from Wiktionary, Creative Commons Attribution/Share-Alike License.
- adjective biology Occurring or having cycles of approximately
Sorry, no etymologies found.
The real answer lies in circadian and circannual rhythmicity, chronobiology, evolution vs. modern life.
If I remember correctly, your posts were primarily about the various rhythms (circadian, circannual, etc.), which is interesting, but is really at a much lower level (early perceptual, pre-cortical, and very primitive) than what I usually deal with, or know much about.
The only well developed visual domains are those involved in controlling the circadian and circannual biological rhythms - the suprachiasmatic nucleus and the retinohypothalamic projections.
The reindeer use those few weeks of spring (and fall) to measure daylength (photoperiod) and thus time their seasonality - or in other words, to reset their internal calendar: the circannual clock.
Controls circadian and circannual rhythms by stimulation of the brain - possibly involved in the maturation of sexual organs