According to the major monotheistic religions—Judaism, Christianity, and Islam—humans have a special nature and destiny, different from and superior to those of other animals. Created by a divine power, humans resemble it in not belonging entirely to the natural world. They exercise a freedom of will no other animal possesses and, thanks to the afterlife, are exempt from mortality.

In Western societies monotheistic ideas no longer prevail in the explicit forms they once did, but the claim that humans have a unique standing has not been renounced. It continues to shape our view of ourselves and our planet, though the defining feature of humanity is now commonly identified as rationality or self-awareness rather than the possession of a soul. As Melanie Challenger writes in How to Be Animal:

For those with deep belief in a creator, we have a soul that is unique to the human body. For secular humanist thinkers, we have soul-like mental powers that are unique to the human brain. Each is a reason for why humans aren’t truly animals. At least, not in any crucial way.

We know from evolutionary biology that humans emerged from the natural world. At the same time, many think we have cast off our animal origins; some think we can direct our future evolution. This discrepancy between what we know from scientific inquiry and the image we have formed of ourselves is Challenger’s central theme: “The truth is that being human is being animal. This is a difficult thing to admit if we are raised on a belief in our distinction.”

Challenger, a British writer on environmental issues, notes that this belief is not confined to monotheistic religions. In Hindu and Buddhist traditions, humans are at times represented as having greater spiritual worth than other animals: “In the Taittiriya Upanishad the god Shiva makes clear that humans are unique in their ability to act on knowledge.” In some currents of Buddhism, humans alone have the potential for deliverance from the cycle of birth, death, and rebirth.

Ancient Greeks and Romans recognized similar distinctions. Aristotle presented a hierarchical view of the cosmos in which a divine intelligence is imperfectly reflected in differing degrees in human beings. Stoic philosophers believed humans are especially valuable compared with other animals because, by exercising their capacity for reason, they can to some extent partake in the godlike rationality, or Logos, of the universe. For both Stoics and Aristotelians, humans have a link with divinity that separates them from other species.

A radical distinction between humans and other animals may not be culturally universal, however. Such a disjunction seems not to have been central in animist cultures. Challenger writes:

For those worldviews loosely clumped together under the term “animism,” there’s less of a gap to justify…. Humans simply possess a share in a sacred cosmos. There are still traces of this original numinous landscape. It’s there in a handful of hunter-gatherer cultures and faintly in polytheistic worldviews. But as a rule, it doesn’t seem to have survived the transition into large agricultural societies.

For animists, there are not two worlds, one natural and material, the other supernatural and spiritual; what we call the natural world is full of spirits. Secular thinkers who understand religion as a belief in a supernatural power invoke a distinction that animists—practitioners of what might be described as the primordial religion of humankind—do not recognize. The very idea of religion as a distinct branch of activity separate from the rest of human life is arguably an inheritance from monotheistic traditions. But that is another story.

Secular cultures like our own, Challenger maintains, have largely rejected monotheistic beliefs while retaining a monotheistic concept of human specialness. When she fleshes out how secular thinking has been shaped by monotheism, she focuses on two members of the Huxley dynasty—the Victorian Thomas Henry Huxley, sometimes known as “Darwin’s bulldog” because of his uncompromising defense of Darwinian natural selection, and his twentieth-century grandson Julian Huxley, a biologist and eugenicist who coined the term “transhumanism.” She quotes Julian: “The human species can, if it wishes, transcend itself…. Man remaining man, but transcending himself, by realising new possibilities of and for his human nature.”

A central issue for transhumanists is which human possibilities are to be expanded, and how—and by whom—this is decided. There is surprisingly little explicit discussion of these questions in Julian Huxley’s work; it is almost as if he believed the answers were obvious. The capacity to be aware of the universe and increase knowledge of how it works is simply assumed to be the most valuable human attribute. Human beings are essentially vehicles for consciousness, and human improvement consists in enhancing it. Whether the most efficient ways of achieving this end are consistent with values of human equality and solidarity is of minor importance, if the question is considered at all.


