Mars are gone with the, er, vacuum.

But there’s also a subtler way.  Even though F&SF specialize in examining our assumptions about the universe, the assumptions that seem plausible shift over time.  Fashions change.  To take a heartening example:  SF stories from the late 1940s and the 1950s tended to take it for granted that there would shortly be a nuclear world war.  (Hence it’s spot-on characterization when the 1955 version of Doc Brown in “Back to the Future” accepts Marty’s recorded appearance in a hazmat suit as logical because of the “fallout from the atomic wars.”)  But for over seventy years, we’ve managed to avoid that particular catastrophe.

One assumption that’s always intrigued me is whether we are likely to meet people like ourselves—and I mean, exactly like ourselves—on another planet.  If we discovered an Earthlike planet of another sun, might we climb down the ladder from our spaceship to shake hands with a biologically human alien?

Not Really Alien

I’m talking about a “convergent evolution” hypothesis—the notion that the human species might have developed independently more than once.  And, incidentally, the standard biological definition of “species” as “interfertile” (a more precise definition can be found on Wikipedia) is what I’m using here; because, obviously, one of the potential uses of the assumption in a story is to make possible a romance between two characters from different worlds, and romance is not unrelated to sex and reproduction.

The Cometeers coverSo we want to set aside, to begin with, a class of stories in which people from different planets are all human because they have a common ancestry.  For example, in Jack Williamson’s classic space opera The Cometeers (1936), Bob Star finds his true love Kay Nymidee among the human subjects of the decidedly nonhuman masters of an immense assemblage of space-traveling planets, the “comet.”  But the reason there are human beings present is that a research ship from Earth was captured by the Cometeers long ago, and these are the descendants of the crew.

It’s not uncommon for the inheritance to work the other way around.  David Weber’s “Mutineers’ Moon” (1991) starts with the eye-opening assumption that our Moon is actually a long-inert giant spaceship—and reveals that the humanity of Earth is descended from the original crew members of that spaceship.  Thus, it’s perfectly plausible when hero Colin MacIntyre falls for a preserved member of the original crew; they’re from the same stock.  Similarly, in at least the original 1978 version of Battlestar Galactica, the human survivors of the “rag-tag fugitive fleet” are human because Earth itself was one of their original colonies, which apparently fell out of touch.

The Era of Planetary Romance

In the early days of modern SF—say, from about 1912 through the 1930s—it was commonly assumed that the answer was yes:  human beings (with minor variations) might be found independently on other planets.  Arguably, this may have been because the early planetary romances—melodramas set on exotic worlds, heavy on adventure and love stories—were less interested in science than in plot devices.  But biology was less advanced in those days; recall that DNA was not identified as the basis of genetic inheritance until 1952.  It’s easy to forget how little we knew about things we take for granted today, even in relatively recent periods.

A classic early case is that of Edgar Rice BurroughsBarsoom.  In A Princess of Mars (1912), Earthman John Carter is transported by obscure means to Mars, called by its inhabitants “Barsoom.”  Those inhabitants include the nonhuman “Green Martians,” but also people identical to humans in several colors, particularly the “Red Martians” among whom Carter finds his lady-love, Dejah Thoris.  As a Red Martian, Dejah is human enough for Carter to mate with, and they have a son, Carthoris, thus meeting the “interfertile” criterion.

Lynn Collins as Dejah Thoris in John Carter of Mars

Lynn Collins as Dejah Thoris

To be sure, the biology here is a little mysterious.  Dejah looks entirely human, and even, to borrow a Heinlein phrase, “adequately mammalian” (see, for example, Lynn Collins’ portrayal in the loosely adapted movie John Carter (2012)).  But Martians don’t bear their young as Earth-humans do; they lay eggs, which then develop for ten years before hatching.  It’s not easy to imagine the genetics that could produce viable offspring from an individual whose genes direct live birth and one whose genes result in egg-laying.  But that didn’t stop Burroughs.

