The “Hidden Genetic Cause” of Mules Natural Sterility: A Fascinating Biological Dialogue between Aristotle and Ibn Sina as Outlined in “The Book of Animals”

Abstract

Faragalla, M. El Moghazy, Magdy Mohamed Zaabal, Hesham H. El-Khdrawy and Wahid Mohamed Ahmed

This study aims to provide a comparative perspective on “The Book of Animals”, contrasting Aristotle’s original text with Ibn Sina’s version – which serves as a commentary on Aristotle’s work, while introducing pivotal insights and theories of Ibn Sina’s own. It further examines the phenomenon of mule natural sterility – a subject that embarrassed thinkers in the past – and explores how early philosophers and scientists who addressed it through exposition and diligent interpretation. The term “hidden cause” originated with Ibn Sina in his great book, “The Book of Animals”, when he examined the ideas and theories of Aristotle and others regarding the causes of mule sterility. Unconvinced by the explanations put forward by these scholars and philosophers, he coined this term – thereby immortalizing his name in the history of human science- as modern scientific discoveries have conclusively confirmed his insight. The person who came closest to a correct scientific understanding and explanation of this phenomenon was the Greek philosopher Democritus, who claimed that the cause of the sterility of mules is a defect in the structure of their wombs, resulting from their being born of non-homogeneous parents. This expression carries, in its profound implications, a meaning that is quintessentially genetic. The main cause of the sterility of mules and hinnies is probably related to failure of pairing of homologous chromosomes at meiosis during spermatogenesis. To understand why mules can’t reproduce, we must first look at chromosomes. Horses boast 64 chromosomes while donkeys have 62. When these two species mate, their offspring—the mule—ends up with an unusual count of 63 chromosomes: 32 from the mare and 31 from the jack. This mismatch creates chaos during meiosis—the process that produces sperm and eggs. There are two types of male and female sterility; primary type affects germ cell causing arrest of germ cell development, and secondary infertility occurs as a result of systemic or syndromes’ genetic defects, including developmental, endocrine, and metabolic defects. Mules these wonderful hybrids, which were born from a male donkey and a female horse, often impress them because of their strength and vitality, but despite this, they are always sterile and this sterility is rooted in their genetic structure.

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