A talented populariser of science, he coined the term "agnosticism" to describe his stance on religious belief . He is credited with inventing the concept of "biogenesis", a theory stating that all cells arise from other cells, and also "abiogenesis," describing the generation of life from non-living matter.

Early life
Huxley was born in Ealing in west London, being the second youngest of eight children of George Huxley, a teacher of mathematics in Ealing. At seventeen he commenced regular medical studies at Charing Cross Hospital where he had obtained a scholarship. At twenty he passed his first M.B. examination at the University of London, winning the gold medal for anatomy and physiology. In 1845 he published his first scientific paper, demonstrating the existence of a hitherto unrecognized layer in the inner sheath of hairs, a layer that has been known since as Huxley's layer.

Huxley then applied for an appointment in the navy. He obtained the post of surgeon to HMS Rattlesnake, about to start for surveying work in Torres Strait. Rattlesnake left England on December 3, 1846, and once they had arrived in the southern hemisphere Huxley devoted his time to the study of marine invertebrates.

He began to send details of his discoveries back to England, and his paper, On the Anatomy and the Affinities of the Family of Medusae was printed by the Royal Society in the Philosophical Transactions in 1849. Huxley united, with the Medusae, the Hydroid and Sertularian polyps, to form a class to which he subsequently gave the name of Hydrozoa. The connection he made was that all the members of the class consisted of two membranes enclosing a central cavity or stomach. This is characteristic of what are now called the Cnidaria. He compared this feature to the serous and mucous structures of embryos of higher animals.

The value of Huxley's work was recognized, and on returning to England in 1850 he was elected a Fellow of the Royal Society. In the following year, at the age of twenty-six, he not only received the Royal medal, but was elected on the council. He secured the friendship of Joseph Dalton Hooker and John Tyndall, who remained his lifelong friends.

The Admiralty retained him as a nominal assistant-surgeon, in order that he might work on the observations he had made during the voyage of Rattlesnake. He was thus enabled to produce various important memoirs, especially those on certain Ascidians, in which he solved the problem of Appendicularian organism whose place in the animal kingdom Johannes Peter Müller had found himself wholly unable to assign and on the morphology of the Cephalous Mollusca.

Huxley resigned from the navy, and in July 1854 he became lecturer at the School of Mines and naturalist to the Geological Survey in the following year. His most important research belonging to this period was the Croonian Lecture delivered before the Royal Society in 1858 on The Theory of the Vertebrate Skull. In this he rejected Richard Owen's view that the bones of the skull and the spine were homologous, an opinion previously held by Goethe and Lorenz Oken.

In 1855 he married Henrietta Anne Heathorn (1825-1915). They had four daughters and two sons, including the writer Leonard Huxley (1860-1933):

Noel Huxley (1856-1860) died aged 4.
Jessie Oriana Huxley (1856-1927), married architect Fred Waller in 1877.
Marian Huxley (1859-1889) married artist John Collier in 1879.
Leonard Huxley (1860-1933) famous author.
Rachel Huxley (1862-1934) married civil engineer Alfred Eckersley in 1884, he died 1895.
Nettie Huxley (1863-1940), married Harold Roller, travelled Europe as a singer.
Henry Huxley (1865-1946), became a fashionable general practitioner in London.
Ethel Huxley (1866-1941) married artist John Collier (widower of sister) in 1889.

Darwin's bulldog
In the frontispiece from his 1863 Evidence as to Man's Place in Nature, Huxley first printed a famous image of his comparing the skeletons of apes to humans.In 1859 Charles Darwin's The Origin of Species was published. Huxley had previously rejected Jean-Baptiste Lamarck's theory of transmutation on the basis that there was insufficient evidence to support it. However he believed that Darwin at least gave a hypothesis which was good enough as a working basis, even though he believed evidence was still lacking, and became one of Darwin's main supporters in the debate that followed the book's publication.

He did this in a lecture at the Royal Institution in February 1860, and spoke in favour of Darwin's theory of natural selection in the debate at the British Association meeting at the Oxford University Museum in June. He was joined on this occasion by his friend Hooker, and they were opposed by the Bishop of Oxford, Samuel Wilberforce and Robert FitzRoy, the captain of HMS Beagle.

Following this Huxley concentrated on the subject of man's origins, maintaining that man was related to apes. In this he was opposed by Richard Owen, who stated that man was clearly marked off from all other animals by the anatomical structure of his brain. This was actually inconsistent with known facts, and was effectually refuted by Huxley in various papers and lectures, summed up in 1863 in Evidence as to Man's Place in Nature.

The thirty-one years during which Huxley occupied the chair of natural history at the School of Mines were largely occupied with palaeontological research. Numerous memoirs on fossil fishes established many far-reaching morphological facts. The study of fossil reptiles led to his demonstrating, in the course of lectures on birds, delivered at the Royal College of Surgeons in 1867, the fundamental affinity of the two groups which he united under the title of Sauropsida.

From 1870 onwards he was drawn away from scientific research by the claims of public duty. From 1862 to 1884 he served on ten Royal Commissions. From 1871 to 1880 he was a secretary of the Royal Society, and from 1881 to 1885 he was president. He was made a Privy Councillor in 1892. In 1870 he was president of the British Association at Liverpool, and in the same year was elected a member of the newly constituted London School Board. In 1888 he was awarded the Copley Medal by the Royal Society.

His health completely broke down in 1885. In 1890 he moved from London to Eastbourne, where after a painful illness he died.

Huxley was the founder of a very distinguished family of British academics, including his grandsons Aldous Huxley (the writer), Sir Julian Huxley (the first Director General of UNESCO and founder of the World Wildlife Fund), and Sir Andrew Huxley (the physiologist and Nobel laureate).

Huxley is credited with the quote, "Try to learn something about everything and everything about something."

Educational Influence
Huxley was a major influence in the direction in which British schools took. In primary schooling he advocated a wide range of disciplines similar to what we have today: reading, writing, arithmetic, art, science, music, etc. In higher education he also foresaw how schools should be run with two years of basic liberal studies followed by two years of some upper-division work focusing on a more specific area of study.

This was a fresh approach to the general study of classics in contemporary English colleges. Much of his educational approaches are found in his work On a Piece of Chalk a profound essay first published in MacMillan's Magazine in London, 1868. The piece reconstructs the geological history of Britain from a simple piece of chalk and demonstrates the methods of science as "organized common sense."

Another significant advocacy of Huxley's that is not seen today was his promotion for teaching the Bible in schools. This may seem out of step with his evolutionary theories but he believed that the Bible had significant literary and moral teachings that were quite relevant to English ethics. He tried to reconcile evolution and ethics in his book Evolution and Ethics, which proposed the principle of the "fitting of as many as possible to survive".