Homo sapiens among other species
My working life to date has led me through various roles that involve working closely with human beings: as a physician, a pastor, a lecturer and a lay magistrate. In each, I have worked within complex systems developed in human societies over many generations: the evidence-based approach of the medical profession; the theology and practices of the Church; pedagogical theories and systems in universities and colleges; and the customs and legal framework of the courts. There is nothing approaching a parallel with any of these in other species. In short, I operate – as, almost certainly, do you – on the often unquestioned assumption that human beings are special and distinct from the other species that inhabit our world. In this article I want to question that assumption. Are we really unique and, if we are, why might that be?
Before considering the evidence, I should say that some people do question the assumption of human exceptionalism. Richard Ryder, philosopher and former chair of council for the RSPCA, called it ‘speciesism’, likening it to, “racism or sexism – a prejudice based upon morally irrelevant physical differences”. [i] Ethicist Peter Singer, who agrees with Ryder, argues that great apes should be given legal rights similar to those of a human infant, leading him to help found the Great Ape Project in response.[ii] This kind of claim is not new. In the 1967 book The Naked Ape, zoologist Desmond Morris, claimed we would be, “a far less worried and more fulfilled animal”, if we just accepted that we are unexceptional.[iii] In saying so, Morris was following the legacy of Charles Darwin, who, a century earlier, asserted that, “the difference in mind between man and the higher animals, great as it is, certainly is one of degree and not of kind”. [iv]
I agree entirely with Ryder and Singer that human beings should not torture animals and accept that we should treat more intelligent animals with greater care than less intelligent ones, but is it correct to predicate animal welfare on the belief that human beings are not exceptional? Am I an unwitting speciesist? Am I just worrying unnecessarily because I am denying my animal instinct? Am I being tricked by my sophisticated mind into thinking I differ from other species in kind as well as degree?
What makes Homo sapiens unique?
Few would deny the unique impact of human beings on our environment, causing extinctions of other species, domesticating and selectively breeding other species, shaping the topography of our planet, and, almost certainly, altering its ecosystem. What makes Homo sapiens so dominant over nature? We can consider this question in terms of physiological, sociological and psychological traits.
Biology – differences of body
The high degree of genetic similarity between humans and chimpanzees, perhaps 96 to 98%, is often presented as evidence of our continuity with the great apes.[v] This statistic is somewhat misleading, since genetic material is organised quite differently in the two species, with the result that only 20 to 30% of human proteins are identical to the chimp equivalent.[vi] The obvious visible differences between humans and chimps, meanwhile, confirm that relatively small differences in DNA sequences can make a big difference. The human body is unusual in several respects: upright posture; manual dexterity due to ‘opposable thumbs’; and brains, which are not the largest on earth (even in proportion to body size) but are unusually complex. Our reproductive biology is also unusual compared to apes: relatively small female pelvises compared to the head of the neonate result in extreme labour pains; longevity of women after menopause allows grandmothers to help care for grandchildren; children take longer to develop to independence; gaps between births are comparatively short; males have no baculum (penis bone), making emotion and desire much stronger factors in successful procreation; and blood loss is inordinately high during menstruation.
Such physical traits certainly make human beings stand out from other species. Evolutionary survival advantages have, however, been postulated for each. The bigger problem with comparisons of DNA is that they confuse the question of human exceptionalism. Geneticist Steve Jones explains, “does the fact that we have genes in common with a mouse, or a banana say anything about human nature? Some claim that genes will tell us exactly what we really are. The idea is absurd”.[vii] Human beings are more than our genes. In order to find out what it really means to be human, we must consider the social lives of human beings.
Sociology – differences of behaviour
Human behaviour patterns are much more complex, unpredictable and variable between cultural groups and individuals than those observed in any other species. [viii] We are alone in using complex language, including writing and names used to label people so we can talk about them in their absence.[ix] Unlike other species, we have recognisable ethnic groups with distinct cultures, dialects and physical appearances. We wear clothing, practice hospitality, learn by instruction rather than simply copying others, make pictures that represent objects for sheer pleasure, and enjoy cuisine (cooking our food not only to avoid infection, but to enhance enjoyment), none of which are seen in other species. We have rites of passage and religion.
