The UK transpecies embryo debate

The trigger for the most recent debate in the UK came in early 2006, when research teams released details of their intention to seek licences from the UK Human Fertilisation and Embryology Authority (HFEA) to create transpecies embryos. The aim was to use non-human eggs or ova combined with nuclear human DNA in order to derive stem cells, giving rise to ‘cytoplasmic hybrid embryos’ or ‘cybrids’ having a human nucleus and non-human ‘outer egg layer’ or ‘shell’. The cybrid is only one of at least four types of transpecies hybrid debated. The existing legislation, dating to the Human Fertilisation and Embryology Act of 1990 (Department of Health, 1990), had effectively outlawed the deliberate creation of transpecies human embryos. However, as discussed below, the original meaning of the Act, and whether cybrid embryos were indeed proscribed by it, became the focus of debate and scrutiny by the regulator and in the High Court.

By November 2006 the HFEA had received two research applications effectively forcing the hand of policy-makers to clarify the regulatory position amidst continuing uncertainty and debate over a range of scientific issues, including the biological value of stem cells derived from genetically unstable sources and the comparability of human and non-human models for stem cell derivation. This has been a debate in which both science and morality became key sites of contention and ambiguity.

Cybrids are not new. Nearly ten years earlier, in 1998, Advanced Cell Technology Inc., had announced the successful creation of an embryo using a cow egg and the nucleus of a cell derived from the cheek of one of the company’s own research scientists. This prompted the then US President to write to the National Bioethics Advisory Commission requesting that they investigate the matter and complaining of being: ‘deeply troubled … by this news of experiments involving the mingling of human and nonhuman species … ’ (President’s Commission on Bioethics, 1998). The event represented a strong disjuncture between political considerations and expert scientific practice, especially in the context of US embryological politics.

Internationally this was just one among a number of developments that continued to put interspecies embryos on the reproductive policy agenda. In early 1999, the Australian company, Amrad had applied for and received a European-wide patent (EP 380646) on processes involved in the creation of transpecies embryos. Later, in 2003, there were a series of public announcements of work undertaken in other countries, notably in China, including the extraction of stem cells from interspecies human embryos created using rabbit ova (Chen et al., Reference Chen, He, Liu, Wang, Mao and Chu2003).

The status of hybrid transpecies embryos remained largely unresolved in a British regulatory context, however, where the banning of such embryos had been foundational to the earlier 1990 Human Fertilisation and Embryology Act (Department of Health, 1990). Prompted by growing research interest, the government moved throughout 2006 to clarify its position. Under the recommendation of the UK Chief Medical Officer, Sir Liam Donaldson, the government’s white paper (Review of Human Fertilisation and Embryology Act) proposed that: ‘the creation of hybrid and chimera embryos in vitro, should not be allowed’ (Department of Health, 2006). This provoked resolute scientific opposition, with the government and Sir Liam Donaldson seen as unduly cautious in their response to a small-scale public consultation suggesting a potential public backlash. The Draft Bill, Human Tissues and Embryos (Department of Health, May 2007) was substantially in keeping with the earlier white paper, prompting further organized challenges from the science lobby, and was hotly debated during the proceedings of the JCHTE, which took evidence and witness statements throughout June 2007.

Those favouring transpecies research cohered to form a formidable institutional alliance. The licence applications highlighted regulatory uncertainty over the existing powers of the HFEA and the exact legal distinction between several classes of transpecies body. ‘True hybrids’—created by fusing two complete gametes of human and non-human origin—were considered to be explicitly forbidden for research by the 1990 legislation. Less clear was whether cytoplasmic or cybrid embryos—created by injecting a human nucleus into a non-human egg—were proscribed in the same way. While much of this debate was prospectively oriented towards the production of new legal provisions, it was also concerned with retrospectively re-interpreting the original purpose and meaning of the 1990 Act. The question for policy-makers was whether cybrid embryos should be legally viewed as ‘hybrid’, in which case they were forbidden under existing legislation, or ‘human’ and permitted for research purposes up to the 14 day stage. The dilemma had been stated on a number of occasions (House of Commons Science and Technology Select Committee, 2005: 32) but now had to be fitted into a formal licensing procedure.

