Aggression in alien species–yes or no?

Picture pilfered from a game site. Apparently the game is called 'Alien'

Last year at worldcon, I attended a panel that dealt with scenarios following a potential first contact. We’ve discovered there are intelligent aliens. What should we do? Talk to them? Hide?

One of the opinions voiced was that if you create a situation where aliens come to Earth, they must be ‘aggressive’. I’ve thought about this a long time in terms of population ecology (which is what I was trained to do) and have come to the conclusion that yes, this is correct, and no, it is not.

The problem lies, I think, with the fact that population ecology attaches a different meaning to the word aggressive than the general public does.

An aggressive species is one that actively colonises available niches, one that has the resilience and comfort range to thrive in a wide range of conditions, and one that produces vast numbers of seeds/eggs/young. Such species will often tolerate high population densities. They will be found at the disturbed edges of established communities (roadsides, building lots). They will have short lifespans, and will often provide food for a lot of species higher in the community’s development.

Rabbits are aggressive species. When given new open land (think golf courses and paddocks), they breed like crazy. Until the trees move in, and the foxes, but by this time, rabbits have already moved onto the next open ground.

Human society, by comparison is an ecological community by itself. Within each human culture, there are those who will colonise new niches and those who build on that colonisation effort. Whether you talk about the first early Africans who moved into colder climates, the first Chinese who moved to Australia, or the first English people who moved to Dubai, it doesn’t matter. Within their community of origin, these ‘first’ groups paved the way for others, in a purely ecological sense. In a plant community, these two functions would be performed by two different species. We can conclude that humans are good at colonising within a fairly narrow temperature range, and are good at holding our territory once we have it.

Are we aggressive? Moderately so, probably. Many writers have dreamed up situations in which ‘truly aggressive’ aliens come to visit us. And this is the part where people confuse aggression with violence.

Ecological aggression–the type that will lead to colonisation of new territory–is a characteristic that needs both back-end pressure (it’s too busy in the home country) and an aim (we need new land). Ecological aggression does not mean destruction. It means invasion of an available ecological niche through settlement and breeding.

If a storm blows over a tree in a forest, and subsequently the pigs dig up the surrounding area for roots, invasive plant species (ones we call weeds) will come up in the newly-bared soil.

Taking this analogy to aliens, or a situation where humans are the invaders, what the newcomers will want is a space to live. They are not numerous enough to take on the population of an entire planet in a battle, and why would they, anyway. The locals are their best bet to learn about what’s available on the planet. They may want to trade, for technology, for unknown riches, or just for a pair of hands to do some work. But they’ll want a place to live for their expanding community.

They will most likely be friendly and cooperative, but oh-so-aggressive.

Terraforming: Mars or Venus?

In an earlier post, I described the difficulty a small planet, like Mars, faces when people are trying to terraform it: the planet simply doesn’t have enough gravity to hang onto the gases we need to survive.

Some people suggested that maybe instead of Mars, we might look at Venus, since it has the right size.

In this post, I look at the most important deciding factors for the success of a terraforming operation.

Distance from the sun:
Venus is at 0.7 AU from the Sun, which is beyond the inner margin of the habitable zone at roughly 0.9 AU – yeah, we’re very close to that. I hope it doesn’t give you nightmares.
Mars is at 1.5 AU from the Sun, on the very outer edge of the habitable zone. However, the width of the habitable zone depends not just on the sun and its strength, but also on the composition of the planet’s atmosphere and on the presence f clouds. With the addition of clouds, the inner boundary of the habitable zone could be made to stretch inwards. However, water vapour and carbon dioxide (the most likely gases to form clouds) are both greenhouse gases, so the effect likely cuts both ways. There is a lot more leeway on the outer side of the habitable zone. With the addition of carbon dioxide clouds, it can be made to stretch outwards, to as much as 2 AU or even more.
Winner: Mars.

Atmosphere composition and density
The atmosphere of Venus is so dense that we can’t see its surface. It consists of mainly carbon dioxide (96%), some nitrogen and sulphur dioxide. Nasty, nasty stuff
The atmosphere of Mars also consists of mainly carbon dioxide, but it is extremely thin. Both atmospheres lack oxygen and nitrogen, but because of its high temperature, Venus also lacks water, of which Mars has quite a bit, even though it’s frozen. Mars also has frozen carbon dioxide. When thawed, both carbon dioxide and water vapour are greenhouse gases, and both would further increase the rate of warming (this is called positive feedback). At Venus, you’d need to get rid of massive quantities of carbon dioxide. Again, this is possible in theory (see Terraforming by Martin Beech), but even if you got it to work, it would be a process taking millennia, while a warming of Mars could be achieved in a few hundred years.
Winner: Mars

