  The biochronometers used to keep time in eukaryotes include short-period
biochronometer (SPB) and long-period biochronometer (LPB). Because the
circadian clock reflects the biological time rhythm of a day, it is considered
as SPB. Telomere shortening, which reflects the decreasing of telomere DNA
length of chromosomes with the increase of cell division times, can be used to
time the lifespan of organisms, so it is regarded as LPB. It is confirmed that
SPB and LPB exist in most eukaryotes, and it is speculated that SPB and LPB are
closely related. In this paper, based on existing studies, it is speculated
that SPB and LPB of most eukaryotes can be co-attenuated with cell division in
the process of aging. Due to the attenuated phenomenon of key components in the
biochronometers during the growth and development of organisms, the
biochronometers attenuate with the aging. Based on existing research results,
it is preliminarily determined that the biochronometers can be rebuilt in the
co-attenuated process. When the key components of biochronometers are reversed
and increased in the organism, it can lead to the reversal of biochronometers,
which further leads to the phenomenon of biological rejuvenation and makes the
organism younger. In addition, the rebuilding of biochronometers can also lead
to the acceleration of biochronometers and the shortening of the original
timing time of biochronometers, thus shortening the life span of organisms. The
rebuilding of biochronometers includes the reversal of biochronometers, the
truncation of biochronometers timing and Uncoordinated co-attenuation of
biochronometer and so on. The reversal of the biochronometers, which leads to
rejuvenation, can give us a whole new understanding of life expectancy to be
different from anti-aging.
