New review explores the evolution of the inner ear

From an evolutionary perspective, mammals have developed an advanced ability to hear high frequency sounds. Yet many of the features of the mammalian inner ear pre-date the emergence of the middle ear, a pre-requisite for the detection of high frequency airborne sounds. This raises the question of how evolutionary selection pressures influenced our hearing range.

The review, published in Trends in Neuroscience and co-led by Dr Belen Elgoyhen (CONICET, Argentina), summarises decades of research and explores how evolutionary changes at the sequence level of proteins in the inner ear have contributed to this.

The researchers looked at two proteins in detail: prestin, a protein that works to amplify and fine-tune sound detection, and the α9α10 nicotinic acetylcholine receptor that modulates the amplification.

Critically, they highlight how most genes that are part of this molecular evolutionary process in mammals are also deafness genes, emphasizing the importance of bringing in evolutionary insights to the study of deafness and vice versa.

Dr Lipovsek said:

“When early vertebrates stepped out of the water and became terrestrial animals, biological changes were needed in order to detect airborne sounds. Each group – amphibians, different reptiles, birds and mammals – did just that, but each in their own way. By examining examples of proteins that have influenced the evolution of mammalian hearing we outline common ground between deafness and the evolution of the ear, highlighting the importance of cross-disciplinary research between these areas.”

Related

• The Evolutionary Tuning of Hearing
• Dr Marcela Lipovsek's academic profle
• UCL Ear Institute

Image credit: Pawel Czerwinski on Unsplash