Why Are There Annual Cycles In Antler Growth?
Believe it or not, the 23 degree tilt of the Earth¹s axis is the ultimate cause for the annual cycles in deer antlers. This tilt is what causes
Earth's annually recurring seasons. Deer have adapted their physiology and
behavior to these seasonal changes, including antler growth. The environmental cue that regulates antler growth is the amount of day length, or photoperiod. The physiological cue is the male hormone testosterone. The way this works
is complicated, but changing day lengths are sensed by the eyes, which sendd this message, via the optic nerve, to the pineal gland. The pineal
gland - a pea-sized organ at the base of the brain - produces many different hormones. One hormone produced is luteinizing hormone, which
controls the amount of testoserone produced in the testes. The antler cycle lags behind the changes in day length because the hormonal changes take time. During fall, decreasing day lengths cause
melatonin production to increase, resulting in decreased production of both luteinizing hormone and testosterone. Decreasing testosterone levels
then cause the antlers to shed
Believe it or not, the 23 degree tilt of the Earth¹s axis is the ultimate cause for the annual cycles in deer antlers. This tilt is what causes
Earth's annually recurring seasons. Deer have adapted their physiology and
behavior to these seasonal changes, including antler growth. The environmental cue that regulates antler growth is the amount of day length, or photoperiod. The physiological cue is the male hormone testosterone. The way this works
is complicated, but changing day lengths are sensed by the eyes, which sendd this message, via the optic nerve, to the pineal gland. The pineal
gland - a pea-sized organ at the base of the brain - produces many different hormones. One hormone produced is luteinizing hormone, which
controls the amount of testoserone produced in the testes. The antler cycle lags behind the changes in day length because the hormonal changes take time. During fall, decreasing day lengths cause
melatonin production to increase, resulting in decreased production of both luteinizing hormone and testosterone. Decreasing testosterone levels
then cause the antlers to shed