I want to say that :

The effective population size differs from British population to Americans from Africans ancestry by a change in the bottleneck.

I am comparing between British population size and the Americans of African Ancestry population size, they are both different only in the bottleneck, which refers for the migration history of both pop.

To simplify my question neglecting all these academic terms, can I say that:

The skin color differs from European to Africans only by a change in melanin?

Can I use the verb "differ" in this way?

Can I say "X differs from A to B by C"?

  • Welcome to ELL RORI! Unfortunately, your question sounds like proofreading, and that is off-topic here.
    – M.A.R.
    Commented Jul 1, 2016 at 10:39
  • We might need more context. What do you exactly mean to say? Please explain the meaning of your sentence by editing it.
    – M.A.R.
    Commented Jul 1, 2016 at 10:56
  • in other words : I want to say that Americans and British are different in the effective size by a change in the bottleneck
    – RORI
    Commented Jul 1, 2016 at 11:02
  • 1
    OP, I'm still trying to understand your sentence. Are you aiming to say that the median age in America is different than that of Britain?
    – M.A.R.
    Commented Jul 1, 2016 at 11:14
  • 1
    What exactly does "bottleneck" mean in this context? How is it the cause of different population sizes? And what populations are being compared? All Britons and all Americans? All Britons and Americans of African ancestry? Britons of African ancestry and Americans of African ancestry? -- All your answers should be included in the question by editing it (there's an edit link immediately beneath the question) so that answerers will understand exactly what you are asking. Commented Jul 1, 2016 at 11:31

1 Answer 1


Can I say "X differs from A to B by C"?


If we are speaking of X, some quality or quantity possessed by both A and B in different amounts, we say that

X differs between (or in) A and B . . .
Mean skin color differs between/in American and British populations of African ancestry . . .

From is used when we compare A with B:

A differs from B in X . . . The American population of African ancestry differs from that of Britain in mean skin color . . .

In either of these, by is used to characterize the scale of the difference, not a cause:

{X differs between A and B / A differs from B in X} by Y
Mean skin color differs between American and British populations by 5.2 points.
The American population differs from the British population in mean skin color by 5.2 points.

If you want to ascribe the difference in X to a difference in some other variable, Z, you have many options: you can mix-and-match various prepositionals (e.g.,because of, due to, by virtue of) with various descriptions of the differential factor (e.g. the difference in their respective Zs, their different Zs, differing Zs, their having different Zs).

The American population of African descent differs in mean skin color from that of Great Britain by 5.2 points by virtue of their having significantly different proportions of melanin.

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