Following lengthy deliberation, the regulator determined that cybrids were to be interpreted as essentially human, and therefore wholly acceptable, under the provisions of the earlier legislation. The ruling relied on a view that came to prevail throughout the debate that the mitochondrial DNA of the animal egg was insignificant in determining the species attributes of the resulting embryo. In effect, the nuclear DNA of the cybrid would be taken to legally define the species attributes of the embryo. Heritable mitochondrial egg DNA was to be disregarded. This privileging of the human and the nuclear is discussed in much greater depth below and became central in defending and promoting the legitimacy of research on cytoplasmic hybrids. The decision of the HFEA would later be unsuccessfully contested in the High Court by opponents claiming that the HFEA had acted outside existing law in granting licence applications on hybrids banned in 1990 and without first waiting for parliament to debate the new legislation (Quintavalle and Christian Legal Centre v. HFEA, 2008).

Although the HFEA had ruled that the licence applications now fell within its jurisdiction (HFEA, 2007a), it decided not to act without first holding a second and more wide-ranging public consultation (April to July 2007). The results of the consultation were interpreted by the HFEA as demonstrating qualified public support for transpecies embryo research, varying widely (35 percent to 61 percent) according to how questions were asked and of whom (HFEA, 2007b). The report itself argued from a traditional deficit model position whereby more knowledge is seen to foster greater trust: ‘there is a clear demand from people to know more about what researchers are doing … highlighting a need for better communication …’ (HFEA, 2007a). But far from being an ‘up-stream’ consultation it was conducted alongside, or even arguably after decisions had been taken, and after repeatedly stating its policy commitment to approve cytoplasmic embryos for research. For example, as early as August 2005, the HFEA commented that pure hybrids (created from the equal fusing of human and non-human gametes) are ‘consistent with research as it is currently allowed’ (HFEA, 2005). Its April 2007 consultation document expressed a desire to see: ‘the current law, which permits the creation of hybrids only for very limited purposes … be extended so that hybrid embryos can be created for the same research purposes as other embryos’ (HFEA, 2007b: 13).

The revised human fertilisation and embryology bill was published in November 2007. By now the government had moved entirely from its December 2006 position, abandoning the prohibition of true hybrids and devolving greater discretionary powers to the HFEA to regulate presently unforeseen classes of interspecies embryo. The publication of the JCHTE report (2007a) played a crucial role in redefining a more permissive framework for the legislation, which received its final hearing in October 2008.

In what follows, this article focuses on the passage of the transpecies embryo through the narrative and historical corridors of UK parliamentary process and, in particular, the discussions and witness testimony presented to the JCHTE. The committee provides a focused forum, which gives an opportunity to understand the difficulties of resolving key contradictions at the heart of hybrid regulatory culture and biology in the UK, and indeed elsewhere. It also offers insights into the institutional dynamics of regulatory change and the hybrid intermixing of biological, political and regulatory matters. Nevertheless, I want to locate the proceedings of the committee in the context of events before and after it convened for that short period during a year in which much changed in the biological landscapes of reproductive regulation.

The un/banned hybrid embryo

The recent controversy on transpecies embryos only makes sense when we look at the way in which the question has evolved over time. For the UK, this goes back to what Mike Mulkay (1997) wrote of as the ‘Great Embryo Debate’ throughout the 1980s. In the earlier parliamentary debate, the mixing of gametes or genes of human and non-human origin represented the worst of all possible reproductive sins. The ‘hybrid embryo’ was morally equivalent to human reproductive cloning, the creation of artificial gametes, germ line human genetic engineering, eugenics and other such horrors. Indeed, the banning of transpecies embryos was announced in parliament as one of the primary purposes of the Human Fertilisation and Embryology Act (1990): ‘It [the Act] … will establish a statutory licensing authority to ensure that treatments … take place in reputable centres and under proper safeguards. It will forbid research developments such as cloning and the creation of hybrids’ (The Prime Minister, House of Commons, 21 November 1989: col. 30). In the debate leading up to the act, the transpecies embryo figures as an unimaginable abhorrence and the subject of urgent prohibitive legislation.

The significance of this position for the recent debate cannot be overstated. The framing of the transpecies embryo in these very pejorative terms, as a source of disgust and moral outrage, makes it much more difficult later to begin normalizing the transpecies embryo or rehabilitating it from its previous scandalous status. It is then much less of a surprise that, in December 2006, the UK government should publish its draft white paper with ‘the ban’ as its default position.