E.E. Smith, whose initial SF writing goes back just about as far as that of Burroughs, was willing to accept this trope as well.  In The Skylark of Space (published 1928, but written between 1915 and 1921), our intrepid heroes travel to a planet inhabited by two nations of essentially human people—although the double wedding in the story does not involve any interplanetary romances, but is between two pairs of characters from Earth.  Smith’s later Lensman series (1948-1954), which features one of the most diverse arrays of intelligent creatures in SF, also allows for apparently interfertile humans from a variety of planets.  My impression is that this sort of duplication was also true of some of the nonhuman species in the Lensman unverse—there might be, say, Velantian-types native to planets other than Velantia.

This approach wasn’t universal in old-time SF.  The more scientifically-minded John W. Campbell’s extraterrestrial character Torlos in Islands of Space (1930) was generally humanoid in form, but quite different in makeup:  his iron bones, for instance.  It’s been argued that a roughly humanoid form has some advantages for an intelligent species, and hence that we might find vaguely humanoid aliens on different planets—though this is pure speculation.  But “humanoid” is a far cry from biologically human.

Darkover Landfall coverWe see some persistence of this tradition into the second half of the twentieth century.   Marion Zimmer Bradley’s iconic planet Darkover, for instance (first novel published 1958), is populated by the descendants of Terran humans from a colony ship and also by the elf-like indigenous Chieri, who, despite minor differences like six fingers and golden eyes, not to mention the ability to change sex at will, have interbred with the Terran immigrants.

An interesting variation can be seen in Julian May’s Saga of Pliocene Exile (first story published in 1981).  When modern humans are sent on a one-way trip into the distant past, they are enslaved by the Tanu, aliens from another galaxy who have settled on Earth.  The story indicates that the Tanu were specifically searching for a place where the local gene pool was similar to theirs—which might also account for why they came all the way from another galaxy (also a somewhat antique trope) to get here.

It’s slightly odd that, even where basically identical human beings turn up on other planets, other animals never seem to be similarly duplicated.  On Burroughs’ Barsoom, one doesn’t ride horses, but thoats; is menaced not by tigers, but by banths; and keeps a calot, not a dog, as a pet.  In a planetary romance or science fantasy setting, one is less likely to see Terran-equivalent fauna than parallel creatures with exotic names and slight differences—whence the SF-writing gaffe “Call a Rabbit a Smeerp” (see TV Tropes and the Turkey City Lexicon).

At the Movies

The all-too-human trope is carried on into the present day in video media—movies and TV.  Again, this may be partly because the science is often subordinated to the plot; but the cost and difficulty of putting convincing nonhuman characters on-screen is surely another factor.  Filmmakers’ ability to depict exotic creatures, however, has changed immensely in the last forty years, to a point where almost any imaginable creature can be created if the budget is sufficient.  Thus, the original Star Trek series of the 1960s stuck largely to slightly disguised humanoid aliens, perhaps relying on the ‘universal humanoid’ hypothesis mentioned above, while later series were able to branch out a bit.  Similarly, the Star Wars movies could readily give us nonhuman characters like Jabba the Hutt, Chewbacca, and C3PO; they, too, grew in variety as the capabilities of CGI and other techniques expanded.

Jupiter Ascending movie posterStill, it may be harder for us to adjust to interactions among characters where we can see their nonhumanity, rather than just reading about it.  So we still tend to see extraterrestrial humans on-screen.  The Kree in Captain Marvel (2019), for example, are indistinguishable from humans—an actual plot point, since this makes it possible for Yon-Rogg to tell Carol that she’s an enhanced Kree rather than a kidnapped human.  The Kree do have blue blood, in the movie; it’s not clear what kind of biological difference (hemocyanin?) might result in that feature.  We also see a number of alien humans in Jupiter Ascending (2015), though I think of that tale as a deliberate throwback to pulpish science fantasy or planetary romance.

A Match Made in Space, fictional coverI keep wanting to cite the fictional novel written by George McFly as shown in the closing scenes of Back to the Future, “A Match Made in Space,” since the cover seems to suggest an interplanetary romance (and one thinks of George as a nerdy romantic); but it isn’t actually clear whether that’s the case.  All we have to go on is the title and the cover, and that could just as easily depict a match between two humans, fostered by an alien matchmaker (or vice versa).

The Modern Era

We don’t see nearly as many extraterrestrial humans in modern SF, and for good reason.

