Colonising is different to visiting. When visiting, changes (like in bone density) are bad, but can be monitored and taken into account when planning the missi

Colonising is different to visiting. When visiting, changes (like in bone density) are bad, but can be monitored and taken into account when planning the mission duration. When colonising, some permanent changes may be fine, since the change in environment is also permanent. If a colonist visited Earth, they would have to take into account the health issues caused by high gravity. I agree that much more research is needed though; even if some physiological changes are acceptable for colonising, we should make damned sure we know what they are, and what the unacceptable changes are.