Planet mass
Mars, at only 15% of the Earth’s mass, with 32% of Earth’s gravity, is below the mass required to hold onto a breathable atmosphere.
Venus, at 81% of Earth’s mass, and 90% Earth gravity, is not.
Basically, providing you can create an atmosphere resembling Earth’s, Venus would retain it without the need to replenish it, whereas Mars would not.
Winner: Venus

Mars has a nice 24-and-a-bit hour day. At Venus, however, the planet’s day (243 Earth days) is longer than its year (225 Earth days). This, in combination with stronger sunlight, would make plant growth extremely hard, unless you could somehow speed up the planet’s rotation. I need not say that this would be hard to achieve, although theoretically possible.
Winner: Mars

Required change in temperature
In order to harbour life, the plant’s average temperature must be high enough for liquid water to exist on its surface. Every degree of change a planet requires to bring its temperature within this range is going to cost effort and time, and a lot of resources.
The freezing point of water is 273K; the average surface temperature of the Earth is 288K.
The temperature of Mars is 210K
The average temperature of Venus is 735K, and is the hottest object in the solar system apart from the sun, hotter even than Mercury.
Add to this that an increase in temperature is probably easier to achieve than a decrease, the clear winner is Mars, by many, many miles.

So yes, while people may have concluded from a previous post that Mars is too hard to terraform, and maybe we should look at Venus, maybe these people need to think again. It seems that its size is just about the only thing it has going for it.

The conclusion from this should probably be that terraforming is never going to be easy, and nor should it be in your fiction. Lots of things to go wrong, lots of things taking longer than expected, lots of unexpected stuff happening.

Growing crops in space #2

In truth, this post should read ‘Growing crops in artificial environments’, because it applies equally to crops grown in a hypothetical space station as it does to crops grown on the Moon, or Mars or any fictional celestial body.

I’ll start off with a few open doors:
– All crops we grow as food today exist in some form in the wild. In all of those cases, humanity has bred better varieties to the point where the original plant bears no more than a passing resemblance to the crop variety. For example, compare a wild rose with the ones you buy at the florist. It’s hard to believe the commercial rose is directly descended from the wild rose. This has come about by selecting varieties with desirable characteristics (in other words: mutations) and propagating them, selecting the best plants out of that crop, and so on, and so forth. While the selection process is human-driven, there is nothing unnatural about the commercial rose’s DNA.
– All plant species evolved to be suited to their native climate. The banana is a tropical crop and will do poorly when temperatures are too low. Similarly, the banana evolved to grow in a climate where the temperature range is fairly narrow (in other words: where it’s always hot), and where the daylength doesn’t vary much either. Never thought about this? Well, here’s an everyday illustration: I live in Sydney (33 degrees south). I go to the gym at 6.30 most mornings. At that time, the TV in the gym has the news on. It’s summer right now, and at 6.30 it’s pretty light in Sydney. If, however, the news program crosses to someone in Cairns (16 degrees south), you’ll see that it’s still pitch dark over there. If they cross to someone in Hobart (42 degrees south), it has been light down there for ages. These three cities are more or less on the same latitude. In winter, exactly the opposite will happen. It will be light in Cairns, dusk in Sydney, and still pitch dark in Hobart.

To sum up, Cairns has much less annual variation in the length of its day. This is, incidentally, why daylight saving in the tropics is neither sensible nor desirable. Trust me, I lived there. You do not want daylight saving. (/soapbox).

What does this have to do with crops?

Well, you’ll probably have noticed that most crops are highly seasonal. People in our cities don’t notice this so much, because food suppliers use two mechanisms to extend availability: 1. storage (if you buy apples in February, I can guarantee that they’re about year old), 2. different source areas (with its handy dual temperate/tropical climate, Australia can grow temperate crops in winter in the tropics and in summer in the temperate regions. Surprise, surprise, most of our staple vegetables are temperate crops).

But the tropical crops that are highly seasonal (fruit trees—the banana is NOT a tree) are only available in summer. This is why mangoes come onto the market in November and tail off in January.

(for the record: Australia imports almost none of its essential fresh food)

OK, seasonal crops. Bowen mangoes flower in late August, and the fruit is ripe in the first week of November.

Why does the mango tree flower in August? Because, as in animals, plant reproduction is a hormonally-induced process that responds to triggers.