The more we understand about genetics, the less likely it seems that another human species, so closely similar as to be interfertile, could evolve independently.  What we know about evolution suggests that there are just too many random chances along the way—cases where the prevailing mutations might have turned out differently.  Even if we assume that humanoid form is probable, why not have six fingers, or hemocyanin rather than hemoglobin?  While I’m not well enough educated in biology to venture any actual probabilities, I think our growing sense of the complexity of the human body and its workings, over the last seventy years or so, has simply made it seem vanishingly unlikely that an independently evolved intelligence would come out that close to the human genotype.

For example, the scientifically-minded Arthur C. Clarke depicted a galaxy in which each intelligent species, including humans, was unique:  The City and the Stars (1956, developed from an earlier story published in 1948).  In one of the unused story fragments he wrote while working on 2001:  A Space Odyssey (1968), his hero, well along on his journey into mystery, thinks:

He did not hesitate to call them people, though by the standards of Earth they would have seemed incredibly alien.  But already, his standards were not those of Earth; he had seen too much, and realized by now that only a few times in the whole history of the Universe could the fall of the genetic dice have produced a duplicate of Man.  The suspicion was rapidly growing in his mind—or had something put it there?—that he had been sent to this place because these creatures were as close an approximation as could readily be found to Homo sapiens, both in appearance and in culture.  (Clarke, The Lost Worlds of 2001, ch. 39, p. 220)

Contemporary SF writers who are really adept at building interesting and coherent aliens—David Brin and Becky Chambers, to name two of the best—give us a wide range of wildly exotic creatures from other planets, but not humans.

The Uplift War, coverIf we are still fond of the idea of interplanetary romance, we might find a possible work-around in the shapeshifter.  The Tymbrimi female Athaclena in Brin’s The Uplift War (1987) uses her species’ unusual abilities to adjust her appearance closer to that of a human female—but of course she has an entirely different genetic heritage, as that ability itself demonstrates.  The result wouldn’t meet our criterion of interfertility, no matter how close the similarity in physical structure.  To adjust one’s genes in the same way would be another order of change altogether.

Starman movie posterThe 1984 movie Starman, in a way, plays off this idea.  The alien in this case is apparently an entity made of pure energy, without a physical structure of its own.  Using hair from the female lead’s deceased husband, it creates a new body with a human genetic structure.  The two do, eventually, prove to be interfertile.  If we’re willing to accept the notion of an energy being in the first place, this approach is actually more plausible than, say, mating with the oviparous Dejah Thoris.

If one were writing a SF story today, it would be rash to assume that Earthborn characters could run across independently evolved humans elsewhere.  The idea may not be entirely inconceivable.  But it’s out of fashion for good reasons.  Attractive as the notion of interplanetary romance may be, at this point we’d best confine it to the kind of case noted above, where some common ancestry—no matter how far-fetched—can account for the common humanity.

The Malleability of Myth

Our stories are always built on other stories.  We draw not only on real life, but on all the other tales, tropes, and archetypes that we’ve encountered.

Some of those stories are especially powerful.  They express patterns that seem particularly meaningful to us.  Tolkien and Lewis called these “myth”—not in the sense of something false,  a “lie breathed through silver,” but in the sense of something fundamental.

Some mythologies are works of imagination:  the Greek or Norse gods, Superman, Star Wars.  Some may be built on elements of truth:  the fall of Troy, King Arthur.  Some may be literally true, though we can select parts of the overall story and express them in imaginative terms—for example, the tales of the American Revolution (Hamilton or 1776,) or what Lewis called the Christian myth (The Prince of Egypt, The Nativity Story).

Whatever their sources, all these tales make up a reservoir of plots, characters, themes, and locales on which authors draw—our cultural inheritance.  In his famous essay On Fairy-Stories, J.R.R. Tolkien described it this way:  “Speaking of the history of stories and especially of fairy-stories we may say that the Pot of Soup, the Cauldron of Story, has always been boiling, and to it have continually been added new bits . . .”  (Pp. 26-27 as reprinted in The Tolkien Reader (Ballantine, 1966); p. 10 in this online reproduction of the full text.)

A good storyteller does not simply repeat a story verbatim.  We give it our own spin or flavor.  In doing so, we draw from the Cauldron elements from all sorts of other tales.  As they say, “When you take stuff from one writer it’s plagiarism, but when you take from many writers it’s called research.”