Perhaps most remarkably, human beings are unique in cooperating altruistically. Other species are known to cooperate in some circumstances for shared benefit, but human beings exhibit a unique desire from an early age to, “help other persons solve their problems, even when the other is a stranger and they receive no benefit at all”,[x] even expecting others to stay committed to goals they have agreed to cooperate on.[xi] Sociologically, it certainly sounds like we exhibit differences of kind, rather than just degree from other species, but for further insight into what makes us different we must turn to psychology.
Psychology – differences of mind
The trait that enables many of our remarkable social characteristics is known as ‘theory of mind’. It may be defined as, “the ability to interpret one’s own and other people’s mental and emotional states, understanding that each person has unique motives, perspectives, etc.”.[xii] Some researchers argue that chimpanzees may have this ability to get inside another individual’s mind,[xiii] but the most reputable reviews of the evidence suggest it is a uniquely human trait.[xiv] It may be true that chimps can, “understand the goals and intentions of others, as well as the perception and knowledge of others”, but, “there is currently no evidence that chimpanzees understand false beliefs”.[xv] Ability to deceive others and recognise deception is a key element of ‘theory of mind’. It seems that only humans can determine what others believe and so predict their hidden desires. We cannot only get inside other’s minds, but we can understand that they can get inside ours and so take measures to try to deceive them.[xvi] Paradoxically, this ability underlies both our amazing potential for cooperation and empathy and our distrust and deceptiveness. We have an innate moral sense, but also an innate ability to contravene it.
Conclusion – genuinely unique
The conclusion is clear. Human beings are unique among species not just by degree but also by kind. Palaeoanthropologist Ian Tattersall writes that, “Homo sapiens is not simply an improved version of its ancestors - it's a new concept”.[xvii] The main difference is in the function of our minds. As Jeremy Taylor writes, “We are a truly exceptional primate with minds that are genuinely discontinuous to other animals”.[xviii] Researchers on theory of mind Derek Penn, Keith Holyoak and Daniel Povinelli write that, “Darwin was mistaken: the profound biological continuity between human and nonhuman animals masks an equally profound discontinuity between human and nonhuman minds”.[xix] Having been led thus far by biology, sociology, and psychology, we must look elsewhere to take the step from asking ‘what human beings are’ to ‘why are human beings unique’.
Why are human beings unique?
The unique and wonderful human mind poses a question: where does our sense of self-awareness and insight into the experience of others come from? As one biologist puts it, “the most challenging frontier for the biological sciences now is to understand how the human brain produces the mind”.[xx] The problem, however, is that physical sciences like biology, although highly effective in helping us understand what is happening in the physical and how it works, are not equipped to answer the ‘why’ question of human existence. No scientific advance in our understanding of what we are and how our minds work can remove the deeper question of whether our lives have meaning. We must look beyond scientific research for purpose.
Consider three uniquely human experiences that are especially difficult to explain in evolutionary terms. We are the only species known to blush.[xxi] Evolutionary biologists suggest blushing helps expose dishonesty, so benefiting the group as a whole, but this is difficult to square with the fact that revealing emotions we would prefer to hide, is counter to individual survival. We are also the only species that weeps, crying not only when we feel pain, but also when we observe suffering or grief in others, including unrelated individuals (so-called psycho-emotional tears). It is odd, from an evolutionary perspective, to waste time and energy, empathising in ways that reduce our own ability to cope and may even paralyse us for people who cannot survive or are outside our kinship group. Finally, we are the only species that faints, losing consciousness due to extreme fear. Fear makes sense in evolutionary terms because it enables us to react quickly to threatening situations, but fainting is highly counterintuitive, since it renders us incapable of fight or flight.
It seems odd that human experience of life in the world is marked by such ambivalence towards our ‘natural environment’. We know joy and pain, either of which may cause us to cry, and we know shame, embarrassment, grief and fear. Relationships with others seem more complex than they ought to be. Death seems foreign, like an enemy rather than a natural part of existence. It doesn’t seem to matter how much we understand the science of the ‘what’ and ‘how’ of these experiences, we still find ourselves believing, hoping or wishing for something transcendent and asking ‘why?’ It seems like we were made for more.
The greatest pointer?
