Re: Speciation - how do you know?

Gerrit Hanenburg (
Sun, 20 Oct 1996 15:18:04 GMT Gotschall) wrote:

>Off hand I'd think there would be a close relationship between
>skeletal and dental tissue. People living in a weightless condition
>loose bone material very quickly. As I understand it, the calcium is
>simply too valuable physiologically, to leave unused in bone. Is this
>what you mean by expensive?

Astronauts do not have a diet short in calcium. Osteoporosis under
extended conditions of weightlessness does not mean that calcium is
too valuable to leave "unused" in bone. It means that one factor
determining bone mineral density (BMD) is the amount of stress to
which the bones are subject.
Another factor is hormones (ask post-menopausal women what they think
of that)