It is worth looking in more detail at the context in which Huxley offered the definition of transhumanism given above. The sentence Challenger quotes, which comes from Huxley’s New Bottles for New Wine (1957), reads in its entirety, “The human species can, if it wishes, transcend itself—not just sporadically, an individual here in one way, an individual there in another way, but in its entirety, as humanity.” Huxley continues:

“I believe in transhumanism”: once there are enough people who can truly say that, the human species will be on the threshold of a new kind of existence, as different from ours as ours is from that of Pekin man. It will at last be consciously fulfilling its real destiny.1

These further passages give a clearer sense of how theological categories continued to inform Huxley’s thinking. The prospect of the human species transcending itself “in its entirety, as humanity” may make sense from a theistic perspective in which humankind has a “destiny” and the purposes of a divine agent unfold through it. But in Darwinian evolution a species is not something that exhibits agency. Genes interact with one another according to natural selection, which has no overall goal or purpose. For a Darwinian, any reference to “humanity” acting “in its entirety” is a category mistake.

Secular thinkers may object that humans, using their powers of conscious thought and collective action, can “rise above” Darwinian evolution. The species may have come into the world by chance, but it can set goals for its future development. In reality, however, they will be the goals of particular human groups. Rather than humankind acting as a single agent, some human beings will appoint themselves as humankind’s representatives. This group will then identify its values with those of humankind. Almost inevitably, human beings who do not accept these values will be regarded as less than fully human.

Huxley’s writing illustrates this tendency. In Africa View (1931), which he wrote after visiting the continent on behalf of the British Colonial Office, he claimed there was “a certain amount of evidence that the negro is an earlier product of human evolution than the Mongolian or the European, and as such might be expected to have advanced less, both in body and mind.” Following the rise of Nazism Huxley modified his views, arguing that the concept of race was unscientific, but he remained a supporter of eugenic theories and policies that effectively dehumanized large sections of our species. Over thirty years after he published Africa View, in a Galton Lecture he delivered in London entitled “Eugenics in Evolutionary Perspective,” he wrote:

[Man] is not merely exceedingly young; he is also exceedingly imperfect, an unfinished and often botched product of evolutionary improvisation…. The process of hominization is very far from complete…. Man, in fact, is in urgent need of further improvement.

This is where eugenics comes into the picture.

Later in the lecture he is more specific about some of the groups in need of further “hominization”:

The marked differential increase of lower-income groups, classes and communities during the last hundred years cannot possibly be eugenic in its effects. The extremely high fertility of the so-called social problem group in the slums of industrial cities is certainly anti-eugenic.

Eugenics, here and elsewhere in Huxley’s writing, covers a range of policies meant to correct the supposed natural overproduction of what he regarded as inferior human beings. One measure of inferiority he invokes is IQ. In the Galton Lecture he writes:

Consider the difference in brain-power between the hordes of average men and women with IQs around 100 and the meagre company of…so-called geniuses with IQs of 160 or over…and then reflect that, since the frequency curve for intelligence is approximately symmetrical, there are as many stupider people with IQs below 100 as there are abler ones with IQs above it.

Understood in this way, human improvement could be promoted by sterilizing people with low IQs and increasing the fertility of those with higher ones. With regard to the first possibility, Huxley favors voluntary sterilization, though he notes that “certified patients are now prevented from reproducing themselves by being confined in mental hospitals.” With regard to more positive eugenic policies, he favors selective breeding using a form of artificial insemination—“eugenic insemination by deliberately preferred donors” whose “superior sperm” has been deep-frozen—a method similar to that imagined in his brother Aldous Huxley’s book Brave New World.

The questions that arise for Huxley’s transhumanism apply to any version of transhumanist thinking, whether or not it involves eugenics. How can some human beings be judged to be less human than others? It seems obvious that, in practice, these judgments will reflect the idealized self-image of those who apply them. Their account of what is most essentially human, and thereby of the most valuable human possibilities, will be an enhanced version of how they imagine themselves to be. Rather than humankind acting in its entirety, in this transhumanist vision some human beings will exercise power over others, and many of the latter will be viewed as a drag on human development.