This is true even when we purport to be retelling an existing story.  The great tales tend to be open to reshaping.  But how far can we go with this sort of adaptation, and still claim to be retelling the original tale?  How much stretching and twisting can a given story take before it becomes something else altogether?

 

The best example may be the Arthuriad, the mythology of the Arthurian tales.  But that’s so large a subject that it deserves a discussion of its own.  A more manageable example is the story of Robin Hood.

One thing that helps us feel free to adapt is the lack of a single, “canonical” original version of the story.  Any presentation of The Lord of the Rings—the movie, for example—will be judged against Tolkien’s book.  But there is no unique original source for Robin Hood.  The earliest sources are a variety of medieval ballads, according to Wikipedia’s extensive discussion.

Cover, Roger Lancelyn Green, Adventures of Robin HoodWhen I went in search of a standard version of the Robin Hood tale for my children’s library, there was no single obvious choice.  There is an influential Howard Pyle version, The Merry Adventures of Robin Hood—I haven’t read it, but apparently it’s written in an invented antique English idiom that might not be ideally accessible to young people.  I ended up with Roger Lancelyn Green’s 1956 The Adventures of Robin Hood, which struck me as a good, middle-of-the-road retelling on which to start a young person.

 

There are enough different elements in the Robin Hood story to allow for a range of  interpretations.  On the surface, there’s the sheer romance of a band of rough but virtuous rogues living cheerfully in the forest:  the “Merry Men” theme. There is the legendary adept or quasi-superhero element:  Best Bowman Ever.  (At least, “best” until you get to Katniss Everdeen, Hawkeye, (Green) Arrow, and other successors — all of whom owe something to the Robin Hood archetype.)

There are also political themes.  The conflict between underdog Saxons and Norman aristocrats got tossed into the Cauldron in the nineteenth century, according to Wikipedia.  More specifically, Robin is often seen as defending the absent Richard the Lionhearted against Prince John’s machinations.  And of course one can focus on the economic aspect, robbing from the rich to give to the poor, and make Robin a hero of the 99% against the 1%.  The tale generally includes a strong romantic element as well.

We can see how these elements can be differently mixed in some of the movie versions, all of which are fairly successful.

 

Poster, Errol Flynn, Adventures of Robin HoodIn the Errol Flynn classic The Adventures of Robin Hood (1938), Robin is good-humored and high-spirited.  Merriment abounds; the dashing Robin treats much of the action almost frivolously—“Where’s your love of fights, risk, adventure?”  He fights with a smile, like John Carter.  Marian says:  “he’s brave and he’s reckless, and yet he’s gentle and kind.”  In keeping with this light touch, much of the soundtrack music has an antic air.  Robin is an expert bowman, of course; we see this especially in the tournament/trap sequence (which seems to have been too frivolous to be used in the later movies, below).

The plot gives us Saxons versus Normans, with Robin a Saxon nobleman (though he had traditionally been portrayed as a yeoman).  In this version, the Sheriff of Nottingham is a fat fool; the villains are Prince John and Guy of Gisborne.  Richard is a noble and honorable king, though he has to be reminded of his homeland duties by Robin.  His return is protracted, and the politics is internal.  Robin (and Marian) speak for one England, not Normans against Saxons, under the one true king.  The climactic battle scene is essentially a civil war—John’s supporters against Richard’s.

Maid Marian is a pampered Londoner, a royal ward, though she comes over to Robin’s side promptly when he shows her the sufferings of the poor.  As usual, there is a competitor for her hand—in this case, Guy.  This Marian is not an action heroine.  She arranges the plan to save Robin from hanging after his capture, but it’s his men who execute the rescue.  The love story is a central thread, and the film ends with Robin and Marian rushing off from the celebration together.

 

Poster, Kevin Costner, Robin Hood - Prince of ThievesRobin Hood:  Prince of Thieves, starring Kevin Costner (1991), presents a more serious treatment.  Wikipedia describes it, accurately, as a “romantic action adventure.”  The Merry Men angle appears only vestigially, befitting Costner’s somewhat dour screen presence.  The Expert Archer trope certainly makes its appearance, as Robin makes progressively more unlikely bowshots to save the day.

