At least in Iron Sky — The Coming Race he was an alien! Good movie, go see it.
Designing Intelligent Aliens
Those of you who know me know that I spend a lot of time 0n Science Daily. Some of it is book research, but 95% is pure curiosity. This part came out of research for a novel (no, I won’t tell you why Homo erectus is relevant to a novel set in the present day), and I was totally shocked.
I always thought Star Trek’s aliens were a joke, but much to my surprise Star Trek got aliens mostly right. Seriously. Unfortunately this article wasn’t planned, and I’m not sure I’ll be able to find all of the research papers I used, but I’ll try to explain why Star Trek was right, and Babylon 5 wrong.
How the Human Body Evolved
Because we only have one intelligent (well, I hope we are intelligent) species to look at, we will take humanity as a baseline. There are good reasons for thinking that the wide species Homo, including Homo naledi, Homo erectus, Neanderthals, Denisovans, Homo floresiensis, Homo luzonensis, and other sub-species make a good baseline. Too look at Homo, we need to consider the environment that Homo evolved in.
- The Sun is a Population 1, or metal rich star, that is brighter than 85% of the stars in the Milky Way galaxy. The planets formed from the leftover protostar disc are also metal rich. This is a necessity for life as we know it. Without heavier elements our bodies wouldn’t work. Population 1 stars can only form late in the history of the universe, as they get their heavy metals from supernovae.
- The planet we evolved on formed very early in the formation of the Solar System. It then went through a series of changes as life acted on it, for example the first photosynthetic organisms released oxygen, which combined with exposed iron. Until the iron was used up, the oxygen levels couldn’t rise high enough for oxygen breathing life to evolve.
- Earth is by chance on the inner edge of the Goldilocks Zone, so on most of the planet water is a liquid.
- Africa, where species Homo evolved is on the equator, providing a warm climate. It is also the second biggest continent with a wide variety of habitats for species to evolve.
- Africa has undergone a wide variety of climatic changes over the last 20 million years, which have driven evolution across all species that live there.
So we got lucky. We had a star with the right characteristics, a planet in the right orbit, and a huge continent on the equator. The first two are solid requirements, the third is a probable requirement.
So the odds of us meeting a six billion year old species are slim and none. The stars that a six billion year old species would have evolved around wouldn’t have had enough metals. A ten thousand year old species? That’s more likely.
But how did Homo become intelligent?
The likeliest answer is Climate Change. The book, Cradle of Life: The Story of Magaliesberg and the Cradle of Humankind by Vincent Carruthers gives a history of South Africa from the Big Bang on, and covers the climatic changes in South Africa, and how they probably impacted the early members of Homo, and our predecessors the Australopiths, driving evolution. Its a great book, go buy it! And no, I don’t get a referral fee from Amazon.
The Last Common Ancestor (LCA) between humans and chimpanzees was probably a tree dweller. Most of our close living relatives are tree dwellers. It is possible that the split occurred when forest shrank due to climate change, and our ancestors took to the ground, while the ancestors of chimpanzees stayed in the trees.
There is solid evidence that Australopiths were no more intelligent than chimpanzees. Studies have shown that Australopiths had no more blood flow to the brain than chimpanzees. Blood flow is how our bodies get energy to our brains.
The brain is the most energy intensive organ that mammals have. Energy use defines nutritional requirements. A reduction in brain size reduces the foraging requirements of a species, so it would seem a good idea, as long as it doesn’t impact the species ability to thrive, and we do have one decrease that I will address later.
So obviously there was an evolutionary advantage to larger brains. But what was it? One school of thought is that brain sized increased to handle social interactions in larger groups, and that this outweighed the increased energy costs. At one time it was thought that tool use was the main driver, however tool use has now been proven to predate the earliest evidence of species Homo by over a million years. Currently we don’t know what the driver was, we just know there was one.
We also know that there were many regional populations of species Homo, that were capable of interbreeding. Yes, Neanderthals were a regional population, not a separate species. We know that Neanderthals and Denisovans interbreed with Homo sapiens. We also know that Neanderthals and Denisovans interbreed, that Neandersovans, the ancestors of Neanderthals and Denisovans interbreed with at least one, probably two archaic Homo populations, and that humans in Africa interbreed with at least one, and probably two archaic populations. Note that all Homo populations except Homo sapiens are generally referred to as archaic. I’m using archaic as a general term for unknown populations in this article.
At the time our ancestors evolved, the following known populations existed.
Neanderthal-Denisovan mixed population
Central Asian Denisovans
Southern Asian Denisovans
Homo erectus (Asia, and some Pacific Islands)
Homo floresiensis (island of Flores in the Pacific)
Homo luzonensis (island of Luzon in the Pacific)
Homo naledi (southern Africa)
Homo sapiens (in southern Africa)
That’s just the ones we have fossil and DNA evidence for. We have additional DNA evidence that shows there were other populations, but we don’t know anything about them, other than their DNA survived in us.
But why is only Homo sapiens the only surviving population? We don’t know. One theory is that Homo sapiens was just a bit smarter, and able to better use the environment. In simple terms, we were better at finding food, which allowed for larger populations. The paper about Neandersovan interbreeding with archaic Homo populations says that they have estimated that the founding population of Neandersovans was only about two hundred individuals, but expanded rapidly, however the Neanderthal population probably never exceeded 40,000 individuals.