Challenger refers to the dangers of racial and social hierarchy when she considers the seventeenth-century English philosopher John Locke’s belief that what constitutes a person is something mental or intellectual—“a soul or res cogitans.” She writes:

If a person is a set of rare mental skills, then we can get humans that aren’t a person and humanoids that are. Saudi Arabian women have been denied legal status as persons on the basis that they lack sufficient capacity to conduct their own affairs. Similar prejudices justified the anti-suffrage movement in early twentieth-century Britain…. Much the same was argued against black suffrage in America.

Human beings who are believed to be deficient in attributes regarded as definitively human are accorded lower status than those who are believed to display these attributes more fully. Aristotle argued that what he considered the highest form of human flourishing—intellectual contemplation of the universe—could only be achieved by property-owning Greek males.

Challenger’s target, however, is not so much the hierarchical implications of mind-body dualism as this dualism itself. In transhumanist thinking, what makes humans unique among animals is the intellect; the physical organism in which it is embedded is unimportant except as a source of vulnerability. For some transhumanists this means improving the human body in order to make it a better vehicle for the mind; for others, it means emancipating the mind from the limitations of the biological organism. Either way, the essence of what it means to be human is mental. Human embodiment is an accident, and progress means reducing the importance of the body in life.

Against this view, Challenger argues that humans are essentially embodied creatures. If a human mind is separated from its biological body and installed in a cyborg or projected into cyberspace, the resulting entity will not be that human being or any other one. It will be more like an angel. In a witty and provocative section entitled “The Modern Angelologists,” Challenger suggests that transhumanist conceptions of the disembodied mind reproduce some medieval theological conceptions:

Angels had something irresistible to say about animal life. If disembodied entities like angels were above humans in the ranks of beings, then intelligence didn’t need a body. The evolution into a superior state lay in the abandonment of flesh.

These days, we have our own latter-day angelologists. Roboticist Han Moravec sees a future of “exes”—short for ex-humans—existing in a post-biological world. “Physical activity,” Moravec tells us, “will gradually transform itself into a web of increasingly pure thought, where every smallest interaction represents a meaningful computation.” Such flesh deniers are everywhere now. For a futurist like Giulio Prisco, the grand frontier of space “will not be colonized by squishy, frail and short-lived flesh-and-blood humans…. It will be up to our post-biological mind-children.” Our enlightenment, these men claim, lies in the freedom from our animal bodies.

That the next phase of human evolution involves emancipation from the flesh is not a new view among transhumanists. Though Challenger does not mention him, the twentieth-century Irish crystallographer and philosopher of science J.D. Bernal developed a similar account of a post-biological future. In The World, the Flesh and the Devil: An Enquiry into the Future of the Three Enemies of the Rational Soul (1929), Bernal wrote that as humans evolved they would cease to be distinct organisms, becoming “completely etherialized” into rays of light. More recently a similar future has been outlined by Ray Kurzweil in The Singularity Is Near: When Humans Transcend Biology (2005), in which he argues for reversing aging, interfacing the brain with computers, and other technological enhancements of the human organism.

Much of Challenger’s argument consists of showing how our minds are integrally connected with not only our brains but the rest of our bodies, our nervous systems and inner organs. She cites the work of the Portuguese-American neuroscientist Antonio Damasio as showing that “the human mind has its foundations in ‘bodily feelings, primordial and modified.’”2 Philosophers such as René Descartes have represented the mind as being categorically distinct from the body. Others, such as Baruch Spinoza, a major influence on Damasio, have argued that mind and body are not different substances but aspects of each other. According to this view, the human mind is not simply an instrument of conscious cognition that can be detached from its organic base. It is a locus of feeling, conscious and unconscious, flowing directly from a somatic foundation.

If our minds are linked with our bodies in this way, “transcending biology” could entail the loss of much that makes us human. Preconscious thought processes that may underlie many kinds of human creativity could be left behind with the body. Forms of artistic creation such as dance and music depend on bodily sensation. It is unclear how these kinds of self-expression could be retained or replicated in transhumanist plans for uncoupling mind and body. The feelings that link us with other living things, including other humans, could also be lost. Empathy is not one of the human attributes that commonly figures on the list of those qualities that transhumanists aim to enhance or preserve. It is hard to resist the conclusion that if anything survived the displacement of the mind from the biological organism, it would not be a human being. Rather than “man remaining man,” as postulated by Huxley, a posthuman species would have come into being.

