During puberty: After infancy, the tween and teen years are the period of most rapid change. For girls, the growth spurt begins between 10 and 11 and lasts until around 15; for boys, it starts about two years later and lasts until age 17 or so. Girls typically stop growing about three years after they've had their first period, but boys continue to grow throughout their teens.
The Syrinx. Humans have a larynx, and parrots have a syrinx, located between the voice box and the bronchial tubes. The syrinx branches out in two directions, with each branch opening into a bronchus. Air from a parrot's lungs passes through the syrinx, and the parrot is able to use all of the air to produce sound.
They can not articulate words, but monkeys understand more than we imagine. Studies made on monkeys revealed they have a so called self consciousness and are gifted with high learning ability. In monkey groups there is a strict hierarchy and the orders of the superior individuals are executed by the whole group.Monkeys are able to communicate their intentions, decisions, satisfactions and dissatisfactions. When the offspring disobey their parents, they are punished.rained orangutans, gorillas and chimps can learn human signal languages like the American one: from several hundreds for orangutans to over 1,000 for gorillas and 800 for chimps. Their rhythm of learning is 40 new words per year.