And yet, even at this early stage, we begin to see a central tension of the debate surface, that between the banned and the unbanned. The 1990 act expressly forbids the deliberate creation of transpecies hybrids for reproductive or research purposes, but paradoxically makes provision for clinicians to conduct a fertility test that indirectly results in the creation of a human-animal hybrid embryo, which by law must be destroyed ‘no later than the two cell stage’ (Department of Health, 1990: Schedule 2, 1, f). The procedure is used to diagnose the viability of human sperm—observing whether or not it is able to fertilize an animal egg, an ova, derived from a hamster in this case—resulting in a ‘true hybrid’ derived from the fusion of human and non-human gametes. The ‘hamster test’ as it came to be known, represents a curious contradictory paradox at the heart of legislation that both rejects and accepts transpecies hybrid embryos.

In the late 1980s debate, the limited gestational viability of the early transpecies embryos justified their creation, the potential survival of any embryo produced through this method being naturally restricted to hours or days. Now, in this case, non-viability legitimates the creation of the human-hamster hybrid. If the embryo is not viable then there is little justification, the argument goes, for it to be banned. Nevertheless, it remains a curious contradiction that other equally non-viable transpecies hybrids are banned. In other words, non-viable ‘pure hybrids’ are both allowed in the hamster test and yet banned. In the most recent debate, there has been ongoing uncertainty on this question of the gestational viability of transpecies hybrids:

Putting aside the genial intimacy of some of these exchanges, excerpts such as this point to acute ambiguities in hybrid embryological knowledge and understanding. The question of viability or non-viability was only one of a number of problematic uncertainties about the nature and ontology of transpecies embryos. For the earlier debate, during the 1980s, it was not the purpose or intention of the fertility test to create a transpecies embryo. Rather, the hamster hybrid is the indirect by-product of the test. However, for the recent debate the object of interest is the hybrid embryo itself, together with questions of viability. Non-viability becomes a question of investigative interest and not, as before, a statement of fact for the purpose of moral defence.

The recent debate also continually returned to the apparent tensions between a regulatory position that allows research on pure embryos but bans research on transpecies embryos. The House of Commons Select Committee on Science and Technology had earlier suggested that while ‘revulsion in some quarters’ at human/non-human mixing was the basis for proscribing hybrid embryos: ‘it could be argued that they are less human, and therefore pose fewer ethical problems for research, than fully human embryos’ (2005: 32). One of the witnesses to the June 2007 JCHTE commented: ‘what I do not understand is why more care or regulation should arise in the context of embryos that combine animal and human components than human embryos …’ (JCHTE, 2007b: Prof. Gillon, Q855). Both of these comments point to the greater regulatory protection paradoxically accorded to the non-human rather than to the human. It is a cause for concern throughout the debate that the transpecies hybrid is framed as more distinctive, more special, and singled out for exceptional protection by being banned. The ban reinforces the hierarchical structure that places humans over other species by protecting the human from the pollution posed by the incorporation of another species. And yet, at the same time, places humans in the morally awkward position of being experimental subjects in a way that transpecies (less than human) embryos are not.

The singling out of the pure hybrid, and the question of contradiction, returns us to the discussion of Agamben (1998) above and his concern with those moments where the state has the power to institute a state of emergency. Law defines the division between ‘bare life’ and politically qualified or protected life. The state of emergency is the inclusion of bare life into politics, entirely in the form of its exclusion. Life has to be included, in order to be set apart, excluded, banned and disqualified. Bare life (zoë) is brought into politics (bios) in order to be expelled. The banned must be politically acknowledged as a prerequisite for its disqualification. It is less of a surprise then that parliament is able to institute exceptions like the hamster test because these constitutional anomalies are actually central to the arbitrary discretionary powers of sovereignty and the law. Agamben’s point is that, paradoxically, exceptions are part of the normal functioning of law.

Over a decade ago Squier (1998) also noted just this state of exception, in her analysis of the earlier interspecies debate. Linked to Freud’s psychoanalytics of denial, for her the prohibition of interspecies embryos is a focus for ‘xenogenic desire’ deliberately focusing on the taboo and monstrosity of interspecies reproduction, in order to deny it. ‘It brings to mind’, she writes, ‘Freud’s 1925 essay, Negation, in which he observes that “the subject-matter of a repressed image or thought can make its way into consciousness on condition that it is denied”’ (1998: 368).