Costner’s Robin is again an aristocrat, allying himself with the downtrodden when he returns from the Crusades.  (The notion that Robin had been on crusade with Richard is unusual:  he is usually seen as being driven to outlawry while Richard is away.)  We have the traditional Saxon-Norman conflict, complicated by throwing in a batch of wild-card Celts as well.  But the ethnic or class difference is not prominent; it is expressed primarily as a revolt against the weirdly evil and almost demented Sheriff of Nottingham.  Curiously, Prince John is not mentioned at all.  But King Richard does make an appearance at the very end, to bless the romance.  (In an entertaining nod to film history, Richard is played by Sean Connery, who had himself played Robin Hood in 1976’s Robin and Marian.)

Prince of Thieves leans heavily on the romance.  Marian, a local aristocrat, was acquainted with Robin when they were children—she despised him.  She takes a shine to him, however, after Robin returns to find the Sheriff has murdered Robin’s father.  Here it is the Sheriff who has designs on Marian’s virtue.  The romantic drama rides on Michael Kamen’s epic score for the music—with a main theme so good that Disney has come to use it as the generic musical cue for Disney’s logo.

 

Poster, Russell Crowe, Robin HoodThe most recent movie version is called simply Robin Hood, directed in 2010 by Ridley Scott, starring Russell Crowe.

Crowe’s Robin is serious-to-grim; no frivolous japes here.  Like Costner’s version, Crowe’s is returning from the Crusades with Richard.  But this Robin is a common archer, not a nobleman.  He does some fancy shooting, but he spends more time swordfighting.  In the climactic battle, he leads a more traditional cavalry charge—and on a beach, not in a forest.  (He does, however, deliver the final coup de grace to Godfrey the villain with a bowshot.)

This film’s whole atmosphere is more cynical than in either of the two versions described above.  For example, where Errol Flynn’s Robin gives King Richard some home truths and is honored for it, Crowe’s Robin gets put in the stocks for giving Richard an honest evaluation, even though Richard specifically asked for honesty.  The movie makes a few more nods to actual history, in the relationships of John, Richard, and Walter Marshal—though with a few minor tweaks, such as an imaginary French invasion.  (The Wikipedia page lists several criticisms on the history.)  Richard is killed near the beginning, in France, rather than returning triumphantly to England.  The focus is more on international politics than in the two preceding versions:  the big final battle here is against the French.

For most of the story, this Robin doesn’t live in the forest.  Nor is he precisely an outlaw, though he and his friends do stop one shipment of grain as “men of the hood.”  Rather, his central role is as a somewhat anachronistic voice for democracy.  Robin’s father Thomas Longstride was a “visionary” who believed in raising up all people; the repeated slogan is “Rise, and rise again, until lambs become lions.”  Thomas wrote a charter of rights, signed even by barons.   In one of the few nods to the Merry Men, these rights include the right for each man “to be as merry as he can”—a livelier form of “the pursuit of happiness.”  There’s a reference to “liberty by law,” as opposed to the despotism of a “strongman” tyrant.  Marion too, though she’s a lady, is shown doing mundane chores alongside the farmers (Robin originally mistakes her for a farm girl).

In this version, the Sheriff is practically a nonentity.  John and the character representing Guy, who has mutated into “Godfrey,” are the villains.  Here John is a much more ambiguous character, rising to an almost heroic role at the climax.  But he then throws that role away by refusing to sign the Magna Carta—a historically dubious twist—and condemning Robin.

The romance element is also strong here, though to some extent it takes a back seat to politics (Wikipedia describes the movie as an “epic historical war film”).  Robin finds himself pretending to be the deceased Sir Robert of “Loxley” on his return to England.  At the real Robert’s father’s insistence, he steps into Robert’s shoes—including becoming (for public relations purposes) “husband” to Robert’s wife Marion.  This puts us somewhere in the region of the “Marriage Before Romance” trope, and allows for some endearing scenes as the two begin to fall for each other.

Marion herself is stronger and more assertive here than either of her film predecessors above (harking back to Green’s description of Marian as an “expert fighter,” p. 222).  She’s competent with sword and bow work; she frees her villagers; she even joins the final battle, in an Eowyn-style armor disguise.  At the same time, she still needs to be rescued occasionally, and is again pursued by unwanted romantic attention from the Sheriff.

