Another more striking example of human engineering is the possibility of making
humans smaller. Human ecological footprints are partly correlated with our size.
modifications to control height are likely to be quite complex and beyond our current
capacities, it nevertheless seems possible now to use PGD to select shorter children. This
would not involve intervening to change the genetic material of embryos, or employing
any clinical methods not currently used. It would simply involve rethinking the criteria
for selecting which embryos to implant.
Another method of affecting height is to use hormone treatment either to affect
somatotropin levels or to trigger the closing of the epiphyseal plate earlier than normal
(this sometimes occurs accidentally through vitamin A overdoses (Rothenberg et al.
2007)). Hormone treatments are used for growth reduction in excessively tall children
(Bramswig et al. 1988; Grüters et al. 1989). Currently, somatostatin (an inhibitor of
growth hormone) is being studied as a safer alternative (Hindmarsh et al. 1995).
Finally, a more speculative and controversial way of reducing adult height is to
reduce birth weight.