Ever since the beginning of our space-faring age scientists have wondered about the likelihood that intelligent life could be found on planets outside our Solar System. At present there are no indications in our cosmic neighbourhood that there are any exocivilisations on exoplanets. The Italian-American physicist Enrico Fermi (1901–1954) was among those wondering about why we have no evidence of any life beyond our Solar System. He considered this with some astronomer colleagues in 1950, and after that this situation came to be known as the ‘Fermi paradox’1 and is still discussed widely.

There is probably no one reason for the rise of language but rather an ensemble of factors which all played a role in the gradual increase in sophistication from simple noises to the flexible system of communication we know today. Among linguists there is much discussion not only of the triggers for language but also of the steps involved and the manner in which Homo sapiens moved from one stage in language development to the next. As has been stated at several points in this book, one has to account not only for the structures of the attested languages across the world but also for the rise of the language faculty, internal to our brains, which makes languages possible in the first place.

First contact has been a topic of discussion among astronomers and other scientists, such as social scientists and philosophers, as well as providing subject matter for science fiction, for some considerable time. In order to discuss it reasonably, the issue needs to be broken down into a set of possible scenarios, some of which are conceivable but well beyond our reach and are likely to remain so as far as we can see.

Learning about the universe can be life changing. When you realise that our galaxy is at least 100,000 light years in diameter, that it contains several hundred billion stars, most with planets, and when you learn that the observable universe may contain anything up to one to two trillion1 such galaxies you cannot pretend that you do not know this and retreat to some earlier period of knowledge to recover a state of innocence when you thought Earth was all that mattered. True, it is where our lives are based, but there are no words to describe how utterly insignificant the Earth is to the universe which contains it.

The great German poet Johann von Goethe (1749–1832) once said that because people can speak they think they are entitled to speak about language.1 The point he was making is that because we have language we think we have the necessary knowledge to make pronouncements on language. However, this is not true. In order to make objective statements about the structure and use of language one needs training as a linguist. So why does one need technical vocabulary when talking about language? The reason is that, although we all speak our native language effortlessly, there is a lot of internal structure involved in this process and we are normally unaware of this. To describe all facets of language one needs an array of technical terms. Bear in mind that most of our knowledge of language is unconscious, like an iceberg where nine-tenths are hidden below the water’s surface.

Humans are mammals, a group of vertebrate animals with backbones, an internal skeleton and a nervous system controlled by a brain. However, the essential feature of mammals is that they give birth to live young, as opposed to other animals1 like reptiles and birds, from which we split off about 300 million years ago (mya), and which lay eggs from which their young later hatch. The word mammal derives from Latin mamma ‘breast’ and refers to the fact that the females of these animals breastfeed their young to begin with. This system is typical of cognitively advanced animals and there is probably a causal connection here. Live birth and breastfeeding result is a greater attachment between mother and young than does egg laying, adding an increased emotional dimension to the lives of the animals in question and thus providing a positive feedback loop for further cognitive development.

The discussions in this book so far have been about how life evolved on Earth and what paths it took, with the possible situation beyond Earth considered at regular intervals against this background. Some might say this approach is too conservative and that we should think outside the box for a while. After all, life could not just look, but also be very different, in principle, from life on Earth.

Is this really the case? Let’s recap on some of the preconditions for life discussed in previous chapters. To reach the level of molecular sophistication, which we observe on our own planet, the biology of an exoplanet would most likely have to be carbon-based because no other element has the same potential to form such a huge array of different molecules. Another point to remember is that high-level functions, like those humans exhibit, with their large brains and intricate physiologies, would require a complex physical substrate.

The language faculty, the ability to understand and acquire human language, is a feature of our neurobiological make-up which has been passed down through the generations in every human being as part of our genetic endowment.1 It is the language faculty which allows us to acquire any language as long as we are exposed to it in our early childhood. Although it cannot be directly observed, the language faculty imposes structural conditions which must be met by all the languages of the world, that is, it provides limits to what can occur in a human language by containing a framework within which language variation can arise.

The options for space travel will determine how much of our corner of the Milky Way we might explore in the future. Whether exobeings will have crossed the frontiers we recognise in this field now is an open question. The speed of light will be the same absolute barrier for them as it is for us. Indeed, reaching a significant fraction of this speed will represent an immense technological challenge. This means that, for all practical purposes, the search for life elsewhere is, and will be in at least the near future, limited to our corner of the Milky Way galaxy. Life can only arise on planets (leaving moons aside for a moment) and these are relatively small compared to stars. And, of course, they only reflect light from the latter so that detecting planets in other galaxies is presently out of the question, despite advances in technology.

Would exobeings have language? The answer to this question without a doubt is: ‘Yes’. They would have language in the sense of a powerful and flexible means of communicating thoughts and ideas between individuals. Why? Complex societies arise through continual differentiated interaction among their members. While many non-human animals do live in communities whose members engage in considerable interaction this does not reach anything like the level characteristic of humans. Furthermore, no beings can acquire all the knowledge of a complex society from scratch on their own. Each generation of a society builds on existing knowledge, which is transferred from generation to generation by being documented using language. To build a technologically advanced society, language would need to be documented in some fixed form, which on Earth means using one of the many writing systems, captured physically, usually on paper, or digitally as bits and bytes in computer storage.

Language is a unique property of humans. It is located in our brains and is intimately connected with our experience of consciousness. Our interaction with other humans via language is the main means by which we can be sure that others experience levels of consciousness like ourselves. However, many animals have communication systems which in principle are similar to language, that is, they are used to convey information between members of a species, though not always by means of sounds. For instance, bees use a special set of movements in which information about a source of nectar, its size and distance from the hive, is transmitted by movements in space by the bees, their ‘dance’. Whales use noises sent out beneath the water to other whales. Other senses can and have been used for communication. For example, many insects exude pheromones, scents with a certain signal value for a member of a species, normally to attract females.

In discussions about the search for life beyond Earth two basic possibilities have been proposed: either we will discover signs that biology exists on other planets through atmospheric analysis or we will detect an unambiguous radio (or maybe laser) signal from outer space which does not have a natural source and hence can be assumed to originate from an exoplanet. The former discovery would be via a biosignature, such as abundant oxygen in the atmosphere of an exoplanet. The reason why this is a good bio-indicator is that free oxygen (as a diatomic gas, O2) is highly reactive and if it existed in the atmosphere of an exoplanet it would disappear quickly by forming molecules like carbon dioxide or water, or rust with iron, unless it were continuously replenished by some biological source, like trees and plants on Earth, which release oxygen into the atmosphere during photosynthesis.