I am an evolutionary biology student, though this depends on details I don't know... The sperm are all produced by the same individual, and so you might expect

I am an evolutionary biology student, though this depends on details I don't know... The sperm are all produced by the same individual, and so you might expect them to be essentially identical aside from the genes they carry, in which case there's no Darwinian selection between them. However, if genes in the sperm are actually expressed (which would be normal for most other cells) then due to the process of meiosis, different sperm will have different genes and so selection between sperm from the same man could indeed occur. Sadly I don't know the details of gene expression in sperm... the question really is whether they get their proteins from the parent cells (all of which are genetically identical to the man) or whether they make some of their own proteins. Ah, I see from Google that there is indeed some gene expression in sperm: http://8e.devbio.com/article.php?ch=19&id=193 http://8e.devbio.com/article.php?ch=19&id=193 (In any case, there could of course be selection at the level of individual human males, with those producing better sperm having higher reproductive success.)