Biological Possibilities in the Next Ten Thousand Years 
Meanwhile we can say that it has already been possible to 
produce an environment in which most people can go through 
life without any serious infectious disease except some virus 
diseases such as common colds which we cannot yet control, 
and others such as measles which we do not trouble to control. 
By the end of the century infectious diseases and deficiency 
diseases should be rare, even if there is a critical period, begin- 
ning perhaps about 1980, when healthy states put pressure on 
the remainder to conform. I shall not, I expect, be there to 
give my advice as to whether a few lice should be preserved 
alive, along with much less dangerous animals such as lions and 
cobras. I would vote against keeping even one Plasmodium. 
About the same time we may hope for methods of preventing 
many or most forms of malignant and cardiovascular diseases. 
These may involve considerable coercion, for example the 
prohibition of tobacco and certain foodstuffs, and compulsory 
exercise for adults. 
It may well be that it will prove practicable to render human 
beings completely aseptic, the useful functions of their intestinal 
flora being taken over by vitamin dosage. The stimulus to such 
an achievement may be the desire to colonize Mars or some 
other skyey body without introducing terrestrial bacteria and 
viruses. It may, of course, well be that aseptic people will lack 
defences against sporadic infections, or suffer some other severe 
handicap. They might equally well avoid cancer and some 
aspects of senility, as Metchnikoff taught. To an aseptic person, 
producing, among other things, inodorous faeces, the rest of 
humanity will appear as ‘‘stinkers”’, and there will be grave 
emotional tensions, including a sexual barrier. This will at least 
be a change from quarrels based on religion, race, political 
affiliation, and economic status. If asepsis is either generally 
advantageous, or permits the development of certain faculties, 
it will, I hope, prevail. 
The next stage in the struggle for health will be against con- 
genital diseases and those of middle and late life. I do not 
doubt that these are largely congenital in the sense that a baby 
of one genotype is likely to die of cerebral haemorrhage due to 
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