HUMAN SENSORS AND LANGUAGE EVOLUTION
When the sensors of the human body detect a stimulus，they send this information through the nervous system（like wires）to the brain.Such signal transmission involves two main systems in our neural system.One is peripheral nervous system，which is a series of branches of single nerves.These are nerves that connect to every sensor in the body.They send signals to other nerves，which send signals to more nerves until the signal reaches the second part of the nervous system：the central nervous system.Central nervous system consists of spinal cord and brain，and is made up of bundles of nerves that are surrounded by bones for protection.Once a signal from a sensor reaches the spinal cord，it is sent up the cord to the brain.The brain decides what to do based on the information received.
The two main sense organs above govern almost all the human senses，which again is related to language evolution closely.Without any doubt，when we are talking，listening，reading and writing，all of our senses are got involved，participatd and concentrated.And almost 70%of human communication is by vision instead of audition，which means 70%information we receive is by the eye.Then here comes the questions that how our eyes coevolve with language evolution？And how does human sense like touching coevolve with language evolution？It is worth considering because the agent and enviroment is not connected by our language.Actually，the interaction between people and enviroment is made through our body.In this sense，we argue that language acquisition is by using instead of learning，and this kind of relationship between body and language should be considered into language evolution.
Figure 4，for example，shows the process of transmitting sound wave from external environment to the inner ear：
Figure 4 The process of transmitting sound waveto the inner ear
Air Conduction
A sound wave is a type of pressure wave that travels through the air.As the wave travels into the external auditory meatus，it first will hit the ear drum（tympanic membrane）.Since the sound wave is actually a pressure wave，it will push against the ear drum which results in a vibration of the ear drum.The ear drum is connected to three little bones（malleus，incus and stapes）—the smallest bones in your body.These bones（together called the ossicular chain）rock back and forth when the ear drum vibrates thereby transmitting the pressure wave down the ossicular chain to the cochlea.The cochlea is a fluid filled sac and the ossicular chain is connected to it.As the ossicular chain vibrates，it pushes against the fluid in the cochlea.This causes the fluid to move around in a particular way so that special hairs within the cochlea are moved.These hair cells are in turn attached to a nerve cell.As the hair cells are moved，they activate the nerve cells which send information down a chain of neurones going up your brain stem，to your thalamus（medial geniculate nucleus）and then to your brain's auditory cortex which is when you perceive sound.Actually，this process just represents the sense of hearing，and back to early 100 years ago，Rudolf Steiner（186-1925）had already identified 12 human senses：Touch，Life，Movement，Balance，Smell，Taste，Vision，Warmth，Hearing，Language，Concept，and Ego.Most of these senses have been confirmed in the modern science.3
From the complex process above，we can see human communication is closely related to the very tiny body movement and delicate sense transmission.So here we should think about how language evolution relates to the transmitting sound wave from the external environment to our inner ear.And if it is true，another question needs us to investigate carefully：what variations could possibly be created in which step during conversation？An interesting research by Dennis Kunkel（2009）sheds some light on these questions that language evolution changes the characteristics of Nerve Cells and Astrocyte.4 Therefore，it is reasonable to argue that human sensors also coevolve with our language.