Interesante este fragmento de ‘The Wisdom of Nature: An Evolutionary Heuristic for Human Enhancement’ de Nick Bostrom. De por si el articulo completo es una lectura obligada sobre la sabiduría de la naturaleza, y de las posibilidades de mejorar el cuerpo humano.
Una interesante hipótesis para el efecto placebo.
2.2.2. The immune system While the immune system serves an essential
function by protecting us from infection and cancer, it also consumes
significant amounts of energy. Experiments have found direct energetic
costs of immune activation. In birds immune activation corresponded to a
29 per cent rise of resting metabolic rate and in humans the rate increases
by 13 per cent per degree centigrade of fever. In addition, the protein
synthesis demands of the immune system are sizeable yet prioritized, as
evidenced by a 70 per cent increase in protein turnover in children during
infection despite a condition of malnourishment. One would expect the
immune system to have evolved a level of activity that strikes a tradeoff
between these and other requirements—a level optimized for life in the
EEA but perhaps no longer ideal.
Such a tradeoff has been proposed as part of an explanation of the placebo
effect. The placebo effect is puzzling because it apparently involves getting
something (accelerated recovery from disease or injury) for nothing (merely
having a belief). If the subjective experience of being treated causes a healthpromoting
response, why are we not always responding that way? Studies
have shown that it is possible chemically to modulate the placebo response
down or up.
One possible explanation is that mobilizing the placebo effect consumes
resources, perhaps through activation of the immune system or other
forms of physiological health investment. Also, to the extent that the
placebo response reduces defensive reactions (such as pain, stiffness, and
inflammation), it might increase our vulnerability to future injury and
microbial assaults. If so, one might expect that natural selection would
have made us such that the placebo response would be triggered by signals
indicating that in the near future we will (a) recover from our current
injury or disease (in which case there is no need to conserve resources to
fight a drawn-out infection and less need to maintain defensive reactions),
(b) have good access to nutrients (in which case, again, there is no need to
conserve resources), and (c) be protected from external threats (in which
case there is less need to keep resources in reserve for immediate action
readiness). Consistent with this model, the evidence does indeed show that
the healing system is activated not only by the expectation that we will
get well soon but also by the impression that external circumstances are
generally favorable. For example, social status, success, having somebody
looking after us, sunshine, and regular meals might all indicate that we are
in circumstances where it is optimal for the body to invest in healing and
long-term health, and they do seem to prompt the body to do just that. By
contrast, conflict, stress, anxiety, uncertainty, rejection, isolation, and
despair appear to shift resources towards immediate readiness to face crises
and away from building long-term health.
En resumen. Combatir una enfermedad consume muchos recursos, por lo tanto es bastante probable que hayamos evolucionado para que nuestro cuerpo valore constantemente si es buena idea usar esos recursos en curar esa enfermedad o en otras cosas muy importantes, como estar lo suficientemente fuertes como para buscar comida, o que incluso al usar esos recursos para curar esa enfermedad seamos más vulnerables en otro sentido.
Imaginaos enfermo, solo y perdido. Vuestro cuerpo podría valorar ( lo digo metafóricamente) ‘ No tengo a nadie que me ayude, si uso los recursos energéticos que tengo en curar la enfermedad, después estaré tan débil que no podré buscar alimento, o agua, tampoco podré escapar de un depredador. Moriré de todas formas. Mejor conservo fuerzas por si acaso’
Ahora imaginaos en una cueva, con toda la familia, te dan mimos, encienden un fuego para que estés calentito, espantan a los depredadores...tu cuerpo valoraría ‘ Me siento protegido, me dan de comer, y de beber. Si uso los recursos ahora para combatir la enfermedad después como me están cuidando tanto estaré en buenas condiciones’
Lo interesante de esta hipótesis, es que el efecto placebo no depende de si el sujeto sabe si lo que le dan es un medicamento real o no, depende del efecto de atención que recibe, lo cual haría valido el efecto placebo incluso en bebes o en animales como los perros.
Normalmente la excusa de muchos magufos es que un perro o un bebe no es consciente que le están medicando, con lo cual el efecto placebo no seria explicación valida. Pues si lo seria.
Este articulo reciente parece indicar eso.