Transpecies hybrids in both scientific debate and cultural discourse are objects of simultaneous exclusion and inclusion, fascination and desire. Mary Douglas too acknowledges that the purpose of profanity goes beyond the reaffirmation of cultural codes including the use of profane bodies to: ‘enrich meaning and to call attention to other levels of existence …’ (1966: 40). As Edmund Leach puts it, myth-making seeks out the anomalous and contradictory: ‘In every myth system we will find a persistent sequence of binary discriminations as between human/superhuman, mortal/immortal, male/female … followed by a “mediation” of the paired categories’ (1967: 4). This coupling of contradictory positions—the prohibition and the sanction, desire and loathing, purity and profanity—is reflected here in the legal regulation of permitted and proscribed embryos.

While the new legislation seeks to resolve some of these tensions and contradictions by now allowing previously banned transpecies embryos, it proceeds on the basis of uncertain knowledge and evidence about viability and a host of other technical questions. As discussed below, this has led to further unresolved contradictory frictions in the debate.

The un/differentiated embryo

At the centre of this debate lies another related fundamental tension. There has been ongoing diversification in the techniques used to produce embryonic entities. These differences in technique have given rise to the equally troublesome question of morally distinguishing between one transpecies hybrid embryo and another. In parallel to this technical heterogenization we have seen concerted efforts to sort out which practices should be allowed and which should not. The original draft bill (May 2007) distinguished between five different kinds of ‘interspecies embryos’. Three were to be regulated as permissible for research. The remaining embryos were either to be banned (as in the case of true human hybrid embryos) or regulated by the Home Office instead (under the Animals Scientific Procedures Act 1986) because they were seen to be more animal than human. For the government, the Chief Medical Officer had argued firmly that allowing cybrid embryos while banning pure hybrids recognized both technical and moral differences between types of transpecies embryo:

Now, in opposition to this technical and moral heterogenization, many in the embryological research community sought to treat interspecies hybrids in morally equivalent terms, regardless of technical differences in their creation: that is, to treat all of these transpecies hybrids symmetrically, and in so doing, resolve the seemingly arbitrary moral distinctions that have resulted in the unbanned banned.

This position was consistently adopted by advocates of permissive regulation, including written statements by institutional scientific bodies. A memorandum by the Academy of Medical Sciences similarly switches between a scientific register that recognizes and acknowledges technical differences between transpecies bodies, and a moral register in which transpecies bodies are treated as morally equivalent to one another. ‘Switching between science and culture’—in the construction of species similarity and difference—has been a long-standing motif in debates about animals and humans in biotechnical controversy (Brown and Michael, Reference Brown and Michael2001).

Nevertheless, arguing that all transpecies embryos should be treated in equivalent terms was in tension with the ubiquitous claim that cybrid embryos (made using a human nucleus and animal egg) were largely human and therefore morally more legitimate. Successfully downplaying the interspecies hybridity of cybrids in this way would minimize their contentiousness. It was common in the debate to invoke statistical percentages in referring to cytoplasmic embryos or cybrids as ‘99.9 percent human’.

Casting the discussion in percentage terms has long been a feature of the debate. Going back to the deliberations in the President’s Commission on Bioethics in 1998, following the creation of a bovine-human cytoplasmic hybrid by Advanced Cell Technology Inc., there was intensive debate over what the proper nomenclature for these kinds of entities should be. Whether, for instance it was appropriate to refer to them as hybrids or chimeras or something else. Even at that early stage, the tendency on the part of scientific witnesses is to stress the importance of the nuclear DNA over the mitochondrial DNA of the egg or ova. That relative ratio of 99.9 percent nuclear and 0.1 percent mitochondrial DNA was seen to be decisive:

The contradiction is that this line of defence conflicts with claims that all transpecies hybrids should be treated in the same way, having no real moral distinguishing features as either human or animal—regardless of proportionality. There is then another tension that arises here between these claims for difference and sameness. On the one hand, cybrids are regarded as different or special by virtue of their proportionally greater humanness (99.9 percent human). The cybrid is a special case. On the other hand, it is argued that all transpecies hybrids should be regarded as essentially the same because of their interspecies origins:

Numbers have been a routine reference point in the metric calculation of humanness across any number of bioscience areas over several decades. The percentage of genes or DNA shared, or not, between humans and distant evolutionary relatives was standard fare in news and commentary throughout the course of the Human Genome Project. Numbers are emblematic of an exacting scientific epistemology (Hacking, Reference Hacking1983; Porter, Reference Porter1995). Ayrn Martin points to the paramount place of enumeration in science and that: ‘whether counting species, continents, or colours of the rainbow, ambiguity invites the communal elaboration of rules and techniques for defining and separating entities …’ (2004: 944). It is highly appropriate for the question of interspecies hybrids that Martin’s focus is the historically variable question of human chromosome counting. First put at 48 from the 1920s but then revised down to 46 in the 1950s, the case nicely illustrates the contingencies of counting and the categorical judgements that structure what is and is not a countable category.

In terms of the species question in the Human Genome Project, Holmberg writes of interspecies ‘ontological gerrymandering’ in the way percentage estimates of species affinity ranged wildly: ‘boundaries are drawn between humans and non-humans with the help of numbers, the certainty produced by absolute and percentage figures conceals that the categorisations could be made in other ways’ (2005: 24). Now, in the context of the Human Genome Project, a small percentage difference between humans and another species really seemed to matter. It metrically separated humans from other primates, drosophila, nematodes and a host of other species. However, here in the transpecies embryo debate small percentage (mitochondrial) differences between humans and other species are presented as not mattering at all.

Jonathan Marks’ book What it means to be 98 percent chimpanzee (2002) explores just this question of the anthropological relevance of genetics for the ongoing reinterpretation of the evolutionary relationship between humans and other species. He focuses on the cultural and historical arbitrariness of the use of genes and numbers in claims to species affinity and non-affinity. His point is that while humans and chimps have an estimated 98 percent of their genetic material in common (and what this means is always open to question) that does not tell us very much about humans, other primates or indeed genes and DNA. It should not, in particular, be taken to suggest that we are mainly chimpanzee, nor that chimpanzees are mainly human. The invocation of 98 percent is a rhetorical device, and small differences, for example in single nucleotide polymorphisms, can be disproportionately significant.

Participants in the transpecies embryo debate have faced the unenviable challenge of agreeing to the numerical percentage threshold at which an embryo should, or should not, be considered human or transpecies or both. The government had proposed that where the weight of humanness exceeds 50 percent, that embryo should be considered subject to the newly formulated human reproductive legislation. Were the weight of humanness to fall below that threshold, then it would be regulated by the Home Office as a question of animal experimentation. Witnesses to the committee were very sceptical about this:

There are, then, acute ambiguities in these discussions of percentages. There is acknowledged uncertainty over whether the government’s 50 percent proposal is scientifically sensible. At the same time, many in the debate continued to use percentage-based arguments to defend the creation of cybrids as predominantly human and insignificantly non-human. While numbers offer the promise of precision, they have proven difficult to stabilize in settling disputes here on the boundaries of humanness.

These problems with the numbering of difference are compounded by time and process. The hybridity of a transpecies embryo is far from static but changes over time and throughout the sometimes short gestational development of transpecies embryos. What may fall under one definitional umbrella for the purposes of licensing and law may well develop into something else in this far from exacting area of developmental biology. It may become possible for these kinds of entities to morph from one kind of hybrid to another during early gestation—and in so doing, migrate from one legal definition to another.

This question of the relationship between the nuclear and mitochondrial DNA, though shrouded in uncertainty, was far from uncontested. A member of one regulatory body and a specialist in mitochondrial genetic diseases contested the claim that nuclear DNA determines the genetic make-up of the cell (personal communication). Ultimately, the claim is inconsistent with the incidence of hereditary mitochondrial disease. While rare, these are well characterized and are inherited exclusively through the matrilineal line, passed on through mitochondrial egg DNA. The member was rather perplexed that the matrilineal female mitochondrion of the animal egg was being downplayed in this way.

