Al-Jahiz (776-869) of Basra wrote the seven volumes of “Book of Animals”, which includes poetic descriptions and proverbs of over 350 varieties of animals. In this work, Al-Jahiz made observations describing evolution such as:
“Animals engage in a struggle for existence; for resources, to avoid being eaten and to breed. Environmental factors influence organisms to develop new characteristics to ensure survival, thus transforming into new species. Animals that survive to breed can pass on their successful characteristics to offspring.”
Al-Khwarizmi (780-850), a Persian mathematician, wrote a work on the Indian numerals translated in the 12th century that introduced the decimal system to the Western world. He presented the first systematic solution to the linear and quadratic equations in Arabic in “The Compendious Book on Calculation by Completion and Balancing”.
His works transmitted the knowledge of mathematics in what we now know as “Algebra” to Europe from the Greek sources. The word “Algorithm” was derived from a pronunciation of his name as well. He wrote about mechanical devices like the astrolabe and sundial, and worked on a project under Caliph al Mamun overseeing 70 geographers to determine the circumference of the Earth and to make a world map. When his works spread to Europe through Latin translations, it had a huge impact in Europe and the advancement of mathematics.
Al-Kindi (801-873) from Iraq oversaw the translation of Greek scientific and philosophical texts into the Arabic language. He contributed greatly to making Greek thought accessible to Muslim audiences, carrying out this work from the “House of Wisdom”, an institute of translation and learning under the Abbasid Caliphate. He played an important role in introducing Indian numerals to the Islamic and Christian world, pioneered several methods of breaking ciphers, developed a scale to allow doctors to quantify the potency of medication, and contributed heavily to various subjects by writing 32 books on geometry, 22 books on medicine, 22 books on philosophy, 9 books on logic and 12 books on physics. His influence in these areas lasted for centuries. He is also well known for formulating the Kalam Cosmological Argument.
Al-Battani (858-929) from Harran made astronomical observations at Antioch and Ar-Raqqah in Syria during the Caliphate of Harun Ar-Rashid. He composed works on astronomy with tables containing his observations of the sun and the moon, which were more accurate than Ptolemy’s “Almagest”. He catalogued 489 stars, refined the values for the length of a year to 365 days, 5 hours, 46 minutes, 24 seconds. He obtained the value of the inclination of the ecliptic (of 23o 35’) and calculated 54.5” per year for the precession of the equinoxes. He used trigonometric methods for his calculations rather than geometric ones as often done in his time, an important advancement. He showed that the earth’s distance from the sun varies, which results in annular eclipses of the sun along with total eclipses. His work influenced scientists such as Tycho Brahe, Kepler, Galileo and Copernicus.
Al-Biruni (973-1048) is one of the major figures of Islamic mathematics. He also contributed to astronomy, physics, medicine and history. Al-Biruni contributed to the introduction of the experimental scientific method to mechanics, unified statics and dynamics into the science of mechanics, and combined the fields of hydrostatics with dynamics to create hydrodynamics.
Bīrūnī also devised his own method of determining the radius of the earth by observing the height of a mountain and carried it out at Nandana in Pind Dadan Khan, India (present-day Pakistan). In addition, due to an apparatus he constructed himself, he succeeded in determining remarkably precise specific gravities for a variety of metals and minerals.
Ibn al- Haytham (965-1040) from Basra was a Muslim polymath and philosopher who made significant contributions to the principles of optics, astronomy, mathematics, meteorology, visual perception and the scientific method. He was honoured as Europe’s “Ptolemy the Second”, and is especially known for his contributions to Optics due to his book entitled “Book of Optics”. He emphasized greatly on the importance of skepticism and relied on systemic experimentation and controlled testing in scientific inquiries and experiment. He famously said,
“The seeker after truth is not one who studies the writings of the ancients and, following his natural disposition, puts his trust in them… but rather the one who suspects his faith in them and questions what he gathers from them, the one who submits to argument and demonstration and not the sayings of human beings whose nature is fraught with all kinds of imperfection and deficiency. Thus the duty of the man who investigates the writings of scientists, if learning the truth is his goal, is to make himself an enemy of all that he reads, and, applying his mind to the core and margins of its content, attack it from every side. he should also suspect himself as he performs his critical examination of it, so that he may avoid falling into either prejudice or leniency.”
