Montagu began life as Israel Ehrenberg, having been born on June 28, 1905, in London, England. According to an interview in 1995 by Leonard Lieberman, Andrew Lyons, and Harriet Lyons, in the publication Current Anthropology, the young Ehrenberg grew up in London's East End. He remembered often being subjected to antisemitic abuse when he ventured out of his own Jewish neighborhood. Montagu attended the Central Foundation Boys' School. He developed an interest in anatomy very early and as a boy was befriended by Arthur Keith under whom he studied informally.
In 1922, at the age of 17, he entered University College London, where he received a diploma in psychology after studying with Karl Pearson and Charles Spearman and taking anthropology courses with Grafton Elliot Smith and Charles Gabriel Seligman. He also studied at the London School of Economics, where he became one of the first students of Bronisław Malinowski. In 1931, he emigrated to the United States. At this time, he wrote a letter introducing himself to Harvard anthropologist Earnest Hooton, claiming to having been "educated at Cambridge, Oxford, London, Florence, and Columbia" and having earned M.A. and PhD degrees. In reality, Montagu had not graduated from Cambridge or Oxford and did not yet have a PhD. He taught anatomy to dental students in the United States, and received his doctorate in 1936, when he produced a dissertation at Columbia University, Coming into being among the Australian Aborigines: A study of the procreative beliefs of the native tribes of Australia which was supervised by cultural anthropologist Ruth Benedict. He became a professor of anthropology at Rutgers University, working there from 1949 until 1955.
During the 1940s, Montagu published a series of works questioning the validity of race as a biological concept, including the UNESCO Statement on Race, and his very well known Man’s Most Dangerous Myth: the Fallacy of Race. He was particularly opposed to the work of Carleton S. Coon, and the term "race". In 1952, together with William Vogt, he gave the first Alfred Korzybski Memorial Lecture, inaugurating the series.
Montagu wrote the Foreword and Bibliography of the 1955 edition of Mutual Aid: A Factor of Evolution by Petr Kropotkin, which was reprinted in 2005.
Due to disputes concerning his involvement with the UNESCO Statement on Race, Montagu became a target for anti-communists, and, untenured, was dismissed from Rutgers University and "found all other academic avenues blocked." He retired from his academic career in 1955 and moved to Princeton, New Jersey to continue his popular writing and public appearances. He became a well-known guest of Johnny Carson's The Tonight Show. He addressed his numerous published studies of the significant relationship of mother and infant to the general public. The humanizing effects of touch informed the studies of isolation-reared monkeys and adult pathological violence that is the subject of his Time-Life documentary Rock A Bye Baby (1970).
Later in life, Montagu actively opposed genital modification and mutilation of children. In 1994, James Prescott, Ph.D., wrote the Ashley Montagu Resolution to End the Genital Mutilation of Children Worldwide: a Petition to the World Court, The Hague, named in honor of Dr. Montagu, who was one of its original signers.
An Ashley Montagu Fellowship for the Public Understanding of Human Sciences has been established at the University of Sydney, in Australia, and is currently held by anthropologist Dr Stephen Juan.
Ashley Montagu wrote a book titled "Statement on Race." In this book, Montagu explains every statement in extreme detail, even though Ashley Montagu only majorly participated in writing the first two UNESCO Statements. Montagu was one of the ten scientists invited to serve on a committee which later came to be known as the Committee of Experts on Race Problems. The main purpose of the organization was to contribute peace and security to others by using science and culture. The UNESCO Statements were developed to help others realize that humans are all one species and "race" is not an issue, biologically speaking.
The first statement says, "Scientists have reached general agreement in recognizing that mankind is one: that all men belong to the same species, Homo sapiens." The first statement was put in such a way that others would be able to understand a scientists point of view. They worded it in a way where people who are not knowledgeable about this subject would understand. Homo sapiens is made up of a number of populations, each one of which differs from the others." That states that even though some people may have a variety of genes, they are all one species and should be treated equally.
The second statement says that since human history is widely divers and complex, there are many human populations that cannot be easily racially classified. However, some anthropologists believe that mankind is classified into at least three major human races. Even though it is believed that there are many human races, it gives no support that there is one race that is superior or inferior to any of the other races. The second statement was written to show that even though there may be more than one race, they are equal.
The third statement gives views on the biological aspect of the race question. It explains that different human groups diverged from a common stock and that is the reason for their biological differences. The third statement also goes into detail about human evolution and how important it is for the human race to survive and grow.
The fourth statement says, "All men are born free and equal both in dignity and in rights." The fourth statement says that racism stultifies development and threatens world peace. "The division of human species into 'races' is partly conventional and partly arbitrary and does not imply any hierarchy whatsoever."
The UNESCO Statements were made to address the race question and to help provide clarity from a scientist perspective. Even though Montagu did not contribute to writing all of the UNESCO Statements, his contribution led to help clarify the question against race.
One of his works, Man's Most Dangerous Myth, was written while race was considered the determinant of people's character and intelligence (Rowman and Littlefield). Montagu presented a unique theory for his time: "in biology race is defined as a subdivision of species which inherits physical characteristics distinguishing it from other populations of the species. In this sense there are many human 'races.' But this is not the sense in which many anthropologists, race-classifiers, and racists have used the term." He admits that in a biological sense, there is the existence of races within mankind. However, he also believes that not all of mankind can be classified. Part of his reasoning has to do with mixed origin, which has resulted in “overlapping” of physicalities. Instead of races and subspecies, he prefers mixed ethnic groups. His writing further emphasizes the complexity of our descent and rejects claims that support one race being superior when compared to others. He also says profoundly that the "so-called" main divisions of mankind are species instead of races. He says this idea or concept of race originated around the 18th century. The concept developing as a direct result of slavery and the slave trade. As a side effect of slavery, naturally, humanity has divided racism, this has carried and proceeded to dominate culture. The physical difference furthered the establishment of races and evident differences between individuals. He mentions Darwin and other forefathers who touched on this topic while they attempted to explain race to all. He touches on society, genetics, psychological, culture, war, democracy, eugenics, and social factors as contributors that enhance this idea of race.Montagu is the writer and director of the film One World or None. Produced in 1946 by The National Committee on Atomic Information, this short documentary exposes the dangers of nuclear weapons and argues that only international cooperation and proper control of atomic energy can avoid war and guarantee the use of this force for the benefit of mankind.
Footage of Ashley Montagu talking with Charlton Heston about his character in the movie appears as a bonus in the special DVD edition of The Omega Man.
Archive footage of him, among others (including Carl Sagan), is featured in The X-Files episode "Gethsemane."
The saying "International law exists only in textbooks on international law," which is often attributed to Albert Einstein, was in fact said to Einstein by Montagu.