This touches on what science studies scholarship has written about as the gendering of the cell (Haraway, Reference Haraway, Shiva and Moser1995; Hird, Reference Hird2002a, Reference Holmberg2002b; M’charek, Reference M’charek2005). Over the course of the debate there were searching questions over whether or not the human nuclear DNA would ultimately determine the species attributes of the cybrid or cytoplasmic hybrid, and specifically the egg/ova mitochondrial DNA. In other words, any embryos created would become more human over time. The nuclear DNA would come to dominate the enucleated egg, overwhelming the non-human mitochondrial DNA of the ova. The debate adds a speciesist twist to observations by feminist scholars and historians of science about the hierarchical positioning of the ‘male’ nucleus over the female mitochondrial periphery. In the debate we have a set of dichotomies that pitch the human nuclear DNA against the subservient nonhuman mitochondrial egg DNA.

Nuclear/Mitochondria

Male/Female

Human/Animal

Speciated core/Despeciated shell

Timeless/Finite

Permanent/Impermanent

Alongside this, the debate has also witnessed some significant shifts in rhetoric. Stephen Minger, one of the key licence applicants to undertake work on transpecies embryos switched from using the term cell ‘enuclation’ to ‘despeciation’ when describing the process by which non-human DNA is removed from egg cells. Just as importantly, during the course of the debate the UK Department of Health substituted the term ‘transpecies’ embryos with ‘human admixed embryos’ in an effort to emphasize the human over the non-human.

These questions of hybrid identity have important implications for regulatory oversight, especially in terms of species boundaries between regulatory authorities. The problem with a ‘true hybrid’—created by the equal fusing of non-human and human gametes—is that it completely confuses the institutional margins of human and non-human regulatory authorities, between the HFEA and the Home Office respectively. This has been written of elsewhere as a question of institutional species identity (Brown et al., Reference Brown, Faulkner, Kent and Michael2006). Regulatory bodies are varyingly modelled on assumptions about the species characteristics of regulated bodies—animals and humans. Today, many of the institutional species assumptions that demarcate regulatory agencies across the human and the non-human are being disrupted in cases like this. Lobbyists for permissive legislation had argued for a simple overarching definition of the embryo and against the government’s efforts to differentiate techniques and resulting embryos. This however came into conflict with the species structure of regulation.

Another problem surfaced in relation to the mandate of the Home Office which has no responsibility for any embryos until half way through their gestational development. It is then conceivable that a hybrid animal-human embryo may go completely unregulated until the midpoint in its development. While this feature of law could result in under-regulation, it could also conceivably result in over-regulation where gestation may be very short, as is the case with mice embryos, which reach the gestational mid-point at about nine and a half days. As one witness put it, an interspecies mouse may be subject to greater protection than a human embryo because of: ‘the administrative inconvenience of having to coordinate two regulatory regimes which is not to me a very persuasive argument’ (JCHTE, 2007b: Q940). There is then a conflict between the institutionalization of hybrid regulation and the more fluid aspects of scientific innovation and biology. In other words, the interface and borders between regulatory bodies are likely to be of greater importance than the individual regulatory characteristics of agencies.

What can be seen throughout these discussions is that science’s more traditional epistemological commitment to differentiation, taxonomy and distinction has been set aside. Most scientists consulted in the debate argued strongly that while technically different, the various classes of transpecies embryo should be regarded as morally and culturally equal. Nevertheless, this moral dedifferentiation is at odds with the presentation of the cybrid embryo as proportionally more human, and therefore more legitimate for human reproductive research. The marginalization of the non-human mitochondria, drawing on a historical gendering of the cell, was strategically important in this respect. The attempt to flatten the moral terrain of reproductive research ultimately undermined the government’s argument that embryos produced by different means and of different species origins are likely to be publicly received in culturally uneven ways. That moral levelling of embryo types also disrupted government efforts to unambiguously demarcate the regulatory zones of animal and human research.