Challenger mounts a searching critique of our ingrained sense that we are not wholly animal. Her argument poses two large questions. The first is how this understanding has become so deeply entrenched. The second is what, if anything, can be done to free ourselves from it.

In an intriguing subsection, she considers the possibility that mind-body dualism may be a defense against the awareness of mortality. The American cultural anthropologist Ernest Becker believed that humankind is trapped in “a material fleshy casing that is alien…in many ways—the strangest and most repugnant way being that it aches and bleeds and will decay and die.” For Becker, drawing on Freud and later psychoanalytical theorists such as Rollo May, it is the denial of death that fuels most religions and much of human civilization.3

Transhumanist thinking expresses the same impulse. Kurzweil has said, “Death is a great tragedy…a profound loss…. I don’t accept it.” His interest in transhumanism has been linked with his desire to reincarnate his deceased father in the form of a virtual replica with which he could converse. The attempt to reestablish communication with the dead is one of several affinities between transhumanism and nineteenth- and early-twentieth-century spiritualism and psychical research, which also sought to deny the reality of mortality.

Denial of mortality fuels religion, which in turn has fostered dualism. But if fear of death is the primary source of a dichotomy between mind and body, it is not easy to see how humans can ever fully accept that they are animals. Many who embrace a supposedly materialist belief system have continued to hold that mortality can somehow be overcome. We may not be born with immortal souls, transhumanists argue, but we can fashion a technological surrogate for them. Kurzweil and others have proposed that death be avoided by uploading the contents of the brain into cyberspace. There are questions regarding the entity that would thereby be created. Would it be a continuation of the human being that once existed, or only a copy? Would it be sentient in the way its predecessor was?

There is also the issue of whether this virtual mind could in fact avoid death. Cyberspace is a projection from a material infrastructure, which is vulnerable to damage and destruction by financial collapse, war, terrorism, and revolution. Climate change or other environmental disasters could render this infrastructure inoperable. When it fails, any virtual minds it has created will be extinguished. The idea that death can be abolished by using technology to transcend biology is a fantasy. Yet the desire to overcome mortality is a recurring human impulse.

A sense of difference from other living things may be an incurable human illusion. The ultimate basis of this illusion, Challenger speculates, might lie in the experience of self-conscious awareness:

When we concentrate, our own thoughts are so absorbing that we can momentarily forget that we have a body. Then something brings us back. A pang of hunger. A noise. And this expansive, floating projection of thought cascades through the body again and into a whole awareness of ourselves and the room. This is both bewitching and more than a little odd. Our intuition tells us that we are not really the creature of muscle and bone that stares out from the mirror. We are the conscious thing in our heads. In this way, we don’t have to believe in dualism to be under the illusion of it. We are trapped in a sensation of personal experience.

The implication of this analysis is paradoxical: the human propensity to illusion increases along with conscious self-awareness. Modifying our beliefs might not dislodge the sensation that we are mental beings accidentally located in physical bodies. The more we are self-conscious, the more we may be liable to think of ourselves as essentially different from other animals.

Evolutionary biology, however, has demonstrated that differences in self-awareness are matters of degree. Where humans differ most from other animals may be in our capacity and need for illusion. In one form or another, some sense that we are minds separate from our bodies may be coextensive with being human. Though animist cultures do not restrict the prospect of a posthumous existence to humans, they contain practices suggesting that something of the human animal continues after bodily death. Many people in secular cultures today cannot help having a similar intuition when they suffer bereavement.

We might not be as different from animists as we like to think. Scientific inquiry may show us that our minds are aspects of our bodies. So may everyday life. The loss of mental powers that occurs as a result of brain injury, dementia, or aging is a common part of human experience. Yet we cannot altogether rid ourselves of the sense that we are not wholly physical beings. Our knowledge and our self-understanding are at odds with each other.

The upshot of Challenger’s argument, then, seems to be that we cannot live as other animals do. So far as we know, our animal kin do not imagine themselves to be distinct from their frail and mortal bodies. Humans, on the other hand, seem drawn to a view of themselves that many know to be false.