The Neandersovans moved into areas that the archaics were not able to inhabit, splitting into the lineages above, and then the archaics disappeared. The archaic population has been estimated at 20,000 individuals, so there were twice as many Neanderthals. We don’t have a solid population size on the Denisovans yet, but the combined Neanderthal and Denisovan populations would have been far larger than the archaic population.
The disappearance of the archaics is probably be linked to a larger population size of Neanderthals and Denisovans. In effect the archaics could have been subsumed into the larger populations. They got beaten by demographics.
When Homo sapiens left Africa, the same thing may have happened. The Neanderthal population of 40,000 individuals isn’t that large. We don’t know the size of the Denisovan population, but while it would have been larger than the archaics due to the Denisovans being capable of flourishing in areas the archaics weren’t able to inhabit, but it also seems to have been relatively low, at least by Homo sapiens standards. We may have subsumed the Neanderthal and Denisovan populations.
While we have little fossil evidence on Denisovans, we have a lot of fossil evidence on Neanderthals. One interesting point is that Neanderthals had larger brains than Homo sapiens, which would have required more energy to operate. Why don’t Homo sapiens have brains that large?
Because Neanderthals had larger bodies. Brain size and body size are linked. The larger your body, the larger the brain required to operated it, assuming equal intelligence. Since Homo sapiens was smaller, we didn’t require as large a brain.
But brain size isn’t the only factor. Some brains are more efficient than others. Recent studies have shown that reading to children causes changes to brain wiring, making the brain more efficient at solving problems. Childhood is where the most changes occur, as the brain grows, but adult brains have a limited capability of rewiring themselves in cases of damage. It appears that Homo sapiens had enough of a cognitive edge to allow for larger numbers in the same geographic area.
This doesn’t mean that the other populations were stupid. It just means that they weren’t as good at solving problems. The best example I can think of is dogs and cats. Anyone who lives with either can tell you they are quite smart in their own way. Yes, their intelligence is limited. No cat would have invented cat videos, because no cat could conceive of such a thing. It takes a human for that.
The last point is we evolved as a cooperative species. Our closest living relatives, chimpanzees, bonobos, and gorillas are all cooperative species as well. It is likely that any intelligent species would be cooperative, otherwise we wouldn’t need to be intelligent.
All Earth vertebrates are bilateral. This includes brain tissue. There is solid reason to believe that bilateral is going to be a standard for any intelligent species. Again, it comes down to energy use in the brain. A trilateral species would require a larger brain to handle the extra limbs. A bilateral layout is simpler, easier, and requires less energy.
This also means that four limbs will probably also be the standard. A centaur might look interesting, but the extra pair of limbs will require a larger brain, which will require more energy to operate. A species like the Shadows in Babylon 5 is extremely unlikely, the brain required to handle the extra limbs, and the seven eyes would need to be fairly large, and energy intensive.
That doesn’t mean a tail isn’t possible of course. We still have one, or the remnants of one, and we probably still have most of the area of the brain that controlled our tails back when we still had them. But it depends upon the tail. A fully prehensile tail would require a larger brain to operate than a simple tail like a dog has.
So most likely an intelligent species would look a lot like us because of the brain’s energy requirements. Two legs, two arms, two eyes, two ears. It is unlikely that they would have more than five fingers, again because of energy requirements. They’d have to have at least two fingers to be able to manipulate their environment, and it seems extremely likely that being able to manipulate your environment is a requirement for intelligence to arise.
An intelligent species is probably going to be an air breathing species, and is likely to use oxygen. While I have great respect for Hal Clement (he was a great guy), his novel Iceworld (read it) has an alien race with a totally different chemical basis, and one that seems very unlikely. Oxygen is far more likely to be the basis for the body chemistry of any alien species.
Some nonhuman species show interesting signs of intelligence. We know chimpanzees make tools, but also some birds (using their beaks) make and use tools as well. Octopi seem to be fairly intelligent too. Unfortunately we don’t have a good method of measuring the intelligence of birds or octopi at present. While chimpanzees are quite intelligent, they don’t have human level intelligence. They can, and do learn from humans, but are incapable of the sort of original thought that humans are capable of.
So what does this mean?
It means that any intelligent alien is going to be simple a simple alien. The following all require larger brains with higher energy requirements, and are unlikely.
- Having more than two arms, or two legs
- Having prehensile tentacles like the Pak’ma’ra in Babylon 5
- Being hugely strong like Vulcans
- Having prehensile tails
- Having a vastly larger body size
- Having a vastly smaller body size
- Having the ability to survive a wide range of climates without clothes
It doesn’t mean they aren’t possible, but if you have something really different than human, the question is going to be how did it come to be that way? Why would a species have a prehensile tail? I absolutely loved Vesta the Vegian in Masters of the Vortex, but we never find out why Vegians had tails. There must have been some evolutionary reason, but it is never mentioned, and that doesn’t even get into Darjeeb and Luda!
James White has the same problem. Why would Hudlars have developed intelligence? You’ve got an intelligent creature that has skin so tough that it can survive for extended periods of time in space. Why does it need intelligence? Hudlars are effectively living tanks. Think rhinoceros cubed. The same could be said about several other species in the Sector General series. But we all owe James White a huge vote of thanks for his species classification system.
I saved James White for last, because the odds are that most aliens we meet will fit under his DBDG classification. The same classification that humans fit under.
All of the above also works with unintelligent alien creatures. In effect we are talking evolution by parsimony. The simplest solution is the most likely solution.
Have fun — I expect to get blasted over my conclusions in the comments.
Tuesday February 25, 2020