Conclusion—beasting the embryo

In November 2008, parliament voted in favour of a radically revised bill in which the prohibition of ‘true hybrids’ had been entirely abandoned by the government. The revised definitions were now much more flexible than originally proposed, with the addition of a new and contentious provision for the ad hoc regulation of as yet unforeseen kinds of transpecies embryonic entity. The final wording of the 2008 act defines an interspecies embryo as, among other things: ‘any embryo … in which the animal DNA is not predominant’ (Department of Health, 2008: 4, 6, e). An earlier version of this section had however been heavily criticized for its ambiguity and for failing to adequately distinguish between the differing regulatory responsibilities of the Home Office (research animals) and the HFEA: ‘For the purpose of this Act an interspecies embryo is … such other thing as may be specified in regulations’ (draft bill: clause 4.2, italics added). It was argued that both formulations (‘any embryo’ and ‘such other thing’) would ‘future-proof’ the legislation against painstaking revision and enshrine the novel unpredictability of hybrid biology in legal statute. It would give the Secretary of State for Health the powers to add new interspecies entities as and when they arise. Nevertheless, the meaning of ‘predominant’ in the final bill and its stability both biologically and legally remains unclear. The section represents a curious compromise between different sides in the debate and is a concession that indirectly preserves the suggestion of a 50 percent division in settling the regulatory identity of interspecies embryos. On the one hand, the clause biologically acknowledges the instabilities of genetic species identity, on the other it institutionally persists with an increasingly troubled partitioning of human and animal governance. Hybrids are profane and unruly in this way signalling the frailty of the ‘modern constitutional’ order and threatening to overwhelm legislative boundaries that are arguably already outmoded even before they become law (Latour, Reference Latour1993).

The story told here traces a debate in which an organized lobby succeeded in steering and directing the political reproductive agenda. To this extent, hard classificatory borders have been softened and the traditional taxonomical regime of science (as a ‘difference machine’) has been substituted with an open-ended moral pragmatism. Rigid regulatory orders have been replaced with suitably leaky ones, advancing the interspecies direction of an emerging embryological research order.

Important in explaining the outcome of this debate has been the moral flattening and homogenization of the different classes of embryos described in the legislation. The early attempts by the UK government and its Chief Medical Officer to acknowledge in law potentially varied cultural and political readings of, for example, ‘pure hybrids’ as distinct from ‘cybrids’, failed. Advocates of ‘permissive’ legislation from the embryological research community successfully petitioned for a dedifferentiation of the moral and cultural landscape that applied to research embryos. Difference would be levelled within what Agamben (1998) calls a generalized ‘zone of indistinction’, smoothing an otherwise technically and morally uneven area of scientific research. Indistinction implies just this kind of erasure in which the unevenness of embodied difference and species identity is reduced to the bareness of life itself.

The hybrid has become the central expression of contemporary corporeal and institutional innovation. Hybrid bodies (both biological and social) are, in cases like this, embroiled in a process of ‘institutional biosociality’ (Brown and Michael, Reference Brown and Michael2004; Rabinow, Reference Rabinow and Biagioli1999) and mutual revision. The making of regulatory zones like the UK’s reproductive space is the outcome of an ongoing and unfinished reclassification of innovated nature and political jurisdiction. It remains to be seen whether, and to what extent, these kinds of corporal and institutional fluidities are practically worked out in the course of regulatory business. The vacuum that lies between the duties and responsibilities of animal (Home Office) and human (HFEA) regulatory bodies is likely to be a continuing source of controversy. The legacy of the existing regulatory order remains problematic for the governance of simultaneously transpecies and transinstitutional hybrid bodies. Interspecies bodies trouble the metric rationality of taxonomical order and challenge the normative boundaries separating the human from the non-human. Male and female, human and animal defy precise definition here at the margins of institutional and embodied hybridity (Weston, Reference Weston2002). These contradictory instabilities are unlikely to be resolved by legislation that preserves a binary separation between the regulation of the human and the non-human. The contrasting poles of the human and the non-human remain precarious and unstable havens into which regulatory policy-making retreats when confronted with the monstrous.

Crucially, it is important not to mistake the creation of interspecies bodies for an erosion of the humanist species hierarchies to which Agamben refers in the opening passage of this article. The sustained effort to stress, for example, the humanness of cytoplasmic embryos, illustrates the continuing privileging of the human and not a cultural erosion of species boundaries. Again echoing Latour’s modern constitution above, the notion of ‘beasting’ applies asymmetrically. That is, the gathering pace of hybrid interspecies research is radically at odds with a cultural emphasis on the humanness of beasted embryos. It is certainly the case that this debate has involved a far-reaching transformation of species boundaries in terms of paving the way for an increased range of embryological transpecies research. Nevertheless, the recent legislation represents a constitutional refortification of traditional speciesist hierarchies.