These triggers are:

– Temperature. Many plants need a cold period to flower. If you’re sick of your Phalaenopsis orchids always flowering in May, put them in a cool room at 15C for two weeks, and they’ll flower any time of the year.
– A dormant period. This is especially important in temperate plants. Dormancy is often controlled by temperature, but only because temperature triggers the production of certain plant hormones. Are you a Sydneysider who has lived in Europe? Have you ever noticed how the paltry few European oak trees in Sydney hardly lose their leaves in winter, much less produce acorns? This is why. No loss of leaves = no dormant period = no acorns.
– The real biggie: daylength. Almost all plants will react to changes in daylength by speeding up their maturity, or delaying it. This is what you are doing trying to grow a crop outside its native climate zone. Parsley, a temperate herb, is a natural biannual, but when you grow parsley in the tropics, it will neither flower nor die after two years. Parsley needs a short day (in other words: a temperate winter) to induce flowering.

And now you’re taking this hotchpotch of plants with their varying requirements into space and growing them in a controlled environment. Each species has its own maturity triggers and sensitivities. Some plants (tomatoes) are pretty much insensitive to anything you throw at them. Others (wheat, maize, rice) can be far more fussy. And daylength rhythms can be disturbed by something the strength of a street light at night (ever noticed how oak tree branches surrounding a street light are weeks ahead of the rest of the tree?)

If you want anything approaching the full range of crops you can buy in a regular supermarket, you’d have to make some adaptations to your artificial environment design. You could modify the artificial environment but supplying a few chambers with different conditions, or you could breed plants that are less sensitive to daylength (this sensitivity is controlled by a single gene). In any case, taking everyday Earth crops into space for mass food production will require a lot of thought. That, or your characters will get mightily sick of eating tomatoes.

Science and the writer

When I say that I used to work in science, some people assume that I Must Know Everything. Wouldn’t that be nice? Instead, I feel the opposite is true. When I write about astronomy, chemistry and physics, either here or elsewhere, those are my study notes. I might know a little bit more than what’s written, but not terribly much. I was never an astronomist, a mathematician or a physiologist.

At its root, science is not knowledge; it’s a state of mind. Being a scientist means acknowledging what you don’t know and taking reproducible steps to acquire that knowledge. And the more you learn, the less you know. Because there is so much to know, it’s impossible to know, or remember, everything.

I left science about ten years ago, but recently, through writing Science Fiction, I’ve re-acquainted myself with science. And, hey, science and I are still talking. This is the first part of a series of posts about science and the writer.

Where did it all begin for me? Well, I worked in population ecology.


Ecology is one of those buzzwords that goes with global warming, recycling and sustainability, right?

Well, really, you couldn’t be more wrong.

As any ecologist will tell you, ecology is the science of numbers. Numbers of individuals doing thing A, numbers of individuals doing thing B. Poking the population with a sharp stick, watching what happens and re-counting those numbers, and then trying to make sense of the difference. The tools of the trade of a plant ecologist are a sturdy 4WD vehicle, a quadrat (a metal frame of a certain dimension, usually 50x100cm), a piece of cloth to pick up said quadrat (you won’t believe how hot it gets in 40C heat), a palmtop computer (to record numbers), a 50m tape measure, coloured plastic tags (to stick in ground so you can come back to the same spot a few months later), and a carton of beer (remember the heat?). Tools that are very useful for an ecologist working in inland Australia are long stick (for bashing covers over our weather station controls to scare snakes away before opening said covers), a GPS, sock protectors (you won’t believe what speargrass seeds get up to), and a six-seater aircraft. You get the gist. Do not apply if you love your lattes and are scared of spiders, or flying in small aircraft.

Back in the lab (which we called lab, but was really more office than lab), we had computers to download our counts, and heavy-duty statistics programs to do calculations.

Counting and statistics. I guess my alter ego could find a job at the Australian Bureau of Statistics.
So what did we count?


Let me explain a bit more about the environment.

The entire northern half of Australia (and much of the south, but I never did much work south of the capricorn) is made up of soil types that manages to be deficient in almost every imaginable element required by plants to grow. Nowhere else in the world does standard plant fertiliser contain sulphur. Nowhere else in the world is plant growth stunted by lack of micro-elements as exotic as molybdenum.

It is also prime beef cattle country. Properties are huge, herd densities are as low as a few heads per square kilometre. There are few fences and graziers may see their animals as little as once a year, if at all.

Australian beef is valued, because it is clean, organic and cheap. It’s a big export. But the climate is unbelievably harsh. There may be devastating floods one year and this may be followed by years, yes years, of no rain at all. Not a single drop. Naturally, graziers are looking for ways to insure themselves against the times of drought, and to keep their animals healthier for longer so they will sell for better prices. Their options for doing so are limited. They can’t hand-feed their cattle; the scale is just too great, so the only way to improve lies in improving the land itself. But then again, if you have a property the size of a decent province in some small European country, you can’t exactly roll out the tractor and spread fertiliser either.

Enter the humble legume.

