My family & other animals: what is it that makes Homo sapiens unique?

It's a curious thing, but I can't recall ever having come across a comprehensive assessment of what differentiates Homo sapiens from all other animals. Hence this post is a brief examination on what I have found out over the years. I originally thought of dividing it into three neat sections, but quickly discovered that this would be, as Richard Dawkins once put it, 'a gratuitously manufactured discontinuity in a continuous reality.' In fact, I found a reasonably smooth gradation between these segments:

1. Long-held differences now found to be false
2. Possibly distinctions - but with caveats
3. Uniquely human traits

Despite the carefully-observed, animal-centered stories of early civilisations - Aesop's fable of The Crow and the Pitcher springs to mind - the conventional wisdom until recently was that animals are primarily automatons and as such readily exploitable by humanity. Other animals were deemed vastly inferior to us by a question of kind, not just degree, with a complete lack of awareness of themselves as individuals.

The mirror test developed in 1970 has disproved that for a range of animals, from the great apes to elephants, dolphins to New Caledonian crows. Therefore, individuals of some species can differentiate themselves from their kin, leading to complex and fluid hierarchies within groups - and in the case of primates, some highly Machiavellian behaviour.

Man the tool-maker has been a stalwart example of humanity's uniqueness, but a wide range of animals in addition to the usual suspects (i.e. great apes, dolphins and Corvidae birds) are now known to make and use tools on a regular basis. Examples include sea otters, fish, elephants, and numerous bird species, the latter creating everything from fish bait to insect probes. Even octopuses are known to construct fences and shelters, such as stacking coconut shells - but then they do have eight ancillary brains in addition to the main one!

We recognise regional variations in human societies as the result of culture, but some animal species also have geographically-differentiated traits or tools that are the obvious equivalent. Chimpanzees are well known for their variety of techniques used in obtaining food or making tools. These skills are handed down through the generations, remaining different to those used in neighbouring groups.

Interestingly, farming has really only been adopted by the most humble of organisms, namely the social insects. Ants and termites farm aphids and fungi in their complex, air-conditioned cities that have more than a touch of Aldous Huxley's Brave New World about them; in a few species, the colonies may even largely consist of clones!

Although many animals construct nests, tunnels, dams, islets or mounds, these appear to serve purely functional purposes: there is no equivalent of the human architectural aesthetic. Octopus constructions aside, birds for example will always build a structure that resembles the same blueprint used by the rest of their kind.

Many species communicate by aural, gestural or pheremonal languages, but only humans can store information outside of the body and across generations living at different times. Bird song might sound pretty, but again, this appears to be a series of basic, hard-wired, communications. Conversely, humpback whale song may contain artistic values but we just don't know enough about it to judge it in this light.

Birds and monkeys are happy to hoard interesting objects, but there is little aesthetic sense in animals other than that required to identify a high-quality mate. In contrast, there is evidence to suggest that other species in the hominin line, such as Neanderthals and Homo erectus, created art in forms recognisable today, including geometric engravings and jewellery.

Some of our ancestor's earliest artworks are realistic representations, whereas when armed with a paint brush, captive chimps and elephants produce abstract work reminiscent of pre-school children. We should remember that only since the start of the Twentieth Century has abstract art become an acceptable form for professional artists.

Jane Goodall's research on the Gombe chimps shows that humans are not the only animal to fight and kill members of the same species for reasons other than predation or rivalry. Sustained group conflict may be on a smaller scale and have less rules than sanctioned warfare, but it still has enough similarity to our own violence to say that humanity is not its sole perpetrator. One interesting point is that although chimps have been known to use sharpened sticks to spear prey, they haven't as yet used their weapons on each other.

Chimpanzees again have been shown to empathise with other members of their group, for example after the death of a close relative. Altruism has also been observed in the wild, but research suggests there is frequently another motive involved as part of a long-term strategy. This is countered with the notion that humans are deemed able to offer support without the expectation of profit or gain in the future; then again, what percentage of such interactions are due to a profitless motivation is open to suggestion.

A tricky area is to speculate on the uniqueness of ritual to Homo sapiens. While we may have usurped the alpha male position in domesticated species such as dogs, their devotion and loyalty seems too far from deity worship to be a useful comparison; certainly the idea of organised religion has to be alien to all other species? Archaeological evidence shows what appears to be Neanderthal rituals centred on cave bears, as well as funereal rites, but the DNA evidence for interbreeding with modern humans doesn't give enough separation to allow religion to be seen as anything other than a human invention. What is probably true though is that we are the only species aware of our own mortality.

One area in which humans used to be deemed sole practitioners is abstract thought, but even here there is evidence that the great apes have some capability, albeit no greater than that of a pre-schooler. Common chimps and bonobos raised in captivity have learnt - in some cases by observation, rather than being directly taught - how to use sign language or lexigrams to represent objects and basic grammar. It's one thing to see a button with a banana on it and to learn that pressing it produces a banana, but to receive the same reward for pressing an abstract symbol shows a deeper understanding of relationship and causality.

A consideration of a potential future is also shared with birds of the Corvidae family, who are able to plan several steps ahead. Where humans are clearly far ahead is due to a gain in degree rather than just kind. Namely, we have the ability to consider numerous future paths and act accordingly; this level of sophistication and branch analysis appears to be uniquely human, allowing us to cogitate about possibilities in the future that might occur - or may never be possible. Both prose and poetic literature are likely to be uniquely human; at least until we can decipher humpback whale song.

Finally, there is science, possibly the greatest of human inventions. The multifarious aspects of the scientific endeavour, from tentative hypothesis to experimentation, advanced mathematics to working theory, are unlikely to be understood let alone attempted by any other species. The combination of creative and critical thinking, rigour and repetition, and objectivity and analysis require the most sophisticated object in the known universe, the human brain. That's not to say there aren't far more intelligent beings out there somewhere, but for now there is one clear activity that defines us as unique. And thank goodness it isn't war!