Another pointer beyond the experience of life as we know it, perhaps the greatest one of all, is morality. Darwin thought it was the best candidate for a genuinely unique human quality, writing that, “The moral sense perhaps affords the best and highest distinction between man and the lower animals”.[xxii] Some modern researchers, for example Dutch primatologist Frans de Waal, claim that chimps and other species exhibit traits that might indicate rudimentary morality, such as, “sympathy, empathy, reciprocity”.[xxiii] Such claims, however, reflect a poor understanding of how morality functions. Expert in child development, Helene Guldberg, insists, that when properly understood, morality is a distinctively human trait, since our unique quality of theory of mind is necessary for us to look beyond our instincts and self-interest to make choices on the basis of moral values.[xxiv] Where does morality come from?
One candidate for the origins of morality is social conditioning. Moral standards arise from attempts to order society for the benefit of the many. The standard explanation for morality offered by evolutionary theorists is that it developed as a mechanism enabling selfish individuals to live peaceably in societies, thus enhancing the survival of the social group as a whole. [xxv] There are, however, reasons to think that morality is not simply cultural. Some moral standards appear to be universal across cultures (for example, adultery is frowned upon in both monogamous and polygamous societies). A growing body of evidence, meanwhile, suggests that some moral standards, such as favouring altruism over selfishness, are innate in human nature, since they are observable in very young babies.[xxvi] We are moral by nature, not merely by nurture. It is conceivable that the universal nature of such standards indicates a genetic basis, but it is far from clear how a trait like altruism could advance our evolution, since it does not obviously benefit the survival of one’s own genes. To sacrifice our own survival advantage for the sake even of relatives is hard to square with the survival of the fittest. We must remember that genes are not sentient and have no values. Even if we can imagine a benefit, however, ‘conflict management’ theory reflects a highly reductionistic understanding of morality.
The absence of conflict falls short of most people’s vision of ultimate good. Morality also relates to an individual’s desire for integrity – being true to their conscience – and convictions about ultimate purpose – accountability to a higher moral authority.[xxvii] We care about doing what is right not only because we want to get along with others, but also because of personal values and a sense of ultimate good. We feel instinctively that we are not at peace with ourselves or with the world even when we are at peace with other people. We feel as if we are broken – failing to match up to what we ought to be – and in need of fixing.
The roots of morality?
Our challenge is that any higher standard of good requires a moral code, which raises the question of where moral authority rests. As mentioned, there are basic values that seem to be universal, but who adjudicates when they appear to be in tension? Atheist Richard Dawkins claims that human beings can transcend the impulses of their genes to create a superior morality. [xxviii] The problem, however, is that his definition of that standard generally rests on his own opinion. More fundamentally, atheism lacks any motivator for why we should be moral. Even if I know something is good, why should I bother to do it, especially if I am clever enough to evade being caught?
Morality inevitably has more than just a social dimension. Despite the claims of evolutionary theorists and philosophers that human instinct or reason can lead to unselfishness and fairness, history does not support that conclusion. Values like equality, and human rights and commitments to universal education and healthcare that arose from them, did not develop equally in all cultures. They flowered in Europe, with its deep Christian heritage. Rationalistic Enlightenment philosophy certainly hastened their spread, but they originated in the Christian gospel, which regards every individual as a beloved creation of God, and were enacted by Christian communities long before they gained mainstream appeal. Morality developed historically not merely by incremental improvements based on instinct or reason, but by the injection of ideas that claimed to come from beyond human experience. It advanced by appeals to divine revelation.
Among all the moral ideas of great teachers, Jesus’ teachings were genuinely revolutionary. The ‘golden rule’ is often cited as an example of a universal morality found in diverse human cultures. Many philosophers proposed the principle that we ought not do to another person something we would not want them to do to us.[xxix] Amazingly, however, Jesus went much further than this standard, replacing the negative principle of minimising harm with a positive, directive version of the rule that aims to maximise the good: we should do to others what we would like them to do to us.[xxx] This is a distinctively Christian principle, although Christians have, admittedly, often failed to embody it. It exposes the contradiction in human nature between our ability to be selfishly aggressive and to be selflessly altruistic. Evolution can explain the former, but not the latter.