The mention of Buber's father's interests appears in French in Eva Telkes-Klein's book "L'université hébraïque de Jérusalem à travers ses acteurs" (Paris: Honoré Champion, 2004), p. 163. The sentence appears there, as you quoted it, with no reference, although she most likely drew this from Maurice Friedman's 3-volume biography. Interestingly, there it appears with a qualification, undermining the significance Telkes-Klein attributed to it.
I have found an obscure reference to Martin Buber 'Père lit Darwin et Renan', which might / not be available in published form. Does anyone have any idea where I might find it?
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