In place of the usual happy ending, Robin is finally declared an outlaw at the very end—riding off into the sunset, as it were, as a perennial spirit of rebellion.  “And so the legend begins,” a title tells us.

 

As noted above, my view is that all of these movie treatments work, despite their varied treatments of Robin’s character, his martial prowess, the political angles, the villains, and the romance.  They all seem to be acceptable ways of telling the Robin Hood story.  One can appreciate the same tale rendered in a number of different ways, mutually inconsistent in their details, but able to coexist in the viewer’s mind.

On the other hand, there are limits to this variability.

The Robin Hood subgenre also offers an example of distorting the underlying myth too far — stretching the rubber band till it breaks.  Robin McKinley’s novel The Outlaws of Sherwood tries so hard to avoid the usual tropes that, in my estimation, it fails as a Robin Hood story.

 

Cover, Robin McKinley, Outlaws of SherwoodMcKinley’s Robin is anything but merry—he’s a gloomy, plodding yeoman forest ranger.  The Norman-Saxon conflict is active, but Robin has no political awareness at all; he has to be chivvied into revolt by Marian and Much the miller’s son, who handle most of the overall strategy.  Adding insult to injury, he can’t hit the broad side of the barn with an arrow.  All the fancy shooting is done by others, including Marian.  This is a pleasant nod to female action-hero equality, but leaves our image of Robin himself sadly lacking.

About the only thing McKinley’s Robin is good at is provisioning a comfortable forest home for his followers and their families.  You might say he makes a fine quartermaster, but he’s hardly a leader.

The political themes are muted.  Guy and the Sheriff are the villains, and larger national or international issues are not prominent.  Richard the Lionheart does appear, to receive the main characters’ fealty and thus end their outlawry, though he then takes them to the Crusades as a sort of penance.

The Robin-and-Marian romance is integral to the story, but it proceeds in slower and more complex ways than in the movies.  Robin is hesitant and tongue-tied, the opposite of the dashing Errol Flynn.  Only when Marian is injured, after taking Robin’s place in the famous tournament, does he admit to loving her.

McKinley is aware of the way in which authors construct tales in different shapes as they draw their preferred elements from the Cauldron of Story.  She notes in an afterword that “[m]any people have strong ideas about who Robin was and what he was like; and a lot of our ideas are as incompatible with each other as they are with history” (p. 277).  Her version has its points; but to my mind, it stretches the main themes and tropes too far to be a satisfactory iteration of the Robin Hood legend.

 

We can adapt a myth in any number of ways, but not infinitely many.  There are boundaries that must be observed if the story is to remain recognizable at all.  A story seems to have an “essence,” and violating that essence makes it into something different.  The something different may be valuable in itself; it isn’t necessarily a bad thing to adapt familiar bits from the Cauldron of Story into a new tale.  But that—of course—is another story.

How to Stage an Alien Invasion

We love our alien invasions.  Since The War of the Worlds (1897), poor Earth has suffered a steady stream of hostile arrivals—frequently from Mars, but recently from farther afield, as the possibility of other intelligent life in our solar system wanes.

We have one coming up this month, with the June 24 movie premiere of Independence Day:  Resurgence, a sequel to one of the more successful invasions of the last twenty years.  It seems like a good time to look closely at our opponents.

Footfall, a 1985 novel by Larry Niven & Jerry Pournelle (still available in print), is not only a great yarn, but a textbook model of how to write a modern invasion story.  We can look at it as a test case, like an existence proof in mathematics:  What kinds of conditions have to be fulfilled for a believable alien invasion, given what we now know about other planets?

 

Let’s define the target.  We’re talking about the good old classic invasion story, where the bad guys show up in person, make a direct assault, and we beat them.  That isn’t the only possibility.  There are other variants, such as infiltration, or scenarios where the Earthlings lose and end up a subject species.  But let’s look at what premises make a triumphant Independence Day-style plot viable.

 

It was easy for Wells.  His relatively nearby Martians could fire off a series of cannon shells, more or less, to land on Earth, break out their tripods, and mount their campaign.  Wells’ tour de force ending, of course, has the Martians beaten not by human opposition, but by humble bacteria.  (Arguably the best moment in the original Independence Day is when Jeff Goldblum realizes we can best the enemy by using a contemporary analogue of the Wellsian microbes—a computer virus.)

