He Was Prepared To Lay Down His Life for Eight Cousins or Two Brothers

J. B. S. Haldane? John Maynard Smith? W. D. Hamilton? Apocryphal?

jbshaldane10Dear Quote Investigator: Kin selection is an important and sometimes controversial idea in genetics. The prominent biologist J. B. S. Haldane reportedly said:

I would gladly give up my life for two brothers or eight cousins.

I have been unable to find a citation for this remark. Would you please help?

Quote Investigator: In August 1975 the influential evolutionary biologist John Maynard Smith published a book review in the periodical “New Scientist”. Within the review Maynard Smith described encountering his mentor J. B. S. Haldane at a public house called the Orange Tree. The time was not specified in the article, but Haldane died in 1964. Boldface has been added to excerpts: 1

I first heard the idea in the now-demolished Orange Tree off the Euston Road; J. B. S. Haldane who had been calculating on the back of an envelope for some minutes, announced that he was prepared to lay down his life for eight cousins or two brothers. This remark contained the essence of an idea which W. D. Hamilton, a lecturer in zoology at Imperial College, London, was later to generalise. Unfortunately, Haldane, although he referred to the idea in an article in Penguin New Biology, did not follow it up, and may not have appreciated its importance.

QI believes that the quotation under examination was based on Maynard Smith’s testimony. The common version in circulation has been grammatically altered so that it fits the form of a direct statement by Haldane.

Maynard Smith referred to a 1955 article by Haldane in the journal “New Biology” titled “Population Genetics”. The kernel of the idea of kin selection was presented by Haldane at this early date, but the quotation was quite different: 2 3

What is more interesting, it is only in such small populations that natural selection would favour the spread of genes making for certain kinds of altruistic behaviour. Let us suppose that you carry a rare gene which affects your behaviour so that you jump into a river and save a child, but you have one chance in ten of being drowned, while I do not possess the gene, and stand on the bank and watch the child drown.

If the child is your own child or your brother or sister, there is an even chance that the child will also have the gene, so five such genes will be saved in children for one lost in an adult. If you save a grandchild or nephew the advantage is only two and a half to one. If you only save a first cousin, the effect is very slight. If you try to save your first cousin once removed the population is more likely to lose this valuable gene than to gain it. But on the two occasions when I have pulled possibly drowning people out of the water (at an infinitesimal risk to myself) I had no time to make such calculations.

Here are additional selected citations in chronological order.

In July 1976 the top scientist W. D. Hamilton sent a letter to “New Scientist” that expressed skepticism about Maynard Smith’s anecdote and pointed to the similarity of Haldane’s supposed remark and a statement published by Hamilton in 1964: 4

I was astonished and rather dismayed by an historical anecdote in it which I had not heard before. This concerns J. R. S. Haldane’s insight into the conditions for the selection of “altruism”. According to Maynard Smith, after a calculation on the back of an envelope in a public house he announced that he was “prepared to lay down his life for eight cousins or two brothers”.

Haldane’s phrase is closely similar to phrases which I chose in my first two papers on the same subject. For instance my paper of 1964 had: “. . . in the world of our model organisms . . . everyone would sacrifice it [his life] when he can thereby save more than two brothers, or four half brothers or eight first cousins . . .”

Later in the month of July, John Maynard Smith replied to the letter of Hamilton. Maynard Smith stated that he did not think his memory was faulty, and he guessed that the remark by Haldane was made at the time of the “New Biology” article in 1955. Maynard Smith also gave high praise to his colleague Hamilton: 5

. . . I have come to regard Hamilton as the most original and creative person working on evolution theory. I would be sorry if any words of mine were to delay a general recognition of his work.

In conclusion, J. B. S. Haldane did write a passage in 1955 that expressed some key facets of kin selection although the passage did not contain a match to the quotation being explored. Many years later in 1976 the scientist John Maynard Smith presented an anecdote about Haldane that included a strong match for the quotation.

Fellow scientist W. D. Hamilton expressed skepticism about the anecdote. The provenance of the quotation has become intertwined with issues of scientific originality and prestige.

Image Notes: Simplified diagram based on a Wikimedia Commons diagram for “X dominant affected father”. Photo of J. B. S. Haldane in Oxford, UK circa 1914; accessed via Wikimedia Commons. Images have been retouched, resized, and cropped.

(Great thanks to Professor William Flesch whose inquiry led QI to formulate this question and perform this exploration. Special thanks to Glenn Branch who pointed out that John Maynard Smith’s surname was Maynard Smith.)

Update History: On November 9, 2017 the article was updated to reflect the fact that John Maynard Smith’s surname was Maynard Smith.


  1. 1975 August 28, New Scientist, Survival through suicide by John Maynard Smith, (Book Review of Edward O. Wilson’s “Sociobiology—The New Synthesis”), Quote Page 496, Column 2, Published by New Science Publications, London; Now Published by Reed Business Information, UK. (Google Books Full View) link
  2. 1955 April, New Biology, Volume 18, Edited by: M. L. Johnson, Michael Abercrombie, and G. E. Fogg, Population Genetics by J. B. S. Haldane, Start Page 34, Quote Page 44, Penguin Books, London and New York. (This citation has not yet been verified by QI; it is based on the webpage of a lab in the Department of Genome Sciences, University of Washington, Seattle)
  3. Website: Joe Felsenstein / Kuhner Lab, Location of Lab: Department of Genome Sciences, University of Washington, Seattle, Webpage title: Haldane on kin selection, 1955, Description of webpage: Excerpt from article titled “Population Genetics” by J.B.S. Haldane published in the journal “New Biology” in 1955, Date on website: Undated. (Accessed evolution.gs.washington.edu on May 5, 2016) link
  4. 1976 July 1, New Scientist, Section: Letters, Haldane and altruism, (Letter to the editor from W. D. Hamilton), Quote Page 40, Column 3, Published by New Science Publications, London; Now Published by Reed Business Information, UK. (Google Books Full View) link
  5. 1976 July 29, New Scientist, Section: Letters, Haldane, (Letter to the editor from J. Maynard Smith), Quote Page 247, Column 1 and 2, Published by New Science Publications, London; Now Published by Reed Business Information, UK. (Google Books Full View) link