The plant family Leguminosae contains many familiar crops, such as beans, lentils and soy. Or familiar garden plants like sweet pea and bush plants such as wattles. The humble clover is a legume. So are peanuts. Or Sturt’s Desert Peas.

This plant family is unique in the plant world in that most of its members undergo a symbiosis with Rhizobium bacteria which forms little root nodules, which, when you pull up a plant, are visible as little white lumps. When you cut a nodule open, you will see a tinge of pink, like blood. Just like blood, in fact. It’s a form of haemoglobin, which helps the nodules fix nitrogen from the air. As a result, legumes produce their own fertiliser, which they pass onto the local soil when the plant dies, or pass into whichever animal eats the leaves.

Remember the chronic shortage of essential elements in Australian soil? Aha, all we need to do is increase the content of legume species in pastures.

Australia has many legume species. Unfortunately, most of them are trees (which defy the term ‘pasture’ and which grazing cattle will not eat), are unsuitable for the tropics or, worse, are poisonous.

Back in the 1950s, a number of scientists started looking at plants in similar climates in other places in the world, and identified a hotspot of interest and similarity in Brazil. Subsequently, scientists introduced a range of pasture legumes. We studied their survival, monitored their spread or otherwise. Incidentally, the main mode of spread for these species, member of the Stylosanthes genus, if you must know, is through interaction with cattle. The seeds pass unaffected through the digestive tract of cattle (not goats or sheep or kangaroos) and grow from dung. The seed pods have little hooks that make the seeds stick to fur.

I can hear a number of you cringe in the distance. Yes, that’s right. Scientists back then wilfully introduced plants into Australia and set them loose in northern Australian ecosystems. Bad, bad, bad, we say now, but it wasn’t always seen that way. The plants are still there. Unlike the cane toad, they have not gone crazy. They have made a huge contribution to the beef industry.


When I entered the scene in the 1990s, the perception towards the program was already changing, even in these bastions of anti-conservationism. There were no more introductions of new plants. Our quarantine glasshouse was empty a lot of the time. We spent as much time looking at the invasion of introduced species in places where they weren’t wanted as in places they were. Moreover, my own perception was changing. I realised I was more interested in conservation. And we all know how much money there is in that. So when my part of the program was shut down, this was one of the factors that made me decide to develop my online bookshop to sell books that taught people appreciation of nature.

a fertile future

I’m writing a story about a society that has fertility issues. In fact, fertility-related topics commonly pop up in SF and even in fantasy. One such trope is the notion that some time in the future/on another planet, women will no longer give birth, but that babies will be designed and grown in an artificial environment, or carried by a surrogate. There are many variations on this theme, which range from total artificiality to various types of assisted reproduction. Fertility issues make for interesting material, and can be done very well.

For me, the prize for ‘best fertility technique use’ in fiction goes to Ethan of Athos, a novella in the Miles series by Lois McMaster Bujold. In the world she has created (Athos), there are no women. The men clone eggs from a number of female cultures, fertlise them, and babies are grown artificially.

In C.J. Cherryh’s world, some human colonies produce artificial designer people from scratch. Most of these people are specialist workers. In most of her books, they’re not fertile, so the process of creating them has to be repeated.

In Cyteen, C.J. Cherryh creates a clone from an older woman who has been killed. She treats the subject of cloning very well. A person is shaped by his/her genetic material (which is clone-able) just as much as their environment (which is not clone-able), so clones who are identical are not particularly believable to me. Identical twins are natural clones, and identical twins are never completely identical.

The big question is: why? It’s a question that has to be answered satisfactorily for a book to work. Cloning is high-tech stuff. IVF is high-tech stuff. Creating new people from scratch is high-tech stuff. You are not, ever, going to make me believe that these forms of conception will take over from – ahem – the natural way (which costs nothing), without some pretty good arguments.

Athos doesn’t have women. The Cyteen designer people are infertile (so that their bosses can keep their workforce in hand). In both these worlds, there is plenty of natural breeding going on elsewhere in the universe.

I would buy a world in which a big bad virus makes people infertile and some sort of artificial process became necessary. I would buy that rich people would want, and pay for, designer babies, and that they’d leave the discomfort and pain of pregnancy to a surrogate.

However… I would never buy a world in which all people would become reliant on assisted reproduction.

An analogy – plastic surgery may well become very popular in the near future, but you’ll never get all women to submit to it. Some won’t want it, some simply can’t afford it. If assisted reproduction/designer babies are optional (i.e. women are still fertile), there will always be natural conception. It might be messy, uncomfortable and hurt like hell, but it’s free.

If infertily is a disease: like myxomatosis and rabbits, a virus would make 99.9% of people infertile. With 10 billion people on the planet, 0.1% is still a million fertile people – more than enough for a quick repopulation.