Avicenna (980-1037), a polymath known as one of the greatest minds of his time, contributed to many fields (including philosophy, poetry and medicine). He helped define an era of enlightenment in the Islamic world during the middle ages, coined the Islamic Golden Age (thought to be from 786 to 1258CE). It is in the field of medicine where Avicenna’s greatest work is found. The canon of medicine (al-Qānūn fī al-Ṭibb) is an encyclopedia of medicine consisting of five books. The cannon encompasses almost all aspects of medicine, such as causes and descriptions of diseases associated with every organ, advanced anatomy of the human body, and even rules for experimenting with new drugs, a subject on which Avicenna describes the inadequacy of animal testing versus human trials. Avicenna’s canon of medicine was the medical standard across the Islamic world and medieval Europe up until the 16th century, with Sir William Osler, one of the founding professors of John Hopkins Hospital stating it to be ‘the most famous medical textbook ever written.’
The book of healing (Kitab Al-Shifaʾ) is Avicenna’s great work. Combining science and philosophy, this book is an an encyclopedia introducing psychological reasons for illnesses such as mood disorders, and for the first time divided human perception into the five external senses. (i.e., held them responsible for human perception).
However, his contributions to the world of science were not limited to medicine. His early system of formal logic influenced several early European logicians such as Albertus Magnus and William of Ockham. He contributed to physics and argued that if light was perceived as the emission of particles from a luminous source, then light has a finite speed.
Ibn Al Nafis (1213-1288) was an eminent physician in the Islamic golden age. He attended medical school in Damascus, and is noted as the first person to describe the pulmonary circulation of blood (the part of the cardiovascular system carrying deoxygenated blood from the heart to the lungs, and oxygenated blood back to the heart for pumping). He corrected the work of great physicians of the time, including Avicenna, better defining the anatomy of the heart and lungs. Indeed, Ibn Al Nafis is also considered to be the first person to treat anatomy as an individual discipline. Other contributions of Ibn Al Nafis in the field of medicine are concerned with Urology. Eminent physicians in the Islamic golden age such as Muhammad ibn Zakariyā Rāzī and Avicenna believed the bladder to consist of two layers. Ibn Al Nafis in his book Sharh Tashrih al-Qanun more specifically described the base and back of the bladder as being the only parts with two layers, going even further and holding these layers accountable for preventing the backflow of urine from the bladder to the kidneys via the ureters.
Omar Khayyam (1048-1131) from Iran wrote the most important treatise on algebra prior to the modern age in which he provided a method to solve cubic equations geometrically. His most notable works have been in geometry, in fact, but particularly in the theory of proportions. He noticed the importance of a general binomial theorem since he was able to extract roots. Although he was a highly revered mathematician, he is mostly known for his poems, such as his Rubaiyat. For decades he taught the philosophy of Avicenna.
Ibn Rushd (1126-1198) of Spain had a great impact on Christian Europe and has been described as the “founding father of secular thought in Western Europe”. He wrote commentaries on Aristotle’s works, which became the foundation for the Aristotelian revival in the 12th and 13th centuries.
He wrote over 20,000 pages in science, theology and philosophy. One of his most important works was “The Incoherence of the Incoherence”, a rebuttal of a work by Hazrat Imam Ghazali (rh) in which he claimed that philosophy and revelation do not contradict each other and that these are different means of reaching the same truth.
He contributed to medicine in his book “Colliget”, he made a compilation of the works of Galen and wrote a commentary on the “Canon of Medicine” by Avicenna. He contributed three books in the area of physics and developed the notion that bodies have an inherent resistance to motion – an idea adopted later by Thomas Aquinas and then by Johannes Kepler who referred to this as “inertia.”