it says that the lifetime of humans is changing periodically between 100.000 and 10 years.
And (maybe said in another Sutta?) that at his time, it was around 100.
That means, he is speaking about lifetime of jati of physical body, right? The human bhava can be longer.
That would make sense, since the limiting factor in the lifetime is the composite material system, i.e. the body, and his tendency to decay. The reason why human lifetime becomes 10 years old only must be related to the changes in the physical body, which becomes more prone to decay.
Daniel asked: “That means, he is speaking about lifetime of jati of physical body, right? The human bhava can be longer.”
– Yes. The lifetime of the physical body can be very different from time to time. It depends on the environment. It does not decline over time either. Instead, there are “waves” with lifetimes going up and down with time.
– I think one of those suttas says that the current lifetime of about 100 years will decline to 10 years and go back up to many hundreds of years before the next Buddha (Buddha Maitreya) is born.
– Yes. the lifetime at the time of Gotama Buddha was about the same as now. It may take millions of years to see any significant change.
– On the other hand, the duration of the human bhava depends only on kammic energy.