(from the Greek words for “end” and “part”). When the differentiated cells of higher organisms undergo mitosis, the ordinary process of cell division, not all of the DNA in their nuclei is replicated. The enzyme that copies DNA misses a small piece at the ends of each chromosome, and so the chromosomes get slightly shorter each time a cell divides. As long as each telomere remains to buffer its chromosome against the shortening process, mitosis does not bite into any genes (remember that the telomeres are noncoding, much like the leaders at the ends of a reel of film). Eventually, however, the telomeres get so short that they can no longer protect the vital parts of the chromosome. At that point the cell usually stops dividing and dies.
(Ronald Hart, Angelo Turturro, and Julian Leakey, 1997, 48)
The question, accordingly, is whether Dolly started life with cells whose chromosomes had telomeres whose length was comparable to those in the cells of a six‐year‐old sheep. Perhaps not, since it may be that once a nucleus has been transplanted into an egg from which the nucleus has been removed, there is some mechanism that will produce an enzyme – called telomerase – that can create full‐length telomeres. The risk, however, is surely a serious one, and provides grounds, in view of the following argument, for holding, not only that one should not at this point attempt to produce people by cloning, but also that there should be a temporary legal prohibition on cloning humans where the goal is to produce persons.
The argument rests on what is known as the “non‐identity problem,” which was the first discussed by Gregory Kavka in his article “The Paradox of Future Individuals” (1981), and then considered at length by Derek Parfit (1984, 351–79). The problem can be raised by comparing two cases:
Mary learns that if she becomes pregnant immediately, her child will suffer from defect X, but still have a life worth living, whereas if she waits three months to become pregnant, she will have a completely normal child. Mary decides not to wait, and gives birth to Johnny.
Jane is pregnant, and learns that unless she takes a certain drug – which has no side effects – she will give birth to a child who will suffer from defect X, but still have a life worth living. Jane decides not to take the drug, and gives birth to Billy.
How does Mary’s action compare with Jane’s? Most people, I think, initially view the two actions as equally bad. Notice, however, that while Billy can later argue that what Jane did was seriously wrong because he was worse off because of what Jane decided not to do, Johnny cannot argue that what Mary did was seriously wrong because of what Mary did, since Johnny has a life worth living, and had Mary waited, Johnny would not have existed, so Mary has not made Johnny worse off.
If Mary’s action is morally as problematic as Jane’s, and if it is true that a cloned person will have a significantly lower life expectancy than a person who is not cloned, then we have a serious objection to cloning that aims at producing a person,, unless the cloned person will have a life that is significantly better in other ways, or there is no other way of producing a person in the circumstances that will be satisfactory. The former scenario seems rather unlikely, but this is not so for the second possibility, since there is a type of case, to be discussed shortly, where cloning may very well be morally justified, namely, where parents want to clone one of their children to have a child who can save the first child’s life. In an earlier essay on cloning, I failed to consider such possibilities, and thus mistakenly concluded that the possibility of a reduction in life expectancy in the case of cloned individuals provided strong grounds for “a temporary, legal prohibition on the cloning of humans when the goal is to produce persons” (1998, 76).
Subsequent developments, however, provide serious grounds for concluding that the telomere‐shortening argument is unsound. First of all, an article by Narumi Ogonuki and others, entitled “Early Death of Mice Cloned from Somatic Cells,” says that it appears that, in the case of mice, early deaths resulted, not from shortened telomeres but from some “malfunction in the immune system” (2002, 253), and the authors also note that
Telomere shortening is known to be associated with cellular aging. It has recently been reported that, after cloning, telomere length can be restored to its original length by nuclear transfer, implying that the lifespan of clones might not be shortened” (2002, 254).
The most important and detailed scientific publication to date seems to be one by K. D. Sinclair et al. – “Healthy Ageing of Cloned Sheep.” In that study, they closely examined “13 cloned sheep aged (7–9 years old), including four from the cell line that gave rise to Dolly” (2016, 1), and there they say that the consensus is that “telomere length is generally restored during nuclear reprogramming” (2016, 7). The concluding paragraph of their article is then as follows:
In conclusion, although the efficiency of SCNT [somatic‐cell nuclear transfer] has improved in recent years, its overall efficiency remains low, with high embryonic and gestational losses compared to natural mating and assisted reproduction. A relatively high proportion of clones also fail to successfully make the transition to extra‐uterine life, some harboring congenital defects, such as observed in the kidney. For those clones that survive beyond the perinatal period, however, the emerging consensus, supported by the current data, is that they are healthy and seem to age normally” (2016, 8).
In the light of the above, I believe that there are good grounds for setting aside the telomere‐shortening argument against human cloning aimed at producing persons. This is an important conclusion, since if telomere shortening and reduced life expectancy were the case, then one would have a strong argument against cloning where the goal is to produce a person.
3.2.2 The low rate of success objection
Can one then appeal instead to the unreliability of the outcome to argue that there should be a legal ban on human cloning where the goal is to produce a person? That is an ethically difficult question. On the one hand, with regard to the “high embryonic and gestational losses compared to natural mating and assisted reproduction,” it is very doubtful that many women would make an informed choice to run those risks associated with cloning, but if a woman had a very strong desire to produce a cloned individual, or was willing to take part in such an experiment if adequately compensated, then it is hard to see how “embryonic and gestational losses” could justify a legal prohibition.
On the other hand, the situation differs as regards failures “to successfully make the transition to extra‐uterine life,” since there the crucial issue is whether cloning may lead to the death of a neo‐Lockean person. That in turn depends on the answer to the scientific question of when developing humans acquire the capacities that are relevant to neo‐Lockean personhood – especially the capacity for thought.
When I surveyed the scientific evidence many years ago (1983, 347–412), it seemed to me that both the psychological and the neurophysiological evidence supported the conclusion that the capacity for thought is only acquired postnatally. It may be that current evidence supports the opposite conclusion, in which case there would be grounds for not allowing human cloning until techniques are improved to eliminate failures “to successfully make the transition to extra‐uterine life.” Or perhaps we do not yet have a definitive answer to the scientific question, in which case a legal prohibition would be in order until either we do have an answer, or until cloning techniques are appropriately improved.
3.2.3 Brave New World objections
Next, there is an objection not frequently encountered in scholarly discussions, but rather common in the popular press, involving scenarios where human beings are cloned in large numbers to serve as slaves, or as enthusiastic soldiers in a dictator's army. Such scenarios, however, seem very implausible.