But modern invaders have to come from a greater distance.  Regrettably, none of the plausible abodes of life in the solar system have panned out.  Gone are old-time SF’s sweltering jungles of Venus, the canal-crossed deserts of John Carter’s Mars.  Until we’re ready for an attack by potential microbes from Europa, or hypothetical floating denizens of Jupiter’s atmosphere—neither of which, if they exist, have shown any signs of capability for interplanetary excursions—we have to look to interstellar sparring partners for a really good invasion.

This intensifies a long-standing problem with invasion stories.  If they got here, and across the interstellar gulfs at that, their technology must be literally light-years ahead of ours.  How can we expect to beat critters with such vastly advanced technology?  The balance of power is inherently skewed against us.

Paired with this is the question of motivation.  Why are they here?  What do the invaders want that would drive them to come all the way to Earth for it?

This is the easiest place for invasion stories that aren’t built on sound science to go astray.  We need only mention the 1983 TV mini-series “V,” which, though it had many admirable aspects, fell sadly short on the science side.  V gives not one, but two, implausible motives for the seemingly-benevolent Visitors.  They’re here to steal Earth’s water—as if there weren’t vast amounts of ice scattered around our solar system, and probably most other systems, for the taking.  And they’re here to eat us; apparently not only are humans compatible with a completely alien biology, but we’re a tastier treat than more edible and obtainable animals.  Sensible extraterrestrials need a better reason to traipse across the light-years than a local hamburger shortage.

 

Niven & Pournelle’s epic adventure handles both these questions so beautifully that it might have been plotted specifically to answer them.

Our not-quite-friendly visitors, the fithp (the singular is fi’), arrive in a large interstellar vessel, which launches smaller ships to conduct the attack.  Why are they here?  They’re looking for Lebensraum — living space.  The fithp have been exiled from their homeworld as the result of a conflict among factions—like the Protectors in Niven’s novel Protector.  They need a new place to live.  Among other things, this means “defeat is not an option”:  they can’t go back.  That ups the stakes.

But this exile premise also solves some of the balance-of-power problems.  The fithp’s resources are strictly limited.  There won’t be any reinforcements.  They can’t bring anything more from their homeworld.  All we have to do is defeat this batch of opponents, and we win.

Niven & Pournelle strengthen this limitation on the aliens, and incidentally increase scientific plausibility, by making their mother ship Message Bearer a slower-than-light vessel — a Bussard ramjet.  Their journey takes decades.  This distances the fithp even further from any potential homeworld support.  The authors also use it to introduce another twist:  there’s dissension between the space-born fithp, on one hand, and those who lived on their homeworld and are now awakened from suspended animation, on the other.  This division becomes important as the plot develops.

Without having to account for faster-than-light travel, Niven & Pournelle can give the fithp technology that isn’t too far ahead of our own.  Human numbers—and political, psychological, social characteristics—can make up for the technological imbalance.

In addition, the fithp don’t fully understand their own technology.  They’ve learned a lot of it from records left by their Predecessors, rather than developing the science themselves. This makes them less able to innovate.  By contrast, the humans’ response is a masterpiece of improvisation.  We make the best of what we have.  This, too, helps even the scales.  (Lesson for humans:  Continue fostering that STEM education.)

 

In the course of this worldbuilding, Niven & Pournelle give us fully fleshed-out aliens, with a coherent culture and society, understandable but different from our own — not an easy task.  Among other things, the fithp are sympathetic characters.  They are people, not just faceless attackers.  We see events from their viewpoints as well as our own.  This makes the story not only more believable, but more interesting.

 

The original Independence Day scores modestly on these two plausibility counts.  Motivation:  The aliens travel the stars like locusts, stripping planets of their resources.  No details are given, but the basic idea is not unreasonable, particularly in light of contemporary environmental concerns.  Balance of power:  We’re hopelessly behind in technology—but the aliens’ laziness (using our own satellites for signaling), Goldblum’s bright idea, and a captured alien ship get us (barely) over the hump of the willing suspension of disbelief.

We’ll see shortly how these premises play out in the Independence Day sequel—applying the